EDITORIAL TEAM
Editors Celso Augusto Guimarães Santos, Federal University of Paraíba, Brazil Masuo Kashiwadani, Ehime University, Japan Dragan Savic, University of Exeter, United Kingdom Vicente L. Lopes, Texas State University, United States Richarde Marques da Silva, Federal University of Paraíba, Brazil
Associate Editors Koichi Suzuki, Niihama National College of Technology, Japan Hafzullah Aksoy, Istanbul Technical University, Turkey António Pais Antunes, University of Coimbra, Portugal Roberto Leal Pimentel, Federal University of Paraíba, Brazil Max Billib, Hannover University, Germany Bernardo Arantes do Nascimento Teixeira, Federal University of São Carlos, Brazil Generoso de Angelis Neto, State University of Maringá, Brazil
FOCUS and SCOPE
Journal of Urban and Environmental Engineering (JUEE) provides a forum for original papers and for the exchange of information and views on significant developments in urban and environmental engineering worldwide. The scope of the journal includes:
(a) Water Resources and Waste Management: This topic includes (i) waste and sanitation; (ii) environmental issues; (iii) the hydrological cycle on the Earth; (iv) surface water, groundwater, snow and ice, in all their physical, chemical and biological processes, their interrelationships, and their relationships to geographical factors, atmospheric processes and climate, and Earth processes including erosion and sedimentation; (v) hydrological extremes and their impacts; (vi) measurement, mathematical representation and computational aspects of hydrological processes; (vii) hydrological aspects of the use and management of water resources and their change under the influence of human activity; (viii) water resources systems, including the planning, engineering, management and economic aspects of applied hydrology.
(b) Constructions and Environment: Buildings and infrastructure constructions (bridges/footbridges, pipelines etc) are part of every urban area. In recent years there is a growing interest in seeking rationality of construction systems, in balance with environmental adequacy and harmony in an urban area. This involves, among others, adequacy of structural systems (shapes, functionality, rational design etc), use of alternative materials for construction (recycled, environmentally friendly materials etc) and solutions seeking energy efficiency.
(c) Urban Design: This topic covers the arrangement, appearance and functionality of towns and cities, and in particular the shaping and uses of urban public space (e.g. streets, plazas, parks and public infrastructure), including also urban planning, landscape architecture, or architecture issues (e.g. thermic and acoustic comfort).
(d) Transportation Engineering: This topic covers such area as Traffic & Transport Management, Rail Transport, Air Transport, International Transport, Logistics/Physical Distribution/Supply Chain Management, Management Information Systems & Computer Applications, Motor Transport, Regulation/Law, Transport Policy, and Water Transport.
SUMMARY
EVALUATION OF THE STORM EVENT MODEL DWSM ON A MEDIUM-SIZED WATERSHED IN CENTRAL NEW YORK, USA Peng Gao, Deva K. Borah, Maria Josefson
DEVELOPING SUSTAINABILITY INDICATORS FOR WATER RESOURCES MANAGEMENT IN TIETÊ-JACARÉ BASIN, BRAZIL Michele Almeida Corrêa, Bernardo Arantes do Nascimento Teixeira
EVALUATION OF NEW TOWNS CONSTRUCTION IN THE AROUND OF TEHRAN MEGACITIY Nader Zali, Sajjad Hatamzadeh, Seyed Reza Azadeh, Taravat Ershadi Salmani
ARSENIC CONTAMINATION IN GROUNDWATER: A STATISTICAL MODELING Palas Roy, Naba Kumar Mondal, Biswajit Das, Kousik Das
A REVIEW ON EFFICACIOUS METHODS TO DECOLORIZE REACTIVE AZO DYE Josephraj Vijayaraghavan, S. J. Sardhar Basha, Joe Jegan
MATHEMATICAL MODEL FOR THE SIMULATION OF WATER QUALITY IN RIVERS USING THE VENSIM PLE® SOFTWARE Julio Cesar Souza Inácio Gonçalves; Marcius F. Giorgetti
URBAN SPRAWL IN SMALL CITIES, ANALYSIS OF THE MUNICIPALITY OF SÃO PEDRO (SP): POTENTIALS AND CONSTRAINS Priscila Carrara Fracassi, José Augusto Lollo
A REVIEW ON EFFICACIOUS METHODS TO DECOLORIZE REACTIVE AZO DYE Sivaraja Subramania Pillai, Ryuichiro Yoshie
URBAN GROWTH AND WATER QUALITY IN THIMPHU, BHUTAN Nandu Giri, O. P. Singh
MANAGING PHYSICAL DEVELOPMENT IN PERI-URBAN AREAS OF KUMASI, GHANA: A CASE OF ABUAKWA Paul Amoateng, Patrick Brandful Cobbinah, Kwasi Owusu-Adade
BIOGAS POTENTIAL OF ORGANIC WASTE IN NIGERIA Chima Ngumah, Jude N. Ogbulie, Justina C. Orji, Ekpewerechi S. Amadi
OPERATIONAL PERFORMANCE OF VERTICAL UPFLOW ROUGHING FILTER FOR PRE- TREATMENT OF LEACHATE USING LIMESTONE FILTER MEDIA Augustine Chioma Affam
PERFORMANCE ANALYSIS OF A HELICAL SAVONIUS ROTOR WITHOUT SHAFT AT 45° TWIST ANGLE USING CFD Bachu Deb, Rajat Gupta, R.D. Misra
EFFECTIVENESS OF WASTE STABILIZATION PONDS IN REMOVAL OF LINEAR ALKYL BENZENE SALFONATE (LAS) Ahmad Mohmed Abdelrahman, Ahmed Mohmed, Ali Gad, Mohmed Hashem
THE ACTORS OF A WIND POWER CLUSTER: A CASE OF A WIND POWER CAPITAL Jari Matti Sarja
FLOW PHYSICS OF 3-BLADED STRAIGHT CHORD H-DARRIEUS WIND TURBINE Rajat Gupta, Agnimitra Biswas
ANAEROBIC EFFLUENT POST-TREATMENT APPLYING PHOTOLYTIC REACTOR PRIOR TO AGRICULTURAL USE IN BRAZILIAN'S SEMIARID REGION José Tavares Sousa, Geralda Lima, Wilton Silva Lopes, Eclésio Cavalcante Santo, José Lima Oliveira Júnior
RETROFITTING OF REINFORCED CONCRETE BEAMS USING FIBRE REINFORCED POLYMER (FRP) COMPOSITES – A REVIEW Namasivayam Aravind, Amiya K. Samanta, D. K. Singha Roy, Joseph V. Thanikal
KOHONEN NEURAL NETWORKS FOR RAINFALL-RUNOFF MODELING: CASE STUDY OF PIANCÓ RIVER BASIN Camilo A. S. Farias, Celso A. G. Santos, Artur M. G. Lourenço and Tatiane C. Carneiro
AN ANALYSIS OF REGIONAL DISPARITIES SITUATION IN THE EAST AZARBAIJAN PROVINCE OF IRAN Nader Zali, Hassan Ahmadi, Seyed Mohammadreza Faroughi
Gao, Borah and Josefson 1
Journal of Urban and Environmental Journal of Urban and E Engineering, v.7, n.1, p.1-7 Environmental Engineering ISSN 1982-3932 J E www.journal-uee.org U doi: 10.4090/juee.2013.v7n1.001007
EVALUATION OF THE STORM EVENT MODEL DWSM ON A MEDIUM-SIZED WATERSHED IN CENTRAL NEW YORK, USA
Peng Gao1 , Deva K. Borah2, and Maria Josefson1
1* Department of Geography, Syracuse University, Syracuse, New York 13244 USA 2 Borah Hydro-Environmental Modeling LLC, 1105 Haverhill Court, Chesapeake, VA 23322 USA
Received 10 December 2012; received in revised form 20 January 2013; accepted 28 March 2007
Abstract: DWSM is a dynamic watershed simulation model that predicts distributed hydrograph and associated sediment discharge graph (sedigraph) of a watershed for a given storm event. Its performance, however, is not extensively tested in medium and large watersheds. Here, we applied DWSM to Upper Oneida Creek watershed located in central New York, USA with an area of 311 km² by dividing it into topographically connected 42 overland elements and 21 channel sections. Field-measured water discharge and sediment concentration data during two storm events, one on 9/30/2010 and the other on 6/28/2010, were used to test the performance of DWSM. Model simulation was performed by calibrating the key adjustable parameters in the input file till the best outcomes were achieved. The final results showed that during calibration for the 9/30/2010 event, DWSM successfully predicted the peak water discharge and its arriving time with the errors of 3.3% and 0%, respectively, and peak sediment discharge and its arriving time with the errors of 0.6% and 0.03%, respectively. For the whole event, DWSM under-predicted total water volume and event sediment load by 10.7% and 22.3%, respectively. Sensitivity analysis indicated that DWSM is most sensitive to the curve number adjustment factor, as well as factors representing flow resistance and flow detachment ability. During validation using the 6/28/2010 event, DWSM showed even better performance in predicting not only the peak values, but also event total values. These results showed that DWSM has the potential of successfully predicting event hydrology and sediment transport in the study watershed.
Keywords: Watershed modeling, DWSM, Sediment transport, Model calibration, Model validation © 2013 Journal of Urban and Environmental Engineering (JUEE). All rights reserved.
Correspondence to: Peng Gao, [email protected] Phone: 315-443-3679.
Journal of Urban and Environmental Engineering (JUEE), v.7, n.1, p.1-7, 2013 Gao, Borah and Josefson 2
INTRODUCTION mean annual precipitation is more than 1270 mm. With more than half of the area used for agriculture (e.g., The complex transport processes of suspended sediment dairy farms and cultivated lands) and urbanization, the at the watershed scale may be more efficiently watershed supplies significantly high sediment loads characterized by physically-based watershed models than other sub-watersheds to Oneida Lake and serves as (Borah and Bera, 2004; Singh and Frebert, 2006). the main source of sediment pollution to the Lake. Among various existing watershed models, Dynamic Quantifying sediment load and its variation is essential Watershed Simulation Model (DWSM) is the one of for the design and implementation of sediment-related relatively high efficiency with a relatively simple best management practices (BMP). The middle and model structure that involves a set of overland elements upper sections of the Oneida Creek watershed were and the connected stream segments (Borah, 2011; Borah selected as the study watershed (Fig. 1) to take and Bera, 2004). It uses several mathematical equations advantage of hydrological data available in a gauging to characterize various surface and subsurface station established by United State Geological Survey hydrological processes, and sediment entrainment and (USGS) near the outlet and to capture the topographic transport processes both on hillslopes and in stream diversity of the area. The study watershed has the area channels during a single rainfall event. Spatial of 311 km2, and thus is a medium-sized watershed variations of topographic, soil, and land use and land (Singh, 1995). cover characteristics are simplified by assigning single values to each of the divided elements. By routing water Data preparation and sediment discharges through the divided elements, DWSM predicts both hydrograph and sediment Stage recording and water sampling were performed discharge graph (sedigraph) of the watershed at the through a long-term monitoring station established at outlet for a given rainfall event. Although DWSM has the outlet of the study watershed. The monitoring been very successful in predicting suspended sediment station involves an automatic pumping sampler installed transport during storms of small watersheds (Borah et at the outlet of the study watershed that consists of a al., 2002), it has not been widely tested for watersheds marine battery to supply power to the sampler, a with relatively big sizes in various climatic regions. In pressure transducer to record stages of the flowing this study, we applied DWSM to a medium-size water, and a sampling tube to collect suspended watershed in central New York, USA. Using measured sediment samples by sucking sediment-laden water into data of water discharge and sediment concentrations for a series of 24 sample bottles. two events of 2010 (one in summer and the other in The stages of the flow were constantly recorded at fall), we tested its abilities of predicting (1) peak water 15-minute intervals. When a pre-determined threshold and sediment discharges and (2) event total water value of flow stage was exceeded, the sampler began to volume and sediment yield, and performed sensitivity collect sediment-laden flow samples every three or four analysis for the key adjustable model parameters to hours and stopped when the stage dropped below the investigate the behavior of DWSM in the study threshold at the end of the rainfall event. watershed.
METHOD
Study watershed
Oneida Creek watershed is one of seven sub-watersheds discharging to Oneida Lake of central New York, USA. Its main stream, Oneida Creek originates from the southwestern side of the watershed, flows southeast and then turns to north till reaching Oneida Lake (Fig. 1). Its main tributary, Sconondoa Creek extends upstream to the southeast of the watershed. Topographically, the downstream part of the watershed is quite flat, while the middle- and upper-stream ones vary greatly in elevations ranging approximately from 120 to 570 m. The Oneida creek watershed has a typical continental climate with moderate temperatures and rainfalls in summers and cold, intensive snowfalls in winter. Its Fig. 1 The studied watershed
Journal of Urban and Environmental Engineering (JUEE), v.7, n.1, p.1-7, 2013 Gao, Borah and Josefson 3
elements and breakpoint cumulative precipitation data (Borah 1989). The second is the interception-infiltration procedure in which the rate of rainfall excess is calculated by subtracting rainfall losses in interception (both tree canopies and ground covers) and infiltration from rainfall intensity (Borah et al., 2002). The first method has been commonly and successfully used in modeling both Q and Qs because of its simplicity and hence is adopted in this study. Using the prepared input data, DWSM was conducted to predict the hydrograph and the corresponding sedigraph of the selected events that can fit observed ones as accurate as possible.
RESULTS
Fig. 2 Comparison of measured with modeled hydrograph and Model calibration sedigraph of the 9/30/2010 event
The September 30, 2010 storm event generated a single- The samples were subsequently taken back to the mode hydrograph with peak water discharge (Q ) of Physical Geography Laboratory at Syracuse University peak 85.35 m3/s (Fig. 2). The modeled Q value is 88.15 for analysis to obtain sediment concentrations (C). peak m3/s, 3.3% higher than the measured one. The predicted Water discharges (Q; hydrograph) of the event were arriving time of Q is only 15 minute later than the determined in terms of the correlation between peak measured one. Associated with the hydrograph is a measured Q at the outlet and the associated Q recorded single-mode sedigraph with the peak sediment discharge at the USGS gauging station (Fig. 1). A sediment rating (Q ) of 89.29 kg/s. The modeled Q value is 89.76 curve was subsequently established using the measured speak speak kg/s, merely 0.6% more than the measured one. pairs of C and Q. Sediment discharge, Q , was then s Furthermore, the modeled arriving time Q is one calculated by Q = QC and used to determine the event speak s hour earlier than the measured one. These results sediment yield by summing Q over the time period of s demonstrated clearly that DWSM is capable of the event (Gao and Josefson, 2012a). simulating both magnitude and timing of Q and The study watershed was spatially divided into 42 peak Q . overland elements and 21 stream segments using the speak The modeled rising limb of the hydrograph is steeper ArcHydro technique (Maidment, 2002) for modeling. than the measured one, while the modeled falling limb Each element or segment was assigned a set of follows along the measured one first and then decreases parameters to represent its physiographic and land use with a gentler slope than the measured one giving rise to and land cover (LULC) conditions. The basic input higher predicted Q values than the measured ones parameters, such as slope and slope length, overland toward the end. Overall, the total volume of storm water area, and stream segment length were determined based (V ) generated by the event is 8.38 × 106 m3 whereas the on the DEM data with the resolution of 10 × 10 meter. w modeled one is 7.49 × 106 m3, about 10.7% less than the Soil and LULC parameters were determined using GIS measured one. This under-estimation is mainly caused in terms of available GIS layers. Four different median by the delayed but fast increased storm flows predicted sizes of sediment fractions and their corresponding by DWSM during the rising limb of the event. percentages were determined based on particle size Nonetheless, the small predicted percent errors for Q analysis for several samples collected at the outlet of the peak and V further indicates that DWSM successfully studied watershed. These values were entered into the w captures the hydrological behavior of the storm event. input data file. Rainfall information of the modeled Simulated sediment discharge values generally events was obtained from the National Oceanic and agreed well with the measured ones. The under- Atmospheric Administration (NOAA) website by email estimation over the lower section of the rising limb is request. Model calibration and validation were primarily caused by the under-estimation of Q during performed by adjusting a set of parameters that will be the same period. Although DWSM correctly predicts elaborated in the sensitivity analysis section. Q both in magnitude and timing, it does not simulate DWSM has two different methods of simulating speak sediment discharge values very well for the earlier rainfall excess. The first is the SCS runoff curve number section of the falling limb (Fig. 4). However, the (CN) procedure in which the rainfall excess (direct predicted event sediment yield, SSY is 4465 ton, which runoff rate) is calculated from CN values of overland e is only 22.3% less than the measured SSYe (5748 ton).
Journal of Urban and Environmental Engineering (JUEE), v.7, n.1, p.1-7, 2013 Gao, Borah and Josefson 4
Given the complexity of sediment transport processes, by 60%, both Qpeak and Vw increase by 31% and 17%, this predicting error is very well acceptable. These respectively. On the other hand, as FRICO increases, results showed that DWSM correctly characterizes Qpeak almost remains the same, but Vw decreases physical processes controlling water movement and gradually with no more than 14% when it is increased suspended sediment transport in the study watershed by 60% (Fig. 3). The different response of Qpeak and Vw and hence is capable of predicting both Qspeak and SSYe. to variable FRICO suggests that increasing FRICO largely increases the modeled Q values for the lower Sensitivity analysis part of the falling limb, but has no obvious impact on Qpeak. FRICC has a similar pattern of sensitivity to In the DWSM input file, there are two types of FRICO, but its degree of sensitivity is less than that of parameters. The first are those determined in terms of FRICO suggesting that overland elements are more watershed topographical features, channel morphology, influential than channel segments on the output. Change and sediment information, such as slope length and area of VOG does not have a significant impact on both Qpeak of overland element or channel segment, coefficients of and Vw values. In addition to these five main adjustable the relationship between wetted perimeter and flow parameters, we further tested others such as initial area, and percentages of sediment sizes in three interception storage (VIN) and ratio of the interception different ranges. These parameters are not adjustable storage capacity of a typical canopy cover to that of a once determined. The second are those representing typical ground cover (VOR). Their changes do not have watershed surface conditions, land use and land cover, significant impact on Qpeak and Vw values. Although not and soil characteristics, such as uniform curve number showing in Fig. 3, our analysis also indicated that the adjustment factor for model calibration (CNAF), arriving time of Qpeak is significantly affected by the Manning’s roughness coefficient of overland and change of CNAF, FRICO, and FRICC. Therefore, the channel (FRICO and FRICC), and interception storage most important parameters controlling the modeled capacity for a typical ground cover (VOG). These hydrological behavior of an event are CNAF, FRICO, parameters are adjustable. Modeling event-based and FRICC, the first reflects the comprehensive effect hydrological response and sediment transport is of soil, land use and land cover on surface runoff and essentially identifying a set of values for these subsurface flow, and the other two represent the parameters that can generate the results best fit the different surface resistance due to overland and channel measured Q and Qs values. Therefore, understanding the bed and banks. sensitivity of these parameters to the predicted Modeling sediment discharges of an event mainly hydrological and sediment values is critical for requires adjustment of two parameters: rainfall examining the predictability of DWSM. detachment coefficient (RDC) and flow detachment We tested the sensitivity of main adjustable coefficient (FDC). We performed sensitivity analysis parameters that may affect predicted Q and Qs values. for both Qspeak and SSYe with respect to these two For Q, the percent changes of Qpeak and event total water parameters (Fig. 4). As RDC changes (either reduces up volume (Vw), as four main parameters change (i.e., to 60% or increases to 100%), Qspeak does not vary CNAF, FRICO, FRICC, and VOG), are shown in Fig. significantly, while SSYe changes in an approximate 3. Modeled Qpeak and Vw results are considerably linear fashion. However, the percent changes (either sensitive to CNAF (the reason that both curves end at increase or decrease) are all less than 0.5%. The arriving 30% change of CNAF is because no values are time of Qspeak always remains the same as RDC changes. generated when CNAF is reduced more than 30%). A These results suggest that RDC is not quite sensitive to 10% increase of CNAF could cause 500% and 50% the predicted sediment discharges. The magnitudes of increase of Qpeak and Vw, respectively (Fig. 3). In the modeled Qspeak and SSYe values are very sensitive to addition to CNAF, both FRICO and FRICC also have the change of FDC. Increase of FDC by 100% could significant influence on predicted Qpeak and Vw values, lead to 79% increase of Qspeak and 94% increase of SSY but at a less degree than CNAF is. As FRICO decreases
Table 1 Comparison of six key variables between modeled and measured values for the 6/28/2010 event Measured Modeled Error 3 Qpeak (m /s) 37.10 37.32 0.6% Arriving time of Qpeak (min) 1425 1395 2.2% 3 6 6 Vwater (m ) 3.04 × 10 2.91 × 10 4.5% Qspeak (kg/s) 36.12 32.42 10.2% Arriving time of Qspeak (min) 1425 1395 2.2% SSYe (ton) 1723 1561 9.4%
Journal of Urban and Environmental Engineering (JUEE), v.7, n.1, p.1-7, 2013 Gao, Borah and Josefson 5
(a)
(b)
Fig. 5 Comparison of measured with modeled hydrograph and sedigraph of the 6/28/2010 event
(Fig. 4), though the arriving time of Qspeak still does not affected. This clearly shows that suspended sediment transport in the study watershed is more controlled by hydraulic forces caused by surface runoff than by impact energy generated by rainfall drops.
Fig. 3 Hydrological sensitivity analysis for the four main parameters. (a) Qpeak; (b) Vw. Model validation
To assure model performance, DWSM is subsequently validated using a different storm event occurred on June 28, 2010. Both modeled and measured hydrograph and sedigraph are shown in Fig. 5 where modeled ones agree generally well with the measured ones. The detailed values of key output variables for both water and sediment discharges and the relative predictive errors are demonstrated in Table 1. DWSM only over-predicted Qpeak by 0.6% with the arriving time being over-predicted by 2.2%, but it under-predicted Vwater by 4.5%. For sediment transport, Qspeak was only over-predicted by 10.2% and SSYe was under-predicted by 9.4%. Predictions on the event hydrology are generally better than those on event sediment transport. However, the largest error is only Fig. 4 Sediment sensitivity analysis for the two relevant parameters 10.2% for Qspeak, much less than the largest error of SSYe for the first event. Thus, the numerical results in Table
Journal of Urban and Environmental Engineering (JUEE), v.7, n.1, p.1-7, 2013 Gao, Borah and Josefson 6
1 confirm the visual observation shown in Fig. 5. appropriate values of parameters to achieve the best DWSM successfully predicted water discharges and model prediction is practically challenging. sediment transport rates in the second event, which The accuracy of model prediction to a large degree validate the ability of DWSM in characterizing event- depends on the accuracy of input data. In this modeling, based processes controlling water movement and rainfall data were obtained from a station near the sediment transport in the study watershed. Comparing studied watershed by NOAA. Although its daily values of the sensitive adjustable parameters between accumulation is consistent with those obtained from the this and the previous events showed that all of them sites within the watershed by an independent group, its except CNAF are the same in the two events. The hourly distribution may not be very accurate. This different values of CNAF (0.84 for the 9/30/2010 and uncertainty serves as a source of errors in the model 1.24 for the 6/28/2010 events, respectively) are outputs. The success of modeling sediment transport of reasonable because the two events had different rainfall one event does not guaranty its achievement for intensities and amounts. modeling other events. Further modeling work is necessary for assuring the performance of DWSM in the DISCUSSION study watershed in general.
Although DWSM is a watershed model aiming at CONCLUSIONS simulating event-based sediment transport processes, the first and critical step is to adjust parameters, such In this study, DWSM, a Dynamic Watershed Simulation that it predicts a well fitted event hydrograph. The exact Model, was employed to predict both water and values of these parameters are not known a priori and sediment discharges in the Upper Oneida Creek need to be determined by an iterative process. Because watershed, a medium-sized watershed in central New of the complicated inter-connection among York. The predicted results for the two events in 2010, mathematical equations adopted in DWSM, The initial one for calibration (9/30/2010) and the other for values of these parameters often fail to lead to the final validation (6/28/2010), indicated that DWSM can correct ones. Therefore, selection and change of reasonably well reproduce the measured hydrograph and parameter values based partially on their concepts sedigraph of the events, which suggests that DWSM would increase the possibility of modeling success. For may capture the synoptic effect of complex processes instance, FRICO by definition should be greater than controlling water movement and sediment transport in FRICC because resistance to flow induced by hillslope this medium-sized watershed. The fact that values of surface is generally much greater than that due to stream adjustable parameters except CNAF are the same for the channels. This hydraulic nature suggests that we should two events occurred in different seasons (summer vs. assign a higher value to FRICO than to FRICC. In our fall) implies that the difference of land use and land case of modeling the first event, the best fitting was cover and soil conditions in these two different seasons achieved by using FRICO = 0.115 and FRICC = 0.023. may be simply accounted for by using different values Given that channel segments of Oneida Creek ranges of CNAF. Because these two events are relatively big from bed-rock channel with water fall to gravel-bed comparing with other events occurred in 2010 (Gao and channels with well vegetated banks, the final value of Josefson, 2012b), the model should be further evaluated FRICC is a reasonable representation of overall flow for small events to assure its reliability. Performing resistance from all these channel segments. Once the DWSM modeling under a variety of storm events at best fit for a hydrograph is determined, modeling different times of a year will provide further guidance sedigraph is a relatively easy task of mainly adjusting towards estimating parameter values and enhancing FDC. versatility of this relatively simple physically-based The change of CNAF adjusts runoff curve numbers model with only a small number of adjustable determined for the 42 overland elements (ranging from parameters. 60 to 73) uniformly. The high sensitivity of CNAF to the model outputs suggests that curve number is a parameter sufficiently reflecting main hydrological REFERENCES response of watershed to a rainfall event and thus is the Borah, D.K. (1989) Runoff simulation model for small watersheds. key parameter to adjust. However, the impact of CNAF Transactions of the ASAE, 32(3), 881-886. to the model outputs shows an abnormal trend (Fig. 3) Borah, D.K. (2011) Hydrologic procedures of storm event watershed models: a comprehensive review and comparison. Hydrological that is, as CNAF increases from 10% to 30%, both Qpeak and V decrease. This apparent contradiction implies Processes, doi: 10.1002/hyp.8075. w Borah, D.K., Bera, M. (2004) Watershed-scale huydrologic and that the structure of DWSM may become unstable for nonpoint-source pollution models: Review of applications. some values of parameters. Thus, searching for the Transactions of the ASAE, 47, 789-803.
Journal of Urban and Environmental Engineering (JUEE), v.7, n.1, p.1-7, 2013 Gao, Borah and Josefson 7
Borah, D. K., Xia, R., Bera, M. (2002) DWSM - a dynamic Gao, P. and Josefson, M. (2012b) Temporal variations of suspended watershed simulation model. Mathematical models of small sediment transport in Oneida Creek watershed, Central New watershed hydrology and applications, in Mathematical models of York. J. Hydrol 426-427, 17-27. small watershed hydrology and applications, edited by V. P. Maidment, D.R. (2002). Arc Hydro, GIS for Water Resources, ESRI, Singh and D. Frevert, Water Resources Publications, LLC., Redland, 203p. Highlands Ranch, Colorado, 113-166. Singh, V.P. (1995) Watershed modeling, in Computer models of Gao, P., Josefson, M. (2012a) Event-based suspended sediment watershed hydrology, edited by V. P. Singh, Water Resources dynamics in a central New York watershed. Geomorphology, Publications, Littleton, CO, 1-22. 139-140, 425-437. Singh, V.P., Frebert, D.K. (2006) Watershed models, Talyor & Francis, Boca Raton, 653p.
Journal of Urban and Environmental Engineering (JUEE), v.7, n.1, p.1-7, 2013 Corrêa and Teixeira 8
Journal of Urban and Environmental Journal of Urban and E Engineering, v.7, n.1, p.8-14 Environmental Engineering ISSN 1982-3932 J E www.journal-uee.org U doi: 10.4090/juee.2013.v7n1.008014
DEVELOPING SUSTAINABILITY INDICATORS FOR WATER RESOURCES MANAGEMENT IN TIETÊ-JACARÉ BASIN, BRAZIL
Michele de Almeida Corrêa1 and Bernardo Arantes do Nascimento Teixeira1 1 Graduate Program in Urban Engineering, Federal University of São Carlos, Brazil
Received 5 March 2012; received in revised form 19 January 2013; accepted 30 January 2013
Abstract: This paper describes a tool to assist in developing water resources management, focusing on the sustainability concept, by a Basin Committee. This tool consists of a set of sustainability indicators for water resources management denominated CISGRH, which was identified by a conceptual and empirical review to meet the specific needs of the study herein - the basin committee of Tietê-Jacaré Rivers (CBH-TJ). The framework of CISGRH came about through consecutive consultation processes. In the first consultation, the priority problems were identified for the study objectives, listing some possible management sustainability indicators. These preliminary indicators were also submitted to academic specialists and technicians working in CBH-TJ for a new consultation process. After these consultation stages, the CISGRH analysis and structuring were introduced. To verify the indicators’ adaptation and to compose a group as proposed by the study, these were classified according to specific sustainability principles for water resources management. The objective of the CISGRH implementation is to diagnose current conditions of water resources and its management, as well as to evaluate future conditions evidenced by tendencies and interventions undertaken by the committee.
Keywords: Water resources management; sustainable development; basin committee.
© 2013 Journal of Urban and Environmental Engineering (JUEE). All rights reserved.
Correspondence to: Michele de Almeida Corrêa, Tel.: +55 14 9703 4815; E-mail: [email protected]
Journal of Urban and Environmental Engineering (JUEE), v.7, n.1, p.8-14, 2013 Corrêa and Teixeira 9
INTRODUCTION domain of rivers; and deviations of concepts and fundamentals that should guide the implementation of In Brazil, water resources management has been SINGREH, with a greater focus on implementing frequently discussed in the last years, addressing, for management instruments. example: The document also introduces suggestions and (a) the 1934 Water Code promulgation (Ordinance No. questions to improve the water resources management 24.643 of July 10, 1934) with a centralized view on process, seeking, among other aspects, to increase the some sections, mainly the electric power generation participation of civil society and users of water, and to section; consolidate proposals that should be assessed within the (b) the Brazilian Constitution of 1988, that stipulated scope of the basin committee. the institution of a National System of Water The publication of Water Resources Conjuncture in Resources Management; and Brazil (ANA, 2009), requested by the Water Resources (c) the Water Resources National Politics in 1997 National Council (denominated CNRH) through the (Federal Law No. 9.433, BRASIL, 1997), the latter resolution no. 58/2006, promoted a progress analysis of responsible for instituting effective legal water resources management and the evaluation of instruments in Brazil, as transcribed below. recently implemented instruments as proposed in the Water Resources National Policies. In agreement with Article 5 of the Water Resources The conclusions of the Water Resources Conjuncture National Politics, the instruments of the Water in Brazil (ANA, 2009) emphasize the need of Resources National Policies are: considering the planning as a continuous process of (a) Water Resources Plans; perception, listening, interactions and concretizing the (b) Formulating water bodies in classes, according to opportunities and effectuation of the plan by means of the importance of water use; negotiation and a participative management. (c) Grants rights for the use of water resources; It emphasizes that this is the responsibility of the (d) Levy collection for the use of water resources; Basins Committees, the monitoring actions proposed in (e) Compensation to municipal districts; the State’s Plans and in the Basin’s Plans through (f) Water Resources Information System. instruments not mentioned in the applicable legislation, but that can be annually reported, presenting data on: The use of river basins as water resource the quality and amount of water resources; and management units is foreseen as one of the foundations evaluation of the implemented programs foreseen in the for the Water Resources National Policy (Federal Law aforementioned plans, as well as adjustment proposals. No. 9.433/1997) and also as one of the principles of the Figure 1 presents the situation of the Brazilian states State Policy for Water Resources in São Paulo State concerning the institution of basin committees, as (State Law No. 7.663, SÃO PAULO, 1991). Monitoring shown the home page of the Basin Committee water resources management is also contemplated in (www.cbh.gov.br) in 2010. these legal instruments. In 2007, the Environment Ministry of Brazil (MMA), the Water National Agency – ANA, also a Brazilian agency, and the United Nations Program for the Environment - PNUMA launched the first publication of the global project of environmental evaluations, denominated GEO (Global Environment Outlook), created by PNUMA in 1995. This publication, denominated GEO Brazil: Water Resources (MMA, 2007), helps to understand and evaluate the concepts and foundations, as well as the agency’s framework, legal instruments, and other water Fig. 1 Number of Committees according to the Brazilian States. resources management instruments, which comprise the Abbreviations of Brazilian States: National System of Water Resources Management AC: Acre; AL: Alagoas; AP: Amapá; AM: Amazonas; BA: Bahia; CE: Ceará; DF: Distrito Federal; ES: Espírito Santo; GO: Goiás; (denominated SINGREH). MA: Maranhão; MT: Mato Grosso; MS: Mato Grosso do Sul; MG: Some of the structural problems detailed in MMA Minas Gerais; PA: Pará; PB: Paraíba; PR: Paraná; PE: Pernambuco; (2007) are: disorganization in the legislation of water PI: Piauí; RJ: Rio de Janeiro; RN: Rio Grande do Norte; RS: Rio resources and in the juridical-administrative substratum; Grande do Sul; RO: Rondônia; RR: Roraima; SC: Santa Catarina; SP: São Paulo; SE: Sergipe; and TO: Tocantins. deep-rooted difficulties correlated to the administrative culture of the State; standstill situations related to the
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This research also discussed concepts related to and communicate conditions (with current information sustainability, from the apprehensive viewpoint with the or of forecast of tendencies), besides proposing the exploratory use of the natural resources. The necessary actions and facilitating the participation of sustainability or sustainable development concept was several stakeholders in the decision process. discussed in several international conferences, which Thus, to verify if the indicators proposed for a culminated in documents and definitions such as “Our certain place are enough to calculate all aspects of Common Future” and “Agenda 21”. sustainability to this specific case, it was proposed to Besides the concepts in these documents there are verify the compliance to specific principles of sustainability indicators as monitoring tools, which can sustainability within the context, as systematized by be used for water resources management, as suggested Corrêa and Teixeira (2006). In the present study the at “Agenda 21”. specific principles of sustainability were used for water The indicators calculate the progress of water resources management in basins, as presented below. resources management under the optics of (a) Universal access to Water Resources; sustainability, observing the results of actions (b) Responsible use of Water Resources and preventive implemented in the basin, the water resources management performance; management unit adopted in Brazil and in the State of (c) Integrated planning, systematic and including Water São Paulo, in accordance with the Federal Law no. Resources use considering: Economical, Social, 9.433/97 and State Law no. 7.663/91, respectively. Ecological, Political and Cultural aspects in Water Tunstall and Van Bellen (2002) highlight as Resources Management; important indicator characteristics, the capacity to (d) Decentralized basins management; evaluate existing conditions and tendencies; the (e) Management participation in Water Resources; possibility to make comparisons in spacial and temporal (f) International and inter-regional cooperation; scales, and to evaluate the conditions and tendencies in (g) Organization and supply of information; relation to goals and objectives; and the ability to supply (h) Economical value of Water Resources; information, conditions and tendencies. Van Bellen (i) Education for Water Resources management; (2002) describes indicators as variables, in other words, (j) Negotiated solution of conflicts. a simplified representation of an attribute belonging to a system, or an abstraction of a real attribute. OBJECTIVES For Hezri (2004), the choice of sustainability indicators should follow some criteria, as described The main objective of this research was the below: development of a group of sustainability indicators as a (a) robustness (scientifically accepted, measurable, tool for water resources management, in the sensitive to changes, the practical focus is limited to management of the basin or unit (UGRHI). a number of themes and comparisons with the For this main objective, the specific objectives were: objectives, based on appropriate perspectives); (a) Identify previous experiences or indicator proposals (b) democratic inclusion with all inclusive for water resources management; participation, including society, specialists and (b) Identify priority problems in UGRHI Tietê-Jacaré stakeholders; transparent, with accessible methods in the State of São Paulo - Brazil; and explicit analysis; (c) Identify and present guidelines to implement the (c) longevity (capacity to be repeatedly calculated, to proposed indicators, with emphasis on UGRHI be interactive and adaptable to change; and to have Tietê-Jacaré. positive cost-effectiveness); (d) relevance (institutional capacity to obtain, to METHODOLOGY maintain and to document the necessary data; assist the public and users; present simple structure; and The process to structure CISGRH was executed in three guided by a clear view of sustainability). main phases. In the first phase, the conceptual base was studied, with a discussion on sustainability aspects and Steinemann and Cavalcanti (2006) define indicators water resources management found in the literature and as variables that characterize drought conditions, the management model adopted in Brazil and in the stating: specific values of indicators for activating State of São Paulo. In this discussion, the attributions of drought responses. The authors used this concept for the Basin Committee and guidelines for water resources Georgia’s first state drought plan. management were analyzed. In this phase, the According to Brugmann (1997) cited at Ioris et al definitions of the general indicators and sustainability (2007), the sustainability in water resources indicators were discussed and the international and management requires using indicators that can describe
Journal of Urban and Environmental Engineering (JUEE), v.7, n.1, p.8-14, 2013 Corrêa and Teixeira 11 national experiences of indicators used and proposals 2004-2007). The major municipal districts are: Bauru, were presented. São Carlos, Araraquara and Jaú. With these experiences, a list of possible indicators In agreement with PERH (2004-2007), UGRHI-13 is to be used on water resources management was located in the central area of the State of São Paulo, and obtained. It was observed from this preliminary list that it is defined by the rivers basins Tietê, Jacaré-Pepira, many indicators would not be appropriate to the needs Jacaré-Guaçu, Jaú and Bauru. The main land uses are of the empiric objective (CBH-TJ – Basin Committee of urban activities, industrial and agricultural, pastures and Tietê-Jacaré Rivers). Thus, the conditions of the water cultivation areas, such as coffee, sugar-cane, corn and resources management was characterized in CBH-TJ, citrus. then came the second phase of the research, The recommendations of CETESB (2004) for this corresponding to the consultation processes. unit prioritizes domestic waste treatment, forest Three consultation processes were systematized, recovery and soil conservation to avoid erosion process. different publics and, therefore, different focuses and The State Basin Water Resources Report in 2000 approach strategies. In the first process, five pointed out the following main problems: consultations took place with the committee members - (a) high demands of irrigation water; CBH-TJ and other participants, two of these correspond (b) risks of intense lowering of underground water to meetings and three to public audiences were held in levels in the urban areas of Bauru and Araraquara; 2006. The three public audiences intended to gather (c) risk of pollution of underground waters in the urban information and suggestions to assist in the elaboration areas of Bauru and Araraquara and surrounding of the Basin Tietê-Jacaré River Plan. areas; This first consultation was to contextualize the (d) low rates of sewer treatment; problems regarding the water resources and its (e) average discharge susceptibility to floods in sub- management at CBH-TJ, with the agreement of the basins of the rivers Jacaré-Guaçu and Jacaré-Pepira, committee members and the participants of meetings mainly in urbanized areas; and public audiences. The consultation used a (f) susceptibility to erosion process in the northwest questionnaire containing a list of possible problems in and southeast of the management unit. the committee. They were requested to prioritize the agreements with regards to the reality observed at Tietê- RESULTS Jacaré River basin or the municipal district where the respondents reside or work. In the first consultation stage, prioritized problems were After the problems were identified and prioritized, a obtained for Tietê-Jacaré basin, presented in Table 1, set of sustainability indicators were selected to monitor already associated to sustainability indicators. The them. In the second consultation process, specialists and committee members and other participants of the academic members, involved or not with CBH-TJ, plenary meetings and public audiences were consulted evaluated the acceptance for each indicator proposed, in this process. and indicators that presented a level of acceptance lower It was observed that the participants were from 20 than 57% were eliminated (except for some exceptions). municipal districts of CBH-TJ, mostly members of the In the third consultation process, the results were municipal public administration and higher education evaluated, verifying the indicators related to the institutions. respective problems and to water resources management The main problems pointed out were: absence of in CBH-TJ. This consultation was accomplished in the riparian vegetation; occurrence of erosive process; small form of discussions among the CISGRH participants, society participation in the decision processes; problems guided by the researcher. in the water supply system; irregular occupation in Finally, the correlation between the CISGRH’ protected areas (margins, hillsides, riparian); pollution sustainability indicators and the specific principles of sources (wastewater and solid waste); the need for sustainability to water resources management environmental education; and the lack of planning. previously defined (Corrêa & Teixeira, 2006) were In the second consultation, 73 indicators were identified. proposed to the specialists, and the result obtained was: 12 indicators were accepted by 100% of the STUDY AREA participants; 30 indicators were accepted by 86% of the participants and 12 indicators were considered as The management unit named UGRHI-13 under the pertinent by 71% of the interviewees. responsibility of CBH Tietê-Jacaré was founded in In agreement with the answers, approximately 75% 30/12/1991. It has 37 municipal districts and a of the proposed indicators had a positive answer. The population of 1.484.078 inhabitants for 2010 (PERH, remaining, about 25%, correspond to cases in which the
Journal of Urban and Environmental Engineering (JUEE), v.7, n.1, p.8-14, 2013 Corrêa and Teixeira 12 indicators were considered inadequate (15%) or the water bodies use as interviewee did not have a technical opinion (10%). source to human The selection of indicators submitted to consultation supply Index of physical was carried out using national and international 9 – Losses in water losses in water % bibliographical revisions, such as the indicators supply system supply system proposed by PERH (20042007), used to formulate the Ratio between State Report of the basin committees in the State of São amount of SW 10 – Solid Waste Paulo. The international bibliography studied to propose without correct (SW) inadequate % the sustainability indicators area were summarized destination and disposition below: total amount of (a) Network of Cities and Towns towards SW Sustainability in Barcelona; Ratio between (b) Department of Australian environment and the licensed outflow Council of Conservation and environment of and total outflow % 13 – Absence of susceptible to Australia and New Zealand (ANZECC) in management license Australia (Fairweather, 1998) and New Zealand; instruments (license Ratio between (c) Environmental Protection Agency (EPA) Technical and payment) paid outflow and Report in the United States of America. total outflow % susceptible to Once the consultation phase was concluded, a payment Number of discussion was promoted based on the degree of 16 – Occurrence of occurrences of acceptance levels by the specialists of the academic area problems in storm significant Un. and technical area, as well as the positive and negative water drainage problems in points identified in the literature experiences studied. (SWD) SWD Based on this discussion, the CISGRH was proposed as 19 – Water Index of water presented in Table 2, related to the problem previously resources Pollution 0−1100 quality prioritized. and contamination Ratio between Table 1. CISGRH – Set of Sustainability Indicators for Water population Resources Management 22 – Insufficient serviced by Unit of % Proposed wastewater system wastewater Sustainability Associated Problem Sustainability system and total Indicators to Indicator population be calculated 23 – Groundwater Index of Ratio between pollution and groundwater 0−1100 1 – Absence of vegetation area % contamination quality riparian vegetation and total basin Ratio between área demand and Ratio between 24 – Insufficient water surface stream length water surface availability % 1 – Absence of with riparian % availability (domestic, riparian vegetation vegetation and agricultural and total stream industrial uses) length Ratio between Number of population 2 – Occurrence of 25 – Insufficient significant Un. serviced by erosive processes water supply % erosion process water supply Number of civil system 3 – Low society system and total society entities participation in Un. population registered in the Number of decision process 26 – Occurrence of committee occurrences of Number of wells diseases related to wa Un. 6 – Excessive diseases related with significant resources (WR) groundwater % to WR water level Number of extraction 29 – Conflicts due decrease conflicts water resource Un. 8 – Pollution or Index of water managed by 0−100 multiple use contamination in supply quality basin committee
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The CISGRH should be structured from existing data b) Responsible use of Water Resources and preventive management sources, using consistent scientific methodologies, performance; c) Integrated planning, systematic and including Water Resources assuring reliability and validity for the obtained results. use considering: Economical, Social, Ecological, Political and The research then proposed a correlation of specific Cultural aspects in Water Resources Management; principles of sustainability for water resources d) Decentralized basins management; management, previously presented, and the CISGRH e) Management participation in Water Resources; f) International and inter-regional cooperation; (Table 2), to verify if the sustainability indicators g) Organization and supply of information; proposed are sufficient to calculate all aspects of h) Economical value of Water Resources; sustainability for this specific case. i) Education for Water Resources management; Some principles, like Decentralized management by j) Negotiated solution of conflicts. Basins, Organization and supply of information and Education for Water Resources Management could be related in all indicators. Thus, only the International and CONCLUSIONS Inter-regional cooperation principle was not considered. A set of sustainability indicators structured in the Table 2. Sustainability Indicators and corresponding Specific context to be implemented enables the researcher to Principles. consider specific localities, hence facilitating Specific Sustainability Indicator information and systematization to an appropriate scale. Principles* Thus, it can be concluded that the consultation Ratio between vegetation area and b, d, g, i processes in this research collaborated to propose total basin area coherent indicators for the empiric object, CBH-TJ. Ratio between stream length with b, d, g, i These consultation processes enabled, for example, the riparian vegetation and total stream problems to be prioritized by committee members and length Number of significant erosion c, d, g, i participants interested in the subject. The analysis and process selection of sustainability indicators, always associated Number of civil society entities e, d, g, i to prioritized problems, were also the consultation registered in the committee objectives for specialists related to basin activities, with Number of wells with significant a, d, g, i professional performance in academic and technical water level decrease areas. Index of water supply quality b, d, g, i However, the participation was relatively limited, Index of physical losses in water b, d, g, i hence recommending a greater involvement and supply system accompaniment of the entire process by the participants. Ratio between amount of SW c, d, g, i The participation of society is also recommended in without correct destination and total amount of SW the process of the continuous revision of sustainability Ratio between licensed outflow and h, d, g, i indicators, guaranteeing that members assume the roles total outflow susceptible to license of controllers and stakeholders in the water resources Ratio between paid outflow and h, d, g, i management. total outflow susceptible to payment CISGRH enabled to diagnose the current situation of Number of occurrences of c, d, g, i water resources in the Tietê-Jacaré River Basin, by the significant problems in SWD implementation and subsequent analysis of the obtained Index of water quality b, d, g, i data, enabling to propose goals and actions to deficient Ratio between population serviced a, d, g, i areas or to prioritize previously proposed goals. The by wastewater system and total continuous CISGRH application could enable efficient population Index of groundwater quality b, d, g, i evaluation of these actions, seeking for continuous Ratio between demand and water a, d, g, i improvement of the sustainability aspects, which are surface availability (domestic, foreseen in future studies, collecting and adapting other agricultural and industrial uses) indicators. Ratio between population serviced a, d, g, i It is recommended that CISGRH be systematized to by water supply system and total be implemented in CBH-TJ, and this understands the population following stages: development of a methodology to Number of occurrences of diseases c, d, g, i obtain or calculate the indicators, specification of related to WR existing sources and information gaps, establish Number of conflicts managed by the j, d, g, i standards to be reached and determine a certain time to basin committee define the responsibilities, calculations and verification * Specific Principles: a) Universal access to Water Resources;
Journal of Urban and Environmental Engineering (JUEE), v.7, n.1, p.8-14, 2013 Corrêa and Teixeira 14 trends in relation to the previously established Hidrográfica. In: III Encontro Associação Nacional de Pós- standards. Graduação e Pesquisa em Ambiente e Sociedade – ANPPAS, 23 a This procedure should obtain characterization 26 de Maio de 2006, Brasília. EPA’s Draft Report on Environment: Technical Document, 2003. conditions of the water resources and the tendency of United States Environment Protection Agency. Office of Research these conditions with regards to the standards or goals and Development and the Office of Environment Information. established. This evaluation of tendencies for each www.epa.gov/indicators/. acesso 28/09/2005. indicator shows to stakeholders the gaps and priority Fairweather, P.G. & Napier, G.M. Relatório de Indicadores Ambientais. Estado do Meio Ambiente SoE. Relatório Nacional areas that should be undertaken in the next stage. do Estado do Meio Ambiente, Austrália. 1998. Available in It is recommended that sustainability indicators
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Journal of Urban and Environmental Journal of urban and E Engineering, v.7, n.1, p.15-23 Environmental Engineering J E ISSN 1982-3932 U doi: 10.4090/juee.2013.v7n1.015023 WWW.JOURNAL-UEE.ORG
EVALUATION OF NEW TOWNS CONSTRUCTION IN THE AROUND OF TEHRAN MEGACITIY
Nader Zali1 , Seyed Reza Azadeh2, Taravat Ershadi Salmani3 1Assistant professor, Department of Urban Planning, University of Guilan, Iran 2 M.A Student, Department of Regional Planning, University of Guilan, Iran 3 M.A Student, Department of Regional Planning, University of Guilan, Iran
Received 09 May2012; received in revised form 1 June 2012; accepted 20 January 2013
Abstract: Rapid pace of urbanization which has affected third world countries is a by-product of the post-1945 period. In most developing countries like Iran, spatial population distribution is not balanced, leading to the deficiencies in services, hygiene, formation of slums, and etc. To balance those patterns in the country, different strategies have been applied, one of which is the construction of new cities. This study aims to examine the role of new cities in balancing spatial population distribution in Tehran province. For this purpose, first, the changes in the population of Iran and its urban mechanisms are studied; then, the performances of new towns in previous decades are examined. To analyze data and investigate the role of new cities, entropy coefficient model was used. The results showed that new towns of Tehran have not affected population overflow and deconcentration successfully; as a result, urban officials need to revise construction policies in those cities.
Keywords: New towns; urban systems; population; decentralization; the coefficient of entropy; Iran.
© 2013 Journal of Urban and Environmental Engineering (JUEE). All rights reserved.
Correspondence to: Nader Zali. Tel.: +98 914 303 8588. E-mail: [email protected]
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INTRODUCTION
New towns have been created during the history for many commonplace reasons, including: security, economic, demographic concerns and etc. But after Industrial Revolution, the trend of constructing new cities has been completely different from the past (Qrakhlu and Abedini, 2009). Since 1961, following land reformation plans, Islamic Republic of Iran and economic changes at global level, assembly industries were developed beside big cities, leading to rapid urbanization and the expansion of urban areas, creating many problems. Since 19611978, three major factors affecting rapid urbanization included migration of villagers to the cities, urban life’s blooming and fast population growth, and converting rural areas to urban places. The impact of population on the number of urban areas was also evident (Mashhdyzadeh Dehaghani, 2010). Almost all statistics after the revolution have revealed a continuation of large-scale urbanization and an increasing tendency towards the concentration of urban population in a few big cities. The proportion of urban population to the total population of the country in 1976 reached 47%; while, it increased to 61% in 1996. Both the increase in the number of urban places and population increase in the cities have contributed to the process of Fig. 1. Where the caption? urbanization (Fanni, 2006). Based on the statistics of 1957, published by Statistics Research theories and background Department of Iran, the number of the cities were 199. But, the statistics showed the number of 1,000 for the The term “new town” is interchangeable with “new cities in Iran in 2006 (Barakpoor, Asadi, 2011). Regarding community” in many cases. For the purposes of this study the mentioned points, growing urbanization, preventing the following definition was found appropriate: “A self- from the growth of macropolitans and controlling natural contained development with a balance of commercial, growth rate of population, immigration needs to be educational, social, and cultural institutions that satisfies monitored. If this fails, restoring the structures of the old all the needs of families and individuals alike”. The cities is the best method for urban development. In the following is a list of: case this template does not control growing urban − Large scale planned community. population, continuous development of the cities are − Programmed to include a balance of housing, jobs, and considered in the places which are not faced with natural services. or artificial constraints. If these patterns do not work, − A mixture of housing types. other places should be regarded outside the metropolis for − Created in response to clearly stated objectives absorbing its population overflow. Since two first- Controlled by a master developer (Povlovich Howard, mentioned patterns have not fulfilled desired goals, urban 2002). planners and policy-makers have resorted to Spatial decentralization policy based on building decentralization of metropolises as a template to create new cities is one of the most straightforward patterns. new cities (Ebrahimzadeh and Negahban Marvee, 2006). Simply put, the original and still most weighty reason for building new towns in the minds of their advocates and pioneering experimenters was the necessity of reducing the concentration of people and workplaces in large towns, which otherwise cannot be relieved of congestion,
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disorder and squalor and rebuilt on a fully healthy, socially satisfactory, or efficient pattern. In this context, the idea of creating new cities has been attributed to the English people. In 1898, the public in Britain was concerned about the influx of the people to the cities, leading to densely populated urban areas as a result of evacuating rural regions. In such conditions, “Ebenezer Howard”’s solution seemed less troublesome, without relying on any kind of sudden and radical changes or revolution. He was aware of the attractions of metropolises for villagers; so, he aimed to mix the advantages of urban life with the beauty of villages, creating town gardens. Developed in definite distances around a metropolis, such towns have a green belt around, connected via fast public transportation vehicles (Austrufsky, 2008). Until World War II, only two satellite Fig. 1 The process of settlement development in the theory of Joseph cities of Latchverth and Welvynwere built with thirty-five Hilhorst. thousand inhabitants. Great Britain had a population of ten millions; but, despite the predictions of Howard, two development in Jakarta Metropolitan Region: a newly built towns around London could not prevent perspective of spatial segregation», (Firman, 2004) population influx to the capital city of Great Britain. After concluded that the development of new towns in the World War II, the construction model, suggested by Jakarta creates spatial differentiation for three reasons. Howard, revealed its positive results, benefiting from First, it has polarized the average and well-paid groups, governmental support. resulting in scattered ness of exclusive residential areas. The pattern of new towns was adopted as a Second, within the new towns themselves, middle and foundation for the organization and refinement of big high class people occupied exclusively designed areas cities. New towns can be planned and constructed in with the highest possible security. Third, in several new different models of satellite, independent, permanent, towns, urban development management is carried out by recreational and political-administrative types in Europe, the developers instead of the city hall. America, Australia, Asia and Africa. Village garden, In another article titled «A study of commuting pattern of precinct garden, town garden, satellite town and New new town residents in Hong Kong», the suggested results Towns represent different international models that have of Hui et al. (2005) showed that despite the ideal and been planned and constructed on the basis of the garden established imaginations, improper planning laws and cities’ conceptual framework, expanded globally (Ziari, vocational and educational conditions in these cities have 2006). In the third world countries, this theory was led to daily trips from new cities to old suburban areas. In employed to enforce the strategy of decentralization, land a comprehensive study on new cities of America, six key use planning, establishing growth hub, regional factors in the development of new cities were listed as development, transferring the office centers, spatial follows: organization of small towns creating service hubs for rural areas, making centers for integration of village and reconstruction of demolished towns with various results. 1. Timing includes Market Feasibility; Totally, these towns were successful in providing housing 2. Location includes Growth of metropolitan areas; for low-income households; but, their physical, social and distance from metropolitan centers and access to major economic structure was not consistent with local highways or transportation links; environment; therefore, they were considered luxurious 3. Financing includes private or public financing, stable and costly commodities that only caused the social financers and prior ownership; imbalances. Even in some cases the slums were combined 4. Developers include amount of experience, financial with the metropolises because they were designed resources and number of developers; according to local policies, overlooking the 5. Industry includes employment base and expansion of comprehensive national and regional strategies (Seyed services; Fatemi, 2010). In an article titled, «New town
Journal of Urban and Environmental Engineering (JUEE), v.7, n.1, p.15-23, 2013 Zali, Azadeh and Salmani 18
Table 1. Population changes of Iran between 19572007 Number Urbanisatipon Population of Population of Rate of population Total population of Year of cities percent rural areas urban areas growth country 200 31.4 12 952 083 6 002 621 18 954 704 1957 272 38 15 992 912 9 795 810 3.13 25 788 722 1967 373 47 17 854 064 15 854 680 2.71 33 708 744 1977 496 54.3 22 600 449 26 844 561 3.91 49 445 010 1987 612 61.3 23 237 699 36 817 789 1.96 60 055 488 1997 1012 68.6 22 235 818 48 259 964 1.62 70 495 782 2007
6. Government includes permitting process, relationship Entropy coefficient model was used for data analysis. with local region and political support. (Pavlovich This standard model is a measure for examining the Howard, 2002). distribution of urban population and the number of the In recent years, because of the fast growth of big cities cities in a region. This model can be used to examine the in developing countries and the existence of empty new balance of population and city number in urban, towns, some researchers have proposed that development provincial, regional, and national levels. The overall plans should be prepared based on the dynamism of small structure of the model is as follows: and intermediate towns (Shokooi, 2006). One of the most important theories in the field of G = (ΣPi LnPi)/LnKG: Coefficient of Entropy spatial development belongs to Joseph Hylhorst. Due to K: Number of Floors the importance of spatial development strategies to Pi: Abundance eliminate interregional, intraregional, and sectorial LnPi: Frequency logarithm of Nepery duplications, proportional to hierarchy of settlements and residents, Hylhorst suggests four different strategies In this model, if the entropy tends to zero, there will be (quoted by Ardeshiri, 1993): 1. concentrate consolidation; higher concentration or imbalance in population 2. dispersed consolidation; 3. concentrate expansion; 4. distribution in the cities; while, moving toward 1 or above dispersed expansion. reveals a more balance distribution in the region Hylhorst posits two main suppositions in those four (Hekmatniaand & Mousavi, 2006). strategies: expansion and consolidation. Reinforcing self- concentration (i.e. convergent forces), the former is used Changes in population and urbanization growth for the provinces or regions which are at the elementary phases of development, ranked among deprived or poor provinces (Fig. 1a). While, the latter focuses on around Since 18691957, urban mechanisms in Iran were center reinforcements (i.e. divergent forces) (Fig. 1b). homogenous and balanced in a way that no city had Expansion stage has two different strategies based on superiority to the others. Every city served and connected area location. For properly distributed and developed its surrounding villages with convergent and consistent areas convergent concentration is offered (Fig. 1c). concentration (Ziari, 2009). Investment in a new regional center or second-grade Based on the first official statistics of 1957, the regional centers is a basic suggestion of this theory. The population of Iran was estimated to be18.9 million people, last phase of development is using divergent raisnig to 25.7 million people in 1967. Then, Iran had a concentration (Fig. 1d). This strategy suits for the population growth of 3.1%. provinces with balanced spatial structure, aiming to During 19671977, population growth rate was 2.7%, transferdevelopment across the whole region and its reaching 3.9% by the next decade. In 1966, Iran faced nearby (Hilhorst, 1971). with a declining growth rate of the population with the estimated population of 60 million. The next decade Materials and Methods witnessed a declining trend again. In 2006, Iran had a population of 70.4 million. Thus, Iran had a decreasing This study used library method to gather data. Exerting population growth rate in two last decades. extant documents, the performances of the new towns The reasons of the such decline in the annual were studied. Via statistics, population changes and urban population growth rate are attributed partially to the mechanisms were investigated. government’s family planning efforts since 1989 and the dismal economic conditions and general decline in living
Journal of Urban and Environmental Engineering (JUEE), v.7, n.1, p.15-23, 2013 Zali, Azadeh and Salmani 19 standards for the average Iranian households (Ziari, 2006). Population and housing studies in 1957 to 2006 indicate a population increase of about 52 million people in Iran. Like many developing countries, urbanization in Iran has a growing trend. According to the Population and Housing statistics in 1957, the urban population of Iran with 200 urban areas was approximately 6 million people, raising to 15.8 million within twenty years to the Islamic Revolution. After the Islamic Revolution of 1957 until 2006, the urban population of the country increased to 48.2 million. In a fifty-year period from 19572006, urban areas reached 1012 areas. The statistics suggest that the urbanization coefficient increased from 31.7% in 1957 to 68.5% in 2006. Hairy Issue 1: Population growth rate trend from 1957 to 2006. Figure 2 shows that until 1977, rural population was Source: Statistical Center of Iran, adopted by the authors. more than urban population. But after that urban population exceeds. Migration from rural to urban areas is the major reason for rapid urbanization in Iran. The declining employment opportunities and living conditions have forced the rural population to migrate. The important City cities of the country are Tehran, Mashhad, Isfahan, Tabriz Village and Shiraz at the moment. Despite the increase of population in five metropolitan areas, their contribution to the total population of the country was 43.5% in 1956 and 33% in 1996. Due to the inflation of house prices and also settlement in cosmopolitans, the establishment of disordered and sprawling towns at the periphery of the largest cities is observed (Ziari, 2006). The rapid growth of urban population in developing countries in the past decades has resulted in numerous problems such as congestion, Fig. 2 Comparison of the population in rural areas than in urban areas pollution, unemployment, housing shortage, and with populations of 1957 to 2007. inadequate urban services. In order to manage urban Source: Statistical Department of Iran, adopted by the authors. growth and its related problems, developing countries have relied upon several policies such as family planning, Performance of the newtowns in Iran rural development, regulating rural-to-urban migration, limiting the growth of large cities, development of The rapid growth of urban population and the patterns of medium-size cities, and new town development. The urban population distribution require government plans to principal objective of the new town development policy settle the future urban population in the existing urban has been to relieve population pressure in large urban areas and new towns. First, by preparing long term master areas (Atash, Shirazibeheshtiha, 1998). plans, the government will attempt to make the existing As a developing country, Iran has recently faced with urban areas absorb some parts of the surplus urban increasing population and migration. Based on expert population. Second, using new town strategies, the estimates of the population, Iran’s population will reach government plans to distribute the urban population 130 million people in 1400, from which 100 million will among a number of new communities, built around the be living in the cities. existing large cities in the country. Beginning in the mid- 1970s, Iran initiated the new town strategies in order to decentralize population and economic activities from the large cities to new towns around them. In the 1970s,
Journal of Urban and Environmental Engineering (JUEE), v.7, n.1, p.15-23, 2013 Zali, Azadeh and Salmani 20 several new towns were proposed and developed, planned as residential communities or industrial towns around a few large cities such as Tehran and Esfahan (Atash, Shirazibeheshtiha, 1998). The urbanization system of Iran can be evaluated in four periods:
1- In the distance between the two world wars, new towns of Iran were planned without specific strategy evolved around a core rural area. For example, Zahedan and Noshahr which are regarded thriving at the moment. 2- During World War II until the mid-1960s, Iranian Fig. 3 Tehran’s position in the country’s political divisions and towns were developed without specific strategy, urban centers of the province. evolving around an urban core for the development of oil and other industry. 3- From mid-1960 to 1969, new towns were formed with • Dependence on the services of the company; the aim of exploiting natural resources without any • Separation of the town from the network of the cities primary nucleaus, regional development, land use, or and villages in the area; housing. • Lack of development; 4- Aiming to spatially organize and revise metroplitans • Social and cultural conflicts; and balance their economic growth, 28 satellite towns • Heavy maintenance costs; were developed without a primary core to settle 6 • Dormitory nature of the towns (Ziari and Qrakhlu, million people until 2016, absorbing population 2009). overflow. The plan of Urban Development after Islamic revolution was first legislated by the Committee of Governmental Employees Welfare in STUDY SCOPE Housing Ministry which led to Act No. 108328, as the main key in decision-makings for this plan. After As one of the thirty provinces of Iran, Tehran has 15 legislation of this this act, 24 other towns were built cities, 37 districts and 83 villages. Urban areas of the and 11 more towns are being constructed (Ziari, province consist of 56 towns and 1201 villages with 2009). inhabitants. Tehran Province has an area of about 18 814 square kilometers, located in 34 degrees and 52 minutes It is important to point out that the urban population of to 36 degrees and 19 minutes of north latitude and the country was over 48 million persons in 2006, while between 50 degrees and 10 minutes to 53 degrees and 10 only 7.9% (3.8 millions) of this population were settled in minutes east longitude from Greenwich Hour Circle. new towns. On the other hand, the decision was to settle Figure 3 shows the location ofTehran Province and its 1.6% of this population in these towns by the end of the subdivisions with their centers. fourth development program; thus, calculating the present population of these towns, only 0.7% of the urban Population changes and entropy coefficient analysis of population of the country could be settled in new towns. urbanization mechanisms in Tehran The key question is that can any other strategy be a proper alternative in order to attract and settle this 0.7% of urban Development and population density are the main features population, excluding the construction of new towns? of the urbanization mechanisms in Iran. Tehran has The most important problems in these towns are as maintained its superiority in economic and social aspects follow: of this system. As a metropolitan area, Tehranhas • Dependence on one economic activity and the single dominates in political, organizational, and economic base of employment; aspects over other cities. Then, like any other third world • Exclusive ownership of the houses and lands of the city country, Iran has a first urban template (Jajromi and by the company; Gheibi, 2011). • Uniform organizational house pattern;
Journal of Urban and Environmental Engineering (JUEE), v.7, n.1, p.15-23, 2013 Zali, Azadeh and Salmani 21
According to the statistics, released by the Statistics Department of Iran (Table 2), 5.3-million population of Tehran in 1976, with the average annual growth of 4.3% increased to 8.1 million people in 1986. Then, this trend could not be due to the natural growth of population; instead, it resulted from the huge volume of immigration to the province. Especially in this era, refugees of other war-strike cities rushed to Tehran (Ghavidel and Razzaghi, 2008). The population growth rate in the next 10 years had a reduction, showing the average annual growth of 2.5%. Population in 1996 reached 10.3 million. Population growth rate from 1996 to 2006 remains relatively constant with a slight increase. Average annual Fig. 3 Comparing the ratio of Tehran City’s population to the total growth during this period was 2.64%, raising to 13.4 population of Tehran Province. million. Based on the statistics of 1976, 1986, 1996, and 2006 there were 18, 19, 25 and 51 towns in Tehran, respectively. During these years, Tehran Province had 30.71, 26.05, 24.20, and 25.39 percent of the country’s total population in 1976, 1986, 1996, and 2006. In the last four statistics, Tehran has included 25% of the total population of the province (Jajaromi and Gheibi, 2011). A simple review of these statistics shows that the settlement balance of this province is not proper and follows first urban template; in a way that in the past four decades, 85% of the population of Tehran Province have resided in Tehran City itself (Table 2).
Fig. 4 Comparing the ratio of Tehran City population to the total population of Iran.
Table 2. Population changes of Tehran between 19772007 Population Number of Percent of Population in Population in The total population of growth rate Year cities urbanization rural areas urban areas the province (percent) 18 0.92 384 250 4 947 367 - 5 331 627 1355 19 0.90 767 691 7 339 742 4.3 8 107 433 1365 25 0.89 1 093 641 9 250 145 2.5 10 343 965 1375 51 0.91 1 161 935 12 260 431 2.64 13 422 366 1385
Table 3. Details of new cities around Tehran Final predicted Fulfilled Population Year of Distance from New population of the population until projections till beginning metropolice town town 2006 2006 activities (km) 200 000 58 000 90 000 1370 35 Pardis 132 000 100 000 95 000 1371 25 Andishe 150 000 5 900 35 000 1369 40 Parand 500 000 47 320 83 000 1367 65 Hashgerd 982 000 211 220 303 000 Total Source: Statistical department of Iran, adopted by the authors.
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them in a specific period. The related information in this respect are reflected in Table 3. As seen in Table 3, Andisheh Town has been more successful than others in absorbing defined population. Pardis, Hashtgerd, and Parand occupy the next ranks, respectively. Thus, only Andisheh Town has acted relatively successfully in attracting related population. This can be for providing enough educational, recreational, and cultural facilities for the citizens. But, Pardis, Hashtgerd, and Parand in the lower ranks have not had significant performance in this respect. Generally Fig. 5. Entropy changes in the past decade. speaking, these cities have not been successful in their Source: Qrakhlu and Panahandehkhah (2009). missions. Regarding the poor performance of these towns, new ideas in constructing them should be utilized and the old ones should be revised. As mentioned in the earlier Help: sections of this paper, according to four development • The share of the total population of the country’s population stages of Hilhorst, Tehran Province is still at the first of Tehran stage of development. As a result, population attraction • The share of the total population of the province’s population strategies should be fortified, communication with small of Tehran, Tehran and intermediate cities around should be strengthened, and the strategy of scattered cohesion should be utilized to These figures reveal that as a center ofall facilities and balance urbanization and deconstruction of Tehran City. services in recent years, Tehran has witnessed increasing immigration and population growth in itself. The entropy model has analyzed the role of new towns in CONCLUSION urban mechanisms of Tehran Province. Entropy value of below one shows the imbalance of population distribution Reviewing the statistics and analysis reveals that total and settlement in all studied periods. During 19661986, population of Iran and urbanization have had an entropy value has an ascending trend toward 1, revealing ascending trend. Population concentration in some the movement toward balance. But, it reaches 0.265 in specific urban areas reveals the imbalance of population 1996 from entropy value of 0.304 in 1986, revealing its distribution and the lack of considering urban hierarchy in reconcentration. The reason for this result can be the the country. Then, urban policies have revolved around occurrence of Iraq-Iran War which forced the people to the continuum of balancing residents and deconstruction resort to Tehran, escaping from border-line cities. This in the cities. Examining these issues, this study concluded value reached 0.326 in 2006, implying a relative balance. that newly developed cities only respond to the dormitory Totally, based on the statistics, the construction of new conditions of big cities. Not only they were developed towns does not show any significant effect on balancing without economic, social, and vocational considerations; urban mechanism of Tehran Province. but also they could not remove the population overflow from metropolitans. These issues necessitate more careful planning for present and future cities, revising old The performance of new cities in Tehran Province policies, and exerting the successful experiences of newly established towns at regional, national, and international Officially announced aim of developing new towns has levels. Improving the transportation and communication been summarized in a few words: “detached metropolitan of these towns with their neighbors and other development”. In this respect, proper distribution of the metropolitans should be highly regarded as well. overflow of Tehran City’s population in urban areas (Parand, Pardis, Andisheh, Hashtgerd towns) with a REFERENCES comprehensive plan is the main purpose of constructing new towns (Zebardast and Jahanshahloo, 2007). Ardeshiri, M. (1990). The role of small cities in regional balance. At the time of legislating comprehensive plans new Urban Planing of Shiraz University. cities, a definite population was determined for each of
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Austufsky, V.(2008). Contemprory city constructionn from the Hekmatnia,H., Mosavi, N.(2006).Model applications in geography begining until Athen Charter. Translated by Etezadi, L. University using urban planning. New Sciences Publication. Publication. Hui, E C.M., Lam Manfred, C.M. 2005. A study of commuting Atash, F., Shirazibeheshtiha, Y. S. (1998). New towns and their patterns of new towns’ residents in Hong Kong, Habitat practical challenges: The experience of Poolad Shahr in Iran. International ,Vol. 29, Hilhorst, J.G.M. (1971). Regional planning: HABITATITNL., Vol. 22, No. 1, 1-13. A systematic approach. Rotterdam University Press. Barakpoor, N., Asadi, I. (2011). Urban management and organization. Jajromi,K., Gheibi, M. (2011). Analyzing the mechanisms of Tehran Art University Publication. from 1967-2006. Scientific Quarterly of New Attitudes in Human Ebrahimzadeh, I., Negahbanmarvi, M. (2006). Analysis of Geography, 3(3). urbanization and the role of new cities in Iran. Geographic Research Mashhadizadeh, Dehagani, N. (2010). An analysis of urban planning Quarterly, No. 75, summer. features in Iran, Science and Industry University Publication. Fanni, Z. (2006). Cities and urbanization in Iran after the Islamic Pavlovich Howard, Z. (2002). New Towns: An overview of 30 revolution. Cities, Vol. 23, No. 6, 407–411. American new communities. CRP 410: Community Planning Firman, T. (2004). New town development in Jakarta’s Laboratory. metropolitanregion: A perspective of spatial segregation, Habitat Statistics Departmnet of Iran. Available at http://www.sci.org.ir. International, 28. Ziari, K. (2006). The planning and functioning of new towns in Iran. Fatemi, S.M., Hosainzadeh-Dalir,K. (2010). Analysis of Sahand New Towns. Vol. 23, No. 6, 412-21. Town role in spatial order of Tabriz urban region. Urban - Regional Ziari, K., Gharakhlou, M. A. (2009). Study of Iranian new towns Studies and Research Journal, 2(6), Autumn. during pre- and post-revolution. Int. J. Environ. Res., 3(1):143-154, Gharakhloo, M., Abedini, A. (2009). Challenges of new cities and their Winter. success in Iran, case study of Sahand Town, Human Sciences Ziari, K. (2009). New cities plans. Samt Publication. Quarterly, 3(1). Shokooi,H. (2006). New Attitudes In Urban Geography, Vol.1, Samt Gharakhloo, M., Panahandehkhah, M. (2008). Evaluating the Publication. performance of new cities in attracting surplus population of Tehran, Zebardast, S., Jahanshahloo, L. (2007). Investigating the performance case study of new towns around Tehran. Human Geography of new town of Hashtgerd in absorbing population overflow. Researches, No. 67. Geography and Development, No. 10. Ghavidel, S., Razzaghi, H., and Alipoor, Kh.(2008). Examining the reasons for migration to Tehran metropolitan, focusing on Firoozkooh Town, Economic Quarterly, No. 1.
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Journal of Urban and Environmental Journal of Urban and E Engineering, v.7, n.1, p.24-29 Environmental Engineering ISSN 1982-3932 J E www.journal-uee.org U doi: 10.4090/juee.2013.v7n1.024029
ARSENIC CONTAMINATION IN GROUNDWATER: A STATISTICAL MODELING
Palas Roy, Naba Kumar Mondal, Biswajit Das, and Kousik Das Department of Environmental Science, The University of Burdwan, Burdwan, I ndia, WB
Received 27 April 2012; received in revised form 27 January 2013; accepted 30 January 2012
Abstract: High arsenic in natural groundwater in most of the tubewells of the Purbasthali- Block II area of Burdwan district (W.B, India) has recently been focused as a serious environmental concern. This paper is intending to illustrate the statistical modeling of the arsenic contaminated groundwater to identify the interrelation of that arsenic contain with other participating groundwater parameters so that the arsenic contamination level can easily be predicted by analyzing only such parameters. Multivariate data analysis was done with the collected groundwater samples from the 132 tubewells of this contaminated region shows that three variable parameters are significantly related with the arsenic. Based on these relationships, a multiple linear regression model has been developed that estimated the arsenic contamination by measuring such three predictor parameters of the groundwater variables in the contaminated aquifer. This model could also be a suggestive tool while designing the arsenic removal scheme for any affected groundwater.
Keywords: Arsenic; groundwater; statistical modeling; multivariate analysis.
© 2013 Journal of Urban and Environmental Engineering (JUEE). All rights reserved.
Correspondence to: Naba K. Mondal, Mobile.:+919434545694. E-mail: [email protected]
Journal of Urban and Environmental Engineering (JUEE), v.7, n.1, p.24-29 2013 Roy, Mondal, Das and Das 25
INTRODUCTION vomiting in accompanied with watery diarrhea and sever weakness (Das, 2008). Antimony occurs with Arsenic contamination of groundwater is a major public sulfur bed as same as arsenic, generally in the form of health concern in West Bengal and elsewhere (Rahman antimonite (Sb S ) (Siepak et al., 2004). The unstable et al., 2005). Millions of people have been exposed 2 3 Sb S decomposed via atmospheric oxygenation with arsenic through drinking water that comes majorly from 2 3 formation of soluble oxide minerals of antimony and ground water (Duker et al., 2005). Chronic toxicity of migrated into groundwater (Ashley et al., 2003) as a arsenic in human from arsenic contaminated drinking similar way of arsenic. In comparison to other toxic water occurs in 3417 villages over 111 blocks, primarily metals very little information exists on antimony in within 12 districts of this state (Mondal et al., 2011), environmental sample, probably as a result of its low affecting more than 1.5 million of people (De, 2008) of groundwater concentration, normally range from 0.1 to which 25% are suffering arsenical skin lesions. The 0.2 µg/liter (WHO). maximum permissible level of arsenic in drinking water Then, for our present interest, a regional level recommended by World Health Organization (WHO) groundwater quality survey in the Purbasthali- Block II 0.01 mg/liter and in West Bengal it has been adjusted to area of Burdwan district (W.B, India) was conducted, 0.05 mg/liter by the local authorities. Drinking water which is identified as an arsenic polluted area (Biswas, arsenic concentration in West Bengal ranged from 0.05 2010; Mondal et al., 2011). Groundwater samples from to 3.5 mg/liter are reported on those affected zones different tube wells were collected from 33 affected which are in the vicinity of river Ganga (Das, 2008) and villages of the study area (Mondal et al., 2011). The confined within the member delta zone of the upper purpose of this article is also to ascertain the possible delta plain. It has been reported by Nag et al. (1996) interrelation of Arsenic, Sb, Fe, pH, Depth, SWL and that water of the intermediate (second) aquifer is Age of the tubewells through statistical modeling on the polluted with arsenic; though in some areas deep (third) basic on such water samples. aquifer has been detected where there is no clay partition between the second and third aquifer. MATERIALS AND METHODS Drinking water arsenic contamination is originated from the natural release of arsenic through aquifer and Water Sampling sedimentary rocks (Zandsalimi et al., 2011). The element is fundamental constitute of sulphide minerals One hundred and thirty-two tubewell water samples of which pyrite like, arseniopyrite, FeAsS, (McGurie et were collected from different locations of Purbasthali al., 2001) is the most abundant. Arsenopyrite is highly Block-II in Burdwan district, West Bengal, India, in the insoluble in water but due to anthropogenic activities month of September to October, 2011. The samples (Aktar & Ali, 2011) it dissolved via oxygenation with were collected in pre-cleaned sterilized polyethylene formation of soluble arsenate and arsenite. In West bottles of one liter capacity following standard protocol. Bengal arsenic species in contaminated drinking water To avoid any contamination at the source, the samples were found to be arsenate and arsenite in 1:1 ratio (De, were taken by holding the bottles at the bottom and 2008). Pyrite oxidation has been proven to be the most drawn directly from the tubewell after water was allow acceptable hypothesis to explain the occurrence of running at least fifteen (15) minutes (Karthikeyan et al., arsenic in ground level water (Fazal et al., 2001). 2010). The water samples were immediately Therefore, the occurrence of arsenic might be coupled refrigerated after collection and brought to the with the presence of iron (Fe) in water. Analysis of such laboratory with extreme care and preserved for further groundwater in arsenic bearing zones also indicated the analysis. presence of high contain of Fe (Nag et al., 1996). This would strengthen the correlation between arsenic and Reagents and standards iron concentration of ground water more rational.
Though several authors also reported an interrelation of Chemical of analytical grade were procured from M/S, groundwater arsenic concentration with Static water Merck India Ltd; and used through the study without level (SWL) (Welch & Stollenwerk, 2003), Depth further purification. To prepare all reagents and (Chakraborti et al., 2009), pH (Saxena et al., 2004) and standards, double distilled water was used. All Age (time) of the wells (Fazal et al., 2001) at a regional glassware was cleaned by being soaked in 15% HNO level. 3 and rinsed with double distilled water. Each sample was Now a day, interest has been also grown in analyzed three times and the results were found determining of antimony (Sb) in groundwater due to its reproducible within ± 3 error limit. similar chemio-toxicological properties (Gibel, 1997) with arsenic though Sb-induced toxicity is more violent
Journal of Urban and Environmental Engineering (JUEE), v.7, n.1, p.24-29 2013 Roy, Mondal, Das and Das 26
Methodology following statistical modeling of ground water on the contaminated region is performed. The sets of water samples were analyzed in the Loading Plot of Principal Component Analysis Departmental laboratory of Environmental Science,
University of Burdwan (India). The total arsenic contain The loading plot displays the relation among the analysis were estimated by using of atomic absorption variables. The loading are the weight combining of the spectrophotometer (Model No. GBC HG 3000) into Ar- original variable to from the scorer. The loading plot H flame at 193.7 nm wavelength (De, 2008). 2 shows the orientation of the obtained plane in relation to A UV-visible spectrophotometer (Systronics, Vis the original variable. Hence the loading plot of the double beem Spectro 1203) with 1 cm quartz cell was principal component analysis based on two principal used for spectrophotometric determination of Sb and Fe components may explain notably the variances of the metals in water. The metal contains were estimated nature and influences of the selected variables. The using N-phenylbeziumidylthiourea and Phenanthroline loading plot of the principal component analysis methods for Sb (Shrivas et al., 2008) and Fe (De, 2008) portrays very well with the correlations of the water respectively. The pH values of the water samples were parameters in Fig. 1. The parameters are symbolized by examined at the site of sample collection with a portable vectors which have only been indicated for a few pH meter (Eutech, pH Tester 30). variables to avoid cluttering the plot. Variables that are Other parameters of these samples like SWL, Depth most important for the model are found on the periphery and lowering year of the tubewells have been of the loading plot. Conversely, non-influential downloaded, as secondary data, from the official variables are encountered around the origin of plot (0,0). website of Public Health Engineering Department of Parameters having significant influences on arsenic West Bengal Government (WBPHED) web site, have noticeably been found to make clusters among http://www.wbphed.gov.in/main/Static_pages/ArsenicR themselves. This strong relationship of Arsenic with eport/bardhaman.pdf. The lowering year of the other parameters such as Fe and SWL can explicitly be tubewells help us to determine the Age of the tubewell visualized in the lower right quadrant of the graph plot with respect to the date of arsenic detection. (Fig. 1). Similar observations have also been reported
by other investigators Chakraborti et al. (2009) and Statistical analysis of data Mondal et al. (2011), respectively.
Furthermore, the direction and magnitude of The analytical data was statically analyzed with the help each vector indicates its importance as a constituent of of SPSS 7.5 and Minitab 15 (trial) software. The the samples lying in the direction in which the vector Minitab 15 was performed for modeling Principal points. Adversely the parameters particularly Time and Component and Cluster analysis along with the factor pH in the upper right and left quadrant are less analysis of Scree plotting. SPSS 7.5 was only exploring correlated vector cluster of the graph which only to develop multi linear regression model. enriching the plotting. Dissolved Sb and Depth vectors
RESULTS AND DISCUSSIONS Loading Plot of Time, Depth, SWL, Arsenic, pH, Fe, Sb
Analysis was preformed against 132 tubewell water 0.75 Time samples collected from the study area with varied depths of 15, 27, 28, 30, 34, 35, 37, 43, 55, 71, 83 and 0.50 85 meter. The maximum arsenic concentration was found on that depths are 0.085, 0.027, 0.205, 0.012, 0.25 0.091, 0.019, 0.095, 0.076, 0.261, 0.191, 0.120 and 0.001 mg/liter, respectively. Out of 132 samples the pH 0.00 Fe concentration of arsenic in twenty-two samples and Sb Factor Second Sb in thirty-nine samples was recorded below detection -0.25 limit. The pH values of the water samples shows that it Depth is more or less neutral. The maximum Sb concentration -0.50 Ars en ic was found 0.0651 µg/liter in 43 meter depth aquifer SWL whereas maximum of Fe was reported in the 71 meter -1.0 -0.5 0.0 0.5 1.0 depth layer as 11.45 mg/ liter. The SWL of the Firs t Fact or tubewells are ranged from 6.00 to 24.54 meter. On the Fig. 1 Loading plot of the principal component analysis of the basis of the results of the various parameters, the studied groundwater.
Journal of Urban and Environmental Engineering (JUEE), v.7, n.1, p.24-29, 2013
Roy, Mondal, Das and Das 27
also point in the direction of the lower left quadrant in among the pair in compare too other parameters. Time the plot. However, these variables do not directly here is seen to be linked with arsenic also indicate the correlated with Arsenic but indicating that the water oxidative dissolution of arsenic mineral which may samples contain more Sb at higher Depth. These again be consider to release of arsenic in ground water findings are very much consistent with the hierarchical as a time variable parameter. The same phenomenon is cluster analysis that can be found elsewhere. endorsed by Fazal et al. (2001). Group-II is represented by the stream of Depth, pH Hierarchical Cluster Analysis and Sb. The similarity level between Depth and Sb is 53.65, showing that the release of Sb is depth The purpose of the hierarchical cluster analysis was dependent. Cluster analysis strongly supports the defined a cluster solution or small number of cluster observation that was found in the loading plot analysis. solutions that could be analyzed by the hierarchical procedure to identify a single final cluster solution. The Scree Plot of Factor Analysis clustering algorithm in a hierarchical procedure determines how similarity is defined between multiple- Factor analysis was used to determinate the relative member clusters in the clustering process. By using relationship between arsenic and other water hierarchical cluster analysis, variable were interrelated parameters. The main aim of factor analysis us to to each other according to the maximum similarities. explain the variation in a multivariate data set by as few Ward’s method is the most popular hierarchical factors and also to detect the hidden structure of the algorithm and is recommended as distance measures of multivariate data. Factor analysis when applied to the clustering. Plot of hierarchical cluster with Ward’s widely different set of sample data appears to be the linkage is portrayed in Fig. 2. The Ward’s method of moderately successful as a statistical tool for examining hierarchical cluster analysis which was used in this the relationship between the variables within a data set. study has the advantage of not demanding any prior Scree plot of eigenvalues (Fig. 3) is the most knowledge of the number of clusters which the non- acceptable method of this analysis. The Scree plot is a hierarchical method does. graph of each eigenvalue (Y axis) against the factor Cluster analysis suggests two groups in the with which it is associated (X axis). Contribution of dendrogram. The Group-I is composed by Time, SWL, factor is said to be significant when the corresponding Fe, Arsenic and reflected the stronger correlation that eigenvalue is greater than 0.8 (Keshavarzi et al., 2010). may exist among the parameter in the same cluster. The Scree plot (Fig. 3) displayed that four (4) factors similarity level between SWL-Fe, Time–SWL, Time- such as Time, SWL, Fe and Arsenic are very much Arsenic are displayed in the dendrogram. The position significant contributor with eigenvalues 2.37, 1.17, 1.10 of SWL-Fe in the same cluster and Depth-pH in Group- and 0.88 respectively. The solution using the II also reflected their very much distinguishable eigenvalues in four components which represent characteristics
Scree Plot of Time, Depth, SWL, Arsenic, pH, Fe, Sb Dendrogram Ward Linkage, Correlation Coefficient Distance 2.5
2.11 2.0
1.5 1.41 Gr oup-I 43.61 Group-II Eigenvalue 1.0 Distance 46.02 53.65 0.8 0.70 0.5 72.00 76.07
0.00 0.0 Time SWL Fe Arsenic Dept h pH Sb Var i abl e s 7654321 Component Number
Fig. 3 Scree plot of factor analysis of the studied groundwater. Fig. 2 Hierarchical cluster analysis of the studied groundwater.
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Roy, Mondal, Das and Das 28
78.86% total cumulative variance shows that suitable removal plan while treating the groundwater that may factor analysis with scree plotting. This plot motivated have contaminated badly with that. us to also use the standard multiple regression analysis as to the effect of the other three independent variables REFERENCES on arsenic and to design a mathematical relation. Akter, A. & Ali, M.H. (2011) Arsenic contamination in groundwater Multiple Linear Regression Model and its proposed remedial measures. Int. J. Environ. Sci. Technol. 8(2), 433-443. http://www.ijest.org/jufile?c2hvd1BERj00Nzk=&ob=85ae31c795 Generally a multiple regression analysis attempts to fit 70535af6b5856fd17aca93&fileName=full_text.pdf the independent variables for predicting a single Ashley, P.M., Craw, D., Graham, B.P. & Chappell. D.A. dependent variable. In our data 3 censor variables are (2003) Environmental mobility of antimony around observed from scree plot analysis (Fig. 3). This mesothermal stibnite deposits, New South Wales, Australia andsouthern New Zealand. J. Geochem. Explor. 77(1), 1–14. doi: motivated us to also use the multiple regression analysis 10.1016/S0375-6742(02)00251-0 as to the effect of the independent variables on arsenic. Biswas, B. (2010) Geomorphic Controls of Arsenic in Ground Water The multiple regression model has the general form: Purbasthali I & II Blocks of Burdwan District, West Bengal, India. Int. J. Environ. Sci. 1(4), 429-439. Chakraborti, D., Das, B., Rahman, M.M., Chowdhury, U.K., Y = β0 + β1X1 + β2X2 + β3X3 + ……..+ ε Biswas, B., Goswami, A.B., Nayak, B., Pal, A., Sengupta, M.K., Ahamed, S., Hossain, A., Basu, G., Roychowdhury, T. & where X1, X2, X3 denote the independent variables, Y Das D. (2009) Status of groundwater arsenic contamination in the state of West Bengal, India: A 20-year study report. Mol. stands for the dependent variable, β0, β1, β2, β3 represent Nutr. Food Res. 53(5), 542-551. doi: 10.1002/mnfr.200700517 the correlation coefficients, and ε designates the error st Das, A.K. (2008) Bioinorganic Chemistry. 1 edition, Book and term. Allied (P) Ltd, Kolkata (W.B), 351-359. The final fitted model based on the multiple De, A.K. (2008) Environmental Chemistry. 1st edition, New Age regression approach is International Publishers, New Delhi, 222-247. Duker, A.A., Carranza, E.J.M. & Hale, M. (2005) Arsenic geochemistry and health, Environ. Int. 31(5), 631-641. Arsenic = 9.528×10-2 – 5.93×10-4 Fe + 1.01×10-4 SWL -4 doi: 10.1016/j.envint.2004.10.020 – 4.82×10 Age of the tubewells Fazal, M.A., Kawachi, T. & Ichion, E. (2001) Validity of the Latest Research Findings on Causes of Groundwater From this model it clearly results that Fe, SWL and the Arsenic Contamination in Bangladesh. Water Int. 26(3), 380-389. Age of the wells are very much significant for the doi: 10.1080/02508060108686930 Gebel, T. (1997) Arsenic and antimony: comparative approach on arsenic contamination at groundwater level. This model mechanistic toxicology, Chem. Biol. Interact. 107(3), 131-144. may suggest the prediction of the arsenic contamination doi: 10.1016/S0009-2797(97)00087-2 by measuring these thre predictor parameters of the Karthikeyan, K., Nanthakumar, K., Velmurugan, P., Tamilarasi, S. groundwater variables in any contaminated aquifer. This & Lakshmanaperumalsamy, P. (2010) Prevalence of certain inorganic constituents in groundwater samples of Erode model may also be a suggestive tool in predicting district, Tamilnadu, India, with special emphasis on arsenic contamination level while designing the arsenic fluoride, fluorosis and its remedial measures. Environ. Monit. removal activities by the Environmental Scientists. Assess. 160(1-4), 141-155. doi: 10.1007/s10661-008-0664-0 Keshavarzi, B., Moore, F., Esmaeili, A. & Rastmanesh, F. (2010) CONCLUSION The source of fluoride toxicity in Muteh area, Isfahan, Iran. Environ. Earth Sci. 61(4), 777–786. doi: 10.1007/s12665-009- 0390-0 In this study three multivariate analyses (Principal McGuire, M.M., Banfield, J.F. & Hamers, R.J. (2001) Quantitative Component, Cluster and Factor analysis) have been determination of elemental sulfur at the arsenopyrite surface applied in order to study the effect of some groundwater after oxidation by ferric iron: mechanistic implications. Geochem. Trans. 2(4), 25-29. doi: 10.1186/1467-4866-2-25 parameters on arsenic contamination level. These Mondal, N.K., Roy, P., Das, B. & Datta, J.K. (2011) Chronic arsenic models are found to be highly significant. From these toxicity and it’s relation with nutritional status: A Case Study in models it clearly demonstrated that out of seven Purabasthali-II, Burdwan, West Bengal, India. Int. J. Environ. Sci. variables four of them like SWL, Fe, Arsenic and Age 2(2), 1103-1118. of the tubewells are closely interrelated with each other. Nag, J.K., Balaram, V., Rubio, R., Albert, J. & Das, A.K. (1996) Inorganic Arsenic species in Groundwater: A Case Study from Multiple regression model has been developed as a Purbasthali (Burdwan), India. J. Trace Elem. Med. Biol. 10(1), 20- predictor model to perceive an estimation of the arsenic 24. doi: 10.1016/S0946-672X(96)80004-6 contamination level by measuring the three predictor Rahman. M.M., Sengupta, M.K., Ahamed, S., Chowdhury, parameters of the groundwater variables in any U.K., Lodh, D., Hossain, M.A., Das, B., Saha, K.C., Kaies, I., Barua, A.K. & Chakrabort,i D. (2005) Status of contaminated aquifer. Then, further research focusing groundwater arsenic contamination and human suffering in a on these variables will be helpful to guide the Gram Panchayet (cluster of villages) in Murshidabad, one of the Environmental Scientists to design an efficient arsenic
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nine arsenic affected districts in West Bengal. J. Water Health, Siepak, M., Niedzielski, P. & Bierła, K. (2004) Determination of 3(3), 283-296. doi: 10.2166/wh.2005.038 Inorganic Speciation Forms of Arsenic, Antimony and Selenium Saxena, V.K., Kumar, S. & Singh, V.S. (2004) Occurrence, in Water from a Grate Ashes Dumping Ground as an Element of behaviour and speciation of arsenic in groundwater. Curr. Sci. Hydrogeochemical Monitoring of Pollution Spread. Pol. J. Envir. 86(2), 281-284. Stud. 13(6), 709-713. http://www.pjoes.com/pdf/13.6/709-713.pdf Shrivas, K., Agrawal, K. & Harmukh, N. (2008) On-site Welch, A.H. & Stollenwerk, K.G. (2003) Arsenic in Groundwater spectrophotometric determination of antimony in water, soil and Geochemistry and Occurrence. 1st edition, Kluwer Academic dust samples of Central India. J. Hazard. Mater. 155(1-2), 173- Publishers, Dordrecht, USA, 273-274. Zandsalimi, S., Karimi, N. 178. doi: 10.1016/j.jhazmat.2007.11.044 & Kohandel, A. (2011) Arsenic in soil , vegetation and water of a contaminated region. Int. J. Environ. Sci. Technol. 8(2), 331-338.
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Journal of Urban and Environmental Journal of Urban and E Engineering, v.7, n.1, p.30-47 Environmental Engineering ISSN 1982-3932 J E www.journal-uee.org U doi: 10.4090/ juee.2013.v7n1.030047
A REVIEW ON EFFICACIOUS METHODS TO DECOLORIZE REACTIVE AZO DYE
1 2 1 Jagadeesan Vijayaraghavan , S. J. Sardhar Basha and Josephraj Jegan 1 Department of Civil Engineering, Anna University, University college of Engineering, Ramanathapuram, India 2 Department of Chemistry, Anna University, University college of Engineering, Ramanathapuram, India
Received 2 June 2012; received in revised form 28 March 2013; accepted 13 April 2013
Abstract: This paper deals with the intensive review of reactive azo dye, Reactive Black 5. Various physicochemical methods namely photo catalysis, electrochemical, adsorption, hydrolysis and biological methods like microbial degradation, biosorption and bioaccumulation have been analyzed thoroughly along with the merits and demerits of each method. Among these various methods, biological treatment methods are found to be the best for decolorization of Reactive Black 5. With respect to dye biosorption, microbial biomass (bacteria, fungi, microalgae, etc), and outperformed macroscopic materials (seaweeds, crab shell, etc.) are used for decolorization process. The use of living organisms may not be an option for the continuous treatment of highly toxic organic/inorganic contaminants. Once the toxicant concentration becomes too high or the process operated for a long time, the amount of toxicant accumulated will reach saturation. Beyond this point, an organism's metabolism may be interrupted, resulting in death of the organism. This scenario is not existed in the case of dead biomass, which is flexible to environmental conditions and toxicant concentrations. Thus, owing to its favorable characteristics, biosorption has received much attention in recent years.
Keywords: Decolorization, Reactive Black 5, Azo dye, Biosorption, Bioaccumulation, Dead Biomass.
© 2013 Journal of Urban and Environmental Engineering (JUEE). All rights reserved.
Correspondence to: Jagadeesan Vijayaraghavan. E-mail: [email protected]
Journal of Urban and Environmental Engineering (JUEE), v.7, n.1, p.30-47, 2013 Vijayaraghavan, Basha and Jegan 31
INTRODUCTION resistant to aerobic biodegradation processes (Erdal & Taskin, 2010). Increasing population results in rapid industrialization and urbanization. Due to that, the world has been REACTIVE DYES confronted with two major problems. One is depletion of fossil fuels and another one is polluting the A dye is described as a colored substance with affinity environment. Manmade activities on water by domestic, to substrate applied. Dyes are soluble at some stage of agriculture, aquaculture, industrial, shipping, radio- the application process, whereas pigments in general active wastes; on air by industrial pollutants, mobile retain basically their particulate or crystalline form combustion, burning of fuels, ionization radiation, during application. These are used to impart color to cosmic radiation, suspended particulate matter; and on materials of which it becomes an integral part. Aromatic land by domestic wastes, industrial waste, agricultural ring structure coupled with a side chain is usually chemicals and fertilizers, acid rain, animal waste have required for resonance and in turn imparts color. negative influence over biotic and abiotic components Based on the origin and complex molecular of different natural eco-systems. structure, dyes can be classified into three categories: Though water, air and land are equally important, (1) Anionic: acid, direct and reactive dyes; (2) Cationic: especially potable water is of great. Two third of the basic dyes; and (3) Non-ionic: disperse dyes (Gong et earth’s surface is comprised of water. That too it is al., 1993; Mishra & Tripathy, 1993; Fu & Viraraghavan, undeniably the most valuable natural resource existing 2001; Greluk & Hubicki, 2010). on our planet. Industries are polluting the water resource It has been estimated that over 10,000 different is a common occurrence by emanating the effluents. textile dyes and pigments were in common use (Easton, Especially the potable water has become greatly 1995; McMullan et al., 2001). Also it is reported that polluted. Due to many instances, water lost its there are over 100000 commercial dyes are available originality. The discharge of highly colored wastewater with a production of over 7 × 105 metric tons per year into the potable water sources, will convert soon this (Zollinger, 1987; Fu & Viraraghavan, 2001) planet into a desert. Then, it is a serious environmental Among the various classes of dyes, reactive dyes are issue. one of the prominent and most widely used types of azo Dyes and dye pigments are the major sources for dyes and are too difficult to eliminate. They are polluting the water resource. Dyeing process is a extensively used in different industries, including significant consumer of water and producer of huge rubber, textiles, cosmetics, paper, leather, contaminated aqueous waste streams (Barakat, 2010). In pharmaceutical and food (Aksu & Donmez, 2005; a textile industry, 200 to 500 L of water is needed to Vijayaraghavan & Yun, 2008; Wang et al., 2009). produce 1 kg of finished products (Marcucci et al., Because these dyes have favorable characteristics, such 2002). Specifically, the dyeing of 1 Kg of cotton with as wide color spectrum , bright color and color shades, reactive dye demands 70 to 150 L of water, 0.6–0.8 Kg high wet fastness profiles, ease of application, brilliant NaCl and 30 to 60 g of dyestuffs (Colindres et al., colors and minimum energy consumption (Lee & 2010). Pavlostathis, 2004; Aksu, 2005; Vijayaraghavan et al., Effluents emanating from textile, paper, wool, 2008). cotton, silk, paper printing and leather industries contain The most common group reactive dyes are azo, a large varieties of reactive dyes. These dyes are of anthraquinone, phthalocyanine (Axelsson et al., 2006) great environmental anxiety due to their enormous and reactive group dyes (Lin & Peng, 1994; Sanghi et discharge and toxic character (Zollinger, 1987; Crini, al., 2006; Daneshvar et al., 2007). Most of these dyes 2006; Vijayaraghavan & Yun, 2008; Chatterjeea et al., are toxic and carcinogenic (Acuner & Dilek, 2004). 2010). More than 80 000 tons of reactive dyes are Disposal of these dyes into the environment causes produced and consumed each year, making it possible to serious damage, like they may significantly affect the quantify the total amount of pollution caused by their photosynthetic activity of hydrophytes by reducing light use (Maria Rivera et al., 2011). Dyes usually have a penetration (Aksu et al., 2007) and also they may be synthetic origin and complex aromatic molecular toxic to some aquatic organisms due to their breakdown structures, which possibly come from coal-tar based products (Hao et al., 2000; He et al., 2007). hydrocarbons such as benzene, naphthalene, anthracene, Once they are released, they not only produce toxic toluene and xylene. amines by reductive cleavage of azo linkages which To limit our scope, this review takes into causes severe effects on human beings through consideration of Reactive Black 5, which is more damaging the vital organs such as brain, liver, kidneys, difficult to remove. The reactive dyes are the largest central nervous and reproductive systems (Aksu, 2005; class of water soluble synthetic dyes with the greatest Iscen et al., 2007) and light penetration (Brown & De variety of colors and structure and are generally Uito, 1993; Mahony et al., 2002; Yesilada et al., 2003; Forgacs et al., 2004; Kalyani et al., 2007) in aquatic
Journal of Urban and Environmental Engineering (JUEE), v.7, n.1, p.30-47, 2013 32 Vijayaraghavan, Basha and Jegan environment. Therefore, their removal causes a big Greluk & Hubicki (2010) recommended the environmental concern in industrialized countries and is adsorption/ion exchange as an alternative method for subjected to many scientific researches. the removal of reactive dyes. Application of commercial It is estimated that 10–20% of reactive dyes remain anion exchange resins to water contaminated with a in wastewater during the production and nearly 50% of broad range of reactive dyes were studied by Karcher et reactive dyes are lost through hydrolysis during the al. (2001, 2002) and reported that anion exchangers dyeing process and their removal from effluent is possess excellent adsorption capacity (200–1200 difficult by conventional physical/chemical as well as μmol/g) as well as efficient regeneration property for biological treatment (Manu & Chaudhari, 2002; Li et their removal and recovery. The applicability of ion al., 2009; Greluk & Hubicki, 2010). Therefore, a large exchange resin containing acrylic matrix for removing quantity of the dyes appears in wastewater (Heinfling et other classes of dyes were well documented by al., 1997). These dyestuffs are designed to resist Bayramoglu et al. (2009), Dulman et al. (2009), biodegradation. Wawrzkiewicz & Hubicki (2009) and Barsanescu et al. Synthetic reactive dyes are considered as recalcitrant (2009). Thus Acrylic anion exchangers is more xenobiotic compounds, due to the presence of an N=N advantage than styrenics by exhibiting high efficiency bond and groups such as aromatic rings that are not of anion exchange capacities and polluting less. easily degraded. The discharge of these colored compounds into the environment causes considerable By Membrane filtration non-aesthetic pollution and serious health risks (Martínez & Brillas, 2009). Reverse osmosis (RO) and electro dialysis are the important examples of membrane filtration technology. REMOVAL METHODS Electrolyte is important in dyeing process for exhaustion of dye. The concentration of neutral Many processes were employed to remove dye electrolyte like NaCl in the dyeing bath is in the range molecules from industry effluents and the treatment of 2530 g/L for deep tone, 41.5 g/L for light tone and methods can be divided into the following categories: extended to 50 g/L in some exceptional cases. The exhaustion stage in reactive dyeing on cotton also Physical methods requires sufficient quantity of salt. The contribution of reverse osmosis in removing this high salt concentration Physical methods such as Adsorption (Chatterjee et al., is of great. This RO reject can be reused again in the 2009a; Chatterjee et al., 2009b), Ion exchange (Labanda process. For reactive dyeing on cotton, the presence of et al., 2009) and Membrane filtration (Ahmad & Puasa, electrolytes in the waste water causes an increase in the 2007) were employed in the removal of dyes. The main hydrolyzed dye affinity making it difficult to extract. disadvantages of these physical methods were they The total dissolved solids from waste water were simply transfer the dye molecules to another phase removed by reverse osmosis. Though it is suitable for rather than destroying them and they were effective only removing ions and larger species from dye bath when the effluent volume is small (Robinson et al., effluents with high efficiency, it possesses some 2001). disadvantages like clogging of the membrane by dyes after long usage and high capital cost. In electro By Adsorption dialysis, the dissolved salts (ionic in nature) can also be removed by impressing an electrical potential across the Adsorption is the transfer of solute dye molecule at the water, resulting in the migration of cations and anions to interface between two immiscible phases in contact with respective electrodes via anionic and cationic permeable one another. The removal of colour from dye industrial membranes. To avoid membrane fouling it is essential effluents by the adsorption process using granular that turbidity, suspended solids, colloids and trace activated carbon has emerged as a practical and organics are to be removed prior to electro dialysis. economical approach. Chemical methods By Ion Exchange Chemical methods such as chemical oxidation (Osugi et Removal of Anions and Cations from dye industry al., 2009), electrochemical degradation (Yi et al., 2008), effluent can be carried out by Ion exchange method by and ozonation (Moussavi & Mahmoudi, 2009) were passing the waste water through the beds of ion employed in dye removal effectively. exchange resins where some undesirable cations or The treatment of synthetic dye house effluent by anions of waste water get exchanged for sodium or ozonation and hydrogen peroxide in combination with hydrogen ions of the resin. Ultraviolet light was vast in literature. A variety of oxidizing agents were used to decolorize wastes by
Journal of Urban and Environmental Engineering (JUEE), v.7, n.1, p.30-47, 2013 Vijayaraghavan, Basha and Jegan 33 oxidation techniques effectively. Among that sodium photolysis (Ince, 1999) and ozonation are promising in hypochlorite decolorizes dye bath efficiently. Even terms of performance. But in terms of economic aspect, though it is a low cost technique, it forms absorbable these methods have become most challenging problem. toxic organic halides. Ozone on decomposition Consequently, Gutierrez et al. (2001) discussed the generates oxygen and free radicals. The later combines interest in electrochemical methods to decolourise and with coloring agents of effluent, resulting in the degrade dye molecules. The electric current induces destruction of colors. The main disadvantage of this redox reactions resulting in the transformation and technique is that it requires an effective sludge destruction of the organic compounds and almost producing pretreatment. Also, these chemical methods complete oxidation to CO2 and H2O. with high cost were rarely used in the actual treatment At the same time Powell et al. (1994) reported that the process and the disposal of sludge containing chemicals small scale oxidizing methods using Fenton’s reagent, at the end of treatment requires further use of chemicals which has lower costs in comparison with ozone process in (Crini, 2006; Forgacs et al., 2004). dye liquor treatment. The oxidizing effect of the corona discharge is also known and it has been reported by Advanced Oxidation Process (AOP) Goheen et al. (1994) as an effective method to bleach organic dyes using a stainless steel electrode. Steel Philippe et al. (1998); Slokar & Le Marechal (1998) electrodes were used commonly in electrochemical were reported that the conventional water treatment technology to remove color by generating ferrous technologies such as solvent extraction, activated hydroxide and ferric oxyhydroxide. Yang et al. (2000) carbon adsorption and chemical treatment process such reported a new result for the color removal of dye from as oxidation by ozone (O3) often produce hazardous by- wastewater by applying electro generated hypochlorite products and generate large amount of solid wastes, ions and (Ru+ Pt)Ox binary electrodes. Even if the removal which require costly disposal or regeneration method. of dyes from wastewater in an economic way by using Due to these reasons, Mahadwad et al. (2011) electrochemical method, the low-cost electrode production considerable attention had been focused on complete remains a major concern. Zero Valent Iron (ZVI) oxidation of organic compounds to harmless products Chatterjee et al. (2010) discussed the development of such as CO2 and H2O by the AOP. El-Dein et al. (2003) new treatment strategies to degrade the dye molecules supported the AOP and reported that it provides a using Zero-Valent iron (ZVI) particles. These are promising alternative method to treat the textile inexpensive, environmental friendly strong reducing wastewater. The UV-driven AOPs use UV light with an agents and Sun et al. (2006) reported that ZVI can donate oxidizer such as H2O2 and/or ozone to generate two electrons to many environmental contaminants as FeO hydroxyl radicals (OH-) that attack organic compounds Fe² + 2e. non selectively with a high reaction rate. Based on the Chatterjee et al. (2010) also reported that due to its studies from Shu et al. (1994) and Galindo & Kalt effective electron donating capacity, ZVI particles had (1998) it was observed that the decolorization of textile been studied for the treatment of wastewater contaminated dyes using H2O2/UV had shown it to decolorize dilute with chlorinated compounds, nitro aromatic compounds, aqueous solutions (20 mg/L) of azo dyes. nitrates, heavy metals, organochlorine pesticides, and dyes. Fan et al. (2009) reported that the reaction between FeO + Electrochemical Method and H2O or H can generate H atoms, which induce the cleavage of the azo bond (–N N–), thus damaging the The requirement of chemicals and the temperature to chromophore group and conjugated system of azo dyes. carry the electro chemical reaction is less than those of Saxe et al. (2006) reported that ZVI particles convert azo other equivalent non-electrochemical treatment. It can dye into some products that were more susceptible to also prevent the production of unwanted side products. biological degradation process. Chang et al. (2006) But, if suspended or colloidal solids were high in discussed about the other advantages of using ZVI concentration in the waste water, they slow down the particles for the decolorization process include a low iron electrochemical reaction. Therefore, those materials concentration remaining in the sludge, no requirement for need to be sufficiently removed before electrochemical further treatment of effluents and easy recycling of the oxidation. spent iron powder by magnetism. Low-cost, is easy-to- Ceron et al. (2004) reported that many of the obtain, and has good effectiveness and ability of degrading commercially used dyes are resistant to biological and contaminants. physico-chemical methods (Delee et al., 1998; (Vandevivere et al., 1998; Anbia et al., 2010). Also Biological methods Ceron et al. (2004) suggested that coagulation (Vandevivere et al., 1998), coagulation – electro Bioaccumulation and biosorption are the two main oxidation (Xiong et al., 2001), adsorption (Morais et al., technologies in biological process for of dye bearing 1999), electrolysis (Davila-Jimenez et al., 2000), industrial effluents. They possess good potential to
Journal of Urban and Environmental Engineering (JUEE), v.7, n.1, p.30-47, 2013 34 Vijayaraghavan, Basha and Jegan replace conventional methods for the treatment of dyes effectiveness, usage areas, interfere with other industry effluents (Volesky & Holan, 1995; Malik, wastewater components, or cause wastes that require 2004). Biological process can be carried out in situ at retreatment and also they suggested that the biologic the contaminated site, these are usually environmentally treatment method especially anaerobic treatment in the benign i.e., no secondary pollution and they were cost case of azo dyes is an alternative to the physicochemical effective. These are the principle advantages of method which was relatively inexpensive and may be biological technologies for the treatment of dye industry preferred for decolorization based on the investigation effluents. Hence in recent years, research attention has by Van der Zee et al. (2001); Van der Zee & Villaverde been focused greatly on biological methods for the (2005); Carliell et al. (1995) supported the same i.e., in treatment of effluents (Prasad & Freitas, 2003; most cases, the dyes were easily reduced under Vijayaraghavan & Yun, 2008). The disadvantage of this anaerobic condition. The main disadvantage of azo dye degradation process is that it suffers from low reduction under anaerobic conditions were the degradation efficiency or even no degradation for some production of aromatic amines, which usually do not dyes (Stolz, 2001; Pearce et al., 2003) and practical degrade under these conditions (Mendez-Paz et al., difficulty in continuous process. Vijayaraghavan & Yun 2005; Razo-Flores et al., 1996) and tend to accumulate (2008) clearly demonstrated the difference between at toxic levels (Carliell et al. 1995; Gottlieb et al., bioaccumulation and biosorption in their review. 2003). Such amines, however, were reported to be Bioaccumulation is defined as the phenomenon of readily bio-transformed under aerobic conditions (Tan uptake of toxicants by living cells; whereas, biosorption et al. 2000; Iþýk & Sponza, 2004). The color and COD can be defined as the passive uptake of toxicants by removal efficiencies were investigated by Sponza & dead or inactive biological materials. The important Isýk (2002) using anaerobic - aerobic sequential advantage of biosorption than bioaccumulation process processing for treatment of 100 mg/L of di-azo dye with is the use of living organisms is not advisable for the glucose as the carbon source and reported the color continuous treatment of highly toxic effluents. This removal efficiency as 96%. Supaka et al. (2004) problem can be overcome by the use of dead biomass, obtained 78.2% color removal and 90% COD removal which is flexible to environmental conditions and in a sequential anaerobic – aerobic system that was used toxicant concentrations. to treat Remozal Black B dye. Isýk & Sponza (2004) Erdal & Taski (2010) discussed about various reported 92.3 and 95.3% color and COD removal treatment methods exist for the removal of color from efficiencies, respectively, when using an upflow industrial effluents, including physico-chemical and anaerobic sludge blanket -aerobic stirred tank reactor biological processes. Although a number of chemical, sequential system to treat Congo Red dye. Kapdan & physical processes namely flocculation, chemical Oztekin, (2006) investigated Remozal Rot dye and coagulation, precipitation, ozonation and adsorption reported over 90% color removed and more than 85% were employed for the treatment of dye bearing COD removal efficiency in an anaerobic/aerobic SBR wastewaters. Aravindhan et al. (2007) and Sarioglu et system. Khehra et al. (2006) reported 98% color al. (2007) reported that they possess some inherent removal and 95% COD removal efficiency in an limitations such as high cost, formation of hazardous anoxicaerobic sequential bioreactor system used to treat by-products and intensive energy requirements. Acid Red 88 azo dye. Zaoyan et al. (1992) obtained In addition to that Erdal & Taski (2010), Banat et al. 65% color and 74% COD removal efficiencies in textile (1996), Slokar & Marechal, (1998) reported that the wastewater contaminated with azo dyes using an physico-chemical processes were usually inefficient, anaerobic-aerobic rotating biodisc system. costly and not adaptable to a wide range of dye wastewater. Erdal & Taski (2010), Fu & Viraraghavan Enzymatic Treatments (2001); Wang et al. (2009) and Aksu (2005) had suggested the increasing interest of biological processes, Roriz et al. (2009) mentioned that physical and such as biodegradation, bioaccumulation and chemical methods have high costs, low efficiency and biosorption due to their cost effectiveness, ability to cannot be used with a great variety of dyes and they produce less sludge and environmental benignity. suggested that the use of enzyme based methods are Fungi and algae had been played important role in good alternative. Compared to the conventional dye decolorization. Wang et al. (2009) reported that methods, application to recalcitrant materials, operation adsorption rather than degradation plays a major role at high and low contaminant concentrations over a wide during the decolorization process by fungi and algae. pH, temperature and salinity range, biomass acclimatization was irrelevant and straight forward Anaerobic Treatment process control were the potential advantages of the enzymatic treatments reported by Duran & Esposito Karatas et al. (2010) reported the unsuitability of (2000) and Roriz et al. (2009). physicochemical decolorization methods regarding cost
Journal of Urban and Environmental Engineering (JUEE), v.7, n.1, p.30-47, 2013 Vijayaraghavan, Basha and Jegan 35
REACTIVE BLACK 5 TREATMENT same R. oryzae was used as dead fungal cell MECHANISMS adsorbent, Polman & Breckenridge (1996) reported 452 mg/g of dead biomass of R. oryzae. Surprisingly very few studies show the interest Fu & Viraraghavan (2001) distinguish obviously towards continuous operation for dye removal. That about living cells and dead cells of biomass. Lignin too the very low flow rate in micro level was used in modifying enzymes, laccase, manganase peroxidase their investigations. Though a high level of flow rate (MnP) and lignin peroxidase (LiP) were produced in was desired to analyze, multidye treatment was living cells to mineralize the dyes. Also, the relative essential to reach a sustainable solution to dye contribution of laccase, MnP and LiP for the industry effluents since effluents emanating from the decolorization of dyes were different for different industry have the dye mixture (Vijayaraghavan et al., fungus. The mechanism for dead cells is biosorption, 2008). Without intensive research in continuous which involves physico-chemical interactions, such treatment of effluents emanating from dye industries, as adsorption, deposition and ion-exchange. An the problem does not reach the sustainable end obvious comparision was reached by Fu & (Vijayaraghavan & Yun, 2008). The search for Viraraghavan (2001) for living and dead fungal efficient, eco-friendly and cost effective continuous biomass. In screening a number of bacteria, fungi and treatment for wastewater was very limited in yeast for the binding capacity of reactive dyes, literature. Serkan & Taskin, (2010), Karatas et al. Polman & Breckenridge (1996) observed that among (2010), Vijayaraghavan & Yun (2007), 28 microbial species 64% of the dead forms had a Vijayaraghavan et al. (2008), Vijayaraghavan & Yun higher adsorption capacity for the reactive black 5 (2008) and were discussed the continuous operation dye waste. for dye industry waste water treatment. Operating conditions and nutrient supply were the Vijayaraghavan & Yun (2008) reported that the two important constraints for the living cells though industries need to develop on-site or in-plant facilities they had different decolorization mechanisms. to their own effluents and minimize the contaminant Though the biosorptive capacity of dead cells may be concentrations to acceptable limits prior to their greater than or equal to or less than those of living discharge. Also, Vijayaraghavan & Yun (2008) and cells. Dead cells were easy to handle, simple for Atkinson et al. (1998) suggested that, before selecting regeneration and can be utilized as obtained from a wastewater treatment facility, a considerable industrial sources as a waste product. Therefore, amount of laboratory and engineering work must be Kapoor & Viraraghavan (1995) and Fu & completed prior to system design. Hence this review Viraraghavan (2001) suggested that the dead cells limits to a particular dye, i.e. Reactive Black 5 and an were effective than living cells. Though the same was attempt is made to analyze the treatment of reactive supported by the investigation of Polman & black 5 in all circumstances through literature. Breckenridge (1996) using R.oryzae, a contradictory Fu & Viraraghavan (2001) reported in their review was noticed by using Xeromyces bisporus for the that the white rot fungi namely Phanerochaete biosorption of Reactive Black 5 Waste. Table 1, chrysosporium was used in early 1980’s to decolorize Table 2, and Table 3 represents the living cells, dead the lignin containing pulp and paper waste water. cells, Chemical methods for the treatment of reactive Thereafter P.chrysosporium had been examined for black 5, respectively. decolorization of pulp mill waste water and various Mohey El-Dein et al. (2001) reported that the dyes by many researchers (Glenn & Gold, 1983; kinetic parameters for the decolorization of Reactive Lankinen et al., 1991; Cammarto & Sant Anna, 1992; Black 5 with H2O2/UV using batch experiments. The Pasti-Grigsby et al., 1992; Spadaro et al., 1992; decolorization rate is first order with respect to dye Ollikka et al., 1993; Bilgic et al., 1997; Young & Yu, concentration until 90% of the dye was decolorized. 1997; Tatarko & Bumpus, 1998). The dependence on H2O2 concentration was shown to Among various dyes, Young & Yu (1997) reported be first order for low concentrations and zero order that reactive black 5 showed 11.3 % removal after 9 for high concentrations. The reaction coefficient k1 days contact with P. chrysosporium. The initial dye was found to be a linear function of UV intensity, k1 concentration of reactive black 5 used in this = k1o Io with k1o = 10.334 Einstein/L. Little investigation was 40–50 mg/L. The Biosorption is mineralization of C.I. Reactive Black 5 (~20%) took carried out by ligninase catalyzed. place until 90% of the dye was decolorized. 100% At the same time, other than white rot fungi, decolorization corresponded to more or less 40–50% namely Rhizopus oryzae investigated by Gallagher et mineralization. The dye could be further mineralized al. (1997) and Polman & Breckenridge (1996) (70–85%) with extended radiation time. showed an adsorption of 99 mg/g of biomass for Mohey El-Dein et al. (2003) developed a kinetic reactive black 5 dye waste while using this Rhizopus model for the decolorization of the diazo dye oryzae as a living fungal cell. Contradictorily the Reactive black 5 by H2O2/UV.
Journal of Urban and Environmental Engineering (JUEE), v.7, n.1, p.30-47, 2013 36 Vijayaraghavan, Basha and Jegan
Table 1: Earlier investigations on use of living cells for treatment of Reactive Black 5 % Removal (or) Culture Mechanism Reference Dye uptake (mg/g) Candida rugosa 31 mg of dye Polman & Breckenridge Adsorption absorbed/g of biomass (1996) Cryptococcuss heveanensis 60 mg of dye Polman & Breckenridge Adsorption absorbed/g of biomass (1996) 38 mg of dye Polman & Breckenridge Dekkera bruxellensis Adsorption absorbed/g of biomass (1996) Endothiella aggregate 44 mg of dye Polman & Breckenridge Adsorption absorbed/g of biomass (1996) Geotrichum fici 7 mg of dye Polman & Breckenridge Adsorption absorbed/g of biomass (1996) Kluyveromyces waltii (yeast) 60 mg of dye Polman & Breckenridge Adsorption absorbed/g of biomass (1996) Penicillium chrysosporium 11.3% Ligninase-catalyzed Young & Yu (1997)
Pichia carsonii (yeast) 25 mg of dye Polman & Breckenridge Adsorption absorbed/g of biomass (1996) Rhizopus oryzae 99 mg of dye Polman & Breckenridge Adsorption absorbed/g of biomass (1996) Trametes versicolor 15.6% Ligninase-catalyzed Young & Yu (1997)
Tremella fuciformis 92 mg of dye Polman & Breckenridge Adsorption absorbed/g of biomass (1996) Xeromyces bispourus 11 mg of dye Polman & Breckenridge Adsorption absorbed/g of biomass (1996) Penicillium chrysosporium Ali Mazmanci & Ali 21.0% Ünyayar, (2005) Ali Mazmanci & Ali Penicillium florida 40.0% Ünyayar, (2005) Ali Mazmanci & Ali Penicillium eryngii 9.6% Ünyayar (2005) Ali Mazmanci & Ali Penicillium sapidus 3.6% Ünyayar, (2005) Ali Mazmanci & Ali Funalia trogii ATTC 200800 99% Ünyayar (2005) Candida oleophila 200 mg/g Marco S. Lucas et al Biodegradation 100% (2006)
Table 2: Earlier investigations for treatment of Reactive Black 5 by Dead Cells % Removal (or) Culture Mechanism Reference Dye uptake (mg/g) Cryptococcuss heveanensi 76 mg /g Biosorption Polman & Breckenridge, (1996) (yeast) Candida rugosa (yeast) 31 mg /g Biosorption Polman & Breckenridge, (1996) Dekkera 36 mg /g Biosorption Polman & Breckenridge, (1996) bruxellensis (yeast) Endothiella aggregate 44 mg /g Biosorption Polman & Breckenridge, (1996) Geotrichum Fici 45 mg /g Biosorption Polman & Breckenridge, (1996) Kluyveromyce 72 mg /g Biosorption Polman & Breckenridge, (1996) waltii (yeast) Pichia carsonii (yeast) 32 mg /g Biosorption Polman & Breckenridge, (1996) Rhizopus oryzae 452 mg /g Biosorption Polman & Breckenridge, (1996) Treemella fuciformis 79 mg /g Biosorption Polman & Breckenridge, (1996) Xeromyces bisporus 11 mg /g Biosorption Polman & Breckenridge, (1996)
Journal of Urban and Environmental Engineering (JUEE), v.7, n.1, p.30-47, 2013 Vijayaraghavan, Basha and Jegan 37
Corynebacterium 111.8 (L) Biosorption Vijayaraghavan & Yun , (2007a) Glutamicum( raw) Corynebacterium glutamicum 165.2 (L) Biosorption Vijayaraghavan & Yun, (2007a) (protonated) Corynebacterium glutamicum 257.3 (L) Biosorption Vijayaraghavan & Yun, (2007a) (decarboxylated) Corynebacterium glutamicum 75.8 (L) Biosorption Vijayaraghavan & Yun, (2007a) ( polysulfone-raw) Corynebacterium glutamicum (polysulfone- 109.1 (L) Biosorption Vijayaraghavan & Yun, (2007a) protonated) Corynebacterium glutamicum( polysulfone- 180.7 (L) Biosorption Vijayaraghavan & Yun, (2007a) decarboxylated) Pleurotus sajor-caju Kumarasamy murugesan et al (purified laccase from Biosorption 84.4%, .,(2007) a white rot fungus) Corynebacterium 352 mg/g Biosorption Vijayaraghavan et al. (2007) glutamicum (free biomass) Corynebacterium glutamicum (Alginate 282 mg/g Biosorption Vijayaraghavan et al., (2007) immobilized biomass) Corynebacterium glutamicum( Polysulfone 291 mg/g Biosorption Vijayaraghavan et al . (2007) immobilized Biomass) Corynebacterium 419 (L) Biosorption Vijayaraghavan & Yun ,(2007b) glutamicum Corynebacterium 88.9 mg/g glutamicum(Polysulfone- Biosorption Vijayaraghavan & Yun, (2008) 61.8% immobilized) Laminaria sp. (Brown 101.5 (L) , 41.9 mg/g Biosorption Vijayaraghavan & Yun, (2008) seaweed ) 72.7% Corynebacterium glutamicum(Polysulfone- 70.2 mg/g Biosorption Vijayaraghavan et al .,(2008) Immobilized Esterified ) Trametes Pubescens(crude 60% Decolorization Margarida S. Roriz et al. (2009) laccase ) Penicillium Restrictum 142.04 mg/g Biosorption Cansu Filik Iscen et al . (2007) Rhodopseudomonas 100% Biodecolorization Wang Xingzu et al . (2008) Palustris Bacterial strain Biological 92.56% HuiWang et al. (2009) Enterobacter sp. EC3 decolorization Penicillium Chrysogenum Serkan Erdal & Mesut Taskin, 89% Biosorption MT-6 (2010) *L dye uptake by Langmuir model
Journal of Urban and Environmental Engineering (JUEE), v.7, n.1, p.30-47, 2013 38 Vijayaraghavan, Basha and Jegan
Table 3: Earlier investigations for treatment of Reactive Black 5 by chemical methods % Removal (or) Method/chemical Dye uptake Reference (mg/g) Photocatalytic degradation of reactive black-5 dye using TiO2 impregnated ZSM-5. 98% Mahadwad et al., (2011) Batch Reactor Electrochemical cell for the removal of Reactive 100 Maria Rivera et aL., (2011) Black 5. cubic and cylindrical cell configuration Zero-Valent Iron modified with various surfactants Chatterjee et al. (2010) Acid acrylic resins Amberlite IRA-458 and Amberlite Magdalena G & Zbigniew H, NR IRA-958 (2010) Zero - Valent Iron Chompuchan et al. (2009) Fenton/UV-C and ferrioxalate/H O /solar light 2 2 90% Lucas and Peres (2007) processes Combined sonolysis and ozonation 84 Zhiqiao et al. (2007) Solar assisted photocatalytic and photochemical Muruganandham et al. (2006) Degradation Diamond and metal alloys electrodes 95% Ceron Rivera et al. (2004) Hydrogen peroxide and UV radiation 90% Mohey El-Dein et al. (2003) Hydrogen peroxide and UV light 100 % Mohey El-Dein et . (2001)
Ceron Rivera et al. (2004) studied the treatment of degradation using hydrogen peroxide resulted in the Reactive black 5 by electrochemical method using partial removal of the dye. diamond, aluminium, copper and iron - zinc alloy Vijayaraghavan & Yun (2007a) developed a electrodes. The electrode potential range used in this biosorbent from C. glutamicum for the treatment of investigation was 1.0 to 2.5 V. They found that 95% reactive black 5. Also, they suggested that bacteria color removal and up to 65–67% COD removal were possess high reactive dye biosorption capacity only in done with copper and iron electrodes. strong acidic conditions due to the nature of their Ali Mazmanci and Ali Unyayar, (2005) investigated binding sites also used a decarboxylated form of the decolorization of Reactive Black 5 by immobilised C. glutamicum, which can effectively biosorb reactive Funalia trogii. Cultures of F.trogii immobilised on black 5 under moderate pH condition of 4. Even though Luffa cylindrica sponge could effectively decolourise the decarboxylation process may incur additional the dye. The effect of mycelial age was also studied and process cost, this step was necessary to make the decolorization rate of a 3-day-old age culture was higher process feasible. Also, it should be noted that C. (8.22 mg dye/g dmw day) than those of 0- and 6-day- glutamicum can be collected at free of cost from the old cultures (6.86 and 7.80 mg dye/g dmw day). amino acid fermentation industries. The problems of Macroscopic and microscopic examinations showed that reusing the bacterial biomass for multiple cycles were dye was not biosorbed on the fungal mycelium. The solved by immobilizing the biomass in a polysulfone growth of F. trogii was inhibited by all tested dye matrix. Both free and polysulfone immobilized concentrations with compared to controls but this effect decarboxylated C. glutamicum performed well at pH 4 was minimised when the fungus was completely for the biosorption of reactive black 5, with maximum immobilised on the sponge. Using optimal mycelial age, uptakes of 257.3 and 180.7 mg/g dry beads, cultures of L. cylindrica sponge were tested for their respectively, according to the Langmuir model. ability towards dye decolorization at different initial However, the reactive black 5 isotherms were well concentrations. The kinetic parameters of decolorization described by the Redlich-Peterson model with high were calculated according to Lineweaver–Burk plots correlation coefficients compared to the Langmuir (Km of 106.04 mg dye/L and Vmax of 117.64 mg dye/L model. Kinetic experiments revealed the involvement of day). intraparticle diffusion resistance in the case of the Muruganandham et al. (2006) reported the immobilized beads. Desorption was possible only in the photocatalytic oxidative degradation of Reactive Black case of immobilized beads with 0.01 M NaOH as the 5 using TiO2-P25 as photocatalyst and sunlight as elutant. Column experiments proved that immobilized irradiation source in slurry form. A complete beads can be efficient in the continuous biosorption of degradation of 3.85×10−4M dye solution under solar reactive black 5, with the decarboxylated biomass irradiation was observed in 3.5 h. The photochemical recorded at 78.6 mg/g dry beads. Although earlier breakthrough and delayed exhaustion times were
Journal of Urban and Environmental Engineering (JUEE), v.7, n.1, p.30-47, 2013 Vijayaraghavan, Basha and Jegan 39 observed with progressive cycles, the polysulfone Kumarasamy Murugesan et al. (2007) applied the immobilized decarboxylated biomass maintained high response surface methodology (RSM) for the reactive black 5 uptake values of over 74.1 mg/g dry decolorization of the azo dye reactive black 5 using beads during all three cycles. purified laccase from a white rot fungus Pleurotus Marco S. Lucas et al. (2006) used Candida oleophila sajor-caju. They observed that the presence of 1- which efficiently decolorized the commercial textile hydroxybenzotriazole (HBT) was essential for diazo dye Reactive Black 5. Aerobic batch cultures of decolorization of reactive black 5 by purified laccase C.oleophila could completely decolorized up to 200 from P.sajor-caju. Box Behnken design using RSM mg/L. Moreover, this performance was achieved in just with four variables namely dye (25100 mg/l), enzyme 24 h of incubation at 26oC in the presence of as little as (0.52.5 U/ml), redox mediator concentrations (0.51.5 5 g of glucose/L and without visible signs of dye mM) and incubation time (2448 h) were employed in adsorption to yeast cells. It was found that this study to optimize significant correlation between decolorization occured during the exponential growth the effects of these variables on the decolorization of phase and neither laccase nor manganese-dependent reactive black 5. The optimum concentration of dye, peroxidase activities were detected in the culture enzyme, HBT, and time were found to be 62.5 mg/L, medium. 2.5 U/ml, 1.5 mM and 36 h, respectively, for maximum Cansu Filik Iscen et al. (2007) studied the decolourization of Reactive Black 5 (84.4%). A biosorption of Reactive Black 5 dye on dried quadratic model is proposed for dye decolorization Penicillium restrictum biomass with respect to pH, through this design. Increased decolorization was contact time, biosorbent dosage and dye concentrations. observed with increase in enzyme concentration at The effect of temperature on the biosorption efficiency lower dye concentration. Interaction between HBT and was also carried out and the kinetic parameters were dye concentrations was negligible. The optimization of determined. Optimum initial pH, equilibrium time and HBT is independent of dye concentration. biomass concentration for reactive black 5were found Lucas & Peres (2007) studied the feasibility of −3 that 1.0, 75 min and 0.4 g dm at 20 °C, respectively. employing different photoxidation systems like The maximum biosorption capacities (qmax) of reactive Fenton/UV-C and ferrioxalate/H2O2/solar light in the black 5 onto dried P. restrictum biomass were 98.33 and decolorization and mineralization of Reactive Black 5.
112.50 mg/g biomass at 175 mg/L initial dye Batch experiments were carried out to evaluate the o o concentration at 20 C and 50 C, respectively, and it was influence of different processes on Reactive Black 5 142.04 mg/g biomass at 200 mg/L initial dye decolorization in the first stage. During the second stage o concentration at 35 C. The results indicated that the they investigated the optimal operational conditions of biosorption process obeyed a pseudo-second-order Fenton/UV-C and ferrioxalate/H2O2/solar light kinetic model. processes like pH, H2O2 dosage, iron dosage, Reactive Zhiqiao He et al. (2007) investigated the Black 5 concentration and source of light. The results decolorization of the azo dye C.I. Reactive Black 5 indicated that reactive black 5 can be effectively solution by a combination of sonolysis and ozonation. decolorized using Fenton/UV-C and The results showed that the optimum pH for the reaction ferrioxalate/H2O2/solar light processes with a small was 11.0. Increasing the initial concentration of reactive difference between the two processes, 98.1% and black 5 led to a decreasing decolorization rate. Under 93.2%, after 30 min respectively. Although there was the experimental conditions, the decolorization rate lesser difference in dye decolorization, significant increased with an increase in temperature. The increment in TOC removal was found with Fenton/UV- decolorization of reactive black 5 followed pseudo-first- C process (46.4% TOC removal) related to order reaction kinetics. Based on the decolorization rate ferrioxalate/H2O2/solar light process (29.6% TOC constants obtained at different temperatures within the removal). This fact revealed that UV-C low-pressure range 287–338 K and the Arrhenius equation, the mercury lamp although with its small effect on dye apparent activation energy (Ea) was calculated to be decolorization was particularly important in dye 11.2 kJ/mol. This indicated that the reaction had little mineralization, when compared to solar light. However, dependence on temperature. The color decay was ferrioxalate/H2O2/solar light system showed large considerably faster than the decrease in total organic potential on photochemical treatment of textile carbon (TOC), which was attributed to the ease of wastewater with particular interest from the economical chromophore destruction. Hence the efficiency of point of view. decolorization was 84% compared with 4% of TOC Vijayaraghavan et al. (2007) used Corynebacterium removal after 5 min reaction. Additionally, muconic glutamicum, a lysine fermentation industry waste, acid, (2Z)-pent-2-enedioic acid and maleic acid were showed better removal of Reactive black 5. Due to identified as main oxidation products by gas practical difficulties in solid–liquid separation, the free chromatography coupled with mass spectrometry (GC– biomass was immobilized in two polymer matrices: MS) after 150 min of reaction. calcium alginate and polysulfone. Initially, the
Journal of Urban and Environmental Engineering (JUEE), v.7, n.1, p.30-47, 2013 40 Vijayaraghavan, Basha and Jegan optimization of biomass loading in polymeric beads and glutamine or lactate as carbon source with concentration bead dosage were examined. Of the different more than 500 mg/L when lactate is selected, NH4Cl as combinations examined, 4% (with bead dosage of 2 g a nitrogen source with concentration more than 100 per 40 ml) and 14% (with bead dosage of 1 g per 40 ml) mg/L, NaCl concentration not exceeding 5%, and in the case of alginate and polysulfone beads, Reactive Black 5 concentration less than 700 mg/L. The respectively, were identified as the optimal conditions. results showed that partial aromatic amines produced According to the Langmuir model, at pH 1, the with Reactive Black 5 reduction were further degraded maximum reactive black 5 uptakes of 352, 282 and 291 during the extended period. Anaerobic partial mg/g were observed for free, alginate and polysulfone- mineralization of Reactive Black 5 was suggested and a immobilized biomass, respectively. According to the possible degradation pathway was proposed. Weber - Morris model, intraparticle diffusion was found Vijayaraghavan & Yun (2008a) employed to be the potential rate limiting step for the immobilized Polysulfone-immobilized Corynebacterium glutamicum beads. Regeneration experiments, with 0.01 M NaOH as a biosorbent, for the continuous removal of Reactive and Na2CO3 as eluents, revealed that polysulfone beads black 5 from aqueous solution, in an up-flow packed exhibited invariable Reactive Black 5 uptake capacity column. The biosorbent performance was evaluated and very high mechanical stability even at the end of with different bed heights (8–10 cm), flow rates (0.5–1 twentieth cycle, confirming the technical feasibility of ml/min) and initial dye concentrations (50–100 mg/L). the biosorption process for industrial applications. Favorable conditions for Reactive black 5 biosorption Vijayaraghavan & Yun (2007b) used were observed with the highest bed height (10 cm), Corynebacterium glutamicum as a biosorbent for the lowest flow rate (0.5 ml/min) and lowest initial dye treatment of Reactive Black 5. The effect of concentration (50 mg/L); at which the Reactive Black 5 pretreatment on the biosorption capacity of C. uptake and % removal, 88.9 mg/g and 61.8%, glutamicum towards Reactive Black 5 using several respectively, were recorded. Mathematical modeling of chemical agents such as HCl, H2SO4, HNO3, NaOH, experimental data was performed, using a non-linear Na2CO3, CaCl2 and NaCl were reported. Among these form of Thomas modified dose–response and Yoon– reagents, 0.1M HNO3 gave the maximum enhancement Nelson models, to simulate the breakthrough curves. of the Reactive Black 5 uptake, exhibiting 195 mg/g at Very favorable results were obtained with Thomas and pH 1 with an initial Reactive Black 5 concentration of Yoon–Nelson models, which described the experimental 500 mg/L. The solution pH and temperature were found data well, with very high correlation coefficients. In an to affect the biosorption capacity. The biosorption attempt to regenerate the exhausted biosorbent for isotherms derived at different pH and temperatures possible reuse in multiple cycles, 0.1M NaOH was revealed that a low pH (pH = 1) and high temperature employed as elutant. Due to continuous usage of (35oC) favored biosorption. The biosorption isotherm polysulfone-immobilized C.glutamicum in three was well represented using three-parameter models sorption–desorption cycles, a decreased breakthrough (Redlich–Peterson and Sips) compared to two- time, increased exhaustion time, broadened mass parameter models (Langmuir and Freundlich models). transfer zone, flattened breakthrough curve and As a result, high correlation coefficients and low decreased Reactive Black 5 uptake were observed with average percentage error values were observed for progressive cycles. Linear regression of the three-parameter models. According to the Langmuir breakthrough, uptake and critical bed length revealed model, a maximum Reactive uptake of 419 mg/g was that the sorption zone would reach top of the bed after obtained at pH 1 and a temperature of 35oC, according 18 cycles, with the column bed completely exhausted to the Langmuir model. The kinetics of the biosorption after 35 cycles. The elutant, 0.1M NaOH, provided process with different initial concentrations (500–2000 uniform elution efficiencies greater than 99.2% in all mg/L) was also monitored and the data were analyzed three cycles. using pseudo-first and pseudo-second order models, Vijayaraghavan & Yun (2008b) investigated the with the latter describing the data well. This system biosorption of Reactive Black 5 using the brown indicated a spontaneous and endothermic process. The seaweed Laminaria Sp. in both batch and column modes use of a 0.1M NaOH solution successfully desorbed of operation. Protonation of the native Laminaria almost all the dye molecules from dye-loaded C. biomass with 0.1 M HCl, considerably improved its glutamicum biomass at different solid-to-liquid ratios Reactive Black 5 biosorption capacity. At various examined. initial concentrations (50 - 200 mg/L), batch sorption Wang Xingzu et al. (2008) analyzed the strain of equilibrium was reached within 3 h, followed by slow photosynthetic bacterium, Rhodopseudomonas palustris attainment of equilibrium and the kinetic data obtained for the decolorizing Reactive Black 5 efficiently under were interpreted in terms of the pseudo-second order anaerobic condition. By a series of batch tests, the model. Biosorption isotherm experiments, under suitable conditions for Reactive Black 5 decolorization different pH and temperature conditions, revealed that were obtained, namely, pH < 10, light presence, decreasing the pH and increasing the temperature
Journal of Urban and Environmental Engineering (JUEE), v.7, n.1, p.30-47, 2013 Vijayaraghavan, Basha and Jegan 41 favored biosorption. According to the Langmuir model, Reactive Red 198 in synthesized wastewater and the maximum Reactive Black 5 uptake of 101.5 mg/g investigated the effects of the iron particle size, iron was observed at pH 1 and temperature of 40oC. 0.01 M dosage and solution pHs on the destruction of reactive NaOH solution successfully eluted all dye from the black 5 and RR198. The removal kinetic rates (kobs) of Reactive Black 5 -loaded Laminaria biomass. The RB5 (0.0109 min-1) and RR198 (0.0111 min-1) by 0.5% feasibility of the brown seaweed for the continuous NZVI were many times higher than those of microscale removal of Reactive Black 5 from aqueous solution was zerovalent iron (ZVI) (0.0007 min-1 and 0.0008 min-1, examined in an up-flow packed column (1 cm ID and 12 respectively). The iron dosage increment exponentially cm height). With a bed height, flow rate and initial increased the removal efficiencies of both Reactive Reactive Black 5 concentration at 10 cm, 1 ml/min and Black 5 and RR198. Additionally, lowering pH from 9 50 mg/L, respectively, the Laminaria biomass exhibited to 5 increased the decolorization kinetic rates of both an RB5 uptake and removal efficiency of 41.9 mg/g and reactive black 5 and RR198 by NZVI. The destruction 72.7%, respectively. The column was successfully of azo bond (N=N) in the chromospheres of both eluted using 0.01 M NaOH with an elution efficiency of reactive dyes led to decolorization of dye solutions. 97.7%. Greluk & Hubicki (2010) used strongly basic acrylic Vijayaraghavan et al. (2008) reported the ability of anion exchangers namely Amberlite IRA-458 and polysulfone-immobilized esterified Corynebacterium Amberlite IRA-958 for the removal of Reactive Black glutamicum for biosorption of Reactive Black 5 and 5. Adsorption experiments indicated that the amount of Reactive Orange 16 from single- and dual-dye solutions the dye adsorbed on both Amberlite IRA-458 and were investigated. Single-dye biosorption isotherm Amberlite IRA-958 were dependent on the initial dye experiments exposed that polysulfone-immobilized concentration in the range of 50–500 mg/L. Modeling of esterified Corynebacterium glutamicum performed well kinetic results showed that the sorption process of the in the biosorption of Reactive Orange 16, with a higher dye adsorption on both anion exchangers was best experimental uptake of 248.1 mg/g, compared to 174.1 described by the pseudo second-order kinetic model in mg/g for Reactive Black 5. Conversely, the uptake of the investigated concentration domain. The effect of Reactive Orange 16 was suppressed almost 2.5 times in temperature on dye removal showed that the maximum the presence of Reactive Black 5, whereas polysulfone- capacity was obtained at 318 and 308 K for the dye immobilized esterified Corynebacterium glutamicum adsorption on Amberlite IRA-458 and Amberlite IRA- maintained similar Reactive Black 5 uptakes in both 958, respectively. The adsorption isotherm data were single- and dual-dye systems. Several factors might be fitted well to the Langmuir isotherm and according to responsible for this effect, the most important being the this model, Amberlite IRA-458 and Amberlite IRA-958 number of sulfonate groups and the size of each reactive exhibited the highest monolayer sorption capacity of dye. The continuous biosorption of reactive dyes from 1295.93 and 1723.964 mg/g. single- and dual-dye solutions using an upflow packed Chatterjee et al. (2010) used Zero Valent Iron (ZVI) column was successful with polysulfone-immobilized particles for the reductive degradation of Reactive Black esterified Corynebacterium glutamicum being 5 in aqueous solution. The sizes of the synthesized ZVI regenerated and reused for three cycles. particles were in the microscale range, with an average Hui Wang et al. (2009) studied the decolorization of diameter of 13.57μm. The efficiency of surfactant- the Reactive Black 5 by a bacterial strain Enterobacter treated ZVI particles for the decolorization of reactive sp. EC3. The optimal conditions for the decolorizing black 5 solution was studied with three different activity of Enterobacter sp. EC3 were anaerobic surfactants namely Triton X-100, Cetyl Trimethyl conditions with glucose supplementation, at pH 7.0, and Ammonium Bromide and Sodium Dodecyl Sulfate. The 37oC. The maximum decolorization efficiency against normalized residual concentration after decolorization Reactive Black 5 achieved in this study was 92.56%. of 500 mg/L Reactive Black 5 by ZVI for 3 h was Roriz et al. (2009) studied the decolorization of the 0.236, while ZVI particles treated with Triton X-100 Reactive Black 5 by crude laccase from the white-rot (0.5 g/L), Cetyl Trimethyl Ammonium Bromide fungus Trametes pubescens using response surface (CTAB) (1.0 g/L), and Sodium Dodecyl Sulfate (SDS) methodology. The presence of the redox mediator 1- (2.5 g/L) exhibited normalized residual concentration of hydroxybenzotriazole greatly improved the 0.172, 0.154, and 0.393, respectively, after 3 h. The decolorization levels of Reactive Black 5 by crude color removal efficiency was found to be increased with laccase from T.Pubescens. The optimum concentrations the decrease in initial pH of dye solution and ZVI of 1-hydroxybenzotriazole, Reactive Black 5 and exhibited good color removal efficiency at acidic pH. laccase were 1.17mM, 150 mg/L and 500 U/l, Decolorization kinetics by pseudo-first-order rate respectively, for a maximum decolorization of Reactive equation showed that removal rate was increased after Black 5 (about 60% in 20 min). treatment with Triton X-100 as well as CTAB, while Chompuchan et al. (2009) used the nanoscale zero that was reduced after SDS treatment. valent iron (NZVI) to decolorize Reactive Black 5 and
Journal of Urban and Environmental Engineering (JUEE), v.7, n.1, p.30-47, 2013 42 Vijayaraghavan, Basha and Jegan
Karatas et al. (2010) investigated the efficiency of In the presence of the non-inert electrolyte NaCl, the the sequential anaerobic - aerobic system for complete decolorization was detected. However, due to decolorization of Reactive Black 5. The synthetic the chloro-organic compounds formed in the wastewater contained 150 mg/L dye and 3000 mg/L electrochemical oxidation with NaCl, the TOC removal glucose-COD. An upflow anaerobic sludge blanket in the most optimal condition was approximately 93%. (USAB) (CSAR) reactor and continuously stirred Mahadwad et al. (2011) studied the photocatalytic aerobic reactors were used to remove color and COD. degradation of Reactive Black 5 using supported TiO2 The methane gas production efficiencies were also photocatalyst based adsorbent as a semiconductor investigated under the anaerobic conditions. The UASB photocatalyst in a batch reactor. The synthesized - CSAR were operated at different organic loading rates photocatalyst composition was developed using TiO2 as (2.422.5 Kg COD/m3·day) and hydraulic retention photoactive component and zeolite (ZSM-5) as the times (3.2 - 30.1 h). The COD removal efficiencies adsorbent. The optimum formulation of supported decreased from 61 to 36.7% with increases in organic catalyst was found to be (TiO2: ZSM-5 = 0·15:1) which loadings from 2.4 to 22.5 Kg COD/m3/day in the gave the highest efficiency with 98% degradation of 50 anaerobic UASB reactor. The color removal decreased mg/L reactive black 5 solution in 90 min. The reduction from 99.8 to 90.7% when the hydraulic retention time in the chemical oxygen demand (COD, 88%) proves the decreased from 30.1 to 3.2 hours. The methane mineralization of the Reactive Black 5 dye along with production efficiencies obtained were 75 and 38.3% at the colour removal. The supported TiO2 was found to be the organic loading rates of 2.4 and 22.5 Kg COD/m3 stable for repeated use. day respectively. The effects of both sludge retention times and the food/mass (F/M) ratio on the COD CONCLUSION removal efficiencies were investigated in the aerobic reactor. COD removal efficiencies of 62.2 and 86.3% This review makes a simple comparison among various were obtained at 2 and 19 days sludge retention time in physicochemical methods namely photo catalysis, the aerobic reactor. The COD removal efficiencies were electrochemical, adsorption, hydrolysis and biological found to be 86.3 and 62.2% at F/M ratios of 0.112 and methods such as biosorption and bioaccumulation and 1.569 Kg COD/Kg day. The color and COD removal also discussed the merits and demerits of these methods efficiencies obtained were 99.8% and 95% by using 150 involved in the decolorization of reactive black 5. mg/L of Reactive Black 5 dye concentration in the The main disadvantages of the physical methods sequential anaerobic aerobic reactor. such as adsorption, ion exchange and membrane Erdal & Taskin (2010) reported the decolorization of filtration were that they simply transfer the dye Reactive Black 5 by Penicillium chrysogenum MT-6. molecules to another phase rather than destroying them Dye uptake was strongly depended on mycelial and they are effective only when the effluent volume is morphology. Small uniform pellets with 2 mm size and small. nutrient-poor medium were found to be better for dye The main disadvantage of the chemical methods uptake. Optimal conditions for dye uptake were such as chemical oxidation, electrochemical degradation determined as initial pH of 5.0, shaking speed of 150 and ozonation were the requirements of an effective rpm, temperature of 28°C, spore concentration of sludge producing pretreatment. Also, these chemical 107/ml, 10 g/L sucrose and 1 g/L ammonium chloride. methods with high cost were rarely used in the actual The maximum removal/uptake of dye by fungus was treatment process and the disposal of sludge containing 89% (0.267 g removed-dye) with 3.83 g/L of biomass chemicals at the end of treatment requires further use of production at an initial dye concentration of 0.3 g/L in chemicals. 100 h. The fungus was found to be a good bio-system Conventional water treatment technologies such as for the decolorization of the medium containing solvent extraction, activated carbon adsorption and Reactive Black-5. chemical treatment process such as oxidation by ozone Rivera et al. (2011) studied the decolorization of (O3) often produce hazardous by-products and generate Reactive Black 5 by an electrochemical technology in large amount of solid wastes, which require costly both cubic and cylindrical cell configurations. Low disposal or regeneration method. decolorization was detected in the treatment of pure The requirement of chemicals and the temperature solutions of Reactive Black 5, but a significant extent of to carry the electro chemical reaction was less than decolorization was observed in the presence of Na2SO4. those of other equivalent non-electrochemical treatment. The extent of decolorization was largely dependent on It can also prevent the production of unwanted side the cell configuration and the best results were obtained products. But if suspended or colloidal solids were high when the cylindrical cell was employed. Nearly in concentration in the waste water, they slow down the complete decolorization was achieved in 3 h for an electrochemical reaction. Therefore, those materials effluent containing 70 mg/L Reactive Black 5 and 0.1 M need to be sufficiently removed before electrochemical Na2SO4 and the TOC removal was approximately 95%. oxidation.
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Conference, Cairo, Egypt. By considering all the above said factors, as a Barsanescu, A., Buhaceanu, R., Dulman. V. (2009) Removal researcher, our prime aim is to find out the of Basic Blue 3 by sorption onto a weak acid acrylic resin. environmental benign technique to remove hazardous J. Appl. Polym. Sci. 113(6), 607–614. materials from environment. In this concern, from the Bayramoglu G, B. Altinas, M.Y. Arica (2009) Adsorption literature we conclude that, the biosorption is harmless kinetics and thermodynamic parameters of cation– and cost effective method to achieve this goal and also exchange resin. Chem. Eng. J. 152(3), 339– 346. this technique will not produce any secondary Bilgic, H., Gokcay, C.F., Hasirci, N. (1997) Color removal by pollutants. The natural materials like marine algae, white–rot fungi. In: Wise, D.L. (Ed.), Global Environmental Biotechnology. 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Journal of Urban and Environmental Journal of Urban and E Engineering, v.7, n.1, p.48-63 Environmental Engineering ISSN 1982-3932 J E www.journal-uee.org U doi: 10.4090/juee.2013.v7n1.048063
MATHEMATICAL MODEL FOR THE SIMULATION OF WATER QUALITY IN RIVERS USING THE VENSIM PLE® SOFTWARE
Julio Cesar de S. I. Gonçalves1 and Marcius F. Giorgetti2 1Department of Environmental Engineering, Federal University of Triângulo Mineiro, Brazil 2School of Engineering of São Carlos, University of São Paulo, Brazil
Received 25 January 2013; received in revised form 20 March 2013; accepted 04 April 2013
Abstract: Mathematical modeling of water quality in rivers is an important tool for the planning and management of water resources. Nevertheless, the available models frequently show structural and functional limitations. With the objective of reducing these drawbacks, a new model has been developed to simulate water quality in rivers under unsteady conditions; this model runs on the Vensim PLE® software and can also be operated for steady-state conditions. The following eighteen water quality variables can be simulated: DO, BODc, organic nitrogen (No), ammonia nitrogen (Na), nitrite (Ni), nitrate (Nn), organic and inorganic phosphorus (Fo and Fi, respectively), inorganic solids (Si), phytoplankton (F), zooplankton (Z), bottom algae (A), detritus (D), total coliforms (TC), alkalinity (Al.), total inorganic carbon (TIC), pH, and temperature (T). Methane as well as nitrogen and phosphorus compounds that are present in the aerobic and anaerobic layers of the sediment can also be simulated. Several scenarios were generated for computational simulations produced using the new model by using the QUAL2K program, and, when possible, analytical solutions. The results obtained using the new model strongly supported the results from the QUAL family and analytical solutions.
Keywords: Modeling; water quality; Vensim PLE; rivers
© 2013Journal of Urban and Environmental Engineering (JUEE). All rights reserved.
Correspondence to: Julio Cesar de S. I. Gonçalves, Tel.: +55 34 3318 5600. E-mail: [email protected]
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INTRODUCTION a single coefficient of biodegradation for water quality modeling in such a river would underestimate the actual In the past few decades, rivers have become the main impact and reduce the modeling capacity. recipients of wastewater that is generated from Given the relatively high frequency of accidental municipal and industrial sources with little to no spills, the diversity of the effluents being discharged treatment prior to discharge is common practice in many into a stream, and the need for mathematical models to developing countries (Ghosh & McBean, 1998; Zhang be easy to understand and implement, a new modeling et al., 2012). River pollution is one of the most serious system that overcomes the limitations described above water resources problems of the present day. These is needed. To accomplish this, the authors used the problems for various river systems have been reported Vensim PLE® software, developed by Ventana Systems, frequently (Drolc & Koncan, 1996; Liu et al., 2005; Inc. Gonçalves et al., 2011). The potential of the Vensim PLE® software for Water quality modeling is increasingly recognized as modeling unsteady water quality problems was a useful tool for acquiring valuable information for established after a thorough comparison of the software optimal water quality management. In recent years, to the analytical solutions for a hypothetical scenario of water quality models have been widely applied such as a short duration spill, in cases where an analytical QUAL2E and QUAL2K (Ghosh & McBean, 1998; Park solution existed. Other hypothetical scenarios were built & Lee, 2002; Sardinha et al., 2008; Salvai & Bezdan, to demonstrate the tools of the Vensim PLE® software 2008; Zhang et al.et al., 2012). QUAL2K is a modern that facilitate building models for an unsteady-state version of QUAL2E (Brown & Barnwell, 1987). They regime. were developed by the U. S. Environmental Protection
Agency, the EPA, to evaluate the self-depuration THE VENSIM PLE® SOFTWARE capacity of rivers in the United States that receive treated sewage of urban origin. The Vensim PLE® software, adopted for this work, is The QUAL2E model has limitations, as it was made available at the website of Ventana Systems, Inc. created specifically to analyze the effects of steady and can be downloaded free of charge for academic use. sources of pollution under American standards. Models built using this software are much simpler than Simulating a stream that is subjected to unsteady those created with typical programming languages. sources of pollutants is very difficult with the QUAL2E Vensim PLE® models are built as cause diagrams, or model. diagrams of stocks and rates. Stocks are represented by Steady-state modeling is inadequate if the objective rectangles (box variables), and rates are represented by is, for instance, to describe water quality in a stream that arrows on double solid lines pointing into a box (rate in) has been subjected to accidental spills. These may occur or out of a box (rate out). The arrows have valves (two if there is a rupture in a storage tank, or in a pumping opposing small triangles) that can control the rates into line at a sewage treatment station. In such cases, a large and out of a box. Clouds at the extremes represent load of organic matter can be quickly dumped into a sources or sinks of a quantity being transported to or stream, causing an intense deterioration of the aquatic from a box (Fig. 1). environment. Another limitation found in the majority of water quality models, including the QUAL2K, is that it is difficulty (or even impossible) for a user to modify its internal structure. The model includes empirical Fig. 1 Simple example of stock and rates for dissolved oxygen. relationships or equations that reflect the specific conditions for which the model was first developed. Stocks are also called integrals, state variables, or Consequently, the user cannot introduce relationships or lungs; rates are time derivatives. In Fig. 1, the mass of equations that better describe the case under analysis. DO at time t is equal the mass of DO at t = t0 plus the On the other hand, it is impossible when using some integral of the rate of production minus the rate of decay models, but not QUAL2K, to assign different values for over t from t0 to t. The Eq. (1) is as follows: the kinetic coefficients for different stretches along the t ]T dtT[)t(M)t(M (1) length of a river. This becomes a serious limitation O2 O2 0 ∫ p d when effluents with distinct rates of biodegradation are t0 where M : mass of DO (M); T : rate of production of discharged into different points of the stream. Consider, O2 p for instance, the case of a discharge of effluents from a DO (M/T); and Td: rate of decay of DO (M/T). domestic sewage treatment plant and from a pulp and paper mill treatment station into a river. The adoption of
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The Vensim PLE® software offers two alternatives rates of these perturbation discharges and the river’s for numerical integration, namely Euler’s method and flow rate have to be critically examined. the fourth order Runge-Kutta method (RK4). According to Chapra et al. (2003), there are three ways to determine a river’s mean flow velocity - namely BUILDING THE MODEL FOR A WATER weirs, rating curves, and using Manning’s formula. For COLUMN this work, we chose to use the most common alternative given by Eq. (4), Manning’s formula. However, it is The development of a water quality model involves very easy to substitute this with another formulation as building two sub-systems, one for the hydraulics of the follows: water body (balance of volume), and another describing causes for the changes in concentration of the water 1 2 1 quality variables, namely, the chemical, physical and 3 2 =U h IR o (4) biological processes, and the transport mechanisms n represented by advection, diffusion and dispersion. When building a model, a river channel is divided where U: cross-sectional average velocity (L/T); n: 1/3 into control volumes (CV) of length Δx, each one roughness coefficient (T/L ); Rh: hydraulic radius (L); comprising two sub-systems as described in the and Io: longitudinal bottom slope (L/L). preceding paragraph. For a simpler representation of the mass balance, we To balance volume at steady-state conditions, the assume one-dimensional water flow, for which the flow rate out of the CV equals the sum of the flow rates concentration of any variable remains constant across into the CV (flow rate from the upstream CV plus flow each flow section. The resulting partial differential rate from sources of pollution) minus the flow rate of equation derived from the mass balance is as follows: the water sinks (pumping stations). This equation is: ∂ C 1 ∂ (QC) 1 ∂ ∂ C S W AD )( (5) QQQQ (2) ∂ t A ∂ x A ∂ x tL ∂ x V V iCs,ifp,1-ii t t where Qi: flow rate out of CV i and flow rate into where S: sources or sinks (M/T); C: concentration of a 3 3 2 downstream CV i+1 (L /T); Qi-1: flow rate into CV i and variable (M/L ); At: area of the flow section (L ); DL: 3 2 flow rate out of upstream CV i+1 (L /T); Qfp,i: flow rate longitudinal dispersion coefficient (L /T); and W: 3 from sources of pollution into CV i (L /T); and Qcs,i: sources of pollution or sinks of pumping water (M/T). flow rate of water pumped out of i (L3/T). The term S, sources or sinks, represents the The term Qfp,i is also used to represent the flow rate contribution of the physical, chemical, and/or biological from a tributary of the river that can be modeled if processes responsible for the production and/or necessary. consumption of the mass of the variables under The differential equation resulting from the balance simulation. All of the processes modeled are shown in of volume used for modeling with Vensim PLE® is Table 1. shown below: To simulate water temperature, a thermal energy balance is calculated for control volume. This energy dV balance is very similar to the mass balance stated above. QQQQ (3) dt iCs,ifp,1-ii For the thermal (internal) energy balance, both in and out flows of energy are considered. They are The combination of Eqs (2) and (3) gives dV/dt=0. associated with the temperatures of the pollutant Therefore, V, the volume of the CV, does not vary with discharges, linked to the outflow of energy connected to time. water pumping, and linked to sources and sinks of other To simulate an accidental pollutant discharge forms of energy exchange between the water and the (unsteady perturbations) we assume that the flow rate of environment. the pollutant is negligible when compared to the flow The third part is modeled upon the combination of rate of the river. Therefore, the flow rate of the five processes: 1. Short wave solar radiation; 2. Long accidental pollutant is not considered in the balance of wave atmospheric radiation; 3. Short wave radiation volume; the flow rate out is equal to the flow rate in. emitted by the water; 4. Air-water convection; and 5. This simplification limits use of the simulation only Evaporation-condensation. Processes 1 and 2 are when unsteady accidental discharges do not lead to modeled as sources of thermal energy; process 3 is drastic increases in the river flow rate. Therefore, before modeled as a sink of thermal energy; processes 4 and 5 any simulation can begin, the ratios between the flow represent either sources or sinks, depending upon the sign of the temperature difference (water minus air
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temperature). These mathematical formulations are also As previously stated, the software used for this presented in Appendix A. modeling (Vensim PLE®) offers the user the choice of The resulting partial differential equation derived using either the fourth order Runge-Kutta method or the from the balance of thermal energy is as follows: Euler method to calculate how the variables depend upon time. The software does all the work involved in ∂ T 1 ∂ (QT) 1 ∂ ∂ T S W the discretizations discussed in the previous paragraphs. AD )( cc (6) ∂ t A ∂ x A ∂ x tL ∂ x V V ∂ f k ff k t t i 1-i (7) ∂ x Δx 2 3 2 k k k where Sc: sources or sinks of thermal energy (ML /T ); ∂f f2ff 1i i 1-i (8) T: water temperature (Ө); and Wc: polluting sources or 2 2 2 3 ∂ x Δx water extraction (ML /T ). By substituting Eqs (7) and (8) into (5) and (6), the basic forms for the nodes were obtained Eqs (9) and
(10). The parameters At, DL, S, Sc, W, and Wc were METHODS FOR SOLVING MASS AND evaluated for existing conditions at the node (i, k). THERMAL ENERGY TRANSPORT EQUATIONS kkkk kk dC 1 CQCQ 1 AD In its explicit form, the method of finite differences is 1-i1-iii Li ti dt Ak Δx Ak Δx used for spatial discretization of the equations. Time- ti ti (9) partial differentiations are discretized using the fourth k C2C(C kk ) Sk W k order Runge-Kutta method or Euler’s method. 1i 1-ii i i Δx ΔxAk ΔxAk Figure 2 illustrates these operations. The letter “i” is ti ti used to denote position, and the letter “k” is used for the time variable. Terms such as k and k correspond to kkkk kk Ci Ti dT 1 TQ-TQ 1 AD concentration and temperature at position “i” at time 1-i1-iii Li ti dt Ak Δx Ak Δx “k”. Arrows with origins at time “k” indicate that the ti ti (10) variables at time “k+1” have been calculated using the T2T(T kkk ) Sk W k values found for the preceding moment. 1i 1-ii ci ci Δx ΔxAk ΔxAk In the explicit scheme, the space-wise discretization ti ti of first order differentials (advective term) and second order differentials (diffusive terms) was accomplished The numerical solution for the one-dimensional by backward and central finite differences, respectively. transport differential equation using the method of finite In Eqs (7) and (8), “f” is a function that represents differences necessarily carries numerical errors. They either C(x,t), or T(x,t). This approximation carries a manifest themselves in several different ways, including local truncation error on the order of Δx. rounding errors, instability, lack of symmetry, and numerical dispersion. Numerical dispersion is the most important, as shown by Wang & Lacroix (1997).
Using an analysis based on a Taylor series expansion, truncated after its second term, numerical dispersion can be estimated as follows:
Δx 2ΔtU Dn U (11) 2 2
MASS BALANCE FOR SEDIMENT The mathematical expressions used to model the flux of nutrients to and from the sediment and to model the benthonic demand of oxygen are based on studies by Di Toro (2001) and Chapra et al. (2007) that developed the QUAL2K EPA model.
Fig. 2 Computational grid.
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Table 1. Sources and sinks for the water quality variables Variables Sources [M/T] Sinks [M/T] Respiration; degrading of carbonaceous organic DO Reaeration and photosynthesis matter; nitrification; and sediment oxygen demand. Carbonaceous Sedimentation; denitrification; and degradation of biochemical oxygen Dissolution of detritus carbonaceous organic matter demand Organic nitrogen (No) Dissolution of detritus Ammonification Bottom algae and phytoplankton First stage nitrification; photosynthesis by bottom Ammonia (Na) respiration algae and phytoplankton Nitrite (Ni) First stage nitrification Second stage nitrification Denitrification; photosynthesis by bottom algae and Nitrate (Nn) Second stage nitrification phytoplankton Organic phosphorus (Fo) Dissolution of detritus Hydrolysis Inorganic phosphorus Bottom algae and phytoplankton Bottom algae and phytoplankton respiration (Fi) respiration Photosynthesis (nitrate used as Photosynthesis (ammonia used as substrate); Alkalinity (Al) substrate); respiration (ammonia used respiration (nitrate used as substrate); and nitrification as substrate); and denitrification Total coliforms (TC) - Death due to physical factors; and sedimentation Zooplankton (Z) Growth from grazing Respiration Growth due to environmental factors: Respiration and Phytoplankton (F) sunlight, temperature and nutrients grazing Inorganic solid (Si) - Sedimentation Growth due to environmental factors: Bottom algae (A) Respiration and death sunlight, temperature and nutrients Death of bottom algae and Detritus (D) Dissolution and sedimentation phytoplankton grazing Total inorganic carbon Phytoplankton and bottom algae Photosynthesis by phytoplankton and bottom algae (TIC) respiration; organic carbon oxidation; and reaeration Ratio of alkalinity to total inorganic pH Ratio of alkalinity to total inorganic carbon carbon The mathematical formulations used to quantify all of these sources and sinks are presented in Appendix A. As shown in Fig. 3, six processes may be responsible for changes in concentrations occurring in the sediment. Five of them involve mass transport; the sixth involves a biochemical reaction. These processes are as follows: (1) Deposition of particulate organic matter (POM) in the aerobic layer, from the sedimentation of detritus (D) and the carbonaceous BOD; (2) Diagenesis, which is the conversion of organic matter into more soluble forms, such as, , + and 3- (used to account for CH4 NH4 PO4 inorganic phosphorus); (3) Diffusion at the interface of the aerobic layer and the water column; (4) Diffusion of soluble substances across the interface of the two layers; (5) Pseudo-diffusive transport of particulate substances
Fig. 3 Schematic of the two layers of sediment and the processes across the two layers; and (6) Sinking of soluble or occurring in the sediment. Source: Data from Di Toro (2001). particulate substances by incorporation into the soil. Processes (4) and (5) were positively influenced by The sediment was divided into two layers; the first the presence of benthonic organisms. Thus, the was aerobic (Ha) with a thickness of 1 mm, and the coefficients of molecular diffusion, as used when there second was anaerobic (Han) with a thickness of 10 cm is no micro-fauna in the sediment, may be augmented (Fig. 3). two- or three-fold due to the presence of benthonic organisms.
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Fig. 5 Mass balance for the inorganic solids parameter.
Fi. 4 Flux of nutrients in the sediment. Terms associated with sources and sinks are not included in this equation; therefore, it can be used only Figure 4 shows a detailed diagram of the nutrient to simulate the transport of conservative substances. For fluxes and dissolved oxygen consumption in the this example, we considered the substance to be an sediment. The letters “p” and “d” are used to represent inorganic solid not subjected to sedimentation, which parcels in the particulate and dissolved forms, would act as a sink. respectively. Figure 4 shows that the particulate organic Figure 5 is used, with a mass balance for inorganic carbon (POC) freed in the anaerobic layer may originate solids in a control volume, to better understand how Eqs from the sedimentation of particulate detritus and from (9) and (10) were implemented into the Vensim PLE® the particulate carbonaceous BOD. On the other hand, program. Variable number two indicates that control the particulate organic nitrogen (PON) and the volume number two is under study, following control particulate organic phosphorus (POP) are derived volume number one and preceding control volume exclusively from the sedimentation of particulate number three. Arrows with a single line connect detritus. variables, indicating interdependence. For example, to In the anaerobic layer, organic carbon, nitrogen, and determine the concentration of Csi 2, volume two and phosphorus are transformed by mineralization reactions the mass of Si two are needed, as indicated by the into methane, ammonia nitrogen and inorganic arrows in the lower right corner of Fig. 5. Arrows with phosphorus, respectively. These constituents are double lines indicate flow rates in and out of a control transported to the aerobic layer, where methane and volume. For instance, the two horizontal arrows at the ammonia nitrogen can be oxidized, thereby determining bottom account for advective contribution of Si to and the demand for dissolved oxygen. from volume two: (Ad. E.) and (Ad. S.). The hypothetical river used for this simulation is 2 EXAMPLES OF APPLICATIONS km long and received an instantaneous load of 5 kg of inorganic solids dumped at a position of x = 500 m. We Application example 1 assumed a flow rate of 3.456×106 m3/d, a width of 60 m, The first example shows the importance of correcting and a depth of 1.0 m. Also, we assumed that the for numerical dispersion when simulating water quality coefficient of longitudinal dispersion DL is equal to during an accidental spill. The viability of the numerical 3.6×106 m2/d, the Manning coefficient is 0.0456, and solution is established by comparing it to the exact the channel slope is 0.001. These parameters were analytical solution of the advection-dispersion Eq. (12). constant for the stretch of river under simulation, and had to be input by the user; thereafter, the model M Ut])x[(x 2 determined the values of other parameters, such as the t)C(x, exp 1 (12) area of the water section (60 m 2 for a rectangular shape) πD2A t t4D Lt L and the mean flow velocity (57,456 m/d or 0.665 m/s). This 2 km river stretch was divided into 20 control where M: mass of the substance (pollutant) (M); x: volumes (VC) with lengths of ∆x = 100 m. The time -5 position of interest (L); x1: position of the substance increment ∆t was established as ∆t = 10 d. To spill (L); and t: time (T). eliminate the effects of numerical dispersion, which is 6 2 predicted by Eq. (11) to be Dn = 2.86×10 m/d, this value was subtracted from the original coefficient of
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6 longitudinal dispersion, resulting in DL = 0.74×10 2 7 2 m /d, or DL = 7.4×10 m /d. The background concentration of the water body was assumed to be zero; dumping the inorganic solid at time t = 0 raised the concentration of CV 5 to 0.833 mg/L. Figure 6 shows the longitudinal concentration profiles along the 2 km for two moments, t = 0.007 d and t = 0.02 d. The two solid lines correspond to the analytical solutions; the marks correspond to the numerical results of the model’s simulation. The results produced by the two solutions are very similar. For most of the length of the river, the absolute difference is less than 0.005 mg/L. Only for the stretch of 700 m to 1,100 m at time t = 0.007 d did differences reach values of 0.010 mg/L. A second simulation of the same case was run without correcting for numerical dispersion. Figure7 Fig.7 Longitudinal profiles for an inorganic solid. Analytical shows the results for the same instants. The additional solution and model prediction not corrected for numerical effects of numerical dispersion are readily apparent. dispersion.
Application example 2
The objective of the second example is to demonstrate the ability of the new model to simulate a water quality profile under steady conditions. Its results for a DO profile are compared with the results of simulation performed with model QUAL2K. Data for this study were produced by Gonçalves et al. (2012) in his report on the qualitative and quantitative monitoring of rivers of the São Simão basin in the state of São Paulo, Brazil. Gonçalves et al. (2012) studied a fluvial segment of 11,41 km in length, running from its origin to sampling station S6 (Fig. 8). This segment was divided into eight stretches, taking into consideration the flow characteristics, the kinetics of the process, and the availability of quantitative and qualitative pieces of information. Each stretch was subdivided into control volumes (computational elements) with lengths of 0.5 km each. Fig. 6 Longitudinal profiles for an inorganic solid. Analytical solution and model prediction corrected for numerical dispersion. Both QUAL2K and Vensim PLE were calibrated and verified in steady-state mode using average conditions during March 2005 to March 2006. The values of system coefficients were based on the typical values cited in the model documentation (Brown & Barnwell, 1987; Chapra et al. 2007). All values of system coefficients used in QUAL2K were same as those in Vensim PLE. This strategy permitted us to adequately identify the reasons for inconsistencies in the two DO profiles predicted by the different models. Table 2 shows the resulting values for several coefficiens, namely coefficient of deoxygenation Kd, coefficient of surface reaeration K2, and settling rate Ks.
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Fig. 9 DO concentration profiles resulting from simulations with QUAL2K and Vensim PLE®.
Application example 3 In this example, we ran a simulation to showcase some of the tools available in Vensim PLE®. For instance, it is possible for the software to represent any time variation for a pollutant discharge. A simulation was run for the two classical water quality parameters DO and carbonaceous BOD. The concentrations of the other parameters present in the model were assumed to be zero. The hypothetical river modeled in this example is 20 km long, has a flow rate of 69 120 m3/d, a width of 1.5 m, and a depth of 0.8 m. The coefficient of longitudinal dispersion was 1.0368×107 m2/d, the bottom slope was 0.001, the Manning coefficient was 0.0465, and the flow
Fig. 8 Diagram of the stretch of river under simulation. average velocity was 0.36 m/s. As seen in application 1, the model automatically corrects for any numerical Both QUAL2K and Vensim PLE model results were dispersion. compared with fields measurements in figure (Fig. 9). A factory discharges an effluent at x = 500 m in a cyclic manner (every 2.4 h, or every 0.1 d for 15 min), Field measurements are displayed as mean and 95% 3 confidence intervals. Figure 9 shows that both models with a flow rate of 8,640 m /d, carbonaceous BOD represent the field data quite well, since the profiles are concentration of 2 000 mg/L, and DO concentration of quite similar. 0.5 mg/L. The effluent flow rate was introduced into the program using a pulse train, which is a feature of ® Table 2. Parameters for DO modeling Vensim PLE (Fig. 10). In the figure, “Qfp” represents -1 -1 -1 Stretch Kd (d ) K2 (d ) Ks (d ) the flow rate of the source of the pollutant. 1 0.3 0.8 0.1 Fig. 10 shows that the length of the simulation was 2 0.3 0.8 0.1 one day. The first pulse of pollution occurred at 0.1 d 3 1.0 0.3 0.3 and the last time 0.9 d, and there were a total of nine 4 1.0 0.3 0.3 pulses. The initial conditions for the water body were 0 5 1.0 0.3 0.3 mg/L of carbonaceous BOD and 7 mg/L of DO, adopted 6 1.0 0.3 0.3 for the two parameters in all of the CVs and as 7 1.0 1 0.1 boundary conditions upstream and downstream of the 8 1.0 1 0.1 set of CVs.
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Fig. 10 Flow rate variation as a function of time. Fig. 12 Graphical outputs for CDO(x) as functions of time.
Figure 11 shows the results of a simulation of the Another interesting point from Fig. 12 is the carbonaceous biochemical demand concentration for transition from a transient state to a pseudo-harmonic different positions along the river. From position 500 m state, with constant minimum and maximum values for to position 9,000 m, the peak BODc concentration the oscillating DO parameter. Notice that the same type 3 dropped ΔCBODc = 153 – 24.3 = 128.7 g/m . This of transition occurs for BODc in Fig. 11. attenuation along the longitudinal river profile was the result of the combined effects of longitudinal dispersion, Application example 4 biological degradation of organic matter, and sedimentation; the last two processes were sinks for In this example, the behaviors of six water quality BODc. parameters were analyzed, namely organic nitrogen The DO concentration is presented in the same (No), ammonia nitrogen (Na), nitrite (Ni), nitrate (Nn), manner in Fig. 12. At position x = 500 m, the DO organic phosphorus (Fo), and inorganic phosphorus (Fi). concentration reached a saturation level (7.5 mg/L) at The river simulated in this example has a length of 160 km, flow rate of 25 920 m3/d, width of 2.2 m, depth the midpoint of times between effluent discharges. The o same did not occur in the downstream positions, as the of 0.4 m, water temperature of 32 C, bottom slope of utilization of oxygen surpassed its reposition by surface 0.0052, a Manning’s roughness of 0.05, and flow reoxygenation. velocity of 0.66 m/s. For t = 0 (initial condition) and at x = 0 and x= 160 km (boundary conditions), the concentrations of all forms of nitrogen and phosphorus compounds were zero. There was a continuous discharge of polluted water at position x = 1 000 m. Its flow rate was 2 000 m3/d with an organic nitrogen concentration of 15 mg/L and a 5 mg/L concentration of organic phosphorus. For simplicity, the concentration of other water quality parameters, such as phytoplankton and algae, which can contribute to the production and/or use of nitrogen and phosphorus compounds, were assumed to be zero. Therefore, the only source of organic nitrogen and phosphorus was the polluting discharge. The results of the simulation are shown in Fig. 13.
Fig. 11 Graphical outputs for CBODc(x) as functions of time.
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Fig. 13 Concentration profiles for the forms of nitrogen compounds Fig. 14 Concentration profiles for the forms of phosphorus along the simulated river course compounds along the simulated river course
Figure 13 shows that the concentration of organic CONCLUSION nitrogen decreases along the course of the river as it is transformed into ammonia. In this process The model discussed in this paper corrects for (ammonification), the organic nitrogen is consumed as limitations in similar products that have been discussed ammonia nitrogen is produced; however, ammonia elsewhere in the literature, such as the QUAL family. nitrogen in the presence of dissolved oxygen is The reasons for this model are as follows: (1) the user transformed into nitrite (first stage nitrification), and can easily change the internal structure of the model, nitrite is then transformed into nitrate (second stage introducing equations that better represent reality; (2) nitrification). In this example, the DO concentration was the model can be operated very easily under non-steady ® kept at a level of 7.5 mg/L. conditions, as the Vensim PLE software package The last reaction occurs very quickly; therefore, the includes tools, such as pulse train and lookup, that nitrite concentration in the water body fails to reach facilitate the representation of pollutant discharges for elevated values. The kinetic coefficient for the any time variation profile; and (3) the user can choose to conversion of nitrite into nitrate is larger than the kinetic use different values for the many coefficients involved coefficient for the conversion of ammonia into nitrite. in the processes at any position in the body of water. Nitrate may be transformed into gaseous nitrogen if the Numerical errors were corrected satisfactorily, environment was anoxic, which was not the case in this yielding good results when a relatively small spatial example. discretization was used. It is important to note that the model can internally correct for any computational One can verify that the concentrations of Na, Ni, and numerical errors. Nn, at position x = 160 km add up to the difference The simulated results for the DO and BODc of between No at x = 1 km and x = 160 km. The organic nitrogen is sequentially transformed into ammonia, then unsteady regimes were as expected; however, local field into nitrite, and finally into nitrate nitrogen. work, including the monitoring and evaluation of water Figure 14 illustrates the concentration profiles of quality in the presence of instantaneous pollutant organic and inorganic phosphorus. It shows that, unlike discharges, is recommended to calibrate the model and what happened to the nitrogen compounds, the curves thereby ensure a faithful response to transient for the decay of organic phosphorus and production of disturbances. inorganic phosphorus are symmetrical mirror images of Steady state simulations for nitrogen and phosphorus one another. All organic phosphorus consumed along compounds also ran as expected. Organic nitrogen was the river is transformed into inorganic phosphorus; in transformed into nitrate almost completely along the modeled course. other words, the sink of Fo corresponds to an equal The results suggest that using Vensim PLE® as a source of Fi. basic tool to develop environmental models is an excellent option.
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Acknowledgement Joc HK α m e e (34) 1 J This study was supported by the Brazilian National oco Council for Scientific and Technological Development - Joc CNPq. α = m (35) 0 J oco APPENDIX A. EQUATIONS N Kcf =(N) (36) The following are equations that describe the “sources K+N s and sinks” for each water quality variable. )C(C C min(N)K nnna ; fi (37) cf )KC(C )K(C Temperature (T) snnna nf sfi fi ρdTVC e AJ=S= (13) Zooplankton (Z) dt sc dM JJJ(JJJ ev/cocola,oloc ) (14) Z TRTCS (38) dt ZZZ n 0.58+0.24J=J (15) TCERTG= (39) oc topo N fgcaFZ m 20T 4 θRKTR ZrzZ MZ (40) Jola, = εσ()273+T (16) 2 Bottom Algae (A) 1c ( v TT0.9U19cJ ar )() (17) 2 ev/co ( v ee0.95U19J ars )() (18) dMA A A A TMTRTCS A (41) σ(TJ 4 ( C1e0.031A273) ))( (19) dt ol ar ar r TCAK= (42) scaA TM = μ MF (43) Total Coliforms (TC) AaraA FF= (44) dN fa CT TMTSS (20) TR MK= (45) dt CT CT CT AmaA TSVCK= (21) CT ctSct Detritus (D) TM)NK+(K= CTbrCT (22) 20)(T dMD Kb 0.8θCT (23) iDD D TSTDTPS D (46) dt αJ HK ocm e TSAC= υ (47) K r e1 (24) dsdD HK () e TD θDK= 20-T M (48) i D idi D e 0.052CK si 0.174Cd 0.000031Cf (25) ]TG)RE[(1TMTP (49) D A Fdafg Phytoplankton (F) Inorganic Solids (Si) dM F TGTRTCS (26) FFFF dMSi dt Si TSS Si (50) 20T dt TR μ θR frfF FM fF (27) TSAC= υsissiSi (51) CK odresf f e1F (28) C TG [ f θGC 20)(T ] MC (29) Organic Nitrogen (No), Ammonium Nitrogen (Na), F )C(K zg Fz g fs Nitrite (Ni), and Nitrate (Nn) TCL)MN,T,(K= (30) dM cfF F No TDTPS (52) () ( ) () No No No cfcf cf cf LK×NK×TK=K (31) dt 20T TPiNo RTD= nd (53) cf rf máxθFCTK (32) D 20T 2.718f αα θAKTD M (54) 1 0 No oa m No cf LK )e(e (33) eHK dM Na TNTATPS (55) dt Na Na Na Na
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)TR(R+)TR(R+TD=TP (56) dM Na No And Fna OD TRTRTFS )TCR+TCR(F=TA (57) dt OD OD e OD OD (81) AndFnaamNa CC TDesoOD TNOD =F nnna am )C+Kp)(C+Kp( 20T nnnanana (58) eOD θRKTR e2 odS )VC(C (82) KpC + nana TROD occaF occdA )RRTR(+)RRTR(= (83) )C+C)(C+Kp( nnnannna Phytoplankton BottomAlgae 20T 20T aiNa θNKTN FM NaiNa (59) TD TD θDK FM (84) eso OD e DBOc d DBOc c iDBO e1F CK odini (60) Nai TN OD oniNa RTN+RTN= onnNi (85) dM Ni TNTNS (61) TFOD occaF occdA )RRTC(+)RRTC(= (86) Ni Na Ni dt Phytoplankton Bottom Algae θNKTN 20T FM (62) inNi NiiNi
e1F CK odinn (63) Total Inorganic Carbon (TIC) Nii dM Nn dMCIT TD-TA-TN=S= (64) CIT CIT TRTRS eCO dt Nn Ni Nn es Nn dt 2 (87) 20T eCIT TFTD CIT esNn desθNKTD Nn des)F(1M (65)
CK odides eCO CO CO ocit )VFCs(CKTR (88) )e(11F (66) 2 2 2 des )(( TCRTCRF1TA ) (67) TDe e RRTD= Cmol,co (89) Nn AndFnaam CIT DBOc TRCIT Cmol,caF Cmol,cdA )RRTR(+)RRTR(= (90) Organic (F ) and Inorganic (F ) Phosphorous o i Phytoplankton Bottom Algae
dM Fo TFCIT Cmol,caF Cmol,cdA )RRTR(+)RRTR(= (91) Fo Fo TDTPS Fo (68) dt Phytoplankton Bottom Algae TPRTD= (69) iFo D pd 20T Alkalinity (Al.) oiFo θHKTD M Fo (70) fo dN Al. TNTDTDTAS (92) dMFi dt Al. Al. esAl. iAl. Al. FiFi TATPS Fi (71) dt ( na],R[HRRTRFTA ) Al. Cmol,caFam Fi ApdFo Fpa )TR(R+)TR(R+TD=TP (72) Phytoplank ton )TCR+TCR(=TA (73) Fi ApdFpa ( na],R[HRRTRF ) Cmol,cdAam Bottom Algae Carbonaceous Biochemical Demand (BODc) (93) ( Cmol,caFam nn],R[HRRTCF1 ) dMDBOc TPS TD Phytoplankton dt DBOc DBOc DeDBOc (74) ( Cmol,cdAam nn],R[HRRTCF1 ) TDDesDBOc TSDBOc Bottom Algae TPDBOc iD RRTD= occd (75)
TD θDK 20T FM (76) ( na],R[HRRTCFTD ) eDBOc d DBOc DBOci Al. Cmol,caFam e1F CK odidegr (77) Phytoplankton c iDBO ( na],R[HRRTCF ) U Cmol,cdAam 1d i+K=K (78) Bottom Algae H (94) TDRTD= (79) ( Cmol,caFam nn],R[HRRTRF1 ) esDBOc esNn ondes 20T Phytoplankton DBOc DBOcθSKsTS DBOc MDBOc (80) ( nn],R[HRRTRF1 ) Cmol,cdAam Dissolved Oxygen (DO) BottomAlgae + esAl. esNn Nmol, des],R[HRTD=TD (95)
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+ ear: vapor pressure in the atmosphere (mm Hg). iAl. ()Na Nmol,Ni nitri],R[HRTN+TN=TN (96) Efg: efficiency factor for grazing (non-dimensional). : emissivity of water ( 0.97) (non-dimensional). pH es: water vapor pressure (mm Hg). C f: photoperiod (non-dimensional). 27.5pHa ( al. 1) Fa: factor of attenuation for bottom algae respiration Ccit (non-dimensional). Ha Lim Fam: factor of preference for ammonium (non- C K( al. )A- HaHa C 0 dimensional). 1 Lim 0 e cit Ha FDBOci: factor of correction (attenuation) of the 0 (97) coefficient of deoxygenation as a function of DO Ha Lim concentration (non-dimensional). C K( al. )A- HaHa C 1 Fdes: factor of correction (attenuation) of the coefficient 1 Lim 0 e cit Ha of denitrification as a function of DO concentration 0 (non-dimensional). Ha Lim Ff: factor of correction (attenuation) of the coefficient of Cal. K( 2 )A- phytoplankton respiration as a function of DO Lim HaHa 0 C 1 e cit concentration (non-dimensional). Ha 0 FNai: factor of correction (attenuation) for the coefficient of first stage nitrification as a function of DO concentration (non-dimensional). APPENDIX B. NOMENCLATURE FNii: factor of correction (attenuation) for the coefficient A: coefficient related to air temperature and to the of second stage nitrification as a function of DO actual solar radiation and clean sky solar radiation; concentration (non-dimensional). range: 0.5 to 0.7 (non-dimensional) A 0.7 for air Fo: fraction of free inorganic carbon [non-dimensional] temperatures of above 20o C. H: river depth (m). Ha : initial value 1.05 (non-dimensional). A0: coefficient for the beginning of the curve (non- 0 dimensional). HaLim: limiting value for growth; function of temperature (non-dimensional). A1: coefficient for the middle of the curve (non- dimensional). i: coefficient of activity in the bottom mud (non- dimensional). A2: coefficient for the end of the curve (non- dimensional). Ja,ol: short wave radiation flux emitted by the water 2 (cal/cm2 d). As: surface area for each control volume (cm ). o J : convective flux of thermal energy between the water c1: Bowen’s coefficient (mm Hg/ C). c and the atmosphere (cal/cm2 d). Cal.: concentration of calcium carbonate (mgCaCO3/L). J : flux of thermal energy eliminated from the water Cct: concentration of total coliforms (Norg/L). ev/co by evaporation, or gained by condensation (cal/cm2 d). Ccit: concentration of total inorganic carbon (mol/L). J : flux of short wave solar radiation (cal/cm2 d). CCO2s: saturation concentration of CO2 in water (mol/L). oc J : average short wave solar radiation flux (cal/cm2 d). Cd: concentration of detritus (mgD/L). ocm o J : optimal short wave solar radiation flux for Ce: specific heat (cal/g C). oco phytoplankton growth (300 cal/cm2 d). Cf: concentration of phytoplankton (mgA/L). J : flux of long wave radiation from the atmosphere Cfi: concentration of inorganic phosphorus (mgP/L). ol (cal/cm2 d). Cg: kinetic coefficient for zooplankton grazing (L/mgCd). Jtopo: flux of solar radiation at the upper layers of the atmosphere (cal/m2 d), calculated as I senα; I is the Cna: concentration of ammonium nitrogen (mgN/L). o o solar constant, equal to 2.88×107 cal m2/d; α is the Cnn: concentration of nitrate (mgN/L). inclination of solar rays to the horizontal. Cod: concentration of dissolved oxygen (mgO/L). K : coefficient of global transfer of CO (1/d). Cr: coefficient of reflection (non-dimensional). CO2 2 K: growth coefficient (≈27) (non-dimensional). Crfmáx: coefficient for the maximum growth of phytoplankton ( 1.8); this value varies as a function K1: kinetic coefficient for deoxygenation (1/d). of the phytoplankton species (1/d). K2: coefficient of surface reoxygenation (1/d). K : kinetic coefficient for conversion of ammonia into Cs: saturation concentration of dissolved oxygen ai (mgO/L). nitrite (1/d). K : coefficient for coliform death as function of Csi: concentration of inorganic solids (mg/L). b temperature, salinity, and predation (1/d). Cz: concentration of zooplankton (mgC/L).
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Kca: coefficient for the (flux of) growth of bottom algae MNa: mass of ammonium nitrogen (mgN). 2 (gD/m d). MNa: mass of nitrite (mgN). Kcf (L): coefficient for the effect of solar light on MNn: mass of nitrate (mgN). phytoplankton growth (non-dimensional). MNo: mass of organic nitrogen (mgN). Kcf (N): coefficient for the effect of nutrients on MOD: mass of dissolved oxygen (mgO).
phytoplankton growth (non-dimensional). MSi: mass of inorganic solids (mg). Kcf (T): coefficient for the effect of temperature on MZ: mass of zooplankton (mgC). phytoplankton growth (1/d). n: effective daily duration of solar radiation (h). Kd: coefficient of effective deoxygenation in the river Nm: maximum daily duration of solar radiation (h). (1/d). N: nutrient concentration (mg/L). + Kdi: kinetic coefficient for the dissolution of detritus; NAl.: number of hydrogen gram equivalent ions (eqH ). normally in the range 0.3 to 0.7 (1/d). NCT: number of total coliforms (Norg). Kdes: kinetic coefficient for denitrification (1/d). pHa: pH variation caused by autochtonous processes Ke: coefficient of solar light extinction (1/m). (non-dimensional). + Kidegr: coefficient of inhibition of deoxygenation by low R[H ],des: hydrogen gram equivalent ions per nitrogen DO concentration (L/mgO). mol consumed during denitrification (eqH+/molN). + Kides: coefficient of inhibition of denitrification R[H ],na: hydrogen ions freed or consumed per mol of (L/mgO). carbon when ammonium nitrogen is used as substratum + Kin: kinetic coefficient for conversion of nitrite into (eqH /molC) nitrate (1/d). R[H+],nitri: gram equivalent hydrogen ions freed per + Kini: coefficient of inhibition of first stage nitrification mol of nitrified nitrogen (eqH /molN). by low DO concentration (L/mgO). R[H+],nn: hydrogen ions freed or consumed per mol of + Kini: coefficient of inhibition of first stage nitrification carbon when nitrate is used as substratum (eqH /molC). by low DO concentration (L/mgO). Rca: carbon generated per unit of mass of a-chlorophyll Kma: death rate of bottom algae (1/d). (non-dimensional). Koa: kinetic coefficient for conversion of organic Rcd: mass of organic carbon liberated per mass of nitrogen into ammonium (1/d). detritus dissolved in the water (non-dimensional). Koi: kinetic coefficient for conversion of organic Rco: mass of oxidized carbon per mass of consumed phosphorus into orthophosphate (1/d). oxygen (non-dimensional). Kpna: coefficient for preference of bottom algae and Rda: stoichiometric ratio between detritus and a- phytoplankton for ammonium (mgN/L). chlorophyll used to express the mass of phytoplankton Kr: rate of decay of TC due to solar radiation (1/d). (non-dimensional). Kresf: coefficient of inhibition of breathing due to low e Rmol,C: constant to transform mass of carbon into mols DO concentration (L/mgO). (molC/g). Krz: kinetic coefficient for the respiration of Rmol,N: constant to transform mass of nitrogen into mols phytoplankton; normally in the range 0.01 to 0.05 (1/d). (molN/g). Ks: constant of half saturation (mg/L). Rna: mass of nitrogen liberated per mass of a- KSct: first order sedimentation coefficient (1/d). chlorophyll dissolved in the water (non-dimensional). KsDBOc: sedimentation coefficient for the BODc (1/d). Rnd: mass of nitrogen liberated per mass of detritus KSff: constant of half saturation for inorganic dissolved in the water (non-dimensional). phosphorous; normally in the range 0.001 to 0.005 Roc: mass of consumed oxygen per mass of decomposed (mgP/L). carbon (non-dimensional). KSg: constant of half saturation for zooplankton grazing Rondes: mass of non-used carbon per mass of denitrified (mgA/L). nitrate (non-dimensional). KSnf: constant of half saturation for nitrogen; normally Roni: mass of consumed oxygen per mass of oxidized in the range 0.01 to 0.02 (mgN/L). ammonium (non-dimensional). KSfi: constant of half saturation for phosphorus Ronn: mass of consumed oxygen per mass of oxidized (mgP/L). nitrite (non-dimensional). MA: mass of bottom algae (mgD). Rpa: coefficient for conversion of a-chlorophyll into MCIT: inorganic total carbon (mol). phosphorous (non-dimensional). MD: mass of detritus (mgD). Rpd: mass of organic phosphorous liberated per mass of MDBOc: mass of BODc (mgO). detritus dissolved in the water (non-dimensional). o MF: mass of phytoplankton (mgA). T : water temperature ( C) MFi: mass of inorganic phosphorus (mgP). TAAl.: rate of alkalinity increase caused by the aquatic + MFo: mass of organic phosphorus (mgP). vegetable community (eqH /d).
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TAFi: rate of inorganic phosphorus assimilation by TSCT: rate of sedimentation of total coliforms (Norg/d). phytoplankton and bottom algae (mgP/d). TSD: rate of sedimentation of detritus (mgD/d). TANa: rate of ammonium assimilation by phytoplankton TSDBOc: rate of sedimentation of BDOc (mgO/d). and bottom algae (mgN/d). TSsi: rate of sedimentation of inorganic solids (mg/L). TANn: rate of nitrate assimilation by phytoplankton and Uv: wind speed (m/s). bottom algae (mgN/d). α: proportionality constant ( 1) (non-dimensional). o Tar: air temperature ( C). θAm: coefficient of the effect of temperature on TCA: rate of growth of bottom algae (mgD/d). ammonification (non-dimensional). TCF: rate of growth of bottom phytoplankton (mgA/d). θCT: coefficient of the effect of temperature on mortality TCZ: rate of growth of bottom zooplankton (mgC/d). (non-dimensional). TDAl. : rate of alkalinity decay caused by the aquatic θDi: coefficient of the effect of temperature on the vegetable community (eqH+/d). dissolution of detritus (non-dimensional). TDeCIT: rate of increase of total inorganic carbon due to θF: coefficient of the effect of temperature on the oxidation of organic carbon (mol/d). growth of phytoplankton (non-dimensional). TDeDBOc: rate of degradation of organic carbon θGz: coefficient of the effect of temperature on (mgO/d). zooplankton grazing (non-dimensional). TDesAl. : rate of increase of alkalinity due to θHfo: coefficient of the effect of temperature on organic denitrification (eqH+/d). phosphorus hydrolysis (non-dimensional). TDesDBOc: rate of decay of BODc due to denitrification θN: coefficient of the effect of temperature on (mgO/d). nitrification (non-dimensional). TDesNn: rate of denitrification (mgN/d). θRe: coefficient of the effect of temperature on surface TDesOD: rate of deoxygenation caused by the reoxygenation (non-dimensional). degradation of organic carbon (mgO/d). θRf: coefficient of the effect of temperature on TDFo: rate of decay of organic phosphorus (mgP/d). phytoplankton respiration (non-dimensional). TDiD: rate of dissolution of detritus (mgD/d). θRz: coefficient of the effect of temperature on TDNo rate of decay of organic nitrogen (mgN/d). zooplankton respiration (non-dimensional). TFCIT: rate of decay of total inorganic carbon due to θSDBOc: coefficient of the effect of temperature on photosynthesis of phytoplankton and bottom algae sedimentation of BDOc (non-dimensional). (mol/d). μra: rate of respiration of bottom algae (1/d). TFOD: rate of increase dissolved oxygen due to μrf: kinetic coefficient for the respiration of photosynthesis (mgO/d). phytoplankton (1/d). 2 4 TGF: rate of zooplankton grazing (mgA/d). σ: Stefan-Boltzmann constant (cal/cm d K ). TMA: rate of death of bottom algae (mgD/d). υd: apparent settling speed for detritus (m/d). TMCT: rate of death of total coliforms (Norg/d). υsi: apparent settling speed for inorganic solids (m/d). TNiAl.: rate of decay of alkalinity due to nitrification (eqH+/d). REFERENCES TNNa: rate of first stage nitrification (mgN/d). Brown L. C. & Barnwell T, O. (1987) The enhanced stream water TNNi: rate of second stage nitrification (mgN/d). quality models QUAL2E and QUAL2E-UNCAS: Documentation TNOD: rate of DO loss due to nitrification (mgO/d). and user manual. Environmental Research Laboratory, Office of TPD:rate of production of detritus (mgD/d). Research and Development. U.S. EPA/600/3-87 /007. Chapra S. C. & Pelletier G. J. (2003) QUAL2K: A modeling TPDBOc: rate of production of BODc (mgO/d). framework for simulating river and stream water quality: TPFo: rate of production of organic phosphorus (mgP/d). documentation and user manual. Civil and Environmental TPNa: rate of production of ammonium nitrogen Engineering Dept., Tufts University, Medford. (mgN/d). Chapra S. C., Pelletier G. J. & Tao H. (2007) QUAL2K: A modeling TPNo rate of production of organic nitrogen (mgN/d). framework for simulating river and stream water quality: documentation and user manual. Version 2.07. Civil and TRA: rate of respiration of bottom (mgD/d). Environmental Engineering Dept., Tufts University, Medford. TRCIT: rate of increase of inorganic carbon due to Di Toro, D. M. (2001) Sediment Flux Modeling. Wiley-Interscience, respiration of phytoplankton and bottom algae (mol/d). New York, USA. TReCO2: rate of CO2 transfer between water and Drolc, A. & Koncan, J. Z. (1996) Water quality modeling of the atmosphere (mol/d). river sava, Slovenia. Wat. Res. 30(11), 2587–2592. TRe : rate of surface superficial reoxygenation (gO/d). Ghosh, N. C. & Mcbean, E. A. (1998) Water quality modeling of the OD Kali river, India. Water, Air, and Soil Pollution. 102, 91-103. TRF: rate of phytoplankton respiration (mgA/d). Gonçalves, J. C. S. I., Sardinha, D. S. & Boesso, F. F. (2011) TROD: rate of decrease of DO due to respiration by Modelo numérico para a simulação da qualidade da água no phytoplankton and bottom algae (mgO/d). trecho urbano do rio Jaú, Município de Jaú-SP. Revista de TRZ: rate of phytoplankton respiration (mgC/d). Estudos Ambientais. 13(2), 44-56.
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Gonçalves, J. C. S. I., Sardinha, D. S., Souza, A. D. G., Dibiazi, A. Sardinha, D. S., Conceição, F. T., Souza, A. D. G., Silveira, A., de L. B., Godoy, L. H. & Conceição, F. T. (2012) Avaliação espaço- Júlio, M. & Gonçalves, J. C. S. I. (2008) Avaliação da qualidade temporal da qualidade da água e simulação de autodepuração na da água e autodepuração do Ribeirão do Meio, Leme (SP). bacia hidrográfica do córrego São Simão-SP. Revista Ambiente & Engenharia Sanitária e Ambiental. 13(3), 329-338. Água. 7(3), 141-154. Wang, H. Q. & Lacroix, M. (1997) Optimal weighting in the finite Liu, W.C., Liu, S. Y., Hsu, M. S. & Kuo, A. Y. (2005) Water quality difference solution of the convection-dispersion equation. Journal modeling to determine minimum instream flow for fish survival of Hydrology. 200, 228-242. in tidal rivers. Journal of Environmental Management. 52, 55–66. Zhang, R., Qian, X., Li, H., Yuan, X. & Ye, R. (2012) Selection of Park, S. S. & Lee, Y. S. A water quality modeling study of the optimal river water quality improvement programs using Qual2K: Nakdong river, Korea. Ecological Modelling. 152, 65-75. A case study of Taihu Lake Basin, China. Science of the Total Salvai, A. & Bezdan, A. (2008) Water quality model QUAL2K in Environment. 431, 278-285. TMDL development. Balwois Ohrid, Republic of Macedonia. 27, 1-8.
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Journal of Urban and Environmental Journal of Urban and E Engineering, v.7, n.1, p. 64-73 Environmental Engineering ISSN 1982-3932 J E www.journal-uee.org U doi: 10.4090/ juee.2013.v7n1.064073
URBAN SPRAWL IN SMALL CITIES, ANALYSIS OF THE MUNICIPALITY OF SÃO PEDRO (SP): POTENTIALS AND CONSTRAINS
Priscila C. Fracassi1, José A. de Lollo2 1Urban Engineering Post-graduation Program, Federal University of São Carlos, Brazil 2Department of Civil Engineering, Univ. Estadual Paulista (UNESP) at Ilha Solteira, Brazil
Received 5 July 2012; received in revised form 30 January 2013; accepted 28 March 2013
Abstract: Urban sprawl in small cities has led to the occupation of unsuitable areas, resulting in peripheralization and in the occupation of fragile environments. In these occupations, the physical characteristics of the environment are often disrespected. In this context, the present article reports on a case study in the municipality of São Pedro, state of São Paulo, Brazil, which presents and discuss a set of natural factors (geological and geomorphological) conditioning the occurrence of erosion and gravitational mass movements, which are limiting factors for urban sprawl. The methodology employed in this study was based on field work, bibliographic research, and data collection, analysis and GIS-based systematization, which allowed for a spatial reading of the urban sprawl to indicate, from different perspectives, how the phenomenon is manifested. Thus, it was possible to draw up a chart highlighting the areas with the greatest potential for occupation and those with restrictions due to their greater susceptibility to erosion and mass movements. The main identified natural factors of restriction were steepness and soil conditions and law enforced restrictions (environmental protection areas).
Keywords: Urban sprawl; small cities; fragile environments; landslides; erosion; GIS
© 2013 Journal of Urban and Environmental Engineering (JUEE). All rights reserved.
Correspondence to: José A. de Lollo, Tel.: +55 18 3743 1215; Fax: +55 18 3743 1160. E-mail: [email protected]
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INTRODUCTION and was applied to São Pedro (SP), a small city whose Master Plan don´t consider natural environment The process of urbanization of Brazil’s territory conditions to discuss urban expansion. intensified in the early decades of the 20th century, concomitantly with the development of industrial production. This situation led not only to an increase in URBAN SPRAWL IN BRAZIL the number of cities but also to a change in the location According to Santos (1996), the first surge in Brazil’s of residence of the population, most of which moved to urbanization process took place in the late 19th century, urban areas. assuming major proportions only in the second half of In the state of São Paulo, this intensified the 20th century. Driven by industrialization, this urbanization was characterized by allowing for the process, with its multiple economic and social definitive configuration of the Metropolitan Region of repercussions, was seen as an urban attraction which São Paulo and by the shift of economic development encouraged rural to urban migration. toward the interior of the state, with clear repercussions With accelerated urbanization and the instauration of on the urban network. Thus, the region of Campinas, rural exodus, the spatial concentration of the mass of encompassing the municipalities of the Piracicaba River people reached a theretofore inconceivable scale, Basin, consolidated its status as the most important leading to an ecological, political, economic and social economic region in the interior of the state, as attested revolution. Thus, the urban dynamics imposed by new by its accelerated population growth, agricultural and urbanization processes often encountered a totally industrial expansion, and the modernization of its unprepared territory, resulting in consequences for tertiary sector. cultural and spatial formation, transforming landscapes Urban management instruments such as zoning have into increasingly urbanized refuges and inflicting being improper to solve urban problems like dispersed serious damage to the environment and to life in society. urbanization. In urban perimeters, the sprawl occurs due The production of space urban, intensified by to lack of proper criteria in promoting urban growing. urbanization, follows the same logic as the occupation As consequences, urban infrastructure and public of Brazilian territory, whereby history has demonstrated services become absent resulting a set of environmental that land has always been used intensively and with an impacts. immediatist vision, exploiting it to the utmost in an All this urban development has led to the occupation unrestrained quest for profits. For Carvalho (2001), of unsuitable areas through territorial sprawl, resulting peripheral economies are based on the overexploitation in peripheralization and in the occupation of fragile of man – social dumping – and of the environment – environments. In Brazilian Municipalities these environmental dumping – to gain competitiveness, occupations often ignored natural environmental reproducing and exacerbating them in a disorganized conditions like steepness, bedrock, hydrography, and manner and with no predictability of the impacts. soils. Thus, areas subjected to flood as bottom valleys, Thus, the exploitation of spaces is manifested as well as areas with erosion-susceptible soils and steep through the processes of urban sprawl, which, in turn, slopes subject to soil and rock landslides are currently are founded upon two similar actions, but with distinct occupied, posing risks to the local population. social logics. On the one hand is the urban sprawl On the other hand, Brazilian new policies, like characterized by compulsive urbanization, which is 547/2011 Provisional Measure (Brazil, 2011) and generated by a portion of the population with higher 12.608/2012 Law (Brazil, 2012), states the obligation of purchasing power in search of an ideal of nature and prepare engineering geological maps for municipalities tranquility in periurban areas. On the other is the planning in order to reduce events of landslide and process of urban sprawl caused by the marginalization promoting risk management. of poverty, with the excluded population forced to This is a big problem for most of Brazilian cities; occupy unsuitable areas at the periphery of cities. since this survey usually needs high investments and According to Valente (1996), the conditions of the high qualification professional teams. The problem environment in these spaces of urban sprawl are came bigger in smaller cities, where technical and generally ignored, such as relief, geological, financial resources are rare. hydrographic and pedological characteristics inadequate Moreover, most of Brazilian Municipalities Master for human occupation. Hence, populations are subjected Plans are previous of these legal instruments and do not to the occurrence of catastrophic events such as floods, consider the natural environment potential and landslides, loss of soil and urban equipment and intense constrains for planning urban expansion. erosive processes. Focusing these legal and technical needs, this paper Burchell & Mukhjerji (2003) defines sprawl as low intends to show how the use of basic natural density occupation, leapfrog development characterized environmental data can be practicable for delimitation by unlimited expanses, resulting new land uses in and characterization of areas subject to sprawl. Set of relatively untouched environments. According to data includes rock, soils, steepness and hydrography; Johnson (2001), the most important aspects in urban
Journal of Urban and Environmental Engineering (JUEE), v.7, n.1, p. 64-73, 2013 66 Fracassia and Lollo sprawl are the creation of large urban gaps and the problems in the urban and natural environment. This improper use of land. situation is easily perceived in the municipality of São The main characteristics of urban sprawl in Brazilian Pedro, SP. cities are the creation of new housing lots distant from In this sense, it is necessary to adopt measures of the consolidated city center and its site in the urban planning that allow for adequate and ordered surroundings or proximities of perimeter roads, a growth in these small municipalities, as well as phenomenon also observed in small municipalities preservation of the environment in these areas, ensuring (Carbonell & Yaro, 2005). a better quality of urban life. In Limonad (2007) understanding, the form of It should be noted that the Constitution of the State occupation of the different social classes along urban of São Paulo (São Paulo, 1989) determines the fringes is characterized by low density peripheral areas obligation of Master Plan for all its municipalities, and is a worldwide phenomenon. In Brazil, the problem regardless of their size, reaffirming and expanding the became bigger due to natural environmental condition ideas of development that are present in the Federal non consideration in urban plans. Constitution of 1988. However, what one sees in reality According to Ojima & Hogan (2008), border areas is a lack of local political interest, a paucity of available usually concentrate both industrial and residential funds, and minimal practical actions to better deal with occupations, usually low-cost, and in most cases do not urban sprawl in these areas. respect the instruments of urban policy of the In view of the dearth of conceptual and neighboring municipality, leading to major methodological studies about small cities, and the environmental impacts. insufficiency of mechanisms of regulation and territorial Therefore, the process of urban sprawl is revealed as ordering in these places, we highlight the importance of an intensifier of spatial complexity and, as Braga & regional and local studies that can contribute to future Carvalho (2004) argue, when any system or organism analyses of urban sprawl in small municipalities. grows, its part differentiate, “becoming organisms that are more complex, more efficient, greater processors of STUDIED AREA matter and energy, more economically, socially and culturally developed, but also with greater problems: The municipality of São Pedro covers an area of 618 urban impacts, social conflicts, economic and political square kilometers and is located in the central eastern dysfunctions”. portion of the state of São Paulo (Middle Tietê River It is crucial to make advances in our understanding valley), in the region of Piracicaba, 180 kilometers from of spatial production in small cities, since the process of the state capital (São Pedro, 2008), as illustrated in Fig. urban sprawl affects a large portion of the country’s 1. municipalities, regardless of their size, resulting in peripheralization and in the occupation of fragile environments. We must break away from the mistaken notion that these cities remain as bastions of environmental preservation. However, in this scenario, the formation of numerous small cities that multiplied throughout the national territory was significant, either as centers of local importance (given the regional conditions of interconnection with the national economy and the development of specific productive activities), or as locations with notoriously precarious infrastructural conditions (a large part of which emerged due to the laws governing the creation of municipalities and cities Fig. 1 Location of the study area (Fracassi, 2008). in the country). According to the classification of the IBGE (2000), a São Pedro, situated in the Paulista Peripheral small city is defined as one that has a population of up Depression, has a pluviometric index of 1,175.5 to 100 thousand. On the other hand, the IPEA (2001) mm/year, temperatures varying from 12 to 32°C, which classifies small municipalities as those with a total is considered a dry climate, with a predominance of population of less than 50 thousand. cerrado biome (São Pedro, 2008). Despite its population’s, Brazilian small cities The Paulista Peripheral Depression, is a depressed usually have a physical structure that does not meet the erosive strip with portions reaching lengths of 450 real needs of the population, which may, due to kilometers (north/south) and with a mean width of unplanned occupation and low investments in approximately 100 kilometers (narrowing to the north infrastructure, lead to low “quality of life” and serious and widening in its central portion) in Parana Basin.
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Table 1. Main physical characteristics of the study area CLIMATE Tropical Climate with two well defined seasons: DRY-COLD (April to September, with average monthly temperature of 16° to 19°C) and WARM-WET (October to March, with temperatures varying from 22° to 27°C). Mean annual temperatures exceed 22°C. Thermal and rainfall oscillations influenced by altitude and relief. VEGETATION Remnants of the original Latifoliate Forest vegetation, restricted locales predominated by steep slopes and Cerrado vegetation. Original vegetation in large part destroyed to make way for pastureland, sugarcane, citrus, reforestation and annual crops. HYDROGRAPHY Drainage system reflecting control by regional tectonics with preferential NW – SE direction and secondary N – S and NE – SW directions. SOILS Latosol, latosolic quartz sand and hydromorphic soils. TECTONICS Heritage of zones with weak foundations. Meso-cenozoic reactivations. Alignment of the mountain range. Oriented drainage systems. BEDROCK Corumbataí Formation (argillite, stratified clay-bearing rock and siltites), Pirambóia Formation (fine-grained sandstone and clayey sandstone), Botucatu Formation (fine to medium-grained sandstone with minor clay contents of less than 5%) and Itaquerí Formation (conglomerate sandstone with polymictic pebbles, siltites, argillites and stratified clay- bearing rock). Cenozoic deposits – poorly consolidated sediments with medium-grained sand. GEOMORPHOLOGY Based on the geomorphologic division of the state of São Paulo, the study area encompasses three of the five compartments described for the western Paulista plateau (top of the São Pedro mountain range), the peripheral depression (area of the Middle Tietê) and basaltic cuestas. Cenozoic faulting, mainly normal and transcurrent faulting, reflected in the general outlines of the relief and of the regional geomorphology.
In terms of relief, the terrain is relatively even, with and preservation, and rural green zones – RGZ – differences in height of 20 to 50 meters and, in Corumbataí AEP (Area of Environmental Protection). exceptional cases, higher than 100 meters. The most According to article 91, the Zone of Interest for significant morphological characteristics are expressed Urban Expansion is composed by areas with potential in broad horizons and gentle shapes, such as flat-topped and trend for urban growing, defining new occupation hills 550, 650 and 700 meters high, slightly convex, enterprises in the expansion tendencies. dividing broad valleys, complemented by the flat Article 92 states that the Zone of Interest for Urban bottoms of alluvial plains. Expansion definition has the main objectives of propose Despite the predominance of Paleozoic sediments, actions for urban and territorial development, promote there are discontinuous surface areas of intrusive urban densification in disperse occupation areas and magmatic bodies, usually in the form of diabase sills order new urban occupations. and dikes that controls parts of the local relief, However the Master Plan doesn´t present the criteria generating slopes with levels varying according to the for defining this area and inform that Zone of Interest homoclinal structure and lithologies resulting from for Urban Expansion definition is showed in Territorial differential erosion. Macrozoning Map. Observing the map (Fig. 2) we note With regard to the cuestas of the Tietê channel that Urban Expansion Zone limits definition was simple (especially the São Pedro and Itaquerí mountain ranges), Urban Zone corners connections, without consider other these formations exhibit very particular characteristics criteria. This is a very common approach in many that reflect tectonic activity, where the exposure of the Brazilian Cities Master Plans. sandstone to a single lava overflow caused the However, in reality, what one sees is urban sprawl formation of straight vertical walls. Table 1 summarizes unlike that foreseen in the Master Plan, since, according the main physical characteristics of the study area. to the Territorial Macro-zoning Map, there is already a consolidated growth to the southwest of the main urban area of the municipality (Urban Zone outside of the Seat Master Plan of São Pedro of the Municipality – Z10), while the zone of interest In its chapter II (on the Rural Macro-zone), under article for urban expansion is located to the southeast of the 90, the current Master Plan of the municipality of São main urban area. An example of a neighborhood Pedro (São Pedro, 2008) subdivides and delimits this situated in Z-10 is Alpes das Águas, which covers an zone on the Territorial Macro-zoning Map into zones of area equivalent to that occupied by the main urban area interest for urban expansion, urban expansion outside of São Pedro. the seat of the municipality, environmental protection
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Fig. 2 Territorial Macrozoning Map of São Pedro.
METHODOLOGICAL PROCEDURES The purpose of GIS is to underpin decisions based on spatial data, proving a selection of priorities. By Principles means of these procedures, it was possible to The surveys required for the characterization of the systematize, relate and observe the data, in order to attributes involved in this analysis included field trips to draw up a chart identifying the different potentials for identify and understand the areas of expansion of the urban occupation. municipality, a bibliographic survey including official documents of the municipality (its Organic Law and Characterization of the attributes respective Master Plan), as well as the collection of data Bedrock available at the IBGE, the Ministry of Cities, the local city hall, and digital and analogical databases of articles The bedrock of the study area is composed of the and theses. These are the basic information for studied following lithostratigraphic units: Alluvial Deposits area characterization in terms of its natural and social (sandy alluviums with gravel beds and contributions of environment. fine and coarse ramp colluviums); Botucatu Formation The production of the digital database, the spatial (fluvial sandstone at the base and aeolian sandstone at analyses and the creation of thematic charts were the top, fine to medium-grained, with occasional performed with computers using the Geographic conglomerate sandstones bodies at the base); Information System Spring (SPRING, 1996). The Corumbataí Formation (purplish or reddish siltites and collection of natural attributes and its spatial distribution argillites with intercalations of very fine-grained was essential to provide the basis for data treatment sandstones lens); Itaquerí Formation (post-Serra Geral (using algebra map) combining the attributes to sediments constituted of banks of sandstones alternating establish how its combination results more potential or with clayey cement, ferruginous crusts, stratified clay- constrain situations for urban planning. bearing rock and conglomerates in the basal portion); The natural attributes (hydrography, bedrock, soils, Pirambóia Formation (fine and medium-grained and steepness) were obtained from existing surveys and sandstone with a higher proportion of clay fraction in from the municipality’s Master Plan (São Pedro, 2008). the lower portion); Serra Geral Formation (a sequence The choice of these attributes is justified due to the of basaltic overflows (predominantly aphanitic and with nature of the municipality’s most common natural associated intrusions, and dikes with intercalations of phenomena, which may act as limiting factors for urban lenses and sandy layers). Figure 3 shows the bedrock occupation (erosion and gravitational mass movements). map for this area (SÃO PEDRO, 2008).
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Fig. 4 Soil and sediments units map for São Pedro area.
Fig. 3 Bedrock map for São Pedro area. Botucatu Formation, Residual, 20% Sand (Fm. Botuc Rar20): Pejon (1992) states that this unit is The analysis of the influence of the units of the restricted to the areas of escarpments in the São Pedro substrate on the occurrence of erosive processes took mountain range with declivities of more than 20%. This into account the texture and coherence normally unit comprises residual sandy materials of little presented by the units in the area in their undisturbed thickness, with the occurrence of silicified sandstone state and in an altered condition. outcrops of Botucatu Formation. To evaluate the potential for the occurrence of Corumbataí Formation, Reworked, Clayey (Fm. gravitational mass movements, the cohesion and Corumb RTarg): This unit is composed of thick clayey structures of the lithologies in each unit were materials (larger than 5.0 m), of a dark red coloration, considered. related to the lithologies of the Corumbataí Formation, but with contributions of materials originating from Soils and Sediments other, unidentified, formations (Pejon, 1992). According Pejon (1992) describes eleven soil units in São Pedro to Pejon’s notes (1992), the mean percentage of clay Municipality area. The texture of each unit of soil and exceeds 50%, while that of sand is about 15%. Its its cohesion were the criteria for evaluating the average density is 1.60g/cm³, and the natural average influence of this attribute in triggering processes of void index is about 1.30. These values indicate that the erosion and gravitational mass movements. Figure 4 material contains a high quantity of voids, and may presents the soil and sediments units’ spatial distribution exhibit collapsible characteristics. in the study area. Corumbataí Formation, Residual, Clayey (Fm. Hydromorphic (HI): According to Pejon (1992), Corumb Rarg): This unit is constituted of residual hydromorphic materials present special and important materials of the Corumbataí Formation, with characteristics for geotechnics, such as the level of the thicknesses varying from 1.0 to more than 5.0 meters. water table (normally very close to the surface) and the The highest thicknesses present a homogeneous profile, high quantity of organic matter. Therefore, they are well-structured and of red to yellow coloration. On the problematic regions from the standpoint of occupation other hand, the materials with lower thicknesses show a or construction sites. yellow coloration and retain evidence of the original rock (Pejon, 1992). The granulometric analyses indicate that these materials contain, on average, more than 60%
Journal of Urban and Environmental Engineering (JUEE), v.7, n.1, p. 64-73, 2013 70 Fracassia and Lollo of clay and less than 25% of sand. According to Pejon (1992), it can be concluded that these materials are highly compact; however, when the package is thicker, they tend to present higher void indices, possibly due to the greater genetic evolution of the profile. Corumbataí Formation, Residual, Reworked, Clayey (Fm Corumb Rarg + RTarg): This unit, which is associated with the Corumbataí Formation, represents an alternation of residual outcrop materials and reworked materials of little thickness, i.e., less than 2 meters (Pejon, 1992). Itaquerí Formation, Reworked, 30% Sand (Fm. Itaq RTar30): According to Pejon (1992), this unit is constituted of sandy reworked materials associated to the areas of occurrence of the Itaquerí Formation. Its thicknesses vary from 3 to 4 meters, with less than 30% of fines (silt + sand). This unit is found in a restricted portion at the top of the São Pedro mountain range. Pirambóia Formation, Reworked, 20% Sand (Fm. Pir RT20): This highly homogeneous unit comprises very sandy and thick materials (> 5.0m), associated with areas of occurrence of the Pirambóia Formation, corresponding, in pedology, to quartz sands. The percentage of sand is higher than 80%, while the clay fraction does not exceed 15%, and that of silt is practically absent, presenting a high natural compactness. Fig. 5 Map of environmental protection areas in São Pedro. Pirambóia Formation, Reworked, 30% Sandy (Fm Pir RT30): According to Pejon (1992), this unit of reworked materials occurs in higher thicknesses, usually Hydrology more than 3.0 meters, and is distributed in a small The hydrography of the study area is part of the Paraná region of the study area. River basin and its drainage occurs over the Paulista Pirambóia Formation Residual, Reworked, Sandy Peripheral Depression. As can be observed in Fig. 5, (Fm. Pir Rar + RTar): The association of sandy the area of the municipality presents a predominantly materials of small thicknesses (< 0.3 m) genetically dendritic drainage pattern, in which the Piracicaba related to the sandstones of the Pirambóia Formation, River stands out. added to the predominance of the residual over the reworked materials in areas of outcroppings, constitute The southwestern part of the study area shows a reservoir on the Piracicaba River created by the Barra this unit. These materials present common Bonita dam. characteristics with respect to their texture, physical The consideration of the drainage system in the aspects and compaction (Pejon, 1992). As for their process played a restricted role in terms of urban texture, they are considered sandy, since they contain sprawl due to the distance of the water bodies, which more than 70% of sand and only 10% of clay (Pejon, represent only a minor limiting factor to urban 1992). expansion. Serra Geral Formation and Basaltic Intrusion, Residual, Silty Clayey (Fm. SG IB RSarg): This unit is composed of clayey and silty-clayey materials that Steepness result from alteration of the basic magmatites of the Serra Geral Formation and Basaltic Intrusion. Their Most of the terrain is gently hilly, reflecting a thicknesses vary from 1.0 to 5.0 m, with the smaller predominance of gently sloping land lots, with the thicknesses containing a higher percentage of silts, and exception of the areas of high cuestas located toward the thicker ones, of clay (Pejon, 1992). the north of the municipality (Fig. 6). The limits of the Sandy Alluviums: The last unit of unconsolidated classes of steepness de chosen were 10% (the limit for materials corresponds to the alluviums. Pejon (1992) the onset of erosive processes in lands of the peripheral reports that in this region they are mainly sandy, do not depression of the Paraná River basin) and 30% (limit cover extensive areas, and are used mainly to extract imposed by the Forestry Code for land parceling). sand for civil construction.
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Table 2. Classification of the attributes considered Unit No Restriction (0) Low Restriction (1) High Restriction (2) Hydrography >50m <50m Steepness <10% 10-30% >30% Botucatu Formation Serra Geral Formation Substrate Pirambóia Formation Itaquerí Formation Corumbataí Formation Alluvial Deposits Fm Corumb Rarg Fm. Pir RT20 Fm Corumb RTarg Sandy Alluviums Unconsolidated Fm. Pir RT30 Fm Corumb Rarg + RTarg Fm. Botuc Rar20 ma terials Fm. Pir Rar + RTar FM SG IB RSarg Fm. Itaq RTar30 Hi (Hydromorphic)
attribute condition with a high potential to trigger an erosive process or gravitational mass movement. The classification of the attributes according to this criterion is given in Table 2. To analyze the areas of possible urban expansion in the municipality of São Pedro, the attribute hydrography was considered with the definition of Areas of Permanent Preservation (APP) having a width of 50m starting from the banks of the river bed (a more conservative value than the 30m usually employed for water bodies of the size of those existing in the area – Brazilian Forestry Code), matching the restrictive class of distances smaller than or equal to 50m, and greater distances for areas suitable for urbanization.
Potential Urban Occupation Chart Production After creating the basic maps and charts presented in the above figures, the final thematic chart was drawn up by adding the sum of the weights and reclassifying the results of this sum. To this end, the spatial representations of the attributes in matrix form were given values corresponding to their level of restriction. The map algebra consisted of the sum and classification of this result with the generation of a new spatial representation. The operations were performed with a Fig. 6 Steepness chart for São Pedro area. LEGAL algorithm running on version 5.0.4 of SPRING GIS. Attributes Classification The assessment of the potentialities and limitations of RESULTS AND DISCUSSION the area’s natural environment prioritized the The map algebra resulted in a sum of the weights of the identification of the conditions of the environment that attributes under consideration, leading to final values could trigger exogenous processes/phenomena that ranging from zero to eight. The value of “0” represented could cause degradation. Historical records of the area the condition in which the four attributes were favorable under study indicate that these processes/phenomena are for land parceling for urban expansion (no restriction), erosive processes and gravitational mass movements while “8” represented the condition in which all the (landslides). attributes indicated restrictions. Therefore, each of the attributes considered was The results were classified into the following three classified according to its potential contribution to the categories: 0 to 2 – areas favorable for expansion; 6 to 8 onset of erosion and gravitational mass movements, – areas unfavorable for expansion; and 3 to 5 – areas according to a scale from zero to two of susceptibility. with intermediate conditions between the two extremes. On this scale, 0 (zero) represents the absence of any Based on the above classification, a chart was drawn influence in the process, 1 (one) represents a low up indicating the potential for urban expansion based on influence in the process, and 2 (two) represents an the limitations and potentialities of the environment,
Journal of Urban and Environmental Engineering (JUEE), v.7, n.1, p. 64-73, 2013 72 Fracassia and Lollo which took into consideration the susceptibility to the development of erosive processes and gravitational mass movements (Fig. 7). The “without restriction” condition implies a set of attributes of the environment in which one of the attributes classified as restrictive may occur (value 2 – extreme of this class) while the three other attributes are favorable. This is because the unfavorable attribute cannot be a determining factor for the final decision about the occupation of the area. Nonetheless, it should be pointed out that the unfavorable attribute must be analyzed carefully. In the “low restriction” condition there may be too restrictive and two favorable attributes, indicating that the intermediate situation should also be considered very carefully to ascertain which of the attributes match the unfavorable description and the volume of investment required in works to render these areas feasible. The “high restriction” classification indicates a set of at least two unfavorable and two intermediate attributes, which implies strong restrictions. This condition makes parceling the land into lots for urban occupation practically impossible, except if massive investments are made in infrastructure and works to stabilize the land lots in order to prevent degradation of the environment. An analysis of Susceptibility to Urban Sprawl Chart, based on the limitations and potentialities of the Fig. 7 Susceptibility to Urban Sprawl. environment reveals the following. The areas with intermediate conditions are concentrated in the northeast part of the municipality, above the basalt sandstone Taking in account the actual tendencies of urban cuestas, while the favorable areas are distributed in the expansion in the area, we consider three expansion northeast, central and southeast regions of the buffers involving the urban areas of São Pedro (the municipality (in the portions with lower relief). Lastly, main municipality) and Águas de São Pedro (a district the areas classified as restrictive for expansion are those of São Pedro). These buffers had one, two and three located on or at the edges of the cuestas and in the areas kilometers from urban limits and show that the of permanent preservation. expansion areas nearly from urban areas present suitable In fact, the predominant geomorphologic contexts of conditions for urban expansion in all but north area of the three classes also represent the most marked São Pedro. In more distant areas, the natural conditions geological and geotechnical contexts. Hence, the are good to urban expansion with exception only for favorable conditions are generally associated with rock areas up to north of São Pedro. units from Pirambóia and Corumbataí Formations and residual and reworked unconsolidated materials of these formations, with medium to fine texture and good CONCLUSIONS cohesion. The intermediate conditions include areas of The municipality of São Pedro presents a considerable bedrock of the Pirambóia and Itaquerí Formations and potential of areas suitable for urban expansion unconsolidated reworked materials from these intercalated with areas of intermediate and restricted formations. Lastly, the areas classified as restricted have potential. These limiting areas comprise a set of bedrock and residual materials of the Botucatu physical factors (geological and geomorphologic) with a Formation (with a very sandy texture). It should also be high probability for the occurrence of erosion and mass noted that in situations where the substrate of the movements, characterizing them as areas of Botucatu Formation is silicified and the depth of the environmental risk. residual unconsolidated materials is not great, such Therefore, even in areas classified as suitable, urban areas possess suitable conditions to be classified as expansion should be considered carefully, and it is favorable. essential that the guidelines for expansion take into account the natural conditioning factors. Hence, it is
Journal of Urban and Environmental Engineering (JUEE), v.7, n.1, p. 64-73, 2013 Fracassia and Lollo 73 crucial for land use planning to be based on the quality Carbonell, A. & Yaro, R. (2005) American spatial development and and characteristics of the land in order to satisfy certain the new megalopolis - Land Lines. Lincoln Institute of Land Policy. priorities and/or occupy any terrestrial space. Carvalho, P.F. (2001) Environmental problems in social interest It should be pointed out that this analysis was based on housing and cities. In: Carvalho, P.F. & Braga, R. Environmental the conditions of the environment from the standpoint of management outlook in medium cities. Rio Claro: Universidade erosion and gravitational mass movements, which are Estadual Paulista. (In Portuguese) the most significant dynamic processes in the area in Fracassi, P.C. (2008) Urbanization and environmental and social impacts: São Pedro risk areas. Monograph. Rio Claro: question. It should also be noted that in other realities Universidade Estadual Paulista. (In Portuguese) (different municipalities or contexts of the IBGE (2000) 2000 Census. Brazilian Institute of Geography and environment), the selection of the attributes and the Statistics. In: http://www.ibge.gov.br. Access: June 2010. (In definition of the weights for each one may and/or Portuguese) should vary. Considering the buffers around urban areas IPEA (2001) Brazilian Municipalities Database. Institute of Applied Economy Research. In: http://www.ipea.gov.br/portal/. Access: we observe that only the areas in north of São present June 2010. (In Portuguese) high restriction to urban expansion. Johnson, M.P. (2001) Environmental impacts of urban sprawl: a Part of the results reported here coincide with the survey of the literature and proposed research agenda. Master Plan of the municipality, which foresees as a Environment and Planning A. 33: 717 - 735. 2001. zone of interest for urban expansion the area southeast Limonad, E. (2007) Disperse Urbanization: another form of urban expression? Formation Journal, 1: (14). 2007. of the urban seat of São Pedro. The analyses of this Ojima, R. & Hogan, D.J. (2008) Urban growing and periurban study, with their aforementioned restrictions, indicated occupation: spatial distribution of population in new the northeast, central and southeast portions of the environmental frontiers. In: 4th National Meeting of Post- municipality as areas with intermediate conditions for graduation and Research in Environment and Society. Brasília. (In urban expansion, and the latter is the same one Portuguese) Pejon, O.J. (1992) Engineering geological mapping of Piracicaba considered in the Master Plan. Sheet (1:100.000 Scale): methodological aspects of surveying Lastly, it can be stated that this approach enabled attributes. PhD Thesis. São Paulo: Universidade Estadual de São aspects of the current legislation and the characteristics Paulo. (In Portuguese) of the landscape to be analyzed jointly in evaluating the Penteado, M.M. (1968) Geomorphology of center-east sector of suitability of land use, thus serving as a strategy Paulista Peripheral Depression. PhD Thesis. Rio Claro: Faculdade de Filosofia, Ciências e Letras. (In Portuguese) applicable to other situations. Santos, M. (1996) Brazilian urbanization. (3rd ed.). São Paulo: Hucitec. (In Portuguese) São Paulo. (1989) São Paulo State Constitution. In: REFERENCES http://www.al.sp.gov.br/repositorio/ Braga, B. & Carvalho, P.F. (2004) City: space and citizen. In: legislacao/constituicao/1989/constituicao%20de%2005.10.1989.h Giometti, A.B.R. & Braga, R. Citizen Pedagogy: Formation tm. Access. May 2010. (In Portuguese) Books: Geography Education. São Paulo: Universidade Estadual São Pedro (2008) São Pedro Master Plan – #15/08 Law. Public and Paulista. (In Portuguese) Particular Works Department of São Pedro. (In Portuguese) Brazil (2011) Provisional Measure #547/11. Union Official Diary, Camara, G., Souza, R.C.M., Freitas, U.M., Garrido, J. (1996) October 13th 2011. (In Portuguese) SPRING: Integrating remote sensing and GIS by object-oriented Brazil (2012) #12,608/12 Law. Union Official Diary, April 11th data modeling. Computers & Graphics, 20 (3): 395-403. Valente, A.L.S. (1996). Using remote sensing in risk areas 2012. (In Portuguese) th Burchell, R. & Mukhjerji, S. (2003) Conventional development definition. 8 Brazilian Remote Sensing Symposium. Salvador. versus managed growth: the costs of sprawl. American Journal of (In Portuguese) Public Health. 93 (9).
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Journal of Urban and Environmental Journal of Urban and E Engineering, v.7, n.1, p.74-81 Environmental Engineering ISSN 1982-3932 J E www.journal-uee.org U doi: 10.4090/juee.2013.v7n1.074081
FLOW VELOCITY AND SURFACE TEMPERATURE EFFECTS ON CONVECTIVE HEAT TRANSFER COEFFICIENT FROM URBAN CANOPY SURFACES BY NUMERICAL SIMULATION
Sivaraja Subramania Pillai1 and Ryuichiro Yoshie2
1 Sri Venkateswara College of Engineering, Pennalur, Sriperumpudur, India 2 Tokyo Polytechnic University, 1583, Iiyama, Atsugi, Kanagawa 243-0297, Japan
Received 15 August 2012; received in revised form 05 January 2013; accepted 9 February 2013
Abstract: This study investigates the effect of flow velocity and building surface temperature effects on Convective Heat Transfer Coefficient (CHTC) from urban building surfaces by numerical simulation. The thermal effects produced by geometrical and physical properties of urban areas generate a relatively differential heating and uncomfortable environment compared to rural regions called as Urban Heat Island (UHI) phenomena. The urban thermal comfort is directly related to the CHTC from the urban canopy surfaces. This CHTC from urban canopy surfaces expected to depend upon the wind velocity flowing over the urban canopy surfaces, urban canopy configurations, building surface temperature etc. But the most influential parameter on CHTC has not been clarified yet. Urban canopy type experiments in thermally stratified wind tunnel have normally been used to study the heat transfer issues. But, it is not an easy task in wind tunnel experiments to evaluate local CHTC, which vary on individual canyon surfaces such as building roof, walls and ground. Numerical simulation validated by wind tunnel experiments can be an alternative for the prediction of CHTC from building surfaces in an urban area. In our study, wind tunnel experiments were conducted to validate the low-Reynolds-number k-ε model which was used for the evaluation of CHTC from surfaces. The calculated CFD results showed good agreement with experimental results. After this validation, the effects of flow velocity and building surface temperature effects on CHTC from urban building surfaces were investigated. It has been found that the change in velocity remarkably affects the CHTC from urban canopy surfaces and change in surface temperature has almost no effect over the CHTC from urban canopy surfaces.
Keywords: Convective Heat Transfer Coefficient (CHTC), CFD, flow velocity, urban canopy surfaces.
© 2013 Journal of Urban and Environmental Engineering (JUEE). All rights reserved.
Correspondence to: Sivaraja Subramania Pillai, Tel.: +91-(0)9940060358. E-mail: [email protected].
Journal of Urban and Environmental Engineering (JUEE), v.7, n.1, p.74-81, 2013 Pillai and Yoshie 75
INTRODUCTION flow around the building varies the CHTC values on the windward facade. They found that CHTC is a power The Weather Research Forecasting (WRF) model law correlation of wind speed at every “façade”. They coupled with UCM is to represent the transfer of heat also reported the non-suitability of standard wall and momentum from urban environment. This UCM functions for CHTC calculation on the wall surface. provides the description of lower boundary conditions Defraeye et al. (2010) performed CFD simulations of urban area, which improves the prediction of urban using a low-Reynolds-number model to evaluate the momentum and heat transfer by WRF. Hence the forced convective heat transfer at the surfaces of a cube Weather Research Forecasting (WRF) model coupled immersed in a turbulent boundary layer. The CFD with the UCM would be considered as an effective tool simulation was validated by comparison with wind- for the prediction of urban heat island phenomena. The tunnel measurements. The CHTC obtained from the urban canopy model is responsible for predicting the low-Reynolds-number model showed satisfactory heat transfer from the urban area to the overlaying agreement with the experimental data. They also found atmosphere. In single layer Urban Canopy Model that standard wall functions, which are frequently used (Kusaka et al., 2001), the local convective heat transfer for high-Reynolds-number flows, overestimated the from the urban canopy surfaces and its dependence on CHTC significantly compared to the low-Reynolds- urban parameters such as building coverage ratio and number model. building height variations are not explicitly modeled. In The authors conducted CFD simulation with a low- the UCM in WRF, the convective heat transfer Reynolds-number k-ε model to evaluate the convective coefficient from canopy surfaces are evaluated from heat transfer from canyon surfaces. Calculated CFD Jurge’s relation as shown in equation 1 and 2. The results showed good agreement with experimental Jurge’s relation (1924) is based on the CHTC of a results. Further in order to assess the major parameter heated copper square plate, which was oriented that affecting the CHTC was studied by CFD perpendicular to a uniform air flow in a wind tunnel. simulation. The effect of flow velocity and surface
0.78 temperature was analyzed. The results from this study CCwG7.51 U s ( U s 5m/s) (1) will be helpful in choosing the parameter for generalizing the CHTC from urban canopy surfaces.
CCwG6.15 4.18 Us ( U s 5m/s) (2) WIND TUNNEL EXPERIMENT where Cw= CHTC of wall (W/m2oC), CG= CHTC of o Outline of wind tunnel experiment ground (W/m2 C), Us = representative wind speed inside the canopy (m/s). The experiments were carried out in a thermally The Jurge’s relation has its own limitations and may stratified wind tunnel at Tokyo Polytechnic University not be applied for the heat transfer from a surface of the as shown in Fig. 1. The dimensions of the wind tunnel building among the group of buildings (urban area). In are 1.0 m (height) × 1.2 m (width) × 9.4 m (length). The this relation, the local CHTC from building walls and experimental setup consisted of an aluminum cubic ground depends only on the velocity inside the canopy. block array to model different cases of urban canopy. However, this cannot be justified since other urban The array continued upstream of the measured section parameters also contribute to the CHTC. Moreover, this to model the fetch, which is responsible for the model cannot distinguish between CHTC on different development of the turbulent thermal boundary layer on wall surfaces, i.e., windward, leeward, side wall of the the urban canopy. Figure 2 shows the experimental set building and the ground, instead it expresses the CHTC up, in which aluminum blocks with dimensions 0.05m generally as wall. Thus, the authors carried out wind (W) ×0.05 m (D) ×0.05 m (H) are used for the tunnel experiments and CFD simulations to clarify this generation of block arrays. issue. Wind tunnel experiments were firstly conducted Experiment was carried out for 25% Building to roughly grasp the dependence of urban parameters on Coverage Ratio (hereafter referred to as BCR) with bulk heat transfer from an urban canopy in a thermally uniform height building blocks. The inflow velocity and stratified wind tunnel. However, it is not an easy task in temperature of the air at the wind tunnel inlet were wind tunnel experiments to evaluate local CHTC, which uniformly maintained at 1.9m/s and 7.8oC throughout vary on individual canyon surfaces such as building the cross section. The floor temperature was maintained roof, walls and ground. Numerical simulation validated at 53oC to simulate the unstable thermal environment. by wind tunnel experiments can be an alternative for the These conditions were adopted for all experimental prediction of CHTC from building surfaces in an urban cases. The surface temperatures of ground and block area. roof were observed using thermo-camera pictures taken Blocken et al. (2009) conducted CFD simulations to during the experiments. The block roof temperature o evaluate CHTC on the surfaces of a low-rise building reached nearly 50 C because of the higher thermal with low–Reynolds-number model and found that the
Journal of Urban and Environmental Engineering (JUEE), v.7, n.1, p.74-81, 2013 76 Pillai and Yoshie
Bulk convective heat transfer from urban canopy
Heat flow by advection at the measuring section (outlet) can be calculated from the velocity and temperature data using the following equation:
n ATUCQ iiip (3) i1
where Q = heat flow (W), ρ = density of air (kg/m³), Cp = specific heat of air (J/kgoC), Ui = mean wind velocity at measuring point i (m/s), Ti = mean temperature of air at measuring point i (oC), Ai = control area around Fig. 1 Wind Tunnel experimental setup. measuring point i (m²), and n = number of measuring points. conductivity of the aluminum. The X-direction wind The difference between the inlet heat flow (at X=0) velocity component and the temperature were measured and the outlet heat flow (at measuring section in Fig. 2) in the measuring section (outlet) shown in Figs 2 and 3 was considered to be the bulk heat convected from all shows the measuring points (within the moving limit of over the urban canopy surfaces (ground, walls and the traverse system) at the measuring cross section. We roofs). used more measuring points more closely spaced near the floor as shown in Fig. 3 (right side). A split film ∆Q = QUC = Qout – Qin (4) probe and a thermocouple were used to measure the velocity and the temperature, respectively. The velocity where ∆Q = QUC = heat convected from all over the and temperature measurements were made behind the urban canopy (W), Qout = heat flow at the outlet blocks and along the flow passages, as shown in Fig. 3. (measuring section in Fig. 2)(W), and Qin = heat flow at the inlet (W) in Fig 2. Inlet X=0
Fig. 2 Wind Tunnel experimental setup (25% BCR).
Fig. 3 Measuring points in wind tunnel cross section (ex: BCR- 6%).
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0.05m 0.1m
m m
5 5
0 0
. .
0 0
Y
m m
5 5
2 2
0 0
. .
0 0
x
Fig. 4a Grid arrangement in horizontal plane (ex : uniform height, BCR-11% case).
m m
5 5
0 0
. .
0 0 Z
0.05m 0.1m
x
Fig. 4b Grid arrangement in vertical section (ex : uniform height, BCR-11% case).
CFD Simulation the wall surfaces. y+ is defined as follows:
General outline of numerical simulation and yu y * (5) boundary conditions
For the calculation of complex turbulent flows with where = frictional velocity at the surface (m/s), separation and heat transfer, Abe et al. (1994, 1995) y=distance between the wall surface and the first fluid developed a new low-Reynolds number turbulence cell (m), and ν=kienematic viscosity of air (m2/s). The model for flow field and thermal field. This model quite maximal value of y+ was in the range of ‘2’ at edge of successfully predicts the separating and reattaching the windward wall, sidewall and roof of the first block flows in the downstream of a backward-facing step, in the upstream region where the frictional velocity at which involve most of the important physical the surface is higher (higher wall shear stress). We phenomenon of complex turbulent flow around conducted grid sensitivity analyses using fine mesh obstacles. Thus, the authors considered this Low (1939(x)×30(y)×67(z) = 3 897 390) and coarse mesh Reynolds number k-ε model was suitable for urban (1378(x)×20(y)×59(z) = 1 626 040) for BCR25% canopy simulations. uniform case. The differences between wind velocities Figures 4a and 4b shows the grid arrangement in the and temperature profiles and convective heat transfer horizontal plane and vertical section (For example: for the calculated results of the fine mesh and the coarse BCR-11% case with uniform height buildings), mesh were extremely small. Thus we judged that the respectively. The computational domain was an exact grid resolution of the fine mesh was sufficient, and after replica of the wind tunnel in windward length and that grids with similar resolution to the above fine mesh vertical height. Minimum width was selected by were used for other calculation cases. considering symmetry in the Y direction. As shown in Calculation conditions (For example: BCR-11% case Figs 4a and 4b the domain has structured grids with with uniform height buildings) are shown in Table 1. very fine mesh near the wall surfaces. Distance between No slip boundary conditions were applied for wall shear wall surface and first mesh line was 0.2 mm. As a result, stress. For thermal boundary conditions, surface non-dimensional distances from the wall surfaces Y+ temperatures were prescribed and heat conduction were below 1.0 for most of the first fluid cells close to boundary condition was applied for heat flux on the wall surfaces. The surface temperature for various
Journal of Urban and Environmental Engineering (JUEE), v.7, n.1, p.74-81, 2013 78 Pillai and Yoshie
Table 1. Calculation conditions for low Reynolds number k-ε model (For ex: BCR-11% case with uniform height buildings) Computational domain 9.35m(x) × 0.075m(y) ×0.8m(z) Grid resolution 1564(x) × 33(y) × 100(z) = 5 161 200 mesh Boundary conditions for wall shear stress Wall and roof of blocks No slip condition Wind tunnel floor No slip condition Wind tunnel ceiling Symmetric plane Lateral sides of computational domain Symmetric plane Inflow boundary condition Velocity U = 1.9 m/s, Temperature T = 7.8°C Turbulent kinetic energy k= 0.0016m2/s2 (Corresponds to turbulence intensity = 2%) Outflow boundary condition Zero gradient condition
Thermal boundary conditions
Block roof surface Surface temperature 48.5°C, heat conduction (No slip condition) Wind tunnel floor surface Surface temperature 53°C, heat conduction (No slip condition) Block wall surface Surface temperature 50°C (average of above two surface temperatures), heat conduction (No slip condition) simulation cases were obtained from the thermo camera Comparison between experiment and CFD results pictures (roughly 300 pictures for each experiment) taken during the experiments. The average temperature Figures 5a and 5b compares the bulk heat transferred obtained from the thermo-camera pictures were defined (QUC) from urban canopy for experiment and CFD as the heat transfer boundary condition over the surface simulation for different canopy configuration cases with (ground and roof temperature). Lateral sides (in the Y uniform and non-uniform building heights respectively. direction) and the ceiling (in the Z direction) of the As discussed in section 2.3, the difference between inlet computational domain were taken as symmetry plane. heat flow (Fig. 2) and outlet heat flow (at measuring Inflow of the computational domain has the uniform section in Fig. 2) was considered to be the bulk heat velocity and temperature condition as same as the wind transferred from all over the urban canopy surfaces tunnel experiment. Turbulent kinetic energy at the (ground, walls and roofs). The QUC from urban canopy inflow corresponds to the 2% turbulence intensity of the obtained by the experiments and the CFD simulations wind tunnel. Outflow was defined as zero gradient shows good agreement with each other. In addition, the condition. For the discretization schemes for the vertical profiles of wind velocity and temperature (at advection term, a second order upwind scheme was measuring section) calculated by CFD simulations used for the transport equation of momentum, heat, agreed very well with those of the experiments (Sivaraja turbulent kinetic energy and dissipation rate. The et al., 2010). Thus, the authors considered that CFD convergence criteria for the residual was set at 10-10, simulations are appropriate for estimation of convective which is much smaller than the default value of 10-3, heat transfer coefficient from building surfaces for and the convergence was assessed by comparing the further studies. results (velocity and temperature profile) of the latest iteration and considerable previous iteration.
3000 3000 Experiment Experiment CFD CFD 2000 2000 (W) (W) UC UC Q Q 1000 1000
0 0 BCR 6% BCR - 11% BCR - 25% BCR 6% BCR - 11% BCR - 25%
(a) Uniform height case (b) Non-uniform height case
Fig. 5 Comparison between experiment and CFD simulations: Bulk heat transferred (QUC) from urban canopy for various BCR.
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Table 2. Various cases of thermally stratified environment with different flow velocities Reference velocity, U (m/s) (TT (oC) Cases Inflow velocity (m/s) R Rs) Rib Case 1 1.9 2.1 45.2 0.13 Case 2 1 1.15 45.2 0.5 Case 3 0.75 0.85 45.2 0.9
Thermal stratification effects on CHTC of canyon strongly unstable cases of urban thermal environment of surfaces (with change in flow velocity) 25% building coverage ratio with uniform height building case were examined. This various Rib values The effect of thermal stratification in urban can be achieved by change in the inflow velocity and atmosphere has been studied with the help of numerical the surface temperature. But for the first investigation simulation. The unstable thermal environment in real the Rib was achieved by only changing the flow urban area favors the urban heat island phenomena. velocity which is shown clearly in Table 2. The Hence we opted the study of heat transfer coefficient temperature difference between the surface and variation due to the change in the stratification effects in reference position is same for all the cases. The value of a unstable thermal environment. This urban thermal Rib for weakly unstable condition is -0.13 termed as stratification has been characterized by Bulk case1, for unstable condition it is -0.5 termed as case2 Richardson’s number. Bulk Richardson number can be and for strongly unstable it is -0.9 termed as case3. expressed like the following Figures 6a−6d shows the CHTC profile in horizontal direction for roof, windward wall, leeward wall, and ground respectively. From the figures it has gH( TRs T ) Ri been inferred that the CHTC is higher for all the canopy b 2 (5) (TU0 273) R surfaces in weakly unstable environment than the other cases of thermally stratified environment. This shows where Rib = Bulk Richardson number, H = Reference that the flow velocity influences much on the all the height (m), TR = temperature at ref height above the urban canopy surfaces. Thus weakly unstable canopy (oC), (center position of the canopy), and TS = environment favors the mitigation of the urban heat Surface temperature (°C), T0 = Average Inflow island phenomena in urban area rather than the other temperature (°C), and UR = Velocity at reference height cases of urban thermal stratification. This shows the above the canopy (m/s), at the boundar layer height. dependence of convective heat transfer coefficient from The stable and neutral environment not much the building surfaces on the thermal stratification important considering diurnal heat island phenomena, attained with the change in flow velocity over the hence three cases of weakly unstable, unstable and canopy in the urban area.
Fig. 6 (a) CHTC profile for roof in different thermally stratified environment ( with change only in flow velocity); (b) CHTC profile for windward wall in different thermally stratified environment ( with change only in flow velocity); (c) CHTC profile for leeward wall in different thermally stratified environment ( with change only in flow velocity); and (d) CHTC profile for ground in different thermally stratified environment ( with change only in flow velocity).
Journal of Urban and Environmental Engineering (JUEE), v.7, n.1, p.74-81, 2013 80 Pillai and Yoshie
Table 3. Various cases of thermally stratified environment with surface temperatures Reference velocity, U (m/s) (TT o Cases Inflow velocity (m/s) R Rs) ( C) Rib Case 1 1.9 2.1 -45.2 -0.13 Case 2 1.9 2.1 - 67.2 -0.19 Case 3 1.9 2.1 -92.2 -0.28
Thermal stratification effects on CHTC of canyon temperature by keeping the flow velocity as a constant surfaces (without change in flow velocity) one.
Thermal stratification effect in urban area can be This shows the CHTC from the surfaces characterized by Bulk Richardson number. In the above predominantly depends on the flow velocity over the section the various cases of bulk Richardson number has surface irrespective of the surface temperature. Thus been achieved by both the change in inflow velocity. In change in Bulk Richardson number will not affect the this section three cases of bulk Richardson number CHTC from the surfaces unless the scenario (Rib) effects on the CHTC of canopy surfaces were achieved by change in flow velocity. investigated. Here the bulk Richardson number was achieved by change in building surface temperature and Conclusion not the change in inflow velocity. The inflow velocity is maintained constant and the surface temperature was Convective heat transfer from various urban canopy changed which is clearly shown in Table 3. The value cases for different building coverage ratios with uniform of Rib for case1 is 0.13 termed, for case2 it is 0.19 and non-uniform building heights were investigated by and for case3 it is 0.28. wind tunnel experiments and CFD simulation. Low- Figures 7a−7d shows the CHTC profile in Reynolds number turbulence model validated by the horizontal direction for roof, windward wall, leeward authors using experimental data was adopted for further wall and ground respectively. These figures illustrates investigations in CFD simulations. Our main purpose that the there is no variation in the CHTC from the was to clarify the most influential parameter on canyon surfaces for the change in bulk Richardson Convective Heat Transfer Coefficient (CHTC) from the number achieved by change in building surface urban canopy surface. The main conclusions of this study are as follows:
Fig. 7 (a) CHTC profile for roof in different thermally stratified environment (with change only in surface temperature), (b) CHTC profile for windward wall in different thermally stratified environment (with change only in surface temperature), (c) CHTC profile for leeward wall in different thermally stratified environment (with change only in surface temperature), and (d) CHTC profile for ground in different thermally stratified environment (with change only in surface temperature).
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1. Prediction of bulk heat transfer by CFD gratitude to Japan Society for the Promotion of Science simulation with Low-Reynolds number k- (JSPS) for Grant-in-Aid for Scientific Research (B), No. εmodel is satisfactory when compared with the 21360283. experimental results. REFERENCES 2. It has been found that the change in velocity over the canopy remarkably affects the CHTC Abe, K., Kondoh, T., Nagano, Y. (1994) A new turbulence model from urban canopy surfaces and change in for predicting fluid flow and heat transfer in separating and reattaching flows-I.Flow field calculations. International Journal surface temperature has almost no effect over of Heat and Mass transfer. 37(1), 139-151. the CHTC from urban canopy surfaces. Abe, K., Kondoh, T., Nagano, Y. (1995) A new turbulence model for predicting fluid flow and heat transfer in separating and 3. For the generalization of CHTC for urban reattaching flows-II. Thermal field calculations. International canopy surfaces, velocity has to be considered Journal of Heat and Mass transfer. 38(8), 1467-1481. Blocken, B., Defraeye, T., Derome, D., Carmeliet, J. (2009) High- in priority and which was found to be the most resolution CFD simulations of forced convective heat transfer influential parameter affecting CHTC from the coefficients at the facade of a low-rise building. Building and surfaces. Environment 44(12), 2396-2412. Defraeye, T., Blocken, B., Carmeliet, J. (2010) CFD analysis of convective heat transfer at the surfaces of a cube immersed in a 4. Convective heat transfer coefficient (CHTC) turbulent boundary layer. International Journal of Heat and Mass from individual canyon surfaces will be Transfer. 53(2) 297–308. generalized for various urban canopy cases with Jürges, W. (1924) Der Wärmeübergang an einer ebenen Wand (heat the help of the parametric studies performed by transfer at a plane wall). Beihefte zum, Gesundheits-Ingenieur 1 CFD simulation (future work). The different (19). Kusaka, H., Kondo, H., Kikegawa, Y.. Kimura, F. (2001) A Simple cases for parametric studies will be selected by Single –layer urban canopy model for Atmospheric models : varying the Building Coverage Ratio (BCR), comparison with multi-layer and slab models”, Boundary Layer the height of the buildings, Reynolds number Meteorology -101,329-358. and Bulk Richardson number (by varying Launder. B.E. Numerical computation of convective heat transfer in complex turbulent flows: time to abandon wall functions ?”, inflow velocity). Various simulation case results International Journal of Heat and Mass transfer, Vol. 27, No. 9 will be employed to generalize the CHTC from (1984), pp. 1485-1491. the canyon surfaces. The CHTC expressed as Marciotto, E., Amauri, P., Oliveira, S., Hanna, R. (2010) Modeling local Nusselt number will be generalized with study of the aspect ratio influence on urban canopy energy fluxes variables like local canopy velocity expressed in with a modified wall canyon energy budget scheme. Building and Environment 45, 2497-2505. local Reynolds number, building coverage ratio, Pillai, S.S., Yoshie, R. (2012) Experimental and numerical studies height ratio) and canopy Richardson number. on convective heat transfer from various urban canopy Inclusion of this generalized expression for configurations”- Journal of Wind Engineering and Industrial individual urban canopy surfaces in UCM will Aerodynamics 104–106(4), 447-454. Pillai, S.S., Yoshie, R., Chung, J. (2010) Experimental and be expected to increase the prediction accuracy computational studies of heat transfer from urban canopy and its of urban heat transfer by WRF. dependence on urban parameters. Proc. Fifth International Symposium on Computational Wind Engineering (CWE 2010), Acknowledgements This study was funded by the TS6-1, May 2010, North Carolina, United States of America. Ministry of Education, Culture, Sports, Science and Pillai, S.S., Yoshie, R. (2011) Experimental and numerical studies on convective heat transfer from various urban canopy Technology, Japan, through the Global Center of configurations. Abs No. 399, Proc. Thirteenth International Excellence Program, 2008-2013 which is gratefully conference on wind engineering (ICWE13), July 2011, The acknowledged. Also we would like to express our Netherlands.
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Journal of Urban and Environmental Journal of Urban and E Engineering, v.7, n.1, p.82-95 Environmental Engineering ISSN 1982-3932 J E www.journal-uee.org U doi: 10.4090/juee.2013.v7n1.082095
URBAN GROWTH AND WATER QUALITY IN THIMPHU, BHUTAN
Nandu Giri1 and O. P. Singh2 1 Samtse College of Education, Royal University of Bhutan, Bhutan 2 Department of Environmental Studies, North-Eastern Hill University, Shillong, India
Received 10 October 2012; received in revised form 7 January 2013; accepted 01 April 2013
Abstract: Detailed study was undertaken in 2008 and 2009 on assessment of water quality of River Wang Chhu which flows through Thimphu urban area, the capital city of Bhutan. The water samples were examined at upstream of urban area, within the urban area and its downstream. The water quality was analyzed by studying the physico-chemical, biological and benthic macro-invertebrates. The water quality data obtained during present study are discussed in relation to land use/land cover changes (LULC) and various ongoing human activities at upstream, within the each activity areas and it’s downstream. Analyses of satellite imagery of 1990 and 2008 using GIS revealed that over a period of eighteen years the forest, scrub and agricultural areas have decreased whereas urban area and road network have increased considerably. The forest cover, agriculture area and scrub decreased from 43.3% to 42.57%, 6.88% to 5.33% and 42.55% to 29.42%, respectively. The LULC changes effect water quality in many ways. The water temperature, pH, conductivity, total dissolved solids, turbidity, nitrate, phosphate, chloride, total coliform, and biological oxygen demand were lower at upstream and higher in urban area. On the other hand dissolved oxygen was found higher at upstream and lower in urban area. The pollution sensitive benthic macro- invertebrates population were dominant at upstream sampling sites whereas pollution tolerant benthic macro-invertebrates were found abundant in urban area and its immediate downstream. The rapid development of urban infrastructure in Thimphu city may be posing serious threats to water regime in terms of its quality. Though the deterioration of water quality is restricted to a few localized areas, the trend is serious and needs proper attention of policy planners and decision makers. Proper treatment of effluents from urban areas is urgently needed to reduce water pollution in such affected areas to check further deterioration of water quality. This present study which is based on upstream, within urban area and downstream of Thimphu city can be considered as an eye opener.
Keywords: Thimphu, Land use/land cover change, water quality, physico-chemical, benthic macro-invertebrates
© 2013 Journal of Urban and Environmental Engineering (JUEE). All rights reserved.
Correspondence to: Nandu Giri. E-mail: [email protected]
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INTRODUCTION water resources. Keeping this view in mind, a study on water quality in relation to land use/land cover changes Water occupies a special place among other natural was carried out during 2008 and 2009 in Bhutan, one of resources found on earth. It is indeed a valuable natural Asia’s smallest nations situated on the southern slope of resource vital to the existence of all living organisms. It the eastern Himalayas (latitude 26˚40’ − 28˚20’N; is an indispensable liquid required for several purposes longitude 88˚45’ − 92˚25’E). It has a geographical area such as drinking, sanitation, irrigation, navigation, of 38 394 km² with mountainous and heavily forested aquaculture, recreation, industrial uses etc. The water landscapes. The present study was carried out at bodies are closely related to human life and his upstream of urban area, within the urban area and its livelihood. The metabolic activities essential for life downstream of Thimphu, the capital city of Bhutan. take place in aqueous medium inside the living body.
All enzymes, hormones and other biomolecules exist STUDY AREA, MATERIAL AND METHODS and function in presence of water. Water dissolves nutrients and distributes them to cells, regulates body Thimphu, the capital of Bhutan is located in the North temperature, supports structures, and removes waste West at an altitude of 2320 meters above sea level. The products. Thus, all forms of life on earth depend on urban area of Thimphu lies in the valley surrounded by water and all living things, from plants to animals, from forests. River Wang Chhu flows through the Thimphu desert dwellers to aquatic inhabitants and from city. The river originates in the north from snow and microscopic bacteria to gigantic whale, need water to glaciers and it flows south-easterly through west-central survive. It is believed that life first originated in water. Bhutan. It serves as a source of water for two hydro Water forms three-fourth of the weight of a living cell power, agriculture and domestic purposes including (United Nations Environment Programme (UNEP) drinking, sanitation and recreation. The water body Report, 2006). The health and well-being of all the receives a variety of wastes ranging from agricultural, living beings on earth is closely tied up with the quality domestic and natural sources. The study area and of water (United Nations World Water Assessment sampling locations are shown in Fig. 1. Programme (UN-WWAP) Report, 2003).
Currently, humanity is facing a serious water crisis (UN-WWAP, 2003). The United Nations World Water Assessment Programme Report (2003) states that water crises of availability, degradation, conservation and sustainability can be observed more pronouncedly in developing countries all over the world. All indicators suggest that the situation is worsening day by day and it is going to be alarming unless corrective measures are taken soon. The world is facing a number of challenges with regard to the availability, accessibility, use and sustainability of freshwater resources. This would result in serious implications for present and future generations of humanity and also for natural ecosystems. It is estimated that at present 2.8 billion people live under conditions of water stress and by 2030 almost half the world population will live under these conditions if effective measures are not implemented (UNEP, 2009; Bates et al., 2008; OECD, 2008). Freshwater bodies vary from streams and rivulets to huge rivers, ponds and lakes to reservoirs and recreational pools. These aquatic ecosystems are characterized by complex interactions between abiotic and biotic components of the water system. Thus, study on physico-chemical characteristics and biotic attributes of different water bodies is essential to understand the quality of water. Such studies in relation to anthropogenic land use changes and diversified human activities taking place in the catchment area are keys to Fig. 1 Location of different sampling sites at Thimphu study area. understanding the causes and extent of degradation of
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Table 1. Salient features of sampling sites Altitude Upstream/Downstream Sl. No. Study Area Longitude Latitude (meters) Location 1. Dodena (I) 2600 89˚37′38″E 27˚35′40″N Upstream of urban area 2. Pangri Zampa (II) 2480 89˚38′19″E 27˚34′13″N Upstream of urban area 3. India House (III) 2320 89˚36′24″E 27˚31’53″N Within the urban area 4. Chubachu (IV) 2317 89˚38′38″E 27˚29’45″N Within the urban area 5. Babesa (V) 2280 89˚39′40″E 27˚26’34″N Downstream of urban area 6. Charkilo (VI) 2160 89˚35′16″E 27˚23’26″N Downstream of urban area
The study area covers a distance of about 50 km The sampling sites were located at upstream, within the starting from Dodena which is located at an altitude of urban area and downstream, as done in case of water 2600 meters, (longitude 89˚37′38″E; latitude samples. The sampling sites at upstream represent the 27˚35′40″N) till Charkilo located at an altitude of 2160 reference or control in all cases. In order to carry out meters (longitude 89˚35′16″E; latitude 27˚23′26″N). To comparison of macro-invertebrate communities attempts study the impact of urbanization on water quality, were made to choose similar habitat features (similar sampling was done from six sites, two each from bottom substrate, depth and flow velocity) for all upstream of urban area (I & II), within the urban area sampling sites. The substrate chosen contained mainly (III & IV) and downstream of the urban area (V &VI). gravel, cobbles, sand and clay. The substrate samples Details of six sampling sites selected for the study of were analysed to find out its contents. physico-chemical analysis of water and benthic macro- A simple random sampling was done in all the invertebrates are given in Table 1. stations for collection of benthic macro-invertebrates. The sampling sites I and II namely Dodena and The random sampling was also carried out in different Pangri Zampa are located in forest area at upstream of substrates, current velocities, depth and temperature to Wang Chhu. The sampling sites III and IV namely, cover the density of benthic macro-invertebrates. Three India House and Chubachu are located in Thimphu city. replicate sampling units per sampling site were carried The sampling sites V and VI namely Babesa and out during each period. The Surber or Square foot Charkilo are placed downstream of urban area. stream bottom sampler was used to collect benthic macro-invertebrates. The overall method of sampling, as Duration of the study described in APHA (2005) was followed. For sampling the sampler was positioned securely at The study was carried out during the year 20082009 the bottom of the shallow river with net portion facing beginning from January. The water samples and benthic downstream. When the sampler was in place, all stones macro-invertebrates were studied during three different and gravels inside the frame were carefully hand rubbed seasons namely, pre-monsoon, monsoon and post- to dislodge organisms clinging to them. All gravels and monsoon. sand were thoroughly stirred to a depth of 5cm to dislodge bottom dwelling organisms. The organisms
were collected from the net by inverting it into sample Collection of water samples container. The sampler net was rinsed after every use. The water samples were collected in one litre sterilized The organisms were taken out from the net and polythene container using grab sampling method as preserved in 70% ethanol. The soft bodied animals like outlined in American Public Health Association annelid (oligochaetes) were first kept in 5 to 10% buffed (APHA) Standard Methods for the Examination of formalin for some time and then transferred to 70% Water and Wastewater (2005). The samples were also ethanol. This is done to prevent constriction during collected in 300 ml BOD bottles for the estimation of preservation. Dissolved Oxygen. The water samples were collected The collected benthic macro-invertebrates were from one foot below the surface of the water and placed in a shallow white tray with water for sorting. In immediately sealed with a stopper. Three replicates order to facilitate sorting, the organisms were stained were taken for each parameter. The samples were kept with 200 mg/L rose Bengal in the formalin or ethanol in ice box and maintained temperature below 4˚C while preservative for 24 hours. The organisms were separated transferring it to the laboratory. into different taxonomic categories by using a hand lens and dissection microscope. The references used for Collection of Benthic macro-invertebrates taxonomic work were Pennack, (1953) & (1978); Thorp & Kovick (1991); Ward & Whipple (1992). The The shallow locations (less than 1 m) of river were organisms were sorted and kept in vials filled with 70% selected for the study of benthic macro-invertebrates.
Journal of Urban and Environmental Engineering (JUEE), v.7, n.1, p.82-95, 2013 Giri and Singh 85 ethanol. All procedures followed were according to the Land use/land cover changes Standard Method for Water and Wastewater Analysis (APHA, 2005). The study area covered an area of 145.431 km2 starting from Dodena in the north to Charkilo in the south. In Analysis of physical, chemical and biological this study, land use changes taken place between parameters of water 19902008 was analysed using satellite imageries. For accurate analysis of land use changes the study area was United Nations Environment Programme, (2006) states classified into eight categories namely, forests, “Water quality is neither a static condition of a system, agriculture, water bodies, scrub, sandy area, urban area, nor can it be defined by the measurement of only one industry and road. The summary of land use/land cover parameter”. There is a range of physical, chemical and changes during 1990-2008 in Thimphu study area is biological components that determine the water quality. presented in Table 4. The dominant land uses in 1990 These components can be examined and measured were forests and scrub which occupy 85.85% of the accurately to ascertain the quality of water. Various study area. The forest cover occupied 43.3% (62.97 parameters analysed in the present study are described km2) in 1990. The percentage of forest cover in 2008 below. For determination of these parameters, the had decreased to 42.57% (61.906 km2). The slight procedures described in APHA (2005) and Maiti (2001) decrease in forest cover of 0.73% (1.064 km2) is were followed. A summary of the methods for attributed to expansion of urban boundaries and estimation of various water quality parameters is construction of road network. presented in Table 2. Table 3. Monthly rainfall at Thimphu study area during the study period Rainfall in Rainfall in RESULTS AND DISCUSSION Month mm/Month 2008 mm/Month 2009 Rainfall January 15.8 1.0 February 0.0 0.0 March 17.7 0.0 In 2008 the monthly rainfall ranged between 0.00 to April 15.1 27.0 27.5 mm during pre-monsoon, 68.6 to 152.3 mm during May 27.5 146.6 monsoon and 0.00 to 46.7 mm during post-monsoon. June 132.9 18.8 The total rainfall recorded in Thimphu study area during July 152.3 80.9 the 2008 study period was 593.3 mm. In 2009 the August 115.1 127.3 monthly rainfall ranged between 0.00–146.6 mm during September 68.6 46.1 pre-monsoon, 18.8–127.3 mm during monsoon and October 46.7 108.5 1.00–108.5 mm during post-monsoon. The maximum November 0.0 1.2 rainfall recorded was 152.3 mm in July, 2008 and 146.6 December 1.6 4.2 Total 593.3 561.6 mm in May, 2009. The total rainfall recorded in Source: Meteorology Section, Department of Energy, Ministry of Thimphu study area during the 2009 study period was Economic Affairs. 561.6 mm as indicated in Table 3.
Table 2. Summary of procedures used for the measurement of Physico-chemical and biological parameters of water samples Parameters Unit Method Reference Temperature ºC 0-110°C Mercury thermometer APHA (2005) pH pH meter (Delux pH meter 101, EI Product Maiti (2001) Conductivity µS/cm Conductivity meter (conductivity-TDS meter 307) APHA (2005) TDS mg/L Gravimetric method Maiti (2001) and APHA (2005) Turbidity NTU Nephelometric method (Digital Turbidity meter 31, EI APHA (2005) and Maiti (2001) Products) Dissolved Oxygen mg/L Winkler modified method APHA (2005) Nitrate mg/L Phenol Disulphonic acid (PDA) (Spectrophotometer – Maiti (2001) 169) Phosphate mg/L Stannous chloride Colorimetric method APHA (2005) Chloride mg/L Argentrometric method APHA (2005) Total Coliform No./100ml MPN or MF method Maiti (2001) and APHA (2005) BOD mg/L 5 day incubation method APHA (2005) and Maiti (2001) Flow Velocity m s-1 Electromagnetic current meter (PVM-2A) APHA (2005)
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Table 4. Land use changes in Thimphu study area during 1990−2008 Land Use Area in 1990 Area in 2008 Land Use Change Category Total in km2 Percentage Total in km2 Percentage Area in km2 Percentage Forests 62.97 43.3 61.906 42.57 1.064 0.73 Agriculture 10.01 6.88 7.75 5.33 2.26 1.55 Water bodies 1.508 1.04 1.532 1.05 0.024 +0.02 Scrub 61.88 42.55 42.78 29.42 19.1 13.13 Sandy area 0.012 0.01 0.301 0.21 0.289 +0.20 Urban 7.13 4.9 26.51 18.23 19.38 +13.33 Industries 0 0 0 0 0 0 Roads 1.921 1.32 4.652 3.20 2.731 +1.88 Total 145.431 100 145.431 100 44.848 30.84
The agricultural area occupied 6.88% (10.01 km2) of eighteen years 13.13% (19.10 km2) of scrub has been study area in 1990. The main crops grown in the converted into forests and urban area as indicated by the agriculture field are paddy, maize and wheat. Apple, land use map of 2008 (Fig. 3). The sandy area had peach and apricot are the main cash crops grown in the increased to 0.21% (0.301 km2) in 2008. In 1990 urban area. By 2008 the agricultural land decreased to 5.33% area occupied 7.13 km2 (4.90%) of the study area. (7.75 km2). Most of the agricultural land has been Within a span of eighteen years urban area expanded by converted into infrastructure development. In 1990 the more than three times measuring 26.51 km2 (18.23%). water bodies occupied 1.04% (1.508 km2) of study area. With the increase in urban area the agricultural land The water bodies increased from 1.04% in 1990 to and scrub decreased by 13.33% (19.38 km2). The 1.05% in 2008. The slight increase of 0.02% (0.024 increase in urban area led to the increase in road km2) in water bodies is due to the spread of river water network. In 1990 road network covered 1.32% (1.921 caused by silting and construction of sewerage km2) which increased to 3.20% (4.652 km2). The land treatment plant for Thimphu city at Babesa in 1998. The use/land cover maps of 1990 and 2008 are presented in scrub area decreased from 42.55% (61.88 km2) in 1990 Fig. 3. to 29.42% (42.78 km2) in 2008. Within a span of
Fig. 3: Land use land cover map of 1990 and 2008
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Urbanization in Bhutan began in 1961 with the start the past four decades in the Himalayas at the cost of of first five year development plan by the late king, other land uses, particularly forests. Jigme Dorji Wangchuck. Prior to 1961, an urban Our results on agricultural land use change are not in settlement in Bhutan was limited to a few traditional line with Klein Goldewijk (2000) who found that in the clustered villages in the valleys. Before 1953, Thimphu past 300 years agriculture land and pastureland have had just a dzong (fort) surrounded by a few cluster of increased globally by 460% and 560%, respectively. traditional houses. The developmental activities in This may be due to small sample size in the present Thimphu started in a rapid pace with its designation as study and also due to less population pressure in Bhutan capital of Bhutan by the late king, Jigme Dorji compared to other developing countries where food Wangchuck in 1953. The establishment of production to meet the requirements of growing infrastructural, educational and health facilities attracted population is more extensive as well as intensive. If job seekers and entrepreneurs. The public sector and LULC change for entire country is analyzed, which was private sector expanded quickly to provide various beyond the scope of the present study, there is services. This led to the migration of people from rural possibility that result on agriculture area may be areas to Thimphu urban area. However, the land different from the present study. Bruinsma (2003) also availability for urban area is severely limited by the reported that in the developing countries, agriculture topography. land for food production is projected to increase by 13% In 1990 the population of Thimphu urban area was whereas it is declining in developed countries. It is well barely 28 012. By 2008 the population of Thimphu known that when LULC changes occur and forest land urban area increased to over one lakh (National is converted to other uses, the water regime of the area Statistical Bureau, 2008). It is estimated that the is altered. Such alterations may be quantitative and/or population growth rate in Thimphu is 10% per annum. qualitative, which include deterioration in water quality, The rapid increase in population caused housing increase in volume and velocity of runoff, increase in shortage in urban area. This has led to the exponential frequency and severity of flooding, reduction in ground growth of unauthorized housing in the outskirt of the water recharge and perennial flow of streams and rivers, urban boundary. Starting from 1990, the population of increase in TDS due to erosion etc. (Calder, 2000). Thimphu urban area increased rapidly. The expansion of urban area and increase in (d) Study on water quality population in urban area is seen as a worldwide phenomenon. The United States Environmental The studies on Physico-chemical and biological Protection Agency (USEPA, 2001) report confirmed parameters were carried out from 2008 to 2009. The that every urban area has expanded substantially in land physico-chemical parameters of water analysed at area in recent decades. The percentage of the world’s upstream, within the urban area and downstream were population living in urban areas was less than 5 percent water temperature, pH, conductivity, total dissolved in 1800, which had increased to 47 percent in 2000 and solids, turbidity, dissolved oxygen, nitrate, phosphate, it is expected to reach 65 percent by 2030 (United chloride, sulphate and biochemical oxygen demand. The Nations Human Development Report, 1990; 1991). qualitative and quantitative variations in benthic macro- Rao (1991) reported that land available for invertebrates population were also studied. The results productive use in India is decreasing in the alarming are presented separately and sequentially for each trend in the per capita availability of arable land from parameters studied. The following parameters were 0.48 ha in 1951 to 0.20 ha in 1981. Sharma et al. (2007) assessed to study the water quality in and around further stated that increase in population pressure and Thimphu urban area: limited productive agriculture land has been the key factor for the conversion of forest land to other uses. Water Temperature Demirici et al. (2006) analyzed land use changes of Kucukcekmece watershed in Istanbul by using remote The minimum water temperature recorded during the sensing and GIS from 1963 to 2005 and found that study period was 5.88˚C ± 0.47 during post-monsoon of forest and agriculture land had decreased considerably 2009 at sampling site I and the maximum temperature whereas the industrial and residential areas had measured was 19.3˚C ± 0.58 during the monsoon of increased. Singh et al. (1983) and Rai et al. (1994) 2008 at sampling site VI. The water temperature reported that the land use/land cover changes from increased gradually from sampling site I to VI during forest to other uses have been widespread in the pre-monsoon and monsoon. This is because of the Himalayan region. Sharma et al. (1992) also stated that altitudinal variations of different sampling sites. agricultural land area had increased considerably over Sampling site I in all three study areas are located at the highest altitude whereas Sampling sites VI are at the
Journal of Urban and Environmental Engineering (JUEE), v.7, n.1, p.82-95, 2013 Giri and Singh 88 lowest altitude. The altitude of other sampling sites 7. The mean pH values ranging between 7.09 ± 0.16– decreased gradually from site I to site VI. Therefore, 7.71± 0.02 during 2008 and 7.08± 0.26–7.63± 0.12 with decrease in altitude the air and water temperature during 2009. Bhattarai (2005) and National showed increasing trend. This is a usual feature and Environment Commission (2001) also reported that similar results were obtained while studying physico- freshwater in Bhutan is slightly alkaline in nature. The chemical characteristics upstream and downstream of seasonal variation in pH at different sampling sites of Yamuna River in Haryana (Ravindra et al., 2003); Thimphu study area is presented in Fig. 5. Teesta River in North India (CISMHE, 2006); Cauvery The pH values of water at all the sampling sites were River in south India (Begum and Harikrishna, 2008). within the WHO’s permissible limit for drinking water The water temperature did not show much variation i.e., 6.5-8.5 (WHO, 1997). The pH of water was slightly during post-monsoon. In 2005 National Environment higher in urban area and downstream which could be Commission of Bhutan conducted water quality baseline attributed to the overflow from septic tank, discharge of study from Dodena to Babesa in Wang Chhu and sewage and domestic waste into the river. The soap and recorded that water temperature increased gradually as detergents used for washing are alkaline in nature which the river flows downward (National Environment ultimately gets into the river. The National Environment Commission Report, 2005). The seasonal variation in Commission of Bhutan recorded higher pH in urban water temperature at different sampling sites of area as compared to upstream of Wang Chhu (National Thimphu study area is presented in Fig. 4. Environment Commission Report, 2005). One of the major direct impact of urbanization is the degradation of pH water quality (Paul and Meyer, (2001; Tang et al., 2005), which can be attributed to sewage discharge, The pH of the water was slightly alkaline in nature in dumping of wastes etc. all the sampling sites as its pH values were higher than
Fig. 4 Seasonal variation in Water Temperature at different sampling sites.
Fig. 5 Seasonal variation in pH at different sampling sites.
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Fig. 6 Seasonal variation in Conductivity at different sampling sites.
Electrical Conductivity (EC) Total Dissolved Solids (TDS)
The seasonal variation in conductivity at different The seasonal variation in TDS at different sampling sampling sites of Thimphu study area is presented in sites of Thimphu study area is presented in Fig. 7. The Fig. 6. Figure 7 depicted higher conductivity in urban total dissolved solids (TDS) showed similar trend as that area as compared to upstream and downstream in all the of conductivity. Its values were recorded lower at seasons throughout the study period. The lowest upstream and higher in the activity areas and its conductivity measured was 77.39 S/cm ± 2.97 at immediate downstream. The concentration of TDS upstream sampling site II in 2008 and the highest was increased with increase in temperature and addition of 123.73 S/cm ± 3.68 at urban area sampling site IV in ions into water bodies from industries, urban area and 2009. The preliminary conductivity data collected by agriculture field. It was observed that TDS values were NEC for River Wang Chhu in 2002 also indicated that lower than the maximum WHO recommended value of conductivity increased downstream (NEC report 2002). 500 mg/L for drinking water (WHO, 1997). However, Prasad and Patil (2008) reported that conductivity of TDS values were higher in urban area which could be Krishna River kept on decreasing from Sangli town to due to the discharge of inorganic and organic matter village Ghalwad. The constant decrease in conductivity into water bodies. Similar results were also obtained indicated reduction in the number of dissolved inorganic while studying physico-chemical characteristics salts. Studies done by Alam et al. (2007) at Surma river upstream and downstream of Yamuna River in Haryana and Murugan (2008) at Umkhrah River in Shillong also (Ravindra et al., 2003). revealed similar results.
Fig. 7 Seasonal variation in Total Dissolved Solids at different sampling sites.
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Turbidity catchments. The increase in impervious surface cause increase in the volume and rate of surface runoff and The turbidity was found lower at upstream sampling decrease in ground water recharge and base flow which sites and higher in urban area in all the seasons. The will lead to frequent incidents of flooding, decrease in minimum turbidity value recorded was 1.25 NTU ± 0.19 residential and municipal water supplies and reduced during pre-monsoon at upstream sampling site I in 2009 base flow in streams (Carter, 1961; Field et al., 1982; and the maximum was 14.56 NTU ± 2.11 in Hall, 1984; Lazaro, 1990; Harbor, 1994). The land use downstream at sampling site V during monsoon season change from pervious to impervious surfaces can also of 2009. The turbidity values recorded during monsoon impact the quality of storm water runoff. Schueler were much higher than during pre-monsoon and post- (1995) found that pollutant load increases when the monsoon. This could be due to monsoon rain washing surface area is impervious. surface soil particles and other debris into the river. The increase in turbidity of Wang Chhu in urban area is also Dissolved Oxygen (DO) due to the direct discharge of waste water into the river. The seasonal variation in turbidity at different sampling It was observed that dissolved oxygen level was sites of Thimphu study area is presented in Fig. 8. consistently higher at upstream and lower in urban area The NEC also reported increase in turbidity as river and downstream. Similar results were obtained in flows from upstream to urban area (NEC Report, 2005). Pasakha industrial area as well. The highest DO level Similar results were reported by Lanet and Crawford recorded was 10.55 mg/L ± 0.46 at upstream during (1994) who confirmed that suspended sediment yield post-monsoon and lowest was 7.78 mg/L ± 0.24 in was greater in urban catchment than in forested urban area during monsoon of 2009. Similar trend was catchment. Paul and Meyer (2001) found that the major noticed when National Environment Commission of effect of urbanization on freshwater ecosystems was an Bhutan conducted baseline study of Wang chhu in increase in impervious surface areas within urbanized January 1997 (NEC report, 2005).
Fig. 8 Seasonal variation in Turbidity (NTU) at different sampling sites
Fig. 9 Seasonal variation in Dissolved Oxygen (mg/L) at different sampling sites.
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The dissolved oxygen level recorded in urban area by release of sewage and other domestic wastes into the NEC was as low as 7 mg/L. Chattopadhyay et al. (2005) river. Study by Jaji et al. (2007) on nitrate concentration studied linkage between land use pattern and water in Ogun River, Nigeria reported that nitrate content was quality in Chalakudy river basin in Kerala and reported higher (16.7 mg/L) around urban area which could be that DO level in forest area was 7.62 mg/L whereas, in due disposal of organic wastes. urban and agricultural area it was 1.73 and 5.91, respectively. Phosphate
Nitrate The seasonal variation in phosphate at different sampling sites of Thimphu study area is presented in Figure 10 depicted low nitrate level at upstream as Fig. 11. Throughout the study period the phosphate compared to urban area and downstream. The minimum level was recorded low at upstream sampling sites. The nitrate level recoded was 0.04 mg/L ± 0.01 at upstream phosphate level was recorded high in activity area sampling site I during monsoon and maximum was 2.10 throughout the study period. The minimum level of mg/L ± 0.45 at sampling site IV post-monsoon. The phosphate recorded was 0.004 mg/L ± 0.001 at nitrate concentration were found much lower than the sampling site I during pre-monsoon and the maximum highest limit of 45 mg/L set by ICMR for drinking level recorded was 0.027 mg/L ± 0.003 at sampling site water. Since this parameter is present at low level in all IV during post-monsoon. This could be due to the the sampling sites, it does not pose any threat to aquatic release of domestic wastes containing phosphate into and terrestrial beings. However, the slight increase in water bodies. nitrate level in urban area could be attributed to the
Fig. 10 Seasonal variation in Nitrate (mg/L) at different sampling sites of Thimphu study area.
Fig. 11 Seasonal variation in Phosphate (mg/L) at different sampling sites.
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Chloride also reported that concentration of chloride in water around urban area was higher as compared to water The seasonal variation in chloride at different sampling around forest area. sites of Thimphu study area is presented in Fig. 12. The chloride concentration was found lower at upstream as Total Coliform compared to urban area and downstream. The minimum chloride level recorded was 4.47 mg/L ± 0.44 at The seasonal variation in total coliform at different upstream sampling site I during monsoon and the sampling sites of Thimphu study area is presented in maximum was 9.04 mg/L ± 0.60 at downstream during Fig. 13. The total coliform counts were found pre-monsoon. The chloride level recorded throughout consistently low at upstream throughout the study the study period was much lower than the permissible period. The coliform counts were higher in sampling limit of 200 mg/L set by WHO for drinking water sites IV and V in all the seasons. This could be (WHO, 1984). Thus, indicating lesser degree of attributed to the presence of fecal matter along the river pollution that makes Wang Chhu suitable for domestic as shown in Fig. 14. The highest total coliform recorded and industrial purposes. Chloride enters into surface during the study period was 138 colonies/100 ml ± 4.96 water from natural sources like weathering of rock salts. in urban area during pre-monsoon. The National The anthropogenic sources are domestic sewage Environment Commission of Bhutan also reported high effluents and runoff from agriculture fields through level of fecal coliform in urban area of Wang Chhu fertilizers. (NEC report, 2005). Study by Jaji et al. (2007) on Ogun Similar study was carried out by Chattopadhyay et River, Nigeria also reported high concentration of total al. (2005) on linkage between land use pattern and coliform around urban area due to discharge of water quality in Chalakudy river basin in Kerala and untreated sewage into water bodies and non-point reported that chloride content in forest area was lower source pollution such as septic tank overflow, runoff (16.51 mg/L) and higher at urban and agricultural areas and animal wastes. (44.09 mg/L and 18.55 mg/L). Clinton and Vose (2006)
Fig. 12 Seasonal variation in Chloride (mg/L) at different sampling sites of Thimphu study area.
Fig. 13 Seasonal variation in Total Coliform (colonies/100ml) at different sampling sites of Thimphu study area.
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Fig. 14 Seasonal variation in BOD (mg/L) at different sampling sites of Thimphu study area.
Biochemical Oxygen Demand (BOD) invertebrates were observed at upstream sampling sites only. The seasonal variation in BOD at different sampling In Thimphu study area a total of 2432 individuals/m2 sites of Thimphu study area is presented in Fig. 14. The benthic macro-invertebrates were recorded throughout BOD values were found higher in urban area and the study period. The pollution sensitive benthic macro- downstream as compared to upstream. The highest BOD invertebrates were found mostly at upstream whereas, value recorded was 7.33 mg/L ± 0.83 at sampling site V the pollution tolerant benthic macro-invertebrates were during pre-monsoon and the lowest was 0.16 mg/L ± concentrated in urban area and it’s immediate 0.03 at sampling site I in the same season. The downstream. The benthos present in Thimphu study are biological oxygen demand values at sampling sites IV were of the taxonomic orders of Trichoptera and V during pre-monsoon excided the WHO (caddisflies), Ephemeroptera (mayflies), Plecoptera permissible limit of 6 mg/L for drinking water (stoneflies), Coleoptera (aquatic beetles), Diptera (true indicating deterioration in water quality. The BOD flies), Odonata (dragonflies) and tubificida (worms). values during post-monsoon were within the permissible The Shannon-Weiner diversity index of benthic macro- limit. This may be attributed to the low temperature invertebrates in Thimphu urban area during pre- during winter which decreases photosynthetic activity monsoon ranged from 1.5546–0.3389 attaining maxima and less number of phytoplankton (Abdo, 2004). at sampling site I and minimum at sampling sites III. Ravindra et al. (2003) and Schueler (1995) also reported The pollution sensitive benthic macro-invertebrates higher BOD level in urban and industrial areas. were totally absent at sampling sites IV and V which could be due to the discharge of organic and inorganic Bio-monitoring of water quality using Benthic domestic waste from urban area. The Shannon-Weiner Macro-invertebrates diversity index of benthic macro-invertebrates in Thimphu urban area during monsoon ranged from The benthic macro-invertebrates are good indicators of 1.5332–0.2880 attaining maxima at sampling station I water quality. The studies on their community and and minimum at sampling station III. The diversity population in water bodies provide information on index showed benthic macro-invertebrates were not pollution status of the water they inhabit. In all the three evenly distributed at upstream and downstream. The study areas variations in population of benthic macro- diversity index is high in the upstream and low in urban invertebrates were observed throughout the study and downstream areas. This indicates impact on water period. The highly sensitive benthic macro-invertebrates quality in urban area and it’s downstream. It was also belonging to the taxonomic order of Trichoptera, observed that pollution sensitive benthic macro- Ephemeroptera and Plecoptera were found mostly at invertebrates were totally absent at sampling sites III, upstream which indicated relatively clean water. The IV and V which could be due to the discharge of pollution tolerant benthic macro-invertebrates were organic and inorganic domestic waste from urban area. recorded mostly in activity areas and it’s downstream. The Shannon-Weiner diversity index of benthic macro- Rich diversity and evenness of benthic macro- invertebrates in Thimphu urban area during post- monsoon ranged from 1.5084 to 0.6555 attaining
Journal of Urban and Environmental Engineering (JUEE), v.7, n.1, p.82-95, 2013 Giri and Singh 94 maximum at sampling site I and minimum at sampling urban infrastructure are posing threats to water regime station IV and V. The diversity index showed benthic in terms of its quantity and quality. Though the macro-invertebrates were not evenly distributed at deterioration of water quality is restricted to a few upstream and downstream. The evenness ranged from localized areas, the trend is serious and needs proper 0.9826 to 7566 attaining maximum at sampling site III attention of policy planners and decision makers. Proper and minimum at sampling site II. treatment of effluents from industries and urban areas Many studies have reported that benthic are urgently needed to reduce water pollution in such communities have good correlations with the water affected areas to check further deterioration of water quality changes (Rosenberg and Resh, 1992; Richards quality. This present study which is based on a small a and Minshell, 1992; Resh and Jackson, 1993; Resh, area can be considered as an eye opener. However, 1995; Mason, 1996; Omar et al., 2002). Recently, study further studies and in-depth analysis of water quality done by Duran (2006) found that compared to upper and its impact on human health and socio-economy in area, lower area had lower diversity of benthic macro- Bhutan is needed for policy planning and invertebrates at Behzat stream in Turkey which was due implementation. to the release of phosphate and nitrogen ions into the stream. Our findings are in line with earlier studies REFERENCES which revealed that a clean and healthy ecosystem support diversity of benthic macro-invertebrates Abdo, M. H. (2004). Environmental studies on the river Nile at whereas, in dirty and unhealthy ecosystem only a few Damietta branch region, Egypt. 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Journal of Urban and Environmental Journal of Urban and E Engineering, v.7, n.1, p.96-109 Environmental Engineering ISSN 1982-3932 J E www.journal-uee.org U doi: 10.4090/juee.2013.v7n1.096109
MANAGING PHYSICAL DEVELOPMENT IN PERI-URBAN AREAS OF KUMASI, GHANA: A CASE OF ABUAKWA
Paul Amoateng1, Patrick B. Cobbinah1 and Kwasi Owusu-Adade2 1School of Environmental Sciences, Institute for Land, Water and Society, Charles Sturt University, Australia 2Department of Planning, College of Architecture and Planning, Kwame Nkrumah University of Science and Technology, Ghana
Received 17 September 2012; received in revised form 28 March 2013; accepted 13 April 2013
Abstract: A remarkable trait of the 21st century has been the high rate of urbanization which has characterized the growth and development of cities especially in developing countries. This situation has fuelled rapid physical development and expansion of peri-urban areas as urban dwellers relocate to cities’ peripheries. Focusing on Abuakwa a peri-urban area in Kumasi, the second largest city in Ghana, this paper assesses the nature and extent of physical development in peri-urban areas, and identifies the factors contributing to the rapid development of peri-urban areas. The paper further examines the effects of the increasing physical growth on the development of peri-urban Abuakwa. Using a case study approach, both primary and secondary sources of data were collected from decentralized government institutions of Kumasi Metropolitan Assembly (KMA) and Atwima Nwabiagya District Assembly (ANDA), as well as indigenes and relocated urban dwellers in Abuakwa. The paper reveals that the outward drift has manifested itself in an increased scramble for land for residential and commercial purposes in the peri-urban area. The resultant effect has been the fast and spontaneous physical development in the urban periphery which has significantly altered the peri-urban morphology. The paper recommends the establishment of Customary Land Secretariat (CLS) to co-ordinate allocation of land, and the application of settlement growth management approaches to ensure the creation of a functional city and liveable peri-urban areas.
Keywords: Abuakwa; land use; peri-urban areas; physical development
© 2013 Journal of Urban and Environmental Engineering (JUEE). All rights reserved.
Correspondence to: Paul Amoateng, Tel.: +61 0451030256, P.O Box 789, Albury NSW 2460, Australia. E-mail: [email protected]
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INTRODUCTION Abuakwa. The paper concludes with recommendations to ensure efficient and effective management of The 2010 Population and Housing Census of Ghana physical development in peri-urban areas of Kumasi. indicate that the proportion of urban population in
Ghana increased from 43.8 percent in 2000 to 50.9 CHARACTERISTICS OF PERI-URBAN AREAS percent in 2010 (Ghana Statistical Service (GSS), AND PHYSICAL DEVELOPMENT 2012). This high rate of urbanization has accelerated the demand for land to meet the increasing needs of urban The meaning and characteristics of peri-urban areas dwellers particularly in the major cities in Ghana. As a result, there is seemingly rapid expansion of peri-urban According to Organisation for Economic Co-operation areas where basic facilities such as piped water, and Development (OECD) (2007) the term ‘peri-urban’ electricity and sewage services are virtually non- came into public domain and use during the 1980s in existent. Europe. The OECD described peri-urban as a name These peri-urban areas are characterized by fast and given to the ‘grey area’ which is neither entirely urban unplanned physical growth and development. The nor rural in the traditional sense. It is neither fully unregulated pattern of physical development in these urbanized nor completely rural, but often seen as a areas has given rise to complex organic urban growth ‘middle band’ of land with atypical characteristics which predominantly expands horizontally. Explaining (Buxton, 2007). It comprises an unbalanced mixture of this phenomenon, Drabkin (1977) asserts that urban urban and rural functions. population growth is mainly occurring in the outlying Peri-urban area serves as the zone where urban-rural regions of the metropolitan areas due to the engulfment interaction is at its peak (Johnson, 1974). At this zone, of the peri-urban areas by ‘parent city’. As a result, peri- rural activities and modes of life are in rapid retreat, urban physical development pattern is always with extensive urban land use intrusion (that is urban undergoing transformation especially in cities in the area physically and functionally expands into the rural developing world (Drabkin, 1977). Concomitantly, area). these dynamic changes in the land use also occur Peri-urban areas exhibit peculiar characteristics that following improvement in accessibility, natural increase make them distinct from urban and rural areas, and in population, presence of serene living environment, these include accelerated development of urban and availability of vast but low cost land. residential and urban commercial uses, and decrease in In the context of Kumasi, this phenomenon is rural primary activities (Hewitt, 1989), rapid but ostensibly evident. With an annual population growth unplanned growth with inadequate service infrastructure rate of 5.4 percent, Kumasi is considered the fastest (Government of Swaziland, 1997), middle and low growing city in Ghana (Cobbinah & Amoako, 2012). income residents (Johnson, 1974), and serve as The growing population of the city coupled with the receptacles for the growing rental market (Buxton, availability of infrastructure and relatively low land 2007). values at the peripheries has resulted in the inefficient Generally, peri-urban areas can be classified into use and over exploitation of natural resources especially four interrelated categories. These include village peri- land at the outskirts. The city’s peripheries have become urban, diffused peri-urban, in-place peri-urban and the preferred places for housing, industrial and absorbed peri-urban (Drescher & Iaquinta, 2000). The commercial development due to the relatively low land categorization is derived from the underlying socio- values. As a consequence, the peri-urban areas of demographic processes, especially migration. The Kumasi are experiencing intensive and continuous defining features connected the elements of the physical development in an uncontrolled manner. Prime typology in the form of a continuum. agricultural lands in these areas have been utilized for physical development purposes. However, this The concept of physical development uncontrolled pattern of physical development poses urban management challenges to the peri-urban Keeble (1969) explains physical development as the economy, traffic generation and management, growth carrying out of building, engineering, mining or other management, and the provision of ancillary services. operations in, on, over or under land or the making of This paper investigates the management of physical any material or substantial change in the use of any development in peri-urban areas of Kumasi by building or land. Physical development entails the examining the nature and extent of physical carrying out of any operation on or any modification to development in Abuakwa. It explores the factors land by mankind in an attempt to create a liveable and contributing to the increasing physical development in comfortable environment. The ultimate objective of and the effects on the development of peri-urban
Journal of Urban and Environmental Engineering (JUEE), v.7, n.1, p.96-109, 2013 Amoateng, Cobbinah and Owusu-Adade 98 physical development is to sustain the improvement in individuals and firms to relocate to the peri-urban areas the wellbeing of individuals and bestow benefits on all. to take advantage of the availability of large but low At the community level, physical development covers land value (du Plessis & Landman, 2002). land that has been put to some form of use ranging from As a result, low land value is another factor. The a building to an outdoor open space as against land price of land in peri-urban areas is relatively low which has not been touched and is covered with ‘bush’ compared to the parent city (O’Sullivan, 2000). This (Mather, 1989). Physical development manifests itself attracts people of different income groups to the urban in the form of human activities or land uses in towns fringe. Other factors include government public policies and cities. especially on housing provision has broadened the social groups found in the urban fringe locations Linkages between peri-urban areas and physical (Johnson, 1974). development Moreover, movement of retail services to the peripheries of cities as a result of decentralization of The dynamic and integrative nature of peri-urban areas consumers, central area decline and development of has been a major constraint in outlining physical automobile has influenced the physical development of development (land use) pattern of these areas (Johnson, these areas (Balchin et al., 2000). The presence of 1974). While peri-urban areas are multifunctional and serene and conducive environmental conditions is also a interrelated zones with potential for change, the nature contributing factor to the high rate of physical of physical development is complex and does not have development in the peri-urban areas. defined character. It is defined by unauthorized Additionally, Adesina (2007) argues that the practice developments, spatial unit zones, non-contiguous of landowners withholding land from the market in developments and land use changes (Johnson, 1974). order to gain increases in value in the future has Other writers have argued that peri-urban areas influence physical development in the peri-urban areas. experience continuous and alarming rate of physical The above factors have contributed to peri-urban expansion as the population grows (Buxton, 2007). areas experiencing premature and scattered or non- Moreover, literature on peri-urban dynamics suggests contiguous physical development which threatens their that as urban areas grow, most of the growth occurs at sustainability. These are useful lessons for investigating the fringes because of the availability of land at nominal the pattern of physical development in peri-urban cost (O’Sullivan, 2000). Thus, peri-urban areas, by Abuakwa in Kumasi. virtue of their status as dormitory towns, are dominated by moderate and low density residential development. STUDY SETTING AND METHODS Housing in these areas is segregated by socio-economic class or ethnicity and is usually clustered close to a Study setting railway or a major thoroughfare (Johnson, 1974). Another relationship is leap frogging development Geographically, this study focuses on Abuakwa a peri- which is characterized by relatively low-density, non- urban area of Kumasi located in the Atwima Nwabiagya contiguous, automobile dependent, residential and non District (AND). Abuakwa is located along the Kumasi- residential development that consumes farmland Sunyani and Bibiani trunk roads about 12km from the (Mather, 1989). The farmland is converted into housing, Central Business District of Kumasi, the administrative commercial and industrial premises, and infrastructure and cultural capital of the Ashanti Region of Ghana. such as roads, other land-extensive recreational Given its geographical coordinates as 6°40′ 0″ N and facilities, waste dumps, and sewage treatment plants 1°37′ 0″ W, Abuakwa is bounded to the north by (Timms, 2006). Bokankye, east by Tanoso, west by Atwima Maakro and to the south by Abakomadi. Abuakwa has a population Factors influencing rapid physical development in of 23 201, out of which 32 percent are indigenes while peri-urban areas 68 percent are migrants who are basically relocated urban dwellers from Kumasi. Abuakwa’s population Physical development in peri-urban areas is influenced growth is significantly linked to the rapid growth of by the interplay of several factors. These factors operate Kumasi. to regulate the morphology (size and form), With current population of 2 035 064, Kumasi is the arrangement and intensity of land uses; and are fastest growing city in Ghana with an annual growth explained in the subsequent paragraphs. rate of 5.4 which is far above the regional and national Improvement in transport facilities like roads and growth rates of 2.7 and 2.5 respectively (Cobbinah & automobile produce urban decentralization in the outer Amoako, 2012; GSS, 2012). Given its increasing part of cities as they reduce travel time. This attracts population growth, the city accommodates about half of
Journal of Urban and Environmental Engineering (JUEE), v.7, n.1, p.96-109, 2013 Amoateng, Cobbinah and Owusu-Adade 99 the entire population of the Ashanti region which has development from both developed and developing facilitated the spread of development into the countries. The literature review was carried out at two neighbouring districts (GSS, 2012). levels: global and local. Whereas the global literature As a consequence, peri-urban Abuakwa has strong review focused on books and journal articles on the physical and functional links with Kumasi, the second concepts, types and characteristics of peri-urban areas largest city in Ghana. This is based on the fact that and physical development, the local review examined about 60 percent of the working population of Abuakwa documents including district development plans, commutes to and from Kumasi daily to engage in socio- physical development reports and town planning economic activities (ANDA, 2006). Owing to its strong schemes used in monitoring socio-economic and relationship with Kumasi, Abuakwa has developed to physical development of the study area. become one of the major dormitory towns of Kumasi Additionally, the study reviewed other documents although other commercial and industrial developments such as quarterly and annual reports as well as or activities have sprung up. consultancy reports from some of the decentralized Highlighting the influence of Kumasi, peri-urban government institutions of KMA and ANDA such as the Abuakwa is the largest town in the district with an Urban Roads Department, Building Inspectorate annual growth rate of 9.6 percent (National Division and the Town and Country Planning Development Planning Commission (NDPC), 2004). Department (TCPD). The review of these documents Abuakwa is currently experiencing extensive physical was critical in establishing the trends of peri-urban development which has spread to engulf surrounding developments in Kumasi, and further identified the communities like Dadease, Apemhase, Kagyase and major stakeholders involved in managing the physical Arkosah Township. In relation to its spatial structure, development in the peri-urban areas of Kumasi. This Abuakwa has a sector-like or wedge-like morphology process served as a useful ground in determining the due its growth along the two major roads (see Fig. 2). selection of the case study area and the type of Despite the high rate of population growth, institutions and category of respondents to be involved Abuakwa’s physical development over the past two in the study. Ideally, the study intended to cover two decades has been sporadic and uncontrolled leading to peri-urban areas in Kumasi. However, due to unique haphazard and unauthorized physical development characteristics of Abuakwa: high population growth pattern with little or no room for both vehicular and rate, its location in different district, availability of data, pedestrian circulation. Figure 1 shows the location of and physical development challenges, coupled with Abuakwa in relation to the Kumasi metropolis. relatively slow growth rate, and land ownership challenges characterizing the other peri-urban areas, the study was limited to Abuakwa.
Using semi-structured interviews, six institutions were purposively selected to provide data regarding the pattern of physical development in peri-urban areas of Kumasi particularly Abuakwa. These institutions included the TCPD in Kumasi and ANDA, Building
Inspectorate Division of KMA and ANDA, Urban Roads Department of KMA and the Feeder Roads Department of ANDA. The semi-structured interviews allowed for detailed assessment of the phenomena being investigated into (Sarantakos, 1998), and further offered
sufficient flexibility to approach different institutions differently while still covering the same areas of data Fig. 1 Abuakwa in Kumasi Metropolitan Context. collection (Mohd Noor, 2008). Moreover, traditional Source: Owusu-Ansah and O’Connor (2006). authorities and plot allocation committee in the various suburbs of Abuakwa were interviewed to gain first hand Study Methods data on the state and direction of physical development This paper is based on a study conducted in 2010 on the in peri-urban Abuakwa. pattern of physical development in peri-urban areas of With a total housing stock of 1630, a total of 143 Kumasi. Recent data (2012) on the dynamics of house owners comprising indigenes and relocated urban physical development in peri-urban areas of Kumasi dwellers were selected and involved in the study using have been incorporated. Regarding the method used, the structured questionnaires. The determination of the study reviewed relevant and related literature on the sample size was done employing the following 2 characteristics of peri-urban areas and physical mathematical model: n= N/1+N (α) (Miller & Brewer,
Journal of Urban and Environmental Engineering (JUEE), v.7, n.1, p.96-109, 2013 Amoateng, Cobbinah and Owusu-Adade 100
BOKANKYE LEGEND
RESIDENTIAL
COMMERCIAL
EDUCATION
OPEN SPACE TANOSO
CIVIC & CULTURE
ASENEMASO SANITATION
TO SUNYANI ABUA KWA FORM UL ATION INDUSTRY PLANT C L IN IC PL A Z A
L P TO NKAWIE MKT UNDEVELOPED HOTEL FROM KUMASI BAPTIST GARA GE S EMINARY LAND
CIRCULATION NSONYAMEYE
RIVER N
DIRECTION OF GROWTH
ABAKOMADI SCALE: 1:5,000 AGOGO
Fig. 2 State of Physical Development in Abuakwa (1993). Source: Town and Country Planning Department, ANDA
LEGEND BOKANKYE RESIDENTIAL
COMMERCIAL
EDUCATION
OPEN SPACE
TANOSO CIVIC & CULTURE
ASENEMASO HOTEL SANITATION
MIXED USE TO SUNYANI ABUAKWA FO RM ULATION F R PLAN T CLINIC PLAZA INDUSTRY TO NKAWIE MKT L P FROM KUMASI GARAGE BAPTIST UNDEVELOPED SEMIN ARY CEM LAND NSONYAMEYE CIRCULATION
CEM RIVER N DIRECTION OF GROWTH
ABAKOMADI AGOGO SCALE: 1:5,000
Fig. 3 The Extent and Nature of Physical Development in Abuakwa (2010).
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2003), where n is the sample size, N is the total housing town has witnessed rapid physical development in stock (sample frame) and α is the margin of error (0.08). recent times. Despite the introduction of planning The interactions at both institutional and community scheme for the town since the 1993, physical levels revealed the major factors and manifestations of development continues to occur in haphazard and physical development as well as the effects of rapid uncoordinated manner. As a result, the rapid physical physical development on the development of Abuakwa. development has outstripped the ability of development The data collected were analyzed using quantitative control institutions to monitor and regulate it. The and qualitative methods. Statistical Package for Social current state (2010) of Abuakwa is presented in Fig. 3. Sciences (SPSS) was used to facilitate the quantitative The survey showed that the physical expansion of analysis while the qualitative analysis focused on Abuakwa has not spared the areas which are earmarked description and explanation of the pattern of peri-urban as unbuildable areas. Physical development has spread development. The SPSS facilitated the analysis process and encroached on ecologically sensitive areas such as by generating descriptive statistics such as percentages rivers, streams, waterlogged areas and open spaces (see and frequency counts as well as establishing Fig. 4). Developers (house owners) disregard the likely relationships between study variables (peri-urban areas negative socio-environmental consequences such as and physical development). flooding, spread of water related diseases and extinction To ensure the validity and reliability of the study of the natural habitats. Figure 4 shows a building in a findings, data collected from both the institutional and water way in Abuakwa. community levels were harmonized and findings The study further unearthed that virtually none of the presented to stakeholders at the institutional and local areas earmarked for ancillary land uses like education, levels. This process proved useful in addressing any public open space, sanitary areas among others have gaps and inconsistencies that had occurred. been utilized for such purposes. Most of such areas have been converted into residential use as a result of non- adherence to planning regulations, uncoordinated land RESULTS AND DISCUSSIONS allocation by the traditional leaders (chiefs) and weak Physical growth and expansion of Abuakwa enforcement mechanisms. The cumulative effect of this is the current pattern of physical development which can Until 1993, physical development in Abuakwa just like be described as “monotonous development” dominated many other peri-urban areas in Ghana was not guided by residential buildings (shelter zone). by planning scheme. This is because such areas had not been zoned as planning areas under the Town and Land use inventory of Abuakwa (19932010)
Country Planning Ordinance of 1945, (CAP 84) which The major land use types identified in Abuakwa clearly was the legal framework for regulating planning show its transitional nature from rural to urban. During activities in the country then. The study revealed that the land use/physical survey, the following land uses physical development prior to 1993 was mainly were identified; residential, commercial, industrial, open concentrated in the core area and it occurred space, educational, civic and cultural, sanitation, haphazardly. Following the enactment of the Local circulation (road network), mixed uses and undeveloped Government Act, 1993 (Act 462) which declared all land as presented in Table 1. The total planning land settlements in Ghana, both urban and rural, as planning area of Abuakwa is 1,120 acres. These land uses are areas, a planning layout was prepared to control and discussed in the subsequent sub sections. guide the growth of Abuakwa. In relation to its spatial changes, the study results Residential land use show that the town which covered a total land area of 1.7 km2 (432 acres) in 1993 has expanded to a physical The residential land use covers the largest land area and size of 4.6 km2 (1,145 acres) in 2010 (see Figs 2 and 3). it comprises of all types of housing and cuts across all The town experienced a change of 713 acres in land areas of the town. The residential area which covered a area, representing 165.0 percent change in size. This total area of 230 acres representing 20.6 percent in 1993 indicates that the size of the settlement tripled in less increased to 702 acres representing to 62.7 percent of than two decades. the total land area in 2010. The rapid rate of physical development that has The dominance of residential zone is a manifestation characterized Abuakwa over the last two decades is of Abuakwa’s status as a commuters’ residential zone reflected in the ages of the buildings. Survey results within a system of settlements and a dormitory town for indicated that more than 90 percent of houses in workers of Kumasi. Abuakwa are less than 20 years old, indicating that the
Journal of Urban and Environmental Engineering (JUEE), v.7, n.1, p.96-109, 2013 Amoateng, Cobbinah and Owusu-Adade 102
Table 1 Land Use Inventory of Abuakwa
Land Use Proposed Land Actual Land Take Actual Land Take Change in Land Diff. in Land Take Take, 1993 in 1993 in 2010 Take (1993 to (2010 - 2010) Proposed 1993)
Acres % Acres % Acres % Acres % Acres % Residential 410 36.6 230 20.6 702 62.7 472 42.0 292 26.1 Commercial 27 2.4 24 2.1 27 2.4 3 0.3 0 0 Industrial 17 1.5 18 1.6 22 2.0 4 0.4 5 0.5 Open Space 33 2.9 12 1.1 8 0.7 4 0.4 25 2.2 Education 59 5.3 43 3.8 48 4.3 5 0.5 11 1.0 Civic and Culture 22 2.0 8 0.7 17 1.5 9 0.8 5 0.5 Sanitation 8 0.7 5 0.5 5 0.4 0 0.0 3 0.3 Circulation 208 18.6 92 8.2 275 24.5 183 16.3 67 6.0 Mixed Use 14 1.3 14 1.3 Undeveloped land 336 30.0 688 61.4 2 0.2 686 61.3 334 29.8 Total 1,120 100 1,120 100 1,120 100
Source: Field Survey, 2010 (Note: '−' means reduction) Nonetheless, most commercial activities are largely concentrated in the central part of the town generating traffic management challenges as the town center has become relatively congested.
Industrial land use
In 1993, the only industrial activity that existed in the town was Abuakwa Formulation Plant (a company that produces pesticides) which covered a total land area of 18 acres representing 1.6 percent of the built up area. However in 2010, other industrial activities have Fig. 4 Building on Waterway. Source: Field Survey, 2010 emerged in the town and include metal and wood works and bakeries. These activities have increased the The drastic increase in residential land take is industrial land use to 22 acres. However, survey results attributed to the outward movement of people from the indicate that these activities are located on road already congested city of Kumasi to the outskirts in reservations and open spaces within residential areas search of cheaper accommodation. As an important generating noise to the discomfort of the residents. nodal town (point of convergence for Kumasi-Sunyani and Kumasi-Bibiani Roads), Abuakwa has become a Open space receptacle for migrants into Kumasi. The open spaces both active and passive covered 12
Commercial land use acres representing 1.1 percent of the total land area in 1993. However it currently occupies 8 acres This consists of areas allocated for different businesses representing 0.7 percent of the total land area. This including markets, lorry parks, warehouses, hotels and reduction is attributed to encroachment and conversion guest houses, and shops. Commercial land use as at of such areas for residential development. Functions of 1993 was 24 acres representing 2.1 percent of the land open spaces as ‘softening’ physical development and area of Abuakwa. This has increased to 27 acres in 2010 toning down harsh weather conditions are gradually representing 2.4 percent of the town’s land area. The being lost in Abuakwa. Designated play grounds as well increase in commercial land use is due to the rapid as public recreational grounds are non-existent in the development of hotels and restaurants in Abuakwa.
Journal of Urban and Environmental Engineering (JUEE), v.7, n.1, p.96-109, 2013 Amoateng, Cobbinah and Owusu-Adade 103 town. As a result, there is frequent blockade of roads for roads have a total length of 29.3 km. Apart from the social events such as funerals. primary road, all the secondary and access roads are in poor conditions and this hinders easy and smooth Educational land use vehicular accessibility within the town. The roads are
dusty and usually become immotorable in rainy seasons. Educational land use covered 43 acres and 48 acres in Again developers have encroached on the road 1993 and 2010 respectively of the land area of reservations while the development of access roads has Abuakwa. Major educational institutions are Baptist not kept pace with physical development making parts Seminary School, Catabb Vocational Institute, two of the town inaccessible (see Fig. 6). public basic schools and a number of private schools. Currently all the private schools are located on Mixed use residential plots as a result of the uncoordinated development in the town. The absence of undeveloped Given the increasing population growth, there is land for educational use is likely to affect future apparently emerging land use (mixed use) in Abuakwa construction of schools in the town and has the tendency especially residential and commercial uses. As a new to create congestion in the existing schools. land use, mixed uses cover 14 acres representing 1.3 percent of the land area and are located along the major Civic and cultural land use roads and in the central part of Abuakwa. The major problems associated with the mixed uses are congestion This land use covers public buildings such as churches, as it promotes indiscriminate on-street parking and poor mosques, palaces, hospitals, administrative buildings, sanitary conditions as no provision is made for such offices of some public institutions like police station and activities prior to conversion. hospitals. Civic and cultural land use occupied a land area of 8 acres in 1993 and 17 acres in 2010 Undeveloped land representing 0.7 percent and 1.5 percent of the land area of the town respectively. The increase is mainly due to All lands in the town that have not been put to any the development of new churches in the town. The civic urban use or are used for agriculture were classified as and cultural land uses add to the aesthetic qualities of undeveloped land. As presented in Fig. 2, undeveloped the townscape beyond their respective defined roles. land in 1993 covered a considerable land size (61.4 However, the poor location of noise making churches percent) of the total land area of Abuakwa. As a result on residential plots makes them a source of nuisance to of increasing population growth, Fig. 3 shows that there residents. is a significant reduction in the size of the undeveloped land. Table 1 shows that current (2010) undeveloped Sanitation land use land in Abuakwa is only 0.2 percent of the total land
area of Abuakwa. Given the current increasing This land use which includes refuse disposal sites and population coupled with the rate of reduction in the public toilet facilities presently occupies 5 acres of land undeveloped land, it could be argued that there will not which constituted 0.4 percent of the land area. However, be any available undeveloped land in Abuakwa in the the survey results show that there is limited supply of near foreseeable future should the trend continue. refuse disposal sites which has resulted in indiscriminate dumping of refuse in the town especially in the newly developing areas. The indiscriminate Actors involved in physical development in Abuakwa disposal is mostly done on acquired but undeveloped plots within the built up area. This is likely to promote The study identified a number of institutions/individuals the spread of sanitary related diseases such as malaria that are involved in the physical development and diarrhoea in the town if this practice is unchecked. management process in Abuakwa. These actors are expected by law (Act 462) to collaborate and ensure Circulation effective physical development of communities in the
district. This section presents the role of these actors The hierarchies of roads identified in Abuakwa are with respect to physical development of Abuakwa. primary, secondary and access roads. Occupying a total land area of 275 acres, there is a total road length of Private landlords/ladies 34km in the town. The primary roads are the Kumasi- Sunyani and Kumasi-Bibiani Trunk Roads stretch The activities of these individuals influence the within the town and have a length of 1.6km. The length distribution and concentration of land uses such as of the two secondary roads which connect the northern residential, commercial and education. The study and southern parts of the town is 3.1km. The access revealed that about 25 percent of the private
Journal of Urban and Environmental Engineering (JUEE), v.7, n.1, p.96-109, 2013 Amoateng, Cobbinah and Owusu-Adade 104 landlords/ladies have acquired and encroached on land of all the communities in the district including demarcated as unbuildable and environmentally Abuakwa. However, the study results show that the sensitive areas such as marshy and water ways. ANDA is unable to provide the development control institutions with adequate logistics to enable them Traditional leaders function effectively. As a result, there is high prevalence of haphazard and unauthorized physical development in In the context of Ghana, traditional leaders are the most of the communities in the district including considered as custodians of land, and are responsible for Abuakwa. leasing land to both prívate and public developers. However, they are limited by law to determine the use Building Inspectorate Division (BID) of land, which is the responsibility of the TCPD. The study results indicate that there are seven (7) traditional This Division was established under the Metropolitan, leaders in Abuakwa, with each controlling the leasing Municipal and District Assemblies and is responsible and allocation of the land under his jurisdiction to for ensuring the enforcement of and compliance with prospective developers. It was however noted that the building regulations. The Division in the AND is activities of these traditional leaders are not coordinated. supposed to carry out this function by inspecting As a consequence, there have been several cases of progress of development in Abuakwa and other double allocation and land litigation in Abuakwa. In communities in the district. However, the Division constrast to their fundamental role as custodians of the rarely functions as it is handicapped in the areas of land, they have also assumed the role of determining the logistics such as vehicles for inspection. The Division is use in which a paticular land is put to. This situation has also confronted with limited operational powers and resulted in the leasing of lands which are demarcated by lack of support and collaboration from other physical the TCPD for public uses, such as open spaces, for development management stakeholders. residential development. State Housing Company Limited (SHCL) Town and Country Planning Department (TCPD) The SHCL formerly Gold Coast Housing Corporation The TCPD was established in 1945 by the Town and was established in 1955 as the main housing Country Planning Ordinance of 1945 (CAP 84). The development agency of the Government of Ghana to TCPD is a service delivery department under the ensure efficient housing development in the country. Ministry of Environment, Science and Technology at The company’s influence on the physical development the national level and the Ministry of Local Government of Abuakwa is manifested in its acquisition of land and and Rural Development at the local level. It has the construction of houses for the middle income group and responsibility of planning and managing the growth and workers of both the formal and informal sectors in the development of all settlements in the country. From the northern part of the town. The study analysis shows that study it was realized that the TCPD in the AND this action of the company has contributed significantly regulates physical development in Abuakwa through the to the rapid expansion of the town, although the preparation of planning schemes, issuance of development was undertaken in an orderly manner. building/development permits and monitoring and site From the above discussions, it is ostensibly clear that inspection. Unfortunately, the Department is under physical development in Abuakwa involves many resourced in terms of personnel and logistics which actors, some which are categorized under different have hindered planning effort as well as routine parent institutions with diverse interests. As a monitoring of physical development in Abuakwa. The consequence, there is lack of coordination and Department also faces the challenge of poor cooperation among the actors which has contributed to coordination and cooperation from other institutions haphazard development, conflicting land uses and break especially traditional leaders. down of formal development control processes in Abuakwa. Atwima Nwabiagya District Assembly (ANDA) Housing development in Abuakwa The Local Government Act (Act 462) mandates all metropolitan, municipal and district assemblies in Houses are the most important manifestation of physical Ghana with the responsibility of ensuring socio- development in Abuakwa. The acquisition of economic and physical development of all communities development and building permits is the main in the district. As such, the ANDA oversees and prerequisite for carrying out any physical development coordinates the preparation and implementation of in Ghana especially in areas that have Approved planning schemes to guide the growth and development Planning Schemes. This is done to regulate the type,
Journal of Urban and Environmental Engineering (JUEE), v.7, n.1, p.96-109, 2013 Amoateng, Cobbinah and Owusu-Adade 105 nature and characteristics of the housing or physical Land use (in) compatibility development that are carried out on any piece of land. The survey revealed that 58.0 percent of house owners Analysis of land use location and relationship showed acquired development and building permits from that there is high level of land use compatibility in planning authorities while 42.0 percent did not acquire Abuakwa because of the dominance of residential any permits before developing their lands. This development (see Fig. 3). However, major cases of land indicates that almost half of housing development in use incompatibility identified included a noisy making Abuakwa had not been authorized by the planning and obnoxious odour emitting industrial activities such authorities. The reasons cited for the refusal to acquire as metal products, processing firms and a poorly permits were the high cost and bureaucratic processes or managed abattoir all located in the midst of the delays involved in the acquisition of permits. residential areas. These activities need to be grouped on Additionally, the traditional leaders have set a certain a clearly defined location to internalize the problems timeframe for the developers to start construction. This associated with them. timeframe, which differs from one traditional leader to Land use change another, when elapsed, permits the traditional leaders to demand extra money or lease the land to another As presented in Table 1, it was observed from the study developer. As a result, prospective developers resort to that Abuakwa has been characterized by substantial land development without planning authorities’ approval. use conversion mainly from undeveloped to residential This situation further highlights the haphazard and as well as the introduction of mixed uses (e.g. location unregulated nature of physical development in of residential and commercial uses in a single building). Abuakwa. While the residential land use has extended into the The study revealed that majority of the houses (67 undeveloped land and facilitated the lateral growth of percent) fall into the single family detached houses Abuakwa, the mixed uses are concentrated along the category. Other housing types were compound and major roads and in the Central Business District of the semi-detached which constituted 26 percent and 7 town. The development of mixed uses is fuelled by the percent of the total housing stock respectively. The desire of the house owners to earn high rent; as data dominance of the detached houses is attributed to the gathered show that a single residential room earns a settlement’s transformation from rural to urban status monthly average rent of GH¢10.00 while a store room which has led to a steady shift from the traditional goes for GH¢30.00. Despite the emergence of mixed compound housing to modern single family housing uses, none of the house owners acquired permit before system. This current housing preference has contributed effecting the changes in the use of their buildings. This to the rapid expansion of the town as the single family indicates the extent of non-compliance to planning detached houses accommodate few people per square regulations which is a threat to orderly and sustainable kilometer and consumes more land leading to the lateral physical development. The negative consequences of expansion of the town. such unauthorized conversion include traffic congestion and poor sanitary conditions. This land use change is Characteristics of physical development in Abuakwa likely to continue as the town becomes more urbanized Leap frog development and as such efforts should be made by the planning authorities to order its occurrence in the future. It was realized from the study that physical development in the town has occurred in a spatially fragmented Physical development or land use zones pattern, due to speculative buying or acquisition of land. This has resulted in the presence of patched of As a typical peri-urban area, Abuakwa depicts three undeveloped land (brown fields) located within the built distinctive spatial zones. The zones include the core or up areas. The survey found that such green field sites indigenous, newly developed area or urban shadow and occupy about 55 acres of the total residential land area estate housing areas as illustrated spatially in Fig. 5. of the town. According to the TCPD at ANDA, the leap The core or indigenous area is where physical frog development in the town is fuelled by double development started and is dominated by multi-family allocation of lands by land owners (traditional leaders) compound houses with most of them (85%) having which has led to land litigation as well as incremental existed for more than forty years. The zone is housing development, which is a common phenomenon characterized by mixed land uses due to the conversion in Ghana. These undeveloped patches of land serve as of buildings to commercial and residential uses by the den for criminals and sites for indiscriminate disposal of house owners. Figure 5 shows the land use zones in refuse leading to wasteful and unsustainable use of land. Abuakwa.
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institution of chieftaincy has contributed to the distorted and unauthorized physical development in the town. The syndrome of planning chasing development is key factor accounting for Abuakwa’s growth. The study revealed that planning institutions in charge of managing the physical development of peri-urban Abuakwa are constrained in both logistics and personnel. This has hampered their ability to undertake regular inspection of physical development. Moreover, the late preparation of planning scheme to regulate development has resulted in a situation where haphazard physical development in Abuakwa is influencing planning scheme preparation. To illustrate this, the Fig. 5 Spatial Development Zones in Abuakwa, 2010. current planning scheme was prepared as late as 1993 and does not even cover all areas of the town that have The newly developed area started experiencing been developed, and has not been revised. intensive physical development in the mid 1990s and it The government of Ghana’s policies to meet the is mainly dominated by single family-detached houses. housing needs of the citizens has also contributed to the Most of the people who live in these areas are relocated rapid physical development of Abuakwa. Among such settlers from Kumasi who commute daily to the city. policies was the establishment of the SHCL to construct The estate housing area, which is located in the northern houses and sell them to the populace at moderate prices. part of the town, comprises prototype residential houses In the case of Abuakwa a whole area (Kagyaase Stool which were built by the SHCL, Ghana. Most of the Lands) was acquired by SHC and developed into an inhabitants (76%) work in the service sector and estate for workers of both the formal and informal commute to work daily in Kumasi. economy. This action of the SHC led to massive expansion in the size of the town and brought a range of Factors influencing the physical development working-class people to this peri-urban community. pattern in Abuakwa Analysis of the actors involved in the physical development and management process in Abuakwa The pattern of physical development in Abuakwa is revealed that each of the actors have different interests influenced by the interplay of several factors. These with many of them categorized under different parent factors emanate from conditions within and outside the bodies or institutions. For example the TCPD is under town. Seven factors were identified to have accounted the Ministry of Environment, Science and Technology for the physical development pattern in the town. Four at the national level and the Ministry of Local of these factors are peculiar to Abuakwa and they Government and Rural Development at the district include land tenure challenges, the syndrome of level, while the BID is mainly under the ANDA. This planning chasing development, government of Ghana’s situation, according to the study results, has resulted in housing policy and the categorization of planning the Departments being under-resourced, thus serving as institutions under different parent institutions. The three a barrier to effective coordination and collaboration remaining factors are universal and include relatively with the other actors in managing physical development. low land values, good transport system and greenery Discussing the universal factors, the study findings environment. These factors are analyzed in the indicate that the availability of relatively low land value following paragraphs. is Abuakwa has contributed to the unregulated physical Land tenure system in Abuakwa greatly influenced development. This was identified as an important pull physical development pattern. Land in Abuakwa is factor which had contributed to the high rate of physical under stool lands with traditional authorities serving as development. From the survey, 41.3 percent of the custodians. However, the study found out that in house owners indicated that they were attracted to the Abuakwa the land is owned by seven different stools town because of low land value. The price of a who ‘sell’ the lands in an uncoordinated manner without residential plot (80×100 ft) in Abuakwa cost at the time consulting the planning authorities. It was uncovered of the survey GH¢5,000.00 which was relatively through the study that there have been several instances cheaper compared to that of Kwadaso (a suburb within where the traditional authorities have allocated land to the Kumasi Metropolis) which was GH¢7,500.00 developers for various purposes contrary to the (TPCD, ANDA). This has been an important attractive proposals on the planning schemes. This land ownership factor to developers and business operators leading to and management practices that is embedded in the accelerated physical development in Abuakwa.
Journal of Urban and Environmental Engineering (JUEE), v.7, n.1, p.96-109, 2013 Amoateng, Cobbinah and Owusu-Adade 107
Another universal factor relate to the good transport about the water lagging conditions in Abuakwa, a system. As the Kumasi city grows and spreads out into situation which affects residents’ movement especially the surrounding countryside, new investments in during heavy downpours. This phenomenon has transportation infrastructure have been made to open up emanated from the construction of buildings in water previously less accessible lands for physical expansion. ways and waterlogged areas. Among such developments was the improvement of the Abuakwa is characterized by poor internal Sunyani and Bibiani Trunk roads which traverse circulation. The physical survey of the town showed Abuakwa Township (Owusu-Ansah & O’Connor, physical development has encroached on most of the 2006). This made accessibility between Kumasi and access roads and lanes. This happened through the Abuakwa as well as the outlying settlements easy. extension of buildings, erection of fence walls and Given its high accessibility level, the survey showed inappropriate siting of “containers” for commercial that 9.7 percent of the house owners were attracted to purposes. It was realized that in areas where the access the town due to easy access to and from Kumasi. roads exist, they are in deplorable conditions which Greenery and serene environment has also render them unusable by motor vehicles especially contributed to the increasing physical development in during rainy seasons. Examples of these are shown in Abuakwa. The survey results indicate that 32.0 percent Fig. 6. of the respondents were attracted to Abuakwa because of the serene environment in the town. These people perceived the environmental conditions in Kumasi to have been deteriorated by numerous commercial and industrial activities and hence their choice of the peri- urban town. This means that Abuakwa will continue to experience more extensive physical development even as Kumasi continues to urbanize very fast with its associated environmental concerns.
Effects of Increasing Physical Development on Fig. 6 Encroached and Poor of Roads. Abuakwa Source: Field Survey, 2010
The study unraveled that the physical development Abuakwa is a major traffic generation point of pattern in Abuakwa presents both opportunities and Kumasi as about 60.0 percent of the working force challenges. The various consequences which were commute to work in the city daily. This leads to heavy identified are elaborated as follows. traffic congestion on the Kumasi-Abuakwa corridor Loss of agricultural land was identified to be the which results in average travel time of one to two hours major effect of increasing physical development in during peak hours over a distance of 12 km. This has the Abuakwa. Given the location of the town, agricultural potential to affect workers productivity as it results in activities were dominant especially in the 1990s. loss of working hours, tiredness and stress. Again, the However, the study indicated that Abuakwa has conversion of land uses which promotes the growth of expanded over a wide area and consumed valuable commercial activities along the roads and around the agricultural land (undeveloped land). The indigenous central business district further results in traffic people, who are mainly farmers, are being denied their congestion. livelihood. In addition, there is an upsurge in land value Analysis of housing documents reveal that the total from GH¢250.00 in 1993 to GH¢5000.00 in 2010 housing stock in Abuakwa has increased from 1030 in pricing out the indigenes and low income earners from 2000 to about 1630 in 2010. This means that more the land market. housing unit has been built to accommodate the According to the utility service providers, the high increasing influx of people. More importantly the rate of physical development in Abuakwa outstrips their survey revealed that the pattern of physical development capacity to serve all areas of the town. As a result of offers accommodation to the low and middle income this, about 36.9 percent and 25.3 percent of the houses earners most of whom could not have afforded housing are not served with water and electricity respectively in in the city. The development pattern has therefore the town. Most of these houses are found in the newly played a very essential role in meeting the housing developed areas. Again, flooding is a major effect of needs of urban residents especially migrants and middle increasing and unguided physical development. income earners. Although the town has not experienced any major Another positive effect is the increases in flooding, about 3 percent of the respondents complained government revenue. The acquisition and development
Journal of Urban and Environmental Engineering (JUEE), v.7, n.1, p.96-109, 2013 Amoateng, Cobbinah and Owusu-Adade 108 of land for housing, industries and businesses has led to make provision for directing and managing it. The increase in ground rent, taxes and property rates to the major elements of the growth management should ANDA. In Abuakwa, annual ground rents and property include the following; rates are around GH¢8 and GH¢20 respectively per house. This shows the contribution of physical 1. Development should be restricted within development in peri-urban areas to government revenue. defined serviceable boundary. In this regard provision of services should be limited within the boundary. This will promote land use intensification and reduce the cost Managing physical development in peri-urban of providing utility services by forestalling rapid lateral Abuakwa: the way forward expansion; 2. Phasing of development so as to manage Central to this study is the understanding and development in specified areas within a time frame. assessment of the increasing physical development in This will enable development authorities to well monitor the growth of these areas and ensure orderly peri-urban areas. The above discussions have portrayed and functional settlement development in the long run; the nature, extent and intensity of physical development 3. Development and building permits should not in Abuakwa. The following paragraphs suggest ways of be issued for areas where services have not been managing the increasing physical development in peri- provided. This will ensure that every house has access urban Abuakwa. to basic services. Physical development and service To begin with, haphazard physical development in provision should proceed concurrently; Abuakwa needs to be checked through strong 4. The preparation of physical development plans institutions. The practice of planning chasing for peri-urban areas should be done in the framework of development should be checked. In relation to this, the regional planning. Planning of peri-urban areas should study recommends that the state institutions concerned be integrated into a city-wide system. This has the tendency to cater for both the internal and external with physical development and land management factors which interplay to shape the pattern of physical should collaborate with the traditional authorities in the development in peri-urban areas; and allocation of land to developers. The state institutions should be well resourced to help them examine building The preparation of planning schemes to guide permits, undertake routine patrols and engage with development of peri-urban areas should be premised on community members in their efforts to curtail the land capability or classification studies. The potential of unauthorized developments which have characterized every piece of land need to be assessed and utilized for peri-urban areas. such purpose. Agricultural land must be reserved for There is the need for the TCPD to embark on such purpose irrespective of the rate of demand for continuous and intensive public education on the other urban land uses. This will help preserve the processes involved in carrying out physical economic life of the people especially the indigenes. development. Stakeholders especially the traditional However where farming or agriculture cannot be authorities and developers should be sensitized on their maintained, alternative livelihood need to be provided roles in ensuring orderly physical development. Popular for the indigenes or the people. participation in plan preparation should be encouraged to enable the residents understand the dynamics of CONCLUSION physical development. There is the need to establish CLS to co-ordinate the Although this paper has confirmed the general assertion acquisition and allocation of land. This will ensure that that peri-urban areas experience rapid physical decision regarding the allocation of land is well development (O’Sullivan, 2000; Hewitt, 1989; Buxton, controlled and monitored instead of leaving it at the 2007), and that they are characterized by high rates discretion of traditional leaders. This has the potential to physical growth rate with the potential of tripling in ensure that developers receive the needed physical size in every two decades, it has also identified documentation covering their lands before development. certain physical development factors which are locally The establishment of the CLS will help realize the based. objectives of the Land Administration Project (LAP) The paper points out that the pattern of physical which is being implemented on pilot basis in some parts development is influenced by a number of local factors of Ghana. and they include: land tenure system and its associated It is recommended that physical development efforts traditional land management challenges; the in peri-urban areas should embrace the tenets of categorization of planning institutions under different settlement growth management. The growth parent institutions, the syndrome of planning chasing management approach should anticipate the rapid development and the government of Ghana’s housing development which characterizes peri-urban areas and policy. The study has revealed that the resultant
Journal of Urban and Environmental Engineering (JUEE), v.7, n.1, p.96-109, 2013 Amoateng, Cobbinah and Owusu-Adade 109 physical development which emerges through the Drescher. A. W. & Iaquinta D. L. (2000) Defining Peri-urban: interplay of these factors has many negative effects on Understanding Rural- Urban Linkages and their Connection to Institutional Contexts, Paper Presented at the Tenth World the residents of peri-urban areas. These adverse Congress, IRSA, Rio, August. consequences include loss of agricultural land, lack of du Plessis, C. & Landman K. (2002) Sustainability Analysis of access to utility services, incidences of flooding, Human Settlements in South Africa, A report prepared by CSIR unregulated conversion of land uses, poor internal Building and Construction Technology Programme for Sustainable Human Settlement, Pretoria. Retrieved circulation and traffic congestion. fromhttp://researchspace.csir.co.za/dspace/bitstream/10204/3522/ The study therefore recommends the strengthening of 1/u%20Plessis_2002.pdf on 12/07/2012 planning institutions, effective coordination and Ghana Statistical Service (2012) 2010 Population and Housing collaboration between planning institutions and the Census, Summary of Final Results, Accra: Ghana Statistical application of the tenets of settlement growth Service Government of Swaziland (1997) The Draft Peri-Urban Growth management. The growth management approach has the Policy, 1997, Retrieved on 09/08/2010 from potential of foreseeing the rapid development which http://www.ecs.co.sz/periurban/pup_periurban_policy.htm characterizes peri-urban areas as result of fast Hewitt, M. (1989) Defining "rural" Areas: Impact on Health Care urbanization and make provision for it. Consequently, Policy and Research. Health Program, Office of Technology this has the tendency of reversing the trend of ‘planning Assessment, Congress of the United States, Washington, DC Johnson, J.H. (1974) Suburban Growth, Geographical Process at chasing development’ into ‘planning directing and the Edge of the Western City, Aberdeen: Aberdeen University managing development’ in peri-urban Abuakwa. Press. Concomitantly, the adoption and implementation of the Keeble, L. (1969) Principles of Town and Country Planning, settlement growth management approach will promote London: The Estate Gazette Limited. Mather, A.S. (1989) Land Use, New York: Wiley and Sons Inc. orderly physical development in the urban fringes and Miller, R. L. & Brewer, J. D. (2003) A – Z of Social Research. create liveable, functional and sustainable peri-urban London: SAGE Publication Ltd areas. Mohd Noor, K. B. (2008) Case study: A strategic research methodology. American Journal of Applied Sciences, 5(11), REFERENCES 1602-1604. National Development Planning Commission (2004) Atwima District Human Development Report, Accra, Ghana: NDPC. Adesina A, (2007) Socio-Spatial Transformations and the Urban O’Sullivan, A, (2000) Urban Economics, United States: The Fringe Landscape in Developing Countries, Nigeria: Ibadan McGraw Hill Companies Inc. University Press. Organisation for Economic Co-operation and Development (OECD), Atwima Nwabiagya District Assembly (2006) Medium Term (2007) The Growing Peri-Urban Phenomenon, Report of One Development Plan 2006-2009, Nkawie: ANDA Week Conference held in France. Balchin, P.N., Isaac, D. & Chen, J. J. (2000) Urban Ecoomics, A Owusu-Ansah, J. & O.Connor, K. (2006) Transportation and Global Perspective, United States: Palgrave Macmillan. Physical Development around Kumasi in Ghana, Discussion Buxton, M. (2007) Change in Peri-urban Australia: Implications for Paper Submitted to World Academy of Science, Engineering and Land Use Policies, Australia: Department of Environment and Technology. Heritage Publishing Unit. Sarantakos, S. (1998). Social Research, London: McMillan Press Cobbinah, P. B. & Amoako, C. (2012) Urban Sprawl and the Loss of Ltd. Peri-Urban Land in Kumasi, Ghana. International Journal Timms, P. (2006) Peri-Urban Development, Conference Presentation of Social and Human Sciences, 6, 388-397 at the European Aid Co-operation Centre in China. Drabkin, D. H. (1977) Land Policy and Urban Growth, London: Pergamon Press.
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Journal of Urban and Environmental Journal of Urban and E Engineering, v.7, n.1, p.110-116 Environmental Engineering ISSN 1982-3932 J E www.journal-uee.org U doi: 10.4090/juee.2013.v7n1.110116
BIOGAS POTENTIAL OF ORGANIC WASTE IN NIGERIA
Chima C. Ngumah *, Jude N. Ogbulie, Justina C. Orji, and Ekpewerechi S. Amadi
1 Department of Microbiology, Federal University of Technology Owerri, Nigeria
Received 22 November 2012; received in revised form 19 January 2013; accepted 28 March 2013
Abstract: With the growing demerits of fossil fuels - its finitude and its negative impact on the environment and public health - renewable energy is becoming a favoured emerging alternative. For over a millennium anaerobic digestion (AD) has been employed in treating organic waste (biomass). The two main products of anaerobic digestion, biogas and biofertilizer, are very important resources. Since organic wastes are always available and unavoidable too, anaerobic digestion provides an efficient means of converting organic waste to profitable resources. This paper elucidates the potential benefits of organic waste generated in Nigeria as a renewable source of biofuel and biofertilizer. The selected organic wastes studied in this work are livestock wastes (cattle excreta, sheep and goat excreta, pig excreta, poultry excreta; and abattoir waste), human excreta, crop residue, and municipal solid waste (MSW). Using mathematical computation based on standard measurements, Nigeria generates about 542.5 million tons of the above selected organic waste per annum. This in turn has the potential of yielding about 25.53 billion m³ of biogas (about 169 541.66 MWh) and 88.19 million tons of biofertilizer per annum. Both have a combined estimated value of about N 4.54 trillion ($ 29.29 billion). This potential biogas yield will be able to completely displace the use of kerosene and coal for domestic cooking, and reduce the consumption of wood fuel by 66%. An effective biogas programme in Nigeria will also remarkably reduce environmental and public health concerns, deforestation, and greenhouse gas (GHG) emissions.
Keywords: Renewable energy; anaerobic digestion; biogas; biofertilizer; organic waste; Nigeria
© 2013 Journal of Urban and Environmental Engineering (JUEE). All rights reserved.
Correspondence to: Chima C. Ngumah, Tel.: +234 706 266 4079. E-mail: [email protected]
Journal of Urban and Environmental Engineering (JUEE), v.7, n.1, p.110-116, 2013 Ngumah, Ogbulie, Orji and Amadi 111
INTRODUCTION benefits derived in employing AD in treating organic wastes are: Biogas technology, also known as anaerobic digestion
(AD) technology, is the use of biological processes in Benefits for the energy sector:- the absence of oxygen for the breakdown of organic Source of renewable (green) energy, which matter and the stabilization of these material, by conversion to biogas and nearly stable residue leads to a lesser dependency on the finite fossil fuels. (digestate) (Marchaim, 1992). Biogas is a mixture of methane (4575%) and carbon dioxide (2555%); the The use of the digestate decreases the use of actual proportion depending on the feedstock (substrate) fossil fuels in the manufacturing of synthetic used and processes employed. For biogas to be fertilizer. flammable the methane content must be ≥ 40%. Apart It is carbon dioxide neutral. from methane and carbon dioxide, biogas may also contain small amounts (≤ 3%) of impurities, such as Benefits for agriculture: hydrogen sulphide, ammonia, carbon monoxide, and Transformation of organic waste to very high other gases (Monnet, 2003). quality fertilizer. Historical evidence indicates that AD is one of the Improved utilization of nitrogen (by plants) oldest technologies. Even around 3000 BC the from animal manure. Sumerians practiced anaerobic cleansing of waste Balanced phosphorus/potassium ratio in (Deublein & Steinhauser, 2008). However, the digestate. industrialization of anaerobic digestion began in 1859 Homogenous and light fluid slurry. with first AD plant sited in Bombay (India). In 1897, an AD virtually destroy all weed seeds, thus anaerobic digester at Matunga Leper Asylum in reducing the need for herbicides and other weed Bombay used human waste to generate biogas (Khanal, control measures. 2008). According to Deublein & Steinhauser (2008), Provides closed nutrient cycle. other countries that pioneered the evolution of biogas Treated effluent from AD is a good animal feed technology were: when processed with molasses and grains. France, in 1987 the streets lamps of Exeter started running on biogas produced from Benefits for the environment:- wastewater. Reduces emission of greenhouse gases (GHG). China, rural biogas system developed in 1920, Reduces nitrogen leaching into ground and while the national programme started in 1958. surface waters. Germany, agricultural products were used to Improves hygiene through the reduction of produce biogas in 1945. pathogens, worm eggs, and flies. Reduces odour by 80%. Today, China is credited as having the largest Controlled recycling/reduction of waste. biogas programme in the world with over 20 million Reduces deforestation by providing renewable biogas plants installed (Tatlidil et al., 2009). alternative to woodfuel and charcoal. According to Deublein & Steinhauser (2008), biogas Biogas burns “cleaner” than woodfuel, technology was introduced in Africa between 1930 and kerosene, and undigested biowaste. 1940 when It creates an integrated waste management Ducellier and Isman started building simple system which reduces the likelihood of soil and biogas machines in Algeria to supply farmhouses with water pollution compared to the disposal of energy. Despite this early start in Africa the untreated biowastes. development of large scale biogas technology is still in its embryonic stage in this region, though with a lot of Benefits to the economy: potentials. In Nigeria, the status of biogas technology remains abysmal. The earliest record of biogas Provides cheaper energy and fertilizer. technology in Nigeria was in the 80s when a simple biogas plant that could produce 425 litres of biogas per Provides additional income to farmers. day was built at Usman Danfodiyo University, Sokoto Creates job opportunities. (Dangogo & Fernado, 1986). Decentralizes energy generation and About 21 pilot demonstration plants with a environmental protection. capacity range of between 10m320m3 have been sited in different parts of the country. Mountainous heaps of open wastes dumps have The two main products of biogas technology are continued to characterize urban centres in Nigeria. biogas (fuel) and biofertilizer (fertilizer) and the Different waste management institutions saddled with the responsibility of waste management have
Journal of Urban and Environmental Engineering (JUEE), v.7, n.1, p.110-116, 2013 112 Ngumah, Ogbulie, Orji and Amadi continuously failed in their mission. Open waste dumps b. Tonnage of abattoir waste generated per annum are sometimes incinerated, thereby releasing toxic in Nigeria (ECN, 2005). fumes which threaten public health. Other fallouts being c. Tonnage of human excreta generated calculated odour emission, breeding ground for disease vectors and using 1.093 × 10-3 tons/individual/day (Quazi et pathogens, uncontrolled recycling of contaminated al., 2010) with a population of 130 million goods and pollution of water sources (Agunwamba, (ECN2005). 1998). According to FAO (2010), Nigeria has the d. Tonnage of crop residue (waste) generated per highest rate of deforestation in the world, with 55.7% annum in Nigeria (ECN, 2005). (9 587 577 hectares) of her primary forest lost between e. Tonnage of municipal solid waste (MSW) 2000 and 2005. Fifty million tons of woodfuel is generated per annum in Nigeria (ECN, 2005). consumed in Nigeria per annum. Records also show that Nigeria ranks number 8 in the world in methane The following coefficients as deduced from Lil et emission with about 20 billion m3 of methane emission al. (2010); Schnurer & Jarvis (2010); Tatlidil et al. (13% of world emission). 69% of Nigeria’s methane (2009); and Rao et al. (2000) were used to estimate the emission actually comes from gas flaring while 28.8% amount of biogas derivable from each biowaste: 33 m3 comes from untreated organic wastes ton-1 for cattle excreta, 58 m3 ton-1 for sheep and goat (www.factfish.com). According to Akinbami et al. excreta, 60 m3 ton-1 for pig excreta, 78 m3 ton-1 for (2001), if biogas displaces kerosene, at least between poultry excreta, 53 m3 ton-1 for abattoir waste, 50 m3 357 - 60, 952 tons of carbon dioxide emission will be ton-1 for human excreta, 60 m3 ton-1 for crop residue avoided. Also, the electricity generating sector in (waste), and 66 m3 ton-1 for organic fraction of Nigeria has been very inefficient with blame always Municipal Solid waste (MSW). going to insufficient gas supply and reduced water The following coefficients as given by the Lil et levels at the dam. Biogas can be a big relief here too. al. (2010); Yu et al. (2010); Schnurer & Jarvis (2010); The lack of fertilizers, detrimental effects of synthetic Tatlidil et al. (2009); and Rao et al. (2000) were used to fertilizers to soil chemistry and biology, and the huge estimate the biochemical methane potential (BMP) of amount of foreign exchange invested in the importation biogas from various biowastes: 56% for cattle excreta, of synthetic fertilizers can be drastically reduced by 70% for sheep and goat excreta, 60% for pig excreta, using the digestate of AD instead. 66% for poultry excreta, 60% for abattoir waste, 65% In Nigeria, biogas technology has remained at for human excreta, 60% for crop residue, and 66% for the level of institutional research work and pilot organic fraction of MSW. The energy potentials of schemes. Its progress being stunted by ignorance, different biogas volumes generated were based on the researches at universities frequently considered as being calorific value of their methane content, while the too academic, lack of political will, and lack of an tonnage equivalents of selected fuels to different adequate coordinating framework. estimated biogas volumes were based on their energy The main objective of this study is to highlight potentials. the amount of organic waste generated in Nigeria, and The MSW presented in this work is actually the amount of biogas and biofertilizer derivable from only its organic fraction which is 50% of the mass of the such waste generated; with a view to providing data total MSW generated in Nigeria. required for feasibility studies in setting up a biogas The coefficients used in estimating biofertilizer scheme which would in turn proffer a feasible, yields were based on the fraction of the dry mass sustainable, and profitable integrated biodegradable portion of each organic waste that is not converted to waste management system that will take care of the biogas. According to Dublein & Steinhauser (2008) the various endemic environmental issues which have in the dry mass (DM) percentage of fresh organic wastes were past defied various treatment. The scope of this study is given as: 25% for cattle excreta, 18% for sheep and goat limited to organic wastes from selected livestock (cattle, excreta, 20% for pig excreta, 10% for poultry excreta, sheep and goat, pig, poultry, and abattoir waste), human 15% for abattoir waste, 25 % for human excreta, 89% excreta, crop wastes, and municipal solid waste (MSW). for crop residue, and 30% for organic fraction of MSW. While the volatile solids (VS) percentage (which is the MATERIALS AND METHODS portion of the DM that can be potentially converted to biogas) of the DM were given as 80% for cattle excreta, The materials and methods employed in this study are 80% for sheep and goat excreta, 75% for pig excreta, as follows: 70% for poultry excreta, 85% for abattoir waste, 84 % Data on: for human excreta, 85% for crop residue, and 75% for a. The number of cattle, sheep, goat, pig, poultry organic fraction of MSW. 60% of VS is the actual in Nigeria and the total excreta they generate fraction taken to be converted to biogas (Burke, 2001). per annum (Garba, 2010). Hence the following formula for computing the potential dry mass of biofertilizer yield was deduced as:
Journal of Urban and Environmental Engineering (JUEE), v.7, n.1, p.110-116, 2013 Ngumah, Ogbulie, Orji and Amadi 113
estimated at about 542.5 million (Table 1). This Potential biofertilizer yield (dry) from each organic biowaste has the potential of generating 25.53 billion m3 waste = (DM – VS) + (40% of VS) biogas, with 66% (16.66 billion m3) coming from livestock wastes alone, while MSW, human excreta and DM = Dry Mass, mass of solid component of organic crop residue contributed the remaining 5%, 10%, and waste (i.e. organic waste minus moisture content) 19% respectively (Fig. 2 and Table 1).
Table 2 shows the biomethane potentials VS = Volatile Solids, portion of DM that can be (BMP) of biogas from different organic wastes and their potentially converted to gas (i.e. dry mass minus corresponding energy potential values. A total estimated mineral content). 3 BMP of 15.65 billion m per annum has an energy value RESULTS AND DISCUSSION of 610, 350 TJ; with livestock wastes alone contributing 10.11 billion m3 (394 290 TJ) which is approximately Figure 1 shows that 68% of solid biowaste generated in 64.6% of total of potential bio-energy generated from Nigeria came from livestock wastes (excreta and biowaste. The remaining 35.4% came from crop abattoir waste), while 15%, 10%, and 7% came from residue, human excreta, and MSW. crop wastes, human excreta, and MSW respectively. The total tonnage of biowaste generated per annum was
Cattle excreta Sheep and goat excreta Cattle excreta Sheep and goat excreta Pig excreta Poultry excreta Abattoir waste Human excreta Pig excreta Poultry excreta Crop residue Municipal solid waste (MSW) Abattoir waste Human excreta Crop residue Municipal solid waste (MSW) 7% 15% 37%
10% 5% 19% 26%
15% 7% 6% 3% 10% 9%
17% 10%
Fig. 1 Sector tonnage distribution of biomass generated in Nigeria. 4%
Fig. 2 Sector volume distribution of potential biogas obtainable from biomass generated in Nigeria.
Table 1. Potential biogas derivable from biomass generated in Nigeria Organic waste (biomass) Number of Units Total biomass generated Estimated biogas potential (millions) (million tons year-1) (billion m3 year-1) Cattle excreta 21 197.6 6.52 Sheep and goat excreta 100.9 39.6 2.3 Pig excreta 9.6 15.3 0.92 Poultry excreta 112.9 32.6 2.5 Abattoir waste - 83.3 4.42 Human excreta 130 52 2.6 Crop residue - 83 4.98 Municipal solid waste - 39.1 1.29 (MSW) Total 542.5 25.53
Journal of Urban and Environmental Engineering (JUEE), v.7, n.1, p.110-116, 2013 114 Ngumah, Ogbulie, Orji and Amadi
Table 2. Biomethane potential (BMP) and energy values of biomass generated in Nigeria. Organic waste (biomass) Estimated biogas Biomethane potential (BMP) Energy potential of potential (billion m3 of biogas (billion m3 year-1) biogas (TJ) per annum year-1) Cattle excreta 6.52 3.65 142 350 Sheep and goat excreta 2.3 1.61 62 790 Pig excreta 0.92 0.55 21 450 Poultry excreta 2.5 1.65 64 350 Abattoir waste 4.42 2.65 103 350 Human excreta 2.6 1.69 65 910 Crop residue 4.98 3.0 117 000 Municipal solid waste (MSW) 1.29 0.85 33 150 Total 25.53 15.65 610 350
Table 3 shows the tonnage equivalents of wood alone is equivalent to 26.82 million tons of wood fuel, fuel, coal, kerosene, liquefied petroleum gas, and 15.69 million tons of coal, 9.15 million tons of kerosene, liquefied natural million tons of kerosene, 13.15 million 8.5 million tons of liquefied petroleum gas, and 8.72 tons of liquefied petroleum gas, and 13.5 million tons of million tons of liquefied natural gas respectively per liquefied natural gas respectively. While the 16.66 annum. billion m3 of biogas that came from livestock wastes
Table 3. Tonnage equivalents of selected fuels to potential biogas yields in Nigeria Organic waste Estimated biogas Wood fuel Coal Kerosene Liquefied Liquefied (biomass) potential per equivalent equivalent equivalent petroleum natural gas annum (billion per annum per annum per annum gas equivalent per m3 ) (million (million (million equivalent annum tons) tons) tons) per annum (million tons) (million tons) Cattle excreta 6.52 9.68 5.67 3.3 3.07 3.15 Sheep and 2.3 4.27 2.5 1.46 1.35 1.39 goat excreta Pig excreta 0.92 1.46 0.85 0.50 0.46 0.47 Poultry 2.5 4.38 2.56 1.49 1.39 1.42 excreta Abattoir waste 4.42 7.03 4.11 2.40 2.23 2.29 Human 2.6 4.48 2.62 1.53 1.42 1.46 excreta Crop residue 4.98 7.96 4.66 2.72 2.52 2.59 Municipal 1.29 2.26 1.32 0.77 0.71 0.73 solid waste (MSW) Total 25.53 41.52 24.29 14.17 13.15 13.5
Journal of Urban and Environmental Engineering (JUEE), v.7, n.1, p.110-116, 2013 Ngumah, Ogbulie, Orji and Amadi 115
Table 4. Estimated biofertilizer (dry) derivable from biomass generated in Nigeria Organic waste Total biomass Dry mass (DM) of Volatile solids (VS) of Estimated biofertilizer (biomass) generated (million biomass generated DM (million tons year- (dry) potential tons year-1 ) (million tons year-1) 1) (million tons year-1) Cattle excreta 197.6 49.4 39.52 25.69 Sheep and goat 39.6 7.13 5.7 3.71 excreta Pig excreta 15.3 3.06 2.3 1.68 Poultry excreta 32.6 3.26 2.28 1.89 Abattoir waste 83.3 12.5 10.63 6.12 Human excreta 52 13 10.92 6.45 Crop residue 83 73.87 62.79 36.2 Municipal solid 39.1 11.73 8.8 6.45 waste (MSW) Total 542.5 173.95 142.94 88.19
Table 4 reveals the potential amount of use wood fuel and kerosene in domestic cooking. biofertilizer (dry) yield obtainable from different Also from the above computations, Nigeria will be organic wastes in Nigeria. The total organic wastes able to generate about 88.19 million tons of dry evaluated yielded a potential of 88.19 million tons of biofertilizer from biogas technology per annum. dry biofertilizer per annum. While the individual This is about 13 times the tonnage of synthetic organic wastes gave: 25.69, 3.71, 1.68, 1.89, 6.12, 6.45, fertilizer consumed in Nigeria between 2001 and 36.2, and 6.45 million tons for cattle excreta, sheep and goat excreta, pig excreta, poultry excreta, abattoir waste, 2010, for which the Federal Government of Nigeria human excreta, crop residue, and MSW respectively. spent N 64.5 billion ($ 410 828 025.48) on fertilizer subsidy. This potential amount of dry CONCLUSION biofertilizer obtainable is valued at N 3.53 trillion ($ 22.77 billion) per annum. This estimated From the above calculations it is very obvious that potential biofertilizer generated by anaerobic Nigeria has a lot of potentials for a viable, elaborate digestion per annum will be in excess of domestic and sustainable biogas (anaerobic digestion) demand; hence a well planned biogas program in project. A well articulated national and rural biogas Nigeria will serve as a firm base for foreign project will not only solve the chronic solid waste exchange and will considerably reduce greenhouse management problems that has defied successive gas emissions. governments, but will also positively impact on other sectors as: energy, agriculture, economy, REFERENCES public health and environment. The estimated bio- Agunwamba, J.C. (1998) Solid Waste Management in Nigeria: energy Problems and Issues. Env. Manag. 22(6): 849-856. Akinbami, J., Ilori, M., Oyebisi, T., Akinwuni, I., & Adeoti, O. potential of 610, 350 TJ per annum from organic (2001) Biogas Energy Use in Nigeria: Current Status, Future Prospects and Policy Implications. Renew. Sustain. Energ. Rev. waste is equivalent to 169, 541.66 MWh. This is 5: 97-112. valued at approximately N 1.01 trillion ($ 6.52 Burke, D. (2001) Dairy Waste Anaerobic Digestion Handbook. billion). About 17% (4.34 billion m3) of the 25.53 Environmental Energy Company, 1-57. Olympia WA 98516. billion m3 total estimated biogas potential is USA. Dangogo, S. & Fernado, C. (1986) A simple biogas plant with required to totally displace kerosene and coal as additional gas storage system. Nigerian J. Solar Energ. 5: 138- domestic fuel, while 80% (20.42 billion m3) of this 141. total estimated biogas potential will reduce wood Deublien, D. & Steinhauser, A. (2008) Biogas From Waste and Renewable Resources, 27-83. Wiley-VCH Verlag GmbH & Co. fuel consumption by about 66% (with present KGaA. consumption rates per annum being approximately Energy Commision of Nigeria (ECN) (2005) Energy Demand 2.37 million tons for Projection Document, 115-128. FAO (Forestry and Agriculture Organization) (2010) Global Forest kerosene, 12 000 tons for coal, and 50 million tons Resources Assessment, 9-44. Main Report 163. for wood fuel). Displacing wood fuel and kerosene Fertilizer Suppliers Association of Nigeria (FEPSAN) (2010) as domestic fuel will drastically reduce Fertilizer-Free Market, 1-16. Garba, B. Overview of Biomass Energy Resources, Technologies deforestation, and prevent many ailments and and Programmes in Nigeria. deaths associated with indoor pollution due to the
Journal of Urban and Environmental Engineering (JUEE), v.7, n.1, p.110-116, 2013 116 Ngumah, Ogbulie, Orji and Amadi
(http://cgpl.iisc.ernet.in/site/Portals/0/Publications/Presentations/ Quazi, A. & R. Islam. (2005) The Re-use of human Excreta in EGM/10_Nigeria-egm.pdf). Bangladesh. (www.wateraid.org/documents/ch19). Khanal, S.K. (2008) Anaerobic Biotechnology for Bioenergy Rao, S., Singh, S., Singh, A. & Sodha, M. (2000) Bioenergy Production: Principles and Applications. Wiley-Blackwell. Ames. Conversion Studies of the Organic Fraction of MSW: Assessment Lil, S., Liangwei, D., Yong,Y., Xiaodong, P., Zhiyong, W. (2010) of Ultimate Bioenergy Production Potential of Municipal Biogas Production Potential and Characteristics of Manure of Garbage. Appl. Energ. 66(1): 11-18. Sheep, Duck and Rabbit under Anaerobic Digestion. Chin. Soc. Sambo, A. (2009). Strategic Developments in Renewable Energy in of Agric. Eng. 10(1), 22-34. Nigeria, 15-19. International Association of Energy Economy. Marchaim, U. (1992) Biogas Processes for Sustainable Third Quarter. Development, 1-99. FAO. Schnurer, A. & Jarvis, A. (2010) Microbiological Handbook for Matthew, R., Subedi, M., Smith, J., Yongabi, K., Avery, L., Biogas Plants, 1-74. Swedish Waste Management U2009:03. Starchan, N., & Semple, S. (2011) The Potential of Small-Scale Swedish Gas Centre Report 207. Digesters to Alleviate Poverty and Improve Long Term Tatlidil, F., Bayramoglu, Z. & Akturk, D. (2009) Animal Manure as Sustainability of Ecosystem Services in Sub-Saharan Africa. One of the Main Biogas Production Resources: Case of Turkey. DFID NET-RC A06502. J. Anim. and Vet. Adv. 8(2): 2473-2476, 2009. Monnet, F. (2003) An Introduction to Anaerobic Digestion of Yu, Z., M. Morrison, F. Schanbacher. (2010) Biomass to Biofuels: Organic Wastes, 1-43. Final Report. Strategies for Global Industries, 6-9. John Wiley & Sons Ltd. United Kingdom.
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Journal of Urban and Environmental Journal of Urban and E Engineering, v.7, n.1, p.117-125 Environmental Engineering ISSN 1982-3932 J E www.journal-uee.org U doi: 10.4090/juee.2013.v7n1.117125
OPERATIONAL PERFORMANCE OF VERTICAL UPFLOW ROUGHING FILTER FOR PRE-TREATMENT OF LEACHATE USING LIMESTONE FILTER MEDIA
Augustine Chioma Affam1 and Mohd. Nordin Adlan2
1, 2 School of Civil Engineering, Universiti Sains Malaysia, Engineering Campus, Nibong Tebal, Penang, Malaysia 1 Department of Civil Engineering, Universiti Teknologi PETRONAS, Badar Seri Iskandar, Tronoh, Perak, Malaysia
Received 25 April 2012; received in revised form 30 January 2013; accepted 09 February 2013
Abstract: This study was conducted to investigate the removal of COD, BOD, turbidity and colour from leachate using vertical upflow filtration technique. Limestone media with a density of 2554 kg/m3 was crushed and graded in sizes of 48 mm, 812 mm and 1218 mm. Trial runs were done before the main experiment at an interval of 24 h analysis. Leachate was between pH 7.94 to 8.12 before experiments but increased to pH 8.42 after the filtration process. Maximum headloss at steady flow rate 20mL/min was 0.5 cm. The optimum treatment was achieved with 4–8 mm, 8–12 mm & 12–18 mm media size in combination and removal efficiency was 22 to 81%, 22 to 75%, 32 to 86%, and 36 to 62% for BOD, COD, turbidity and colour, respectively. Vertical upflow roughing filter can be used for pre-treatment of leachate before further treatment.
Keywords: Limestone; vertical upflow roughing Filter; leachate; landfill.
© 2013 Journal of Urban and Environmental Engineering (JUEE). All rights reserved.
Correspondence to: Augustine C. Affam, Tel: +60103849701. E-mail: [email protected]
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INTRODUCTION chemicals. Roughing filters mainly act as physical filters and reduce the solid mass. However, the large A leachate stream can be compared to a complex filter surface area available for sedimentation and wastewater stream with varying characteristics not only relatively small filtration rates also supports adsorption because of the different kinds of waste present, but also as well as chemical and biological processes (Nkwonta, varying according to the landfill age (Onay & Pohland, 2010). Roughing filters consist of differently sized filter 1998). The leakage of leachate from landfill which media decreasing successively in the direction of flow. contains high organic, inorganic, suspended solids, Most of the solids are separated by the coarse filter heavy metals and other pollutants can contaminate the media near the filter inlet, with additional removal by ground water and surface water sources (Qasim & the fine granular media in subsequent compartments. Chiang, 1994). The high level of chemical oxygen Minitab is a statistical package having a suite demand (COD), biochemical oxygen demand (BOD), of computer programs that are specialised for statistical turbidity, colour and other impurity components of analysis. It enables data to be processed to obtain results landfill leachate make it very important to devise of standard statistical procedures and statistical appropriate treatment methods. significance tests, without requiring low-level numerical Leachate used in this research was collected from programming. Most statistical packages also provide Pulau Burung Landfill Site (PBLS) which is situated in facilities for data management (Quentin, 2010). Penang, Malaysia. PBLS has a semi-aerobic system and Limestone is a sedimentary rock, which is primarily it is one of the only three sites of its kind found in composed of the mineral calcium carbonate (CaCO ). Malaysia. PBSL has been developed semi-aerobically 3 As a result of the effectiveness of limestone in various into a sanitary landfill Level II by establishing a treatment processes, it has been used for removal of controlled tipping technique in 1991. It was further contaminants from leachate. Sun (2004) reported 100% upgraded to a sanitary landfill Level III employing removal of iron from leachate in 150 min during batch controlled tipping with leachate recirculation in 2001. It experiments in which limestone was used as a filter has been found that the leachate from a semi-aerobic medium to treat an iron acid solution (27.9 mg iron/L). system has slightly lower organic contaminants Aziz et al. (2004) reported 90% removal of iron by compared with an anaerobic landfill in terms of BOD limestone filter from landfill leachate containing 19.5 and COD (Aziz et al., 2001). This site receives 1500 mg/L iron. The concentration of iron remaining in tons of solid waste daily. Table 1 gives the composition solution was 0.1 mg/L which was lower than the of the leachate. standard guidelines of 0.3 mg/L for the protection of There are many different landfill leachate treatment aquatic life. A literature review indicated that limestone options. These include complex and expensive methods is capable of removing 90% of heavy metals such as Cu, from physico-chemical to biological processes for the Zn, Cd, Pb, Ni, Cr, Fe and Mn through a batch process treatment of high strength organics and inorganics. and filtration technique (Aziz et al., 2004). In another These could result in large costs on the long term. research work, Smith et al. (1994) used limestone filter Alternative methods are continually sought to minimize to treat contaminated groundwater containing iron with expenses on leachate treatment (Tchobanoglous et al., concentration of 5 mg/L and reported a final 2003). concentration of 0.2 mg/L. The limestone and the Roughing filtration can be considered as a major pre- limestone/sandstone filters successfully removed an treatment process for wastewater and surface water, average minimum of 97.60% of the iron from solution since the process efficiently separates fine solid on a daily basis. Treatment of landfill leachate under particles over prolonged periods without addition of aerobic batch conditions containing 6.6 mg/L iron and
Table 1. Composition of Leachate from Pulau Burung Landfill Site 1.8 mg/L manganese were also investigated (Ghaly et al., 2007). It was observed that, the removal of Parameters Range of Values, mg/L manganese from solution was not as efficient as iron BOD5 481120 removal. In a related work, Xu et al. (1997) conducted COD 15333600 batch experiments using calcite and quartz grains as Suspended Solid 1591220 filter media and reported iron removal of 99.8% from pH value (no unit) 7.89.4 the acid mine. Adlan et al. (2008) evaluated the Zinc 0.11.8 removals of turbidity, suspended solids, BOD and Manganese 0.6–1.1 coliform organisms from wastewater using different Iron 0.32–7.5 sizes of limestone roughing filter. Results indicated that Copper 0.1–0.4 removal efficiencies depended on the size of the filter Cadmium, < 0.04 Colour, Pt.Co units 2430–8180 medium and applied flow rates. Turbidity, suspended Source: Aziz et al. (2006). solids, BOD and coliform organism removals were
Journal of Urban and Environmental Engineering (JUEE), v.7, n.1, p.117-125, 2013 Affam and Adlan 119 between 75 and 92%, 79 and 88%, 51 and 67%, and 67 and colour were analyzed using DR/2800 Hach and 96%, respectively, with particle sizes between 1.91 Spectrophotometer, method 8000 and 8025 and 16.28 mm. respectively. BOD was analyzed using standard The roughing filter principle has also been used for methods (APHA, 1992 and APHA, 1998) Method the pre-treatment of water before supply to 5210B for wastewater analysis. The pH was measured communities. Table 2 gives a summary as reported by by pH meter (CyberScan 20) while turbidity was various researchers. measured using 2020 Turbidimeter (LaMotte). Analysis There is no report on the use of vertical upflow of variance (ANOVA) and Boxplot was performed roughing filter for pre-treatment of leachate. In this using MINITAB Release 14.0 version. study, limestone being a low cost material is used as Experiments were conducted using both single and filter media in the filtration process for the treatment of combination of media sizes packed in the column. This leachate. The objective of this research was to evaluate provided the opportunity to evaluate simultaneously the limestone as filter media for the pre-treatment and filter performance for the combination of media sizes polishing of leachate and to examine the performance of and hydraulic loading rate over a constant filter length. the upflow vertical roughing filter for the removal of The three media size ranges (48 mm, 812 mm, COD, BOD, turbidity and colour from leachate. and 1218 mm) were used to assess the influence of flow rate, pore size and media density on BOD, COD, MATERIALS AND METHODS colour and turbidity removal efficiency. Filter media size were stacked in decreasing size from bottom Leachate used in this research was collected from Pulau towards the top for all experiments. The media was Burung Landfill Site (PBLS), transported and stored at washed with 20 liters of dilution water before leachate 4˚C in a cold room since weekly sampling was adopted. was passed through the column. Five hydraulic loading Limestone samples used in this study were obtained rates (100 mL/min, 80 mL/min, 60 mL/min, 40 mL/min from the quarry industry located at Ipoh, Malaysia. The and 20 mL/min) were initially assessed in this study to limestone chips composed of 95.5% CaCO3, 3.0% determine the influence of interstitial fluid velocity on MgCO3 and 1.5% impurities (Aziz et al., 2006). They removal efficiency of the various parameters. A were crushed and graded into sizes (1218 mm, peristaltic pressure pump was used to generate the 812 mm and 48 mm) using motorized sieves. COD pressure for flow of the leachate from the residual tank through the vertical upflow roughing filter. The Table 2. Performance of Roughing Filter capacity of the peristaltic pump was 0 to 2000 mL/min. Mean Filtration Three collection and monitoring ports at (300 mm, 600 Percentage Reference Rates Parameters mm and 900 mm) were provided on the filter length. Removed (m/h) (%) Sampling was done after every 24 h and filtered Pacini ( 2005) 1.20 Iron & 85 & 95 through a 0.45 μm membrane filter. Analysis for BOD, Manganese COD, colour and turbidity removal was then conducted. For each of the flow rates, a new set of Dome (2000) 0.3 Algae & 95 & 90 media was packed in the filter bed. There were four turbidity phases in the experiment to ensure that data obtained Mahyi (2004) 1.5 Turbidity 90 were consistent as shown in Table 3. Figure 1 describes the sectional diagram of the filter column used. A detail of the characteristics of the filter Ochieng and 0.75 Turbidity & 90 & 95 column unit is as shown in Table 4. Otieno (2004) algae The formula applied to calculate the percentage of
COD, BOD, colour and turbidity removal efficiency is 63.4, 89 Dastania 1.8 Turbidity, TSS & 94 as per Eq. 1. ( 2007) &
CC fi Jayalath(1994) 1.5 Coliforms 50 & 80 P 100* (1) Colour & Ci Turbidity Rabindra(2008) 1.0 TSS & 95 & 95 where, P = percentage removal of impurity (%), Ci= Turbidity initial concentration of impurity (mg/L or Pt-Co), and C = final Concentration of impurity (mg/L or Pt-Co). Mukhopadhay 0.75 Turbidity 75 f (2008)
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Table 3. Experimental Phases and media packing in the vertical test Table 4. Characteristics and operational parameters of the column column experiment Flow Media Size Dilution Duration Sampling Parameter Data Unit Rate (mm) (days) & Flow rate 20 mL/min (mL/min) Phase 1 Analysis Column Height 1500 mm (hour) Internal Diameter 100 No 1 24 Surface area of 200 mm 1218,812 Column & 2 48 Column material 314 cm No 1 24 Perpex ״ 80 Total bed Vol. plastic No 1 24 *net ״ 60 3 Particle size 28260 cm No 1 24 12-18, 8-12 ״ 40 Limestone density & 4-8 mm No 1 24 Retention time ״ 20 Phase 2 Contact time 2554 kg/m3
Filtration rate 31.4 hours 1218,812 50:50 24 & Water: Mode of flow 24 hours 48 0.2 m/hr Phase 3 Leachate upflow
20 10 24 1218,812 & No 48 RESULTS AND DISCUSSION 1218 10 24 ״ No ״ 12 18 & Quality of raw leachate 10 24 48 No 10 24 ״ 812 No 10 24 Initial analysis of the raw leachate sample collected is ״ 48 No shown in Table 5. The characteristics are representative Phase 4
of the methane fermentation phase. This phase is 50 usually characterized by microorganisms, which 1218, 10 24 812 No converts the acetic acid and hydrogen gas formed by the & 48 acid formers in the acid phase to methane (CH4) and
CO2, which become more predominant. Both methane and acid fermentation proceed simultaneously, but the rate of acid fermentation is considerably reduced compared to the former. Because the acids and the hydrogen gas produced by the acid formers have been converted to CH4 and CO2, the pH within the landfill will rise to more neutral values in the range of 6.8 to 8. In turn, the pH of the leachate will rise, and the concentration of BOD5, COD and conductivity value of the leachate will be reduced. With higher pH values, fewer inorganic constituents are solubilized; as a result, the concentration of heavy metals present in the leachate will also be reduced (Tchobanoglous & Kreith, 2003).
Table 5. Raw Leachate Quality Unit Reading Aziz et. al Parameter (2006) COD mg/L 2100-2530 1533-3600 BOD mg/L 271-370 48- 1120 pH 7.94-8.12 7.8-9.4 Turbidity NTU 226-274 50-450 Colour Pt-Co 3310-3920 2430-8180 Fig. 1 Sectional Diagram of Vertical Upflow Roughing Filter. Column for the Study (Geometric Similarity; 1:3). Source: Wegelin, Weekly observation for three months period. 1996.
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Performance of various media sizes
The removal efficiency of the limestone media (12–18 mm, 812 mm & 48 mm) in combination during the trial runs is shown in Fig. 2. Each flow rate was experimented for 24 h using different set of limestone each day. The best removal was observed at 20 mL/min. It shows that BOD, COD, colour and turbidity were removed 23%, 22%, 38% and 30% respectively. Hence, it was used for the subsequent experiments performed in phase three. Fig. 4 Graph of (12–18 mm, 812 mm & 4–8 mm) removal The removal efficiencies when 50 mL/min flow efficiency (%) of various parameters versus days at 20 mL/min. rate was applied to media 12–18 mm, 8–12 mm & 4–8 mm size is as shown in Fig. 3. It indicates The limestone media 12–18 mm, 812mm & 4– removal in the range of 7% to 18%, 32% to 40%, 8 mm sizes was experimented using a 50:50 20% to 63% and 28% to 40% for BOD, COD, (leachate:water) dilution. It indicated removal of BOD , turbidity and colour respectively. The limestone COD, turbidity and colour of 46% to 68% , 27% to media experienced a breakthrough except for 46%, 58% to 82% and 60% to 70% respectively. turbidity. Adsorption is the major process for removal of soluble organics such as COD from leachate especially when The BOD,COD, turbidity and colour removal by the using columns in batch processes (Christensen et al., 12–18 mm 8–12 mm and 4–8 mm media combination is 2001). This process involves adsorption of the illustrated in Fig. 4. It indicates BOD removal of 22% to contaminants by the microporous calcium carbonate 81% , COD removal of 22% to 75%, turbidity removal (limestone) used as filtration media into their sites. In a of was 32% to 86% and colour removal of 36% to 62%. study, analysis of the limestone media after filtration Except for turbidity, a decline in removal of the other indicated that adsorption and absorption processes were parameters was observed after the sixth day owing to among the mechanisms involved in removal of organics the optimum adsorption reached. (Christensen et al., 2001). The low removal of COD
was probably due to reduction in the concentration of the adsorbate molecules of the leachate onto the limestone media sites (i.e. the molecules being accumulated on the surface and sites of the adsorbent). Figure 5 illustrates limestone media 12–18 mm size removal efficiency. BOD removal was 22% to 41%, COD removal was 9% to 27%, turbidity removal was 62% to 66% and colour removal was 33% to 56%. Low removal in BOD and COD can be attributed to large media size which resulted in reduced specific surface area of the media adsorption.
Fig. 2 Graph of trial run removal efficiency (%) various parameters Figure 6 shows the pattern of removal that occured versus flow rates. in the 12–18 mm & 4–8 mm, media. In the experiment, BOD removal was 34% to 60% , COD removal was 19% to 54%, turbidity removal was 32% to 86% and colour removal was 35% to 52%. After the seventh day, the media was fully adsorbed and hence showed reduction in its removal capacity except for turbidity. The percentage removal for 8–12 mm size media was 14% to 61% , 32% to 62%, 17% to 83% and 34% to 61% for BOD,COD,turbidity and colour respectively. Breakthrough was experienced in all the parameters
Fig. 3 Graph of (1218 mm, 812 & 48 mm) removal efficiency (%) of various parameters versus days at 50 mL/min.
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Table 6. One-Way ANOVA summary for phase 2, 3 & 4 experiments Media size Flow rate P value Phase (mm) (mL/min)
1218,812 50 0.016 4 & 48
1218,812 20 0.011 3 & 48
1218,812 @50% 20 0.090 2 dilution & 48 Fig. 5 Graph of (1218 mm) removal efficiency (%) of various parameters versus days at 20 mL/min.
12–18 20 0.043 3
20 0.082 3 1218 &
48 20 0.317 3
812 20 0.094 3
48
Smaller grain sizes have larger adsorption area and perform better in treatment processes (Tamar, 2008; Fig. 6 Graph of (12–18 mm & 4–8 mm) removal efficiency (%) of Wegelin, 1996). In this experiment, the specific surface various parameters versus days at 20 mL/min. area and particle size arrangement for limestone media 12–18 mm, 812 mm & 4–8 mm were sufficient to except in turbidity which was however not very reduce turbidity of the leachate. pronounced on the tenth day of the experiment. The 8–12 mm media size (graph not shown) had Effect of flow rate on turbidity removal BOD removal of 6% to 23%, COD removal of 24% to
42%, turbidity removal of 18% to 37% and colour was The higher pilot flow rates strongly affected the 39% to 45%. Flow continued until media pores were resultant effluent turbidity values because the main blocked at end of the fifth day causing experiments to mechanism for removing turbidity is filtration. The terminate. higher the flow rate, the less time a particle has to travel One-way ANOVA analysis performed on the the settling distance and stick onto the media’s surface experimental data is shown in Table 6. The P column and layers or be adsorbed. Higher flow rates would have indicates the significance level: a P-value less than 0.05 been desirable if they produced greater quantities of indicate that the variable (factor) is significant to a level treated leachate with better removal efficiency. of 95.0%. The p- value of the media size was p = 0.317 Results obtained from the roughing filtration for > 0.05. This affirms that media 812 mm size was not treatment of water, (Nkwonta & Ochieng, 2009) and significant for the pre-treatment of the leachate. In Muhammad et al. (1996) show that flow rates when several other figures not included in this work, box plots lower will remove turbidity more effectively. However, were also performed to indicate which observations, Wegelin (1996) upholds that pressure drop will be a might be considered outliers in the distribution setback for such filtration unit. With this in mind, efficiency. operational flow rate for a desired turbidity to be achieved was considered and implemented. TURBIDITY REMOVAL COD AND BOD REMOVAL Effect of filter media size on turbidity removal Effect of filter media size on COD and BOD removal The most important factor enhancing turbidity removal with respect to filter media size is the reduced pore Biological “ripening” of filter media may improve spaces between the grains of the media in the filter bed. particle removal efficiency in roughing filters due to
Journal of Urban and Environmental Engineering (JUEE), v.7, n.1, p.117-125, 2013 Affam and Adlan 123 increased stickiness of filter media (Collins et al., Effect of filter media size on colour removal 1994). Exposure of the media to sunlight was avoided to minimize potential errors which can be introduced by The removal of dissolved colour or true colour by biological activity into the column. To evaluate the varying filter media size in roughing filtration has not potential in removal of BOD and COD, the experiment been properly documented. Since, colour is related to was non-recycle and upon final use of the media it was humic substances, it is expected that true colour exists observed to be very sticky by means of touching. In in relatively stable suspension and it is more difficult to addition, media 48 mm, 812 mm and 1218 mm size remove. Collins et al. (1994) reported that removal of had a higher removal as against 812 mm, 48 mm true colour in roughing filters compares favourably to alone and other combinations. This could be as a result that achieved by slow sand filtration. Wegelin (1996) of increased surface area and hence adsorption sites. observed true colour removal in the range of 20 to 50 %. This could be similar to Wegelin (1996) slow sand There has been numerous reports of removal of apparent filtration experiments where removal of pathogens was colour, which is the colour attributed to undissolved by the sedimentation or deposition and effective settling particulate matter. Wolters et al. (1989) and Barret of particles on the grains of the media. Thus, COD and (1989) both found removal of apparent colour to be 45 BOD5 are possible to be reduced from leachate by to 80 %. In this study, the optimum true colour removal limestone media. was 62% using the media 12–18 mm, 812 mm & 48 mm size combination. Effect of flow rate on COD and BOD removal Length of run time on removal efficiencies The flow rate which removed optimum COD and BOD The length of run for each set of media combination was observed to be 20ml/L. This was obvious when study was ten days. The limestone media experienced higher flow rates indicated lower removal of COD and an average breakthrough in a period of six days as found BOD. However, a more critical factor that can be from the laboratory experiments. The length of run was attributed to the low removal was the media saturation basically dependent on the performance of the media in point that must have been reached. Lower flow rate terms of its removal and adsorption capacity. In each allows an increased pathogen removal, which is study, when breakthrough was experienced the especially important in colder climates where biological experiment was terminated. activity is more time dependent (Huisman & Wood, 1974; Wegelin, 1996; Nkwonta & Ochieng, 2009). pH Change during the roughing filtration process Recent research carried out by Jenkins et al. (2009) on intermittently-operated sand filters has highlighted the During the roughing filtration treatment the pH showed importance of sand size and hydraulic loading both of a little variation. The raw leachate sample was between which directly affect microbiological removal. pH 7.94 and pH 8.12 but increased to pH 8.42 after However, it is possible to increase the filtration rate if filtration. This is due to the presence of CO in effective pretreatment has been given and if an effective 3 limestone (Aziz et al., 2004) an unstable oxide of disinfection stage follows after filtration (Ellis, 1987). carbon and declined as removal efficiency reduced. The dissolution of calcium carbonate can increase the COLOUR REMOVAL concentration of alkalinity. Effect of flow rate on colour removal Headloss during length of run time
A report observed that colour removal was poor when The headloss was also considered in this study. higher filtration rates were applied in continually- Although, the main essence of conducting the research operated sand filters, although the filtrate quality was to ascertain the effectiveness of the limestone remained reasonably good (Muhammad et al., 1996). In media in pre-treatment of leachate, a documentary of this study, it was justified and reasonable to apply lower the headloss during each run time for every media flow rates for optimum removal to be obtained. The combination was randomly done. To affirm the limestone media was not capable of removing the colour postulation by Boller & Kavanaugh (1995) which from the leachate. It would therefore require a chemical demonstrated that the rate of headloss build-up in a or biological treatment for effective removal of colour. granular media filter, for a constant mass of solids being
removed, is strongly dependent on the size of the particulates in suspension and the size of the granular media. In addition, the principal cause of the rapid
Journal of Urban and Environmental Engineering (JUEE), v.7, n.1, p.117-125, 2013 Affam and Adlan 124 increase in headloss observed for smaller particles in Aziz, H.A., Othman, N., Yusuff, M.S., Basri, D.R.H., Asaari, many filtration studies is due to the nature of the F.A.H., Adlan, M.N., Othman, F., Johari, M., Perwira, M. (2001) Removal of copper from water using limestone filtration aggregation or deposition process inside the pore spaces technique-determination of mechanism of removal. Environment of the porous media. Observations during this International 26, 395–399. experiment indicated that maximum headloss was 0.5 Barrett, J.M. (1989) Improvement of slow sand filtration of warm cm at 20 mL/min flow rate. According to Amin & Aziz water by using coarse sand. Ph.D Thesis, University of Colorado, USA. (2002), negative heads do not occur in the upflow Boller, M.A., Kavanaugh, M.C. (1995) Particle characteristics and vertical roughing filter bed, however a crack occurs at headloss increase in granular media filtration. Water the bottom layers of filter bed, when headloss reaches Research, Vol. 29, Issue 4, 1139-1149. maximum. It is noteworthy that, during the filtration Boller, M. (1993) Filter mechanisms in roughing filters. Journal of treatment process for media 4–8 mm size, there was an Water Supply Research and Technology - Aqua, Vol. 42, 174- 185. entire blockage and flow stopped abruptly. Collins, M.R., Westersund C., Cole J., Roccaro J. (1994) Evaluation of roughing filtration design variables. AWWARF and AWWA, Denver, USA. 77- 88. CONCLUSION Cooney, D.O. (1999) Adsorption design for wastewater treatment. CRC Press LLC, Florida, USA. Ellis, K.V. (1987) Slow sand filtration as a technique for the tertiary The optimum removal efficiency of BOD, treatment of municipal sewages. Water Research, Vol. 21, 403- COD, colour and turbidity using the limestone 410 media in the vertical upflow roughing filter Galvis, G., Visscher, J.T., Latorre J. (1998) Multi-stage filtration and stacked with 1218 mm, 812 mm and 48 mm innovation water treatment technology. International reference centre for community water supply and sanitation, The Hague, size from bottom towards the top of the column Netherlands and Universidad del valle instituto Cinara, Cali, at 20 mL/min and with no dilution of leachate Colombia. was 81%, 75%, 62% and 86%, respectively. Ghaly, A.E., Kamal, M.A., Mahmoud, N.S., Cote. R. (2007) During the 50:50 water-leachate dilutions, Treatment of landfill leachate using limestone/sandstone filters under aerobic batch conditions. American Journal of colour removal was 70 %. Environmental Sciences 3 (2), 43-53. Huisman, L., Wood, W.E. (1974) Slow sand filtration. W.H.O. Increasing filtration rate and reducing contact Geneva, Switzerland. 44. time simultaneously reduced adsorption and Jenkins, M.W., Tiwari, S.K., Darby, J., Nyakash, D., Saenyi, W., Langenbach, K. (2009) The biosand filter for improved drinking hence removal efficiency. water quality in high risk communities in the Njoro watershed, Kenya. Research brief, SUMAWA, Global livestock The vertical upflow roughing filter can be used collaborative research support program. University of California, for pre-treatment or polishing of leachate before Davis, USA. Mohd .N.A., Aziz H.A., Maung H.T., Hung. Y. (2008) Performance further biological treatment. of horizontal flow roughing filter using limestone media for the removal of turbidity, suspended solids, biochemical oxygen demand and coliform organisms from wastewater, International Acknowledgement The authors are thankful to the Journal of Environment and Waste Management, Vol. 2, No.3, management of the Universiti Sains Malaysia (USM) 203 – 214. Muhammad, N., Ellis K., Parr, J., Smith, M.D. (1996) Optimization for providing facilities for this research. of slow sand filtration. Reaching the unreached: challenges for the 21st century. 22nd WEDC conference New Delhi, India. 283 - 285. REFERENCES Christensen, T.H., Kdelsen, P., Bjerg, P.L., Christensen, J.B., Baun, A., Albrech, H. Biogeocemistry of landfill leachate- review. (2001) Appled Geochemistry 16, 659-718. American Public Health Association, APHA. (1998) Standard methods for examination of water and wastewater, 20th ed. Nkwonta, O.I., Ochieng, G.M. (2009) Passive treatment of mine Washington, D.C. USA. water using roughing filters as a pre-treatment option. Abstracts American Public Health Association, APHA. (1992) Standard of the international mine water conference, Cilla Taylor methods for examination of water and wastewater, 19th ed. Conference, Pretoria, South Africa. 359-365 Washington, D.C. USA. Nkwonta, O.I., Ochieng, G.M. (2009) Roughing filter for water pre- Amin, K.N., Aziz, S.Q. (2002) Pressure distribution in filter media treatment technology in developing countries: A review. in conventional filters. Journal of Dohuk University, Vol.5, No.2, International Journal of Physical Sciences, Vol. 4 (9), 455-463. 56-59. Nkwonta O. (2010) A comparison of horizontal roughing filters and Aziz, H. A., Salina A., Mohd. N. A., Faridah, Asaari A.H., Zahari, vertical roughing filters in wastewater treatment using gravel as a M.S. (2006) Colour removal from landfill leachate by filter media. International Journal of the Physical Sciences. Vol. coagulation and flocculation processes, Bioresource Technology 5(8), 1240-1247. 98, 218–220. Onay, T. T., Pohland, F.G. (1998) In situ nitrogen management in Aziz, H.A., Yusoff M.S., Mohd N.A., Adnan N.H., Salina, A. (2004) controlled bioreactor landfills. Water Resources, Vol. 32, No. 5. Physico-chemical removal of iron from semi-aerobic landfill 1383-1392. leachate by limestone filter. Waste Management 24, 353–358.
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Oasim, S.R., Chiang, W. (1994) Sanitary landfill leachate- Tchobanoglous, G., Franklin, B.H., Stensel, D. (2003) Wastewater generation, control and treatment Technomic Publishing Co. Inc. engineering: Treatment and reuse, fourth edition. Texas, USA. Metcalf & Eddy, Inc. USA. Reinhart, D.R., Townsend T.G. (1998) Landfill bioreactor design Wegelin, M. (1996) Surface water treatment by roughing filters. A and operation, CRC Press LLC: Boca Raton, Florida. USA. Design, construction and operation manual. SANDEC report No. Smith, K.S., Plumlee, G.S., Ficklin, W.H. (1994) Predicting water 2/96. Switzerland. contamination from metal mines and mining wastes. International Wolters, H., Smet, J.E.M., Galvis, J. (1989) Pre-treatment methods land reclamation and mine drainage conference and third for community water supply. Ch.8, IRC, International water and international conference on the abatement of acidic drainage. sanitation centre, Netherlands. U.S. geological survey, report No. 94-264. Xu, C.Y., Schwartz F.W., Traina, S.J. (1997) Treatment of acid- Sun, Q. (2004) Iron and acid removal from acid mine drainage in mine water with calcite and quartz sand. Environmental open limestone systems. PhD dissertation. Retrieved from: https: Engineering Science, 14, 141-152. //etd.wvu.edu/ etd/controller.jsp?moduleName=document Quentin B., 2010. Lean six sigma and Minitab: The Complete data&jsp_etdId=1315 Toolbox Guide for All Lean Six Sigma Practitioners (3rd Ed.) Tchobanoglous, G., Kreith, F. (2003) Handbook of solid waste OPEX Resources Ltd, United Kingdom. management, second ed. McGraw-Hill Inc, New York, USA.
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Journal of Urban and Environmental Journal of Urban and E Engineering, v.7, n.1, p.126-133 Environmental Engineering ISSN 1982-3932 J E www.journal-uee.org U doi: 10.4090/juee.2013.v7n1.126133
PERFORMANCE ANALYSIS OF A HELICAL SAVONIUS ROTOR WITHOUT SHAFT AT 45° TWIST ANGLE USING CFD
Bachu Deb1 , Rajat Gupta2 and R.D. Misra3
1 Department of Mechanical Engineering, NIT Silchar, Silchar - 788010, Assam, India 2 National Institute Technology Srinagar 3 Department of Mechanical Engineering, NIT Silchar
Received 28 December 2012; received in revised form 30 January 2013; accepted 09 February 2013
Abstract: Helical Savonius rotor exhibits better performance characteristics at all the rotor angles compared to conventional Savonius rotor. However studies related to the performance measurement and flow physics of such rotor are very scarce. Keeping this in view, in this paper, a three dimensional Computational Fluid Dynamics analysis using commercial Fluent 6.2 software was done to predict the performance of a two-bucket helical Savonius rotor without shaft and with end plates in a complete cycle of rotation. A two-bucket helical Savonius rotor having height of 60 cm and diameter of 17 cm with 45° bucket twist angle was designed using Gambit. The buckets were connected at the top and bottom circular end plates, which are 1.1 times the rotor diameter. The k-ε turbulence model with second order upwind discretization scheme was adopted with standard wall condition. Power coefficients (Cp) and torque coefficients (Ct) at different tip speed ratios were evaluated at different rotor angles. From the investigation, it was observed that power coefficient increased with increase of tip speed ratio up to an optimum limit, but then decreased even further tip speed ratio was increased. Further investigation was done on the variations of Cp & Ct in a complete cycle of rotation from 0° to 360° in a step of 45° rotor corresponding to the optimum tip speed ratio. The value of Cp at all the rotor angles is positive. Moreover, velocity magnitude contours were analyzed for each rotor angle and it could be concluded that high aerodynamic torque and power can be expected when the rotor is positioned at 45º & 90º with respect to incoming flow.
Keywords: Two-bucket helical Savonius rotor; tip speed ratio; power coefficient; torque coefficient.
© 2013 Journal of Urban and Environmental Engineering (JUEE). All rights reserved.
Correspondence to: Bachu Deb. E-mail: [email protected]
Journal of Urban and Environmental Engineering (JUEE), v.7, n.1, p.126-133, 2013 Deb, Gupta and Misra 127
INTRODUCTION ranging from 5o to 60o in steps of 5o. The optimum angle of twist at which the efficiency and the output power is The Savonius vertical axis wind rotor was first maximum is evaluated. developed by S. J. Savonius in 1929 (Savonius, 1931). Biswas & Gupta (2007) conducted model tests on The design was based on the principle of Flettner’s three-bucket S-rotor, taking tunnel blockage into rotor. He used a rotor which was formed by cutting a consideration, and reported maximum power coefficient Flettner cylinder from top to bottom and then moving of 38%. Further Bhaumik & Gupta (2010) studied the two semi-cylinder surfaces sideways along the experimentally the performance of helical Savonius cutting plane so that the cross-section resembled the rotor at 45º twist angle in a centrifugal blower. They letter ‘S’. To determine the best geometry, Savonius consider the provision of different overlap ratio from tested 30 different models in the wind tunnel as well as 0.106 to 0.186.It is concluded from their result that in the open air. The best of his rotor model had 31% maximum C is obtained as 0.421 at an overlap ratio of efficiency and the maximum efficiency of the prototype p 0.147. Gupta & Deb (2011) studied the CFD analysis of in the natural wind was 37%. Bach (1031) made some a two bucket helical Savonius rotor with shaft at 45º investigations of the S-rotor and related machines. The twist angle. From their study they concluded that the highest measured efficiency was 24%. highest values of dynamic pressure and velocity McPherson (1972) reported a highest efficiency of magnitude were obtained at the chord ends with 450 33% and the maximum power coefficient obtained by bucket twist and 900 rotor angle, which would ensure Newman (1974) was only 20%. Modi et al. (1984) improved performance of the rotor as a whole by reported a power coefficient of 0.22.There had been increasing the aerodynamic torque production of the some works done as to incorporate some modifications rotor. Kamoji et al. (2008) investigates single stages in the design of blades so that Savonius rotor may be modified Savonius rotorsand concluded that at overlap quite useful for small-scale power requirements. In the ratio 0.0 blade arc angle 124º and an aspect ratio of 0.7 last few decades many researchers had worked on the has a maximum coefficient of power at a Reynolds different designs of Savonius rotor and obtained its number of 1 500 000 which is higher than conventional efficiency in the range of 15%38%. In the Savonius rotor. Continuation Grinspan et al. (2001) in this direction led Keeping this in view, a two-bucket helical savonius to the development of a new blade shape with a twist for rotor without shaft having 45° bucket twist angle was the Savonius rotor. They reported a maximum power designed. Computational fluid dynamics (CFD) analysis coefficient of 0.5. Further Saha et al. (1994) performed using fluent package was done to analyse the power experiments on twist bladed Savonius rotor made of coefficient and torque coefficient of the rotor at 45° bamboo in a low-speed wind tunnel. They showed that blade twist angle at different rotor angles. Further their model was independent of wind direction and velocity magnitude contours were analyzed to though the model produced slightly lower rotational understand the flow physics of the rotor at different speed but easy fabrication of such models made their rotor angles. design suitable for small-scale requirements. Further such design can worth hundred times better than those PHYSICAL MODEL using deflecting plates & shielding to increase efficiency, which would make the design structurally The three-dimensional model of the two-bucket helical complex. Again Saha & Rajkumar (2008) performed Savonius rotor without shaft at 45° twist angle is shown work on twist bladed metallic S-rotor and compared the in Fig. 1.The bucket are connected at the top and bottom performance with conventional semicircular blades circular end plates, which is 1.1 times the rotor having no twist. They obtain Cp of 0.14, which was diameter. There is no central shaft in between the top higher than that of the later with Cp of 0.11. The rotor and bottom plates. Both the inner edge and the outer also produced starting torque and larger rotational edge undergo a twist of 45°, a quarter pitch turn. The speeds. The analysis is done by Hussain et al. (2008) on blade retains its semi-circular cross section from the the enhancement of efficiency by modifying the blade bottom (0°) to the top (45°). The buckets were spaced configuration from straight semi circular to a twisted 180° apart and were fixed to the end plates. The semi circular one. The twist in this turbine is assumed to physical models were designed for five rotor angles be given as the bottom cross-sectional surface of the namely 0°, 45°, 90°, 135° and 180°. The height of the blades is fixed and the top cross-sectional surface is rotor (H) is 60 cm, radius of the bucket (R) is 8.5 cm, given the desired twist with respect to the bottom fixed and diameter of the shaft (d) is 3.5 cm. surface. Wind flow analysis is done over each configuration of the rotor with the blade twist angles
Journal of Urban and Environmental Engineering (JUEE), v.7, n.1, p.126-133, 2013 Deb, Gupta and Misra 128
computational model and their corresponding approximation and idealizations.
Continuity Equation
The conservation of mass equation or continuity equation is given by
(1)
where is the density, is the velocity vector.
Momentum Equation
Applying the Newton’s second law (force = mass × acceleration) the conservation of momentum equation is given by:
Fig. 1 Helical Savonius rotor without shaft. (2)
COMPUTATIONAL MODEL where is the density, is the velocity vector, is
Computational Mesh the static pressure, and is the stress tensor.
Turbulence Model Three-dimensional tetrahedral mesh around the rotor was developed in the computational modeling of the rotor. In this study Standard k-ε turbulence model has been used with logarithmic surface function in the analysis of
Boundary conditions turbulent flow (FLUENT, 2005). Momentum equation, x, y and z components of velocity, turbulent kinetic At the inlet of the computation zone, uniform velocity energy (k) and dissipation rate of turbulent kinetic energy (ε) have each been solved with the use of the distribution is set according to the rated design parameters. The outlets are all set to be pressure outlet program. All these equations have been made by using where local atmospheric pressure condition is fulfilled. the iteration method in such a way as to provide each equation in the central point of the cells, and secondary Rotor wall roughness is defined and no slip condition is set at all solid walls. interpolation method with a high reliability level has been employed. In the present study, the standard k-ε Table 1: Solution specifications and controls turbulence model with standard wall condition was Inlet : Velocity Inlet used. The standard k– ε equations can be represented as: Sides : Symmetry
Boundary condition Bucket : Wall Outlet : Pressure Outlet kkui Turbulence level: ±1% txij x (3) t k Mathematical Formulation GYkM kjx Mathematical model can be defined as the combination of dependent and independent variables and relative parameters in the form of a set of differential equations which defines and governs the physical phenomenon. In the following subsections differential form of the governing equation are provided according to the
Journal of Urban and Environmental Engineering (JUEE), v.7, n.1, p.126-133, 2013 Deb, Gupta and Misra 129
t ui tx x x ij j (4) 2 CGC12k kk
Fig. 2 Computation sections in the 3-D flow field.
In these equations, Gk represents the generation of 1122 turbulence kinetic energy due to the mean velocity TFRAVCRAVCDTTT (6) gradients. Y represents the contribution of the 24 M fluctuating dilatation in compressible turbulence to the 2 NT overall dissipation rate. and are constants. PTrotor (7) and are the turbulent Prandtl numbers for k and ε , 60 1 respectively. and are user-defined source terms. P AV 3 (8) max 2 Computational Zone Protor CP (9) P A cuboid is applied as the three-dimensional max computation body in which the rotor is enclosed. The model is cut through or sectioned by a plane at the Variation of power coefficient at different rotor centre. Section 1 shows that plane is cut at the centre angle along the rotor axis i.e. at x = 1, y = 0 & z = 0 similarly section 2 shows that the plane is perpendicular to the Figures 3a−3e show below the maximum coefficient of rotor axis i.e. x = 0, y = 1 & z = 0. For contour analysis, power at different tip speed ratios (λ) whereas Fig. 3f the data on sections 2 are processed and displayed. shows the variation of coefficient of power in a complete cycle of rotation. Tip speed ratio is defined as RESULTS AND DISCUSSION the ratio of blade tip speed over undisturbed wind speed. At 0° rotor angle, the maximum power coefficient is After the convergence of the solution, the power co- 0.0709 at a TSR of 1.636 which is shown in Fig 3.1. efficient (Cp) values are calculated for each value of From Fig 3.2, it is seen that for 45° rotor angle, the input air velocity, rotor rotational speed and position of maximum Cp is 0.462 at a TSR of 1.636. From Fig 3.3, bucket at different rotor angle and tip speed ratio (λ). it is seen that for 90°rotor angle, the maximum Cp is Following are the equation used to get the power around 0.2012 at a TSR of 1.636. At 135°rotor angle, coefficient and torque coefficient. the maximum Cp is 0.0080 at a TSR of 0.589 which is shown in Fig 3.4. From Fig 3.5, it is seen that for 180° udN rotor angle, the maximum Cp is around 0.073 at a TSR (5) of 1.636. From the figure it was observed that the vV60 free maximum Cp of 0.4622 occurred at 45º rotor angle at a maximum TSR of 1.636. Further At maximum TSR of
Journal of Urban and Environmental Engineering (JUEE), v.7, n.1, p.126-133, 2013 Deb, Gupta and Misra 130
1.636 the variation the power coefficient at different from Fig 8 that high power coefficients are obtained at rotor angle in a complete cycle of rotation from 0° to 45º, 90º, 225º and 270º rotor angles, which is 315° in a step of 45° as shown in Fig 3.6. Thus it is seen responsible for maximum performance of the rotor.
Tip Speed Ratio Tip Speed Ratio Tip Speed Ratio
Tip Speed Ratio Tip Speed Ratio Rotor Angle Fig. 3 (a) Variation of Cp at 0° rotor angle with TSR, (b) Variation of Cp at 45° rotor angle with TSR, (c) Variation of Cp at 90° rotor angle with TSR, (d) Variation of Cp at 135° rotor angle with TSR, (e) Variation of Cp at 180° rotor angle with TSR, and (f) Variation of Cp at complete cycle of rotation at maximum TSR=1.636.
Tip Speed Ratio Tip Speed Ratio
Tip Speed Ratio Tip Speed Ratio Tip Speed Ratio Fig. 4 (a) Variation of Ct at 0° rotor angle with TSR, (b) Variation of Ct at 45° rotor angle with TSR, (c) Variation of Ct at 90° rotor angle with TSR, (d) Variation of Ct at 135° rotor angle with TSR, and (e) Variation of Ct at 180° rotor angle with TSR.
Variation of torque coefficient at different rotor maximum Ct is 0.282 at a TSR of 1.636. From Fig 4.3, it angle is seen that for 90° rotor angle, the maximum Ct is around 0.2012 at a TSR of 1.636. At 135° rotor angle, At 0° rotor angle, the maximum torque coefficient (Ct) the maximum Ct is 0.0136 at a TSR of 0.589 which is is 0.0644 at a TSR of 0.981 which is shown in Fig 4.1. shown in Fig 4.4. From Fig 4.5, it is seen that for 180° From Fig 4.2, it is seen that for 45° rotor angle, the rotor angle, the maximum Ct is around 0.0446 at a TSR
Journal of Urban and Environmental Engineering (JUEE), v.7, n.1, p.126-133, 2013 Deb, Gupta and Misra 131 of 1.636. From the figure it is observed that the maximum Ct of 0.282 is obtained at 45° rotor angle at an optimum TSR of 1.636.
Fig. 5 Sweep surface at centre X=0, Y=1, Z=0
Contour Plot Analysis of helical Savonius rotor without shaft Fig. 6a. Velocity magnitude contour at 0° rotor.
The contour plots helps to visualize the flow pattern of the fluid in the rotor in an isoplane surface. The isoplane surface is selected at the centre of the rotor at X=0, Y=1, Z=0 as shown in Fig. 5. The contours of velocity magnitude were obtained for five rotor angles namely 0°, 45°, 90°, 135° & 180°. The velocity magnitude contours show that, for all rotor angles, the velocity decreases from the upstream side to the downstream side of the advancing blade. Fig. 6a−6e show that velocity magnitudes at the twisted end of the chord increase from 9.64 m/sec for 0° rotor angle to 11.3 m/sec for 45° rotor angle through 11.7 m/sec for 90° rotor angle and then decreases to 11.2 m/sec for 135° rotor angle and finally to 9.6 m/sec for 180° rotor angle. High concentration of velocity distribution occurs Fig. 6b. Velocity magnitude contour at 45° rotor. near the chord ends which means high aerodynamic torque production by the rotor. Therefore the helical Savonius rotor without shaft at 45° & 90° rotor angle would be responsible for improved performance of the rotor as a whole during its power stroke in the clockwise direction by increasing the aerodynamic torque production of the rotor.
Fig. 6c. Velocity magnitude contour at 90° rotor.
Journal of Urban and Environmental Engineering (JUEE), v.7, n.1, p.126-133, 2013 Deb, Gupta and Misra 132
2. For two bucket helical Savonius rotor without shaft, the maximum power coefficient obtained is 0.462 for 45° rotor angle at a TSR of 1.636.
3. It can be concluded from the contour analysis that the maximum change in concentration of velocity magnitude is from 11.3 m/sec at 45º rotor angle through 11.7 m/sec for 900 rotor angle and 11.2 m/sec for 135° rotor angle. Thus, helical Savonius rotor without shaft at 45º & 90° rotor angle would be reponsible for improved performance of the rotor as a whole during its power stroke in the clockwise direction by increasing the aerodynamic torque production of the rotor.
NOMENCLATURE
Fig. 6d. Velocity magnitude contour at 135° rotor. D Overall rotor diameter ρ Density d Bucket diameter of the rotor r Bucket radius h Height of the Savonius rotor µ Viscosity µt Turbulent viscosity e Overlap A Swept area T Torque u Blade rotational speed Protor Power of the rotor Pmax Maximum wind power ω Angular velocity Cp Power coefficient λ Tip speed ratio
REFERENCES
Bach, G. (1931). Investigation concerning S-rotor & related
Fig. 6e. Velocity magnitude contour at 180° rotor. machines. Translated into English by Brace Research Institute, Quebec, Canada Bhaumik, T, Gupta. R (2010) Performance measurement of a two CONCLUSIONS bladed helical Savonius rotor. Proc. 37th International & 4th National Conference on Fluid Mechanics and Fluid Power In this paper, a three dimensional Computational Fluid FMFP2010 December 16-18, 2010, IIT Madras, Chennai, India. Dynamics analysis using commercial Fluent 6.2 Biswas, A., Gupta, R., Sharma, K.K. (2007) Experimental investigation of overlap and Blockage effects on Three-Buckets software was done to predict the performance of a two- Savonius Rotors. Journal of Wind Energy 31(5), 363-368. bucket helical Savonius rotor without shaft and with end Biswas, A., Gupta, R., Sharma, K.K. (2007). Experimental plates in a complete cycle of rotation. From the study, Investigation of Overlap and Blockage Effects on Three-Bucket the following conclusions are summarized: Savonius Rotors, Wind Engineering 31(5), 363–368. FLUENT Inc. Fluent 6.0 documentation: user’s guide, 2005. Grinspan, A.S., Kumar, P.S., Mahanta, P, Saha, U.K., Rao, D.V.R., 1. The power and torque coefficients obtained at all the Bhanu, G.V. (2001). Design, development & testing of Savonius rotor angles are positive. Thus, at all rotor angles wind turbine rotor with twisted blades. Proc. of 28th National helical Savonius rotor without shaft produces positive Conference on Fluid Mechanics and Fluid Power, Chandigarh, power. Also significant rise in power and torque Dec 13-15, 428-431. Gupta, R., Deb, B. (2011) CFD analysis of a two-bucket helical coefficient occurs at 45º, 90º, 225º and 270º rotor Savonius rotor with shaft at 45° twist angle. Sharjah International angle. This might be due to favorable pressure Symposium of Nuclear and Renewable Energies for 21st Century gradient across the blades between the end plates.
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(SHJ-NRE11), April 3-5, 2011, College of Sciences, University of Sharjah UAE. Hussain, M., Nawazish, M.S., Ram, R.P. (2008) CFD analysis of low speed vertical axis wind turbine with twisted blades. International Journal of Applied Engineering Research 3(1), 25- 35. Kamoji, M.A., Kedare, S.B., Prabhu, S.V. (2008) Experimental investigation on single stage, two stage and three stage conventional Savonius rotor. International journal of energy research, 32:877-895. Khan, M.H. (1975). Improvement of Savonius Rotor-windmill. M.S. Thesis, University of the Phillipines, Lasbonas. Macpherson, R.B. (1972). Design, development & testing of low head high efficiency kinetic energy machine- An alternative for the future. University of Massachusetts, Amhest. Modi, V.J, Roth, N.J, Fernando, M.S. (1984). Optimal configuration studies and prototype design of a wind energy operated irrigation system. Journal of Wind Engineering and Industrial Aerodynamics, 16(1), 85-96. Newman, B.G. (1974). Measurements on a Savonius rotor with variable air gap. McGill University, Canada. Saha, U.K., Rajkumar M. (2008) Jaya On the performance analysis of Savonius rotor with twisted blades. Journal of Wind Engineering and Industrial Aerodynamics, 96(8-9), 1359-1375. Saha, U.K.; Mahanta, P.; Grispan, A.S. (1994) Twisted bamboo bladed rotor for Savonius wind turbines”. Journal of Solar Energy Society of India, 14(2): 100-110. Savonius, S.J. (1931). The S-rotor and its applications, Mech. Engg., 53(3), 333-338. Sharma, K.K., Gupta, R., Singh, S.K., Singh, S.R. (2005) Experimental investigation of the characteristics of a Savonius wind turbine. Wind Engineering, 29(1), 77-82.
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Journal of Urban and Environmental Journal of Urban and E Engineering, v.7, n.1, p.134-142 Environmental Engineering ISSN 1982-3932 J E www.journal-uee.org U doi: 10.4090/juee.2013.v7n1.134142
EFFECTIVENESS OF WASTE STABILIZATION PONDS IN REMOVAL OF LINEAR ALKYL BENZENE SALFONATE (LAS)
Ahmed. M. Abdel-Rahman 1, Ahmed. A. Mohamed2, Ali. A. M. Gad2 and Mohamed Hashem2
1 M.SC. Researcher, Civil Engineering Department, Faculty of Engineering, Assiut University, Egypt. 2Associate Professor, Civil Engineering Department, Faculty of Engineering, Assiut University, Egypt.
Received 23 February 2013; received in revised form 28 March 2013; accepted 17 April 2013
Abstract: Detergents contain synthetic or organic surface active agents called surfactants, which are derived from petroleum product precursors. They have the common property of lowering the surface tensions of water thus allowing dirt or grease adhered to various articles to be washed off. Linear alkyl benzene sulfonate (LAS) is a most commonly used anionic surfactant. Discharge of raw or treated wastewater containing this chemical substance into the environment causes major public health and enviromental problems. In this study, samples were taken from raw wastewater and effluents of treatment ponds of Elzaraby waste stabilization ponds over a period of one year. The treated effluent is either discharged into surface waters or re-used in agricultural irrigation. The samples were analyzed according to the standard methods. The results obtained from the samples taken in different seasons showed that the highest overall removal efficiency of LAS was achieved in summer season (77%), and the least efficiency was observed in Winter season (55%), while the maximum overall efficiency of BOD5 was in summer (88%) and minimum efficiency was (73%) in winter season. The Dissolved oxygen concentrations along the pond series (DO) ranged from 0.18 to 4.8 mg/l.
Keywords: Waste stabilization ponds (WSPs), aniounic surfactant, Linear Alkyl Benzene Salfonate (LAS).
© 2013 Journal of Urban and Environmental Engineering (JUEE). All rights reserved.
Correspondence to: Ahmed. M. Abdel-Rahman. E-mail: [email protected]
Journal of Urban and Environmental Engineering (JUEE), v.7, n.1, p.134-142, 2013 Abdel-Rahman, Mohamed, Gad and Hashem 135
INTRODUCTION mg/l of LAS in aquatic environment can damage fish gills, cause excess mucus secretion, decrease Waste stabilization ponds (WSP) are large shallow respiration in the common goby, and damage basins enclosed by earth embankments in which swimming patterns in blue mussel larva and LAS raw wastewater is treated by entirely natural concentration of 40~60 mg/kg dry wt. of sludge processes involving both algae and bacteria (Mara. interfere with the reproduction and growth of soil 2004), WSPs are usually the most appropriate invertebrates and earthworms. Surfactants are also method for domestic and municipal wastewater responsible for causing foam in rivers and effluents treatment in developing countries, where the of treatment plants and reduction of water quality. climate is most favorable for their operation. WSPs LAS mainly show eye and skin irritation are low-cost, low-maintenance and highly efficient. potentials and damage human skin (Eagel et al., The only energy they use is direct solar energy, so 1992). Under field conditions, LAS had acute they do not need any electromechanical equipment, effect on freshwater plankton and organisms saving expenditure on electricity and more skilled including bacteria up to crustaceans (Venhuis and operation. WSPs can be classified with respect to Mehrvar, 2004). Range of LAS concentration in the types of biological activity occurring in a pond. sewage of 3~21 mg/L has been reported (Hol t and Three types are distinguished; anaerobic, Bernstein, 1992), while McAvoy et al. (1993), in facultative and maturation ponds. Usually WSPs USA, monitoring at 50 wastewater treatment system comprises a single series of the facilities in eleven states showed average LAS aforementioned three ponds types or several such levels in raw sewage ranging from 4.0 to 5.7 mg /l. series in parallel (H. Ramadan and Victor 2011). LAS levels in raw sewage from five European Environment can be affected by wastewater countries ranged from 4.0 to15.1 mg /1 (DiCorcia pollutants, such as surfactants (surface-active et al., 1994; Feijtel et al., (1995)). agents), which enter domestic wastewater treatment Physical and biological methods of sewage plants (WWTPs) through discharge into municipal treatment partially remove LAS and prevent them sewage systems, and cause major public health from reaching the natural environments. The problems. Surfactants in sewage are found as a removal efficiency of LAS depends on the method result of the use of consumer products like of treatment. Mungray and Kumar (2007) found detergents, cleaning and dish washing agents, and that removal efficiency of LAS in two WSPs in personal care products. Surfactants consisted India were 88% and 47%. A removal efficiency of mainly of four types; anionic (negatively charged LAS more than 99% has been reported by several group), nonionic (uncharged group), cationic researchers for activated sludge process ASP. In (positively charged group) and amphoteric case of up-flow anaerobic sludge blanket (UASB), (positive and negative charged group) (Tsz. K. K, the removal efficiency of LAS was found to be 2011). According to the data reported by 30%, while in trickling filter based STPs, total Comite´Europe´en des Agents de Surface et de removals were found to be lower and more variable leurs Intermediaries Organiques (CESIO) (2004) than ASP It was found in USA, average removals that 998,000 tons of anionics surfactants and of 83% (Trehy et al., 1996) and 77% (McAvoy et 1,231,000 tons of non-ionics were manufactured al., 1993). during the year 2000 in the EU, these together account for about 90% of the total production of synthetic surfactants. Linear Alkylbenzene Sulfonate (LAS) (Fig .1) is the most frequently employed synthetic anionics surfactants, whose production amounts to 1,040,000 t/year in the U.S.A., Japan and, Western Europe (Matthew and Malcolm, 2000). After use, LAS are discharged via WWTPs into aquatic environments, sewage sludges after treatment are Fig. 1. General chemical structure of LAS, where x and y incorporated into soil as soil fertilizers. Venhuis corresponds with the number of CH2 on each side of the and Mehrvar (2004) have reported that 0.02–1.0 benzene sulphonate group (7x+10y) (Liwarska-Bizukojc, Drews & Kraume, 2008)
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Table. 1. Design basis for physical and operational characteristic of Elzaraby WSPs. Dimensions (m)of the water body Design basis Bottom/top Bottom/top Water Water Ponds Length Width Depth Vol ume Flow rate HRT (m) (m) (m) (m³) (m³/day) (day) A1-A2 146/163.6 45.4/63 4.4 37257 8250 4.5 F1-F2 277.8/288.8 154/164 2.5 112680 8250 14 M1-M2 158/164 104/110 1.5 25854 8250 3.0 M3-M4 158/164 104/110 1.5 25854 8250 3.0 M5-M6 158/164 104/110 1.5 25854 8250 3.0
The main objectives of this study are to evaluate the containers of 2 litre capacity. The following parameter removal efficiency of LAS in an existing system of waste were studied; water temperature (T), pH value, dissolved stabilization ponds (WSPs) in Elzaraby village, Abutig, oxygen (DO), biochemical oxygen demand (BOD5) and Assiut governorate Egypt. Also some physical and liner alkyl benzene salfonate (LAS). All analysis have biological characteristics of the waste water through the been carried out according to standard methods for treatment plant are investigated. examination of water and waste water (APHA, 2005). LAS measurement in sampies of sewage as methylene MATERIAL AND METHODS blue active substance (MBAS) using the Spectrophotometer as prescribed in standard methods Description of wastewater treatment plant (APHA, 2005). pH value were measured using; multi meter with pH sensor. Determination of biochemical A recent full-scale system of WSPs was constructed in oxygen demand (BOD5) by; electronic pressure sensor 2009 in Elzaraby village in Upper Egypt. Elzaraby WSPs (Oxidirect) apparatus, determination of dissolved oxygen are designed to treat domestic waste water from Abutig (DO); multi meter with DO sensor. city, with mean daily design flow rate of 16500 m3 /day. The physical characteristics of the ponds are given in RESULTS AND DISCUSSIONS Table 1. The wastewater after screening is used to feed two parallel anaerobic ponds (A1~A2). Each anaerobic In this study, a complete one-year monthly samples of pond has a square with shape 10790 m2 top water surface wastewater were taken from WSPs of Elzaraby plant from area and 4.4 m working depth. The two effluent of the locations S1~S5 totally 60 samples. The average seasonal anaerobic ponds is used to feed two facultative ponds values of T, pH, DO, BOD5 and LAS through the ponds (F1~F2) with top length of 292 m, 166 m top width at the were calculated. water level and 2.5 m working depth. The effluent from the facultative ponds passes through two parallel lines of Wastewater temperatures in the ponds maturation ponds. Each line comprising a first, second and third maturation pond, (M1~M6). Each of the The wastewater temperature for the four season of the maturation ponds has 164 m length and 115 m width at year from (Spt. 2011 to Aug. 2012) through the water the top water level of ponds and working depth 1.5 m. pass in WSPs are illustrated in (Fig. 3). Measured The treated effluent is either discharged into surface water temperatures of wastewater through the ponds ranged or reused for agriculture irrigation. from 180C and 350C. The maximum wastewater temperature in anaerobic ponds was 31.80C in summer Wastewater sampling season while the minimum was 22.10C in winter season. In facultative ponds, the temperature were ranged from Wastewater samples were collected monthly from the 20.1 0C to 30.6 0C in winter and summer, respectively. In plant through a period of one years, from Spt. 2011 to the last maturation ponds the minimum and maximum Aug. 2012 to study the seasonal removal efficiency of temperatures were 18 0C in winter and 27 0C in summer LAS in natural WSPs, Monthly-samples of raw season. As shown in (Fig. 3), it is clear that the wastewater after screening and effluents from each type wastewater temperature decreases along the pass of the of ponds were collected (S1to S5) as shown in (Fig. 2) of ponds and maximum temperature occurs in summer the sampling points. The samples were collected in plastic season . The decreasing rate was found to be much higher
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Fig. 2. The layout of Elzaraby WSPs in the summer season (80C) than that in the winter accumulate so raising the pH value. Similar results season (4.40C), this due to the higher evaporation were found by Mahmod et al .(2010). rate from the surface of the ponds which accomplished with higher latent heat in summer compared with that in winter season. DO concentration along the ponds series pH variations along the pond series The seasonal concentrations of DO in raw wastewater were found to be between 0.11 to 0.25 The average seasonal variation of the measured pH mg/l as a minimum and maximum values in spring values for the raw sewage and effluent from each and summer seasons, respectively, while seasonal type of ponds in the period from Spt. 2011 to Aug. values of DO increased in facultative ponds and 2012 are presented in (Fig. 4). The average pH recorded a range 1.36~2.5 mg/l in winter and value of raw wastewater ranged between 6.63~7.4, summer seasons, and the average values of DO in while increased in anaerobic ponds to be 6.75 and the effluent of maturation ponds recorded 3.8, 3.6, 7.8 as minimum and maximum values in winter 4.93 and 5.8 mg/l in autumn, winter, spring and and summer seasons, respectively. In maturation summer seasons, respectively, as shown in (Fig. 5). ponds the measured pH recorded a maximum value It is clear that the value of DO in the summer in summer 8.8 and a minimum value in winter was season increases relative to the winter season, 7.7. As shown in (Fig. 4), the pH values of the because the rate of algae photosynthesis and the ponds’ wastewater have their it’s highest values in cellular metabolism of microorganisms in the the summer season, and it increases along the ponds are enhanced by high temperatures and wastewater pass with the highest values in the last retarded by low temperatures. Algal oxygen maturation ponds. The increased pH value in production is directly related to photosynthesis, maturation ponds is due to rapid photosynthesis by which depends on temperature variations. From the the pond algae, which consumes Carbon dioxide figure, it is clear that the average concentrations of (CO2 )faster than it can be replaced by bacterial DO along the ponds series ranged from 0.11 mg/l respiration; as a result carbonate and bicarbonate in anaerobic ponds to 5.7 mg/l in the last ions dissociate. Algae fix the resulting CO2 from maturation ponds. Similar results were reported by the dissociation while hydroxyl ions (OH-) Nasr et al. (2007).
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Fig. 3. Wastewater temperature for different season through the wastewater pass in Elzaraby WSPs.
Fig. 4. Seasonal variation of pH value measured along Elzaraby WSPs.
BOD average seasonal concentration value of the last maturation ponds has BOD5 concentrations of 43.5, 51.5, 55 and 73.3 mg/l in For comparison the mean values of the measured autumn, winter, spring and summer seasons, unfiltered BOD5 in the different four seasons of the respectively. year are plotted as shown in (Fig. 5). The average From (Fig. 6). It is clear that the maximum concentration of BOD5 values in raw wastewater BOD5 values occur in summer season, while the ranged between 426.3 mg /l to 305 mg/l in summer minimum BOD5 values are in the winter season. and winter seasons respectively, while they The reason of this phenomenon is due to the high recorded in anaerobic ponds 314~167.5 mg/l as a tempriture of air and and sun light intensity occurs maximum and a minimum values. In facultative in summer season relative to other seasons, which ponds BOD5 concentrations were found to be increased algal grow (Ali et al., 2005). ranged between 275~111 mg/l, while the effluent
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6,00 5,50 Autumn winter Spring Summer 5,00 4,50 mg/l 4,00 3,50 3,00 2,50
concentration 2,00
1,50 DO 1,00 0,50 0,00 Raw waste Anaerobic Facultative Maturation Maturation water(s1) pond(s2) pond(s3) pond(s4) pond(s5) Fig. 5 Seasonal concentration value of DO measured along Elzaraby WSPs.
420 390 Autumn winter Spring Summer 360 330 mg/l 300 270 240 210
concentration 180
150
BOD 120 90 60 30 Raw waste Anaerobic Facultative Maturation Maturation water(s1) pond(s2) pond(s3) pond(s4) pond(s5) Fig. 6 Seasonal concentration value of BOD measured along Elzaraby WSPs.
LAS average seasonal concentration value biodegradation and concentration of LAS in wastewater treatment plant WWTP influents Linear Alkyl Benzene Salfonate (LAS) depends on the length of the sewer, travel time and concentrations at the sampling points were monthly the degree of the microbial activity present in measured in the period from Spt. 2011 to Aug. sewers (Matthijs et al., 1999). So the increased 2012for Elzaraby WSPs. The average seasonal LAS concentration in the winter season influent of concentrations of LAS at the sampling locations are the plant compared with other seasons is due to low plotted as shown in (Fig. 7). water temperature which causing a low microbial LAS concentrations in raw wastewater recorded activity in sewers. In Contrast, LAS concentration an average seasonal values as 6.2, 6.7, 11.9 and in the summer season is higher than those in 14.8 mg/l in autumn, spring, summer and winter autumn and spring seasons which can be attributed season, respectively. Sewers contain microbial to higher concentrations drained from source populations capable of initiating LAS houses. From the figure, it is clear that LAS
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Fig. 7 LAS avareage seasonal concentration value in Elzaraby WSPs
Fig. 8 The average annual variations of LAS, DO and pH for Elzaraby WSPs.
Fig. 9 The monthly overall removal efficiency of LAS and BOD5 for Elzaraby WSPs from Spt. 2011 to Aug. 2012. concentration values in the anaerobic ponds to recorded degradation of LAS in anaerobic condition (Guang 7, 7.6, 13.9 and 16.4 mg/l in autumn, winter, spring and Ying, 2004, John Jensen, 1999). the additional reason is summer seasons, respectively. These values are higher that actual average daily flow rate of Elzaraby WSPs at than those of the concentration values of LAS in raw measurement time was around 10000 m3/ day, which wastewater, similar increase of LAS concentrations leading to an actual HRT in the anaerobic ponds of 7.5 values in anaerobic ponds was reported in Yazd WSPs days causing high water losses by evaporation from the in Iran (Asghr et al,. 2010). The reasons for this increase pond surface, therefore the water volume decreased and in LAS concentration can be attributed to the bad consequently the concentration of LAS increased.
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The LAS concentration in maturation ponds (M1) in cold, and the mean over removal efficiency of recorded 6.1 mg/l as a maximum value in winter season, LAS from the plant found to be around 63%. and recorded 3.2 mg/l as a minimum value in summer season. In effluent of maturation ponds (M6) LAS REFERENCES recorded 6.4 and 2.1 mg/l in winter and summer seasons, respectively. Similar results were reported by APHA (2005). Standard methods for the examination of water and Asghr et al. (2010). wastewater, 20th and 21st ed. American Public Health As presented in (fig. 8), it is clear that the Association, Washington, DC. Bastawey. M.A. (2010). Diurnal variation of some physical – concentration values of LAS, DO and pH along chemical parameters in natural waste stabilization ponds in upper Elzaraby WSPs series were ranged between 10.18~3.15 Egypt. mg/l, 0.18~4.8 mg/l and 6.9~8.2, respectively. From Comite´ Europe´en des Agents de Surface et de leurs Intermediaries figure, it is clear that LAS concentrations in WSPs are Organiques (CESIO) (2004). CESIO 2004 - 6th World Surfactants Congress 20 - 23 June Berlin, Germany. multi-factorial, dependent on a synergistic interaction De Wolf, W., Feijitel, T. (1998). Terrestrial risk assessment for between pH, DO and sun Light. Because of good algal linear alkyl benzene sulfonate (LAS) in sludge-amended soils. growth The high level of algal photosynthetic activity Chemosphere 36(12), 1319–1343. not only raises the pH of the ponds but also increases its DiCorcia, A., Samperi, R., Belloni, A., Marcomini, A., Zanette, M., Lemr, K., Cavalli, L. (1994). LAS pilot study at the ‘‘Roma- DO content and biodegraded LAS. (Mungray & Kumar, Nord’’ sewage treatment plant and in the Tiber River. La Rivista 2008, Martin and Johannes, 1996). Italiana Delle Sostanze Grasse LXXI, 467–475. As shown in (Fig. 9), the overall removal efficiency Eagle, S.C., Barry, B.W., Scott, R.C. (1992) Differential scanning of LAS in comparison with removal efficiency of BOD5 calorimetry and permeation studies to examine surfactant damage in Oct. 2011 were 63%, 78%, and decreased in Jan.2012 to human skin. J Toxicol, Cutan Ocul Toxicol 11(1), 77–93. Ebrahimi, A., Ehrampoosh, M., Samaie, M., Ghelmani, S., Talebi, to be 55%, 73%, and increase in Jul. 2012 to be 77% , P., Dehghan, M., Honardoost, A., Shahsavani, E., 2010. Removal 88%, respectively. From the figure, it is clear that the Efficiency of Linear Alkyl Benzene Sulfonate (LAS) in Yazd overall removal efficiency of LAS and BOD in Elzaraby Stabilization Pond. Scientific Information Database, Iran. WSPs in hot months is higher than in cold months Feijtel, T.C.J., Matthijs, E., Rottiers, A., Rijs, G.B.J., Kiewiet, A., de because of high air temperature and sun light intensity Nijs, A. (1995). AIS/CESIO environmental surfactant monitoring program. Part 1: LAS monitoring study in "de Meer" STP and occurs in summer season relative to other seasons, receiving river "Leidsche Rijn", Chemosphere 30, 1053-1066. which increased algal growth and increased Gad, A., Ali, A., 2005. The performance of an existing system of biodegradation of LAS, similar result were reported by waste stabilization ponds in upper Egypt. In: First Ain Shams Asghr et al. (2010). University International Conference on Environmental Engineering. Guang Guo, Y. (2004). Behavior and effects of surfactants and their CONCLUSION degradation products in the environment. International J. of Environment, 32(4), 417-431. 1. One year detaild fild investigation was completed to Holt, M.S., Bernstein, S.L. (1992). Linear alkylbenzenes in sewage evaluated the removal efficiency of LAS in an sludges and sludge amended soils. Water Research 26, 613–624. Jensen, J. (1999). Fate and effects of linear alkylbenzene sulphonates existing system of waste stabilization ponds (WSPs) (LAS) in the terrestrial environment – a review. Science and in Elzaraby WSPs, also some physical and Total Environment 226, 93–111. biological characteristics of the waste water through Kwok, T.K. (2011). Assessing the effect of surfactants on activated the treatment plant are investigated. sludge processes using sequencing batch reactors. A thesis submitted in fulfillment of the requirements for the degree of Master of Engineering School of Civil, Environmental and 2. From the raw wastewater to the anaerobic ponds Chemical Engineering Science, RMIT University . effluent, pH value does not significantly change Liwarska-Bizukojc, E., Drews, A., Kraume, M. (2008). Effect of because the ponds are organically underloaded with selected non-ionic surfactants on the activated sludge along detinion time the pH values of the ponds’ morphology and activity in a batch system. Journal of Surfactants ’ and Detergents, 11(2), 159–166. wastewater has it s higher values in the summer Mara, D.D. (2004). Domestic Wastewater Treatment in Developing season, and it increases along the wastewater pass Countries. Earthscan, London , Sterling, VA. with the highest values in the last maturation ponds. Martin, W., Johannes, H. (1996). Surface active agents and their influence on oxygen transfer. Wastewater Technology, 34(3), 249-256. 3. The avarege removal efficiency of the unfiltered Matthijs, E., Holt, M.S., Kiewiet, A., Rijs, G.B.J. (1999). BOD5 of the plant were found to be as good as Environmental monitoring for linear alkylbenzene sulfonate, 80.5%. alcohol ethoxylate, alcohol ethoxy sulfate, alcohol sulfate, and soap. Environmental and Toxicological Chemistry 18, 2634– 4. The maximum over all removal efficiency of LAS 2644. McAvoy, D.C., Eckhoff, W.S., Rapaport, R.A. (1993). Fate of linear occurs in warm monthes, while minimum removal lkylbenzene sulfonate in the environment. Environmental and Toxicological Chemistry 12, 977–987.
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Mungray, A.K., Kumar, P. (2008). Occurrence of anionic surfactants Scott, M.J., Jones. M.N. (2000). The biodegradation of surfactants in in treated sewage: Risk assessment to aquatic environment the environment. Biochimica et Biophysica Acta 1508 (2000) Journal of Hazardous Materials 160, 362–370. 235-251. Nasr. F.A., El-Ashmawy. A., Eltaweel. G., El-Shafai. S.A. (2007). Trehy, M.L., Gledhil, W.E., Mieure, J.E., Nielsen, A.M., Perkins, Waste Stabilization Ponds for Wastewater Treatment and Reuse H.O., Eckhoff, W.S. (1996). Environmental monitoring for LAS, in Egypt. Environmental Sciences Division, Department of Water DATS and their biodegradation intermediate. Environmental Pollution Research National Research Center, El-Behoos Street, Toxicology and chemistry 15(3), 233-240. Dokki, Cairo, Egypt. Venhuis, S.H., Mehrvar, M. (2004). Health effects, environmental Ramadan, H., Ponce, V. (2011). Design and Performance of Waste impacts, and photochemical degradation of selected surfactant in Stabilization [email protected] Version 081218. water. International Journal of photoenergy 6(2),155-125.
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Journal of Urban and Environmental Journal of Urban and E Engineering, v.7, n.1, p.143-150 Environmental Engineering ISSN 1982-3932 J E www.journal-uee.org U doi: 10.4090/juee.2013.v7n1.143150
THE ACTORS OF A WIND POWER CLUSTER: A CASE OF A WIND POWER CAPITAL
Jari M. Sarja1 1Raahe Unit, University of Oulu, Finland
Received 5 July 2012; received in revised form 27 March 2013; accepted 28 March 2013
Abstract: Raahe is a medium-sized Finnish town on the western coast of Northern Finland. It has declared itself to become the wind power capital of Finland. The aim of this paper is to find out what being a wind power capital can mean in practice and how it can advance the local industrial business. First, the theoretical framework of this systematic review study was formed by searching theoretical information about the forms of industrial clusters, and it was then examined what kinds of actors take part in these types of clusters. Finally, the actors of the case area were studied. The core companies of wind power clusters are the wind turbine manufacturers, component manufacturers, developers of the wind farms, wind power operators, and service and maintenance organizations. Understanding of the wind power cluster structure may help decision makers to develop the best possible conditions for the emergence of clusters.
Keywords: Cluster, wind power cluster, cluster model, actors of cluster
© 2013 Journal of Urban and Environmental Engineering (JUEE). All rights reserved.
Correspondence to: Jari M. Sarja, Tel.: +358 40 672 1024; Fax: +358 8 221 406. E-mail: [email protected]
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INTRODUCTION The aim of this study was to clarify what kinds of actors take part in wind power clusters and what kinds of possibilities the case area has for the emergence of a wind power cluster. Because there is no specific definition for the concept of wind power cluster, it is first defined on the basis of existing knowledge and combining it using different sources. The actors of a cluster and the possibilities of the case area are then studied. The case area is the city of Raahe and its sub-region. Raahe is a medium-sized Finnish town on the western coast of Northern Finland (64°41'N, 24°28'E). The Fig. 1 Location of the case region. location of the case region is shown in Fig. 1. A significant amount, approximately 20 per cent, of Moreover, the use of renewable energy sources is Finland's wind power capacity is produced in Raahe and constantly growing, and thus wind power construction is its sub-region. In addition, around twenty new wind on the increase and there are numerous wind power farms have been planned for this region (Sarja & projects taking place in Finland. Finnish wind power Halonen, 2012). Wind farms consist of many wind construction is governed by the climate change and turbines set in areas favorable for wind power energy strategy, which is based on the climate and production (e.g. Hossain et al., 2007). energy packet initiated by the European Commission in The local media (e.g. Keskinen, 2011; Nousiainen, 2008 (Ministry of Employment and the Economy, 2008; 2010; Tuikkala, 2010; Veräjänkorva, 2010) has reported European Commission, 2007). about the goal of the city of Raahe to become the wind power capital of Finland. No concrete plans or actions Research and Methods have been commenced yet. The objective of this study is The research method in this study is systematic review. to investigate what being a wind power capital can Systematic review means identifying, evaluating, and mean in practice and how it can advance the local interpreting all available research relevant to a particular industrial business. The wind power capital approach is research question, topic area, or phenomenon of interest studied in the framework of cluster theories. (Kitchenham, 2004). In general, the approach concerns a regional business The theoretical material in this study consists of and know-how center, i.e. a polis or cluster. The polis scientific and professional literature on clustering concepts have been utilized more or less successfully in theories. The empirical materials include professional Northern Finland (e.g. Jauhiainen, 2006). A loose literature, various reports, articles of local media and definition of a polis is a know-how center focused on a web sources of the local public sector, open interviews, certain sector of high technology (Multipolis, 2009). A and for example higher education-level research cluster means a business center in which the networked exercises and theses. companies strive for competitive advantages with the In this review, we have first familiarized with the help of cooperation and common supply chain cluster development theory using especially the management (Silen, 2001). From a wider point of view, diamond model by Porter (1998) and then reviewed the there are also other actors in clusters in addition to the actors of the wind power clusters. Finally, we have core companies, namely the suppliers, support analyzed the possibilities of the case area for wind businesses, and the public sector including education power cluster emergence; what elements and factors and research organizations (Porter, 1998). already exist and for which elements should the best The wind power cluster seems a promising regional possible conditions be developed. This model should undertaking. There is already heavy industry and its also clarify the concept of the wind power capital (of supporting business know-how in the case area, as well Finland). as required infrastructure. It can also be said that the case area already has wind power tradition. The wind LITERATURE REVIEW power capacity of the case area is remarkable in the domestic scale. Besides the conventional energy Regional groups of enterprises have been researched as sources, renewable energy sources including wind a clustering phenomenon already for a long time. Early power play a vital role in satisfying the energy demand researchers, such as Von Thünen (1826), Launhardt (Hossain et al., 2009). (1885), and Weber (1909), explain the benefits of regional networks with savings in transportation costs.
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Marshall (1890) can be regarded as the first real cluster researcher and he is often quoted as the first researcher who brought together business productivity, location, and proximity to other companies in the field (Vom Hofe and Chen, 2006). Marshall found other long-term advantages in clustering, such as the spread of information between enterprises, (skilled) labor market development, and cost benefits by achieving non- commercial sharing inputs (e.g. research and training). Vom Hofe and Chen (2006) have made a comprehensive summary of the past and present state of cluster study. According to them, the starting point of the current cluster research can be considered to be the first edition of Porter’s The Competitive Advantage of Nations in 1990, in which he investigated 883 clusters in 49 different countries. Fig. 2 The diamond model (Porter, 1998). In the last couple of decades, a lot of research has been done on the emergence of clusters. The emergence of regional companies and organizations and the of cluster research is likely to have been affected by formation of competitiveness in a particular industry findings of a specialized industry and regional sector. This model describes the context in which competitiveness increase. The most well-known cluster companies are born and compete. The context is based is probably Silicon Valley located in the San Francisco on four background factors, which are factor conditions Bay area. In previous studies (Cooke 1998, 2003), it has of production; strategy, structure and rivalry; demand been found that there is something systematic in the conditions; and the related and supporting industries. In concentration of industry in the same line of business. this model, the success of enterprises correlates with the According to Nummi and Lahenius (2003), a local favorability of the background factors. innovation system consists of (manufacturer) This study focuses on the key product or the core companies, component suppliers, service providers, companies of the cluster as well as their supporting customers, research and educational institutions, businesses and organizations. This focus area is limited commercial associations, and the public sector actors. by the dotted line in Fig. 2. The formation of the enclosed area is a prerequisite for the emergence of a Cluster Navigators Ltd. (2001) divides clusters into three types; national clusters, regional clusters and cluster. Cluster Navigators Ltd. (2001) has developed a commercial clusters. National clusters resolve national model for the creation of a cluster based on Porter’s matters, such as policy or infrastructure and the scale of model with the focus limitation described above. them (e.g. industry-specific IT-clusters). The regional Cluster Navigators’ (2001) model describes the clusters focus on developing a business environment for leading member companies, their support businesses the member companies and their support businesses as and the types of infrastructure (Fig. 3). well as public sector organizations including educational and research institutions. Commercial clusters are multiple consortia. The wind power cluster planned for the case area is clearly a regional cluster. The concept of cluster can easily be confused with that of network. A network, however, is built around a single company, and it describes the company and its interest groups regardless of the network members’ locations. A cluster means a group of enterprises in a same line of business and their relationship to (regional) networks (Silén, 2001).
Cluster Analysis The “diamond model” (Fig. 2) by Porter (1998) is the most well-known cluster model, and many other models are based on it (Haverinen, 2011). It can be used in Fig. 3 The cluster (Cluster Navigators Ltd., 2001). cluster analysis to understand the operating environment
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The earnings of the core come mainly from outside Sörensen (2011, p. 4) add business developers and the the cluster. The operations of the support companies public sector to the cluster members. Boeckle et al. support the businesses of the member companies (2010, pp. 8–9) extend the concept of wind energy directly or indirectly. The infrastructure can be divided cluster by including the supply chain; according to this into two parts; the knowledge-based organizations definition, raw material manufacturers, electricity grid supporting the core, such as educational and research suppliers, and wind power operators also belong to the institutions, and the material infrastructure, such as cluster. In several independent open interviews, wind transport and telecommunication links (Haverinen, power plant maintenance organizations were seen as 2011). essential actors. Fig. 4 shows the model of the actors of a wind power cluster. The model is based on the general cluster analyses and source materials. MODEL OF THE ACTORS IN A WIND POWER The rough grouping in Fig. 4 illustrates the core CLUSTER members of a wind power cluster (section 1), supporting This section presents a model of the actors of a regional businesses (section 2), soft infrastructure (section 3), wind power cluster. In the literature, wind power and hard infrastructure (section 4). clusters are mentioned occasionally but no universal The core companies of a wind power cluster are definition or model exists. The model proposed here directly involved in the wind energy business; they was created by examining the related literature. After operate in manufacturing or operating of wind power. this, businesses established in the case area that could be The operations of the support businesses support the regarded as actors of the cluster were mapped. Finally, core companies directly or indirectly, for example by the need of new actors in the region was analyzed in providing earthwork or lifting services. The soft order for there to exist a vital cluster, a wind power infrastructure consists of educational and research capital. arrangements which support the wind power business. Bolon et al. (2007, p. 19) and Boeckle et al. (2010, The hard infrastructure enables the functioning of the pp. 8–9) identify wind turbine manufacturers and wind business environment by providing for example farm developers as the core players of a wind energy transportation, telecommunication links, and electricity cluster. Villafafila et al. (2007) define wind turbine grids. In the model, the public sector serves the material manufacturers, part suppliers and research and environment together with private companies as well as educational institutions as the members of a wind power the knowledge environment. cluster. Besides the mentioned actors, Cornett and
Fig. 4 The model of the actors of a wind power cluster.
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The Case of Raahe and its Sub-Region wind power. They are wind turbine manufacturers, component manufacturers, developers of wind farms, This section presents the capabilities of the target areas wind power operators, and service and maintenance of growing into a wind power capital with the help of organizations. the wind power cluster model presented above. Raahe is known for its steel industry. The local The core companies of the wind power cluster steelworks supply both the primary raw material and operate in the wind energy business and are involved in completed towers for wind turbines. There are presently manufacturing or operating sectors. The wind power two wind power operators, and they operate three wind cluster of the case area is in an early stage and thus there farms in the case area. In addition, there exist wind farm exist only a limited number of core companies and they developing and project management businesses. In total, are generally known. The same applies to the 19 new wind power initiatives have been planned for infrastructure elements. the case area; 16 onshore and 3 offshore. There are total The supporting businesses were analyzed using 10 companies behind these projects. The new wind Statistics Finland’s standard industrial classification. power projects are listed in Table 1. A nationally The standard industrial classification TOL 2008 is based important wind power company has also established a on the NACE (Nomenclature générale des Activités maintenance organization in the case area. économiques dans les Communautés Européennes) standard industrial classification. NACE derives from Support Businesses the standard industrial classification ISIC (International Standard Classification of All Economic Activities) of The operations of the support companies support the the United Nations. TOL 2008 is used as a framework businesses of the member companies directly or for economic statistics (Statistics Finland, 2012). indirectly. The supporting businesses were analyzed Figure 5 illustrates the present state of the wind using Statistics Finland’s TOL 2008 standard industrial power cluster in the case area. The current actors of the classification. Industries and supporting businesses that case area have been added to the wind power cluster have shared interests with the wind power industry were model. chosen from the standard industrial classification. The Raahe and its sub-region constitute with their 35 000 focuses of branches were selected according to the same inhabitants an excellent material environment due to principle. The supporting businesses were counted by their comprehensive range of public and commercial selecting companies of the related branches listed in the services and transport links. In the area, there are a great business directory maintained by a local business number of support businesses, some wind power sector service organization (http://rsyp.owla.fi). Companies companies and a large quantity of new wind power that clearly offer consumer products were excluded. initiatives. This listing is for illustrative purposes only, and the companies listed may somewhat overlap with the core The Core companies of the cluster. The supporting businesses are illustrated in Table 2. According to the wind power cluster model, the core companies operate in manufacturing or operating of
Fig. 5 The basis of the case area’s wind power cluster.
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Table 1. The wind power initiatives in the case area Table 2. The supporting businesses in the case area
On the basis of the standard industrial classification, the branches of the selected supporting businesses of the wind power cluster were mining and quarrying (B), manufacturing (C), construction (F), transportation and storage (H), information and communication (J), real estate activities (L), professional, scientific and technical activities (M), and administrative and support Hard Infrastructure service activities (N). In this review, the hard infrastructure comprises mainly In the case area, companies of each of the selected transportation and telecommunications links. The branches can be found. There is a particularly large transportation connections in the case area are excellent number of companies in the manufacturing, in terms of freight traffic, and at least acceptable in construction, transportation and storage, and terms of passenger traffic. The blind track serving heavy professional, scientific and technical activities branches. freight comes to the heart of the case area, and it is connected to the main railway network of the country. Soft Infrastructure The nearest railway station for passenger traffic is In this study, the soft infrastructure comprises mainly located on the edge of the case area. The eighth busiest the educational and research providers of the case area. year-round harbor in Finland with more than 700 ships a The soft infrastructure is relatively broad compared to year is located in the case area. The nearest international the population. The education available includes airport (Oulu Airport) is located 70 kilometers away education from the basic level to higher education. from the case area. One of the main highways of the Besides the upper secondary school, there exist four country (Highway 8) cuts through the case area. The vocational schools in the case area. Two of them offer telecommunications links are excellent in the entire technical programs appropriate for the needs of the country (e.g. Grimes, 2003). cluster. Continuous training is also offered. Higher In addition, it can be concluded that the city of education is offered by the University of Applied Raahe with its 23 000 inhabitants and the entire case Sciences and the Open University. area including the sub-region with its 35 000 inhabitants The higher educational organizations, the branch with comprehensive commercial and public services office of the University of Oulu, and the national compose a functional hard infrastructure for an research centre provide research activities. industrial cluster.
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CONCLUSIONS and research available are able to serve the needs of this kind of cluster also in future. The city of Raahe has announced its plan to become the The practical relevance of this study is to help the wind power capital of Finland. The target is logical decision makers of the case area to piece together the because the case area is already a significant wind present state of the wind power capital and to see what power producer in the national scale, there exist a lot of kinds of actors should be drawn in. This study may also heavy industrial know-how and networks in the area, offer new aspects for the wider local energy cluster and many new wind power initiatives have been strategy, which is a part of the business strategy of the planned. New pillars of business life are being actively case area. The theoretical contribution of this study is sought in the traditionally industrial town, and the city the definition of a universal model of a wind power can offer a strong operational environment for the new cluster in a general level. It can be used in other studies industries. in the field and focused and updated by taking into The study started from the premise that the wind account local circumstances. power capital means that the city grows into a strong wind power cluster. It can be said that there is already a small-scale wind power cluster in the case area with a Acknowledgement The research material for this work few wind energy business companies. However, the was collected in “Green Technology” project supported existing companies operate as relatively independent in part by the European Regional Development Fund actors, and the cluster includes no very noteworthy (ERDF) of the European Union. supply chains.
Because there is no universal definition or model of a wind power cluster in the literature, we have proposed REFERENCES a model of the actors of a wind power cluster by examining the related literature. We propose that the Bolon, E., Commons, M., Des Rosiers, F., Caso de los Cobos, P.G. actors of a wind power cluster are wind turbine & Kukrika, N. (2007) The Spanish wind power cluster. [online] manufacturers, raw material and component Final report Microeconomics of competitiveness, Harvard manufacturers, wind farm developers, wind power Business School, Harvard University. Available from: operators, grid suppliers, service organizations, research http://www.isc.hbs.edu/pdf/Student_Projects/Spain_WindPower Cluster_2007.pdf (Accessed 22 March 2012). and educational institutions, public sector actors, Cluster Navigators Ltd. (2001) Cluster Building: A toolkit. [online] support businesses, and (both private and public) Available in: www.vaxtarsamningur.is/Files/Skra_0023777.pdf. infrastructure providers. Cooke, P. (1998) Introduction: Origins of the Concept. [online] We compared the core companies, support Regional Innovation Systems, 1998. Available at SSRN: http://ssrn.com/abstract=1497770 businesses, infrastructure, and public services of the Cooke, P. (2003) Economic globalization and its future challenges case area with the wind power cluster model. We found for regional development. International Journal in Technology out that there are a few wind power-related companies Management 26 (2), 401–420. in the case area, and they provide a good basis for the Cornett, A.P. & Sörensen, N.K. (2011) Regional economic aspects emergence of a cluster. After sifting, almost 700 support of the Danish Windmill Cluster: The case of the emerging off shore wind energy cluster on the west coast of Jutland”, businesses were found in the case area. There is Proceedings of the 14th Uddevalla Symposium, June 16–18, 2011, education available from the basic level to higher Bergamo, Italy. education, and research support exists, so it can be European Commission (2007) Combating climate change – The EU concluded that soft infrastructure is acceptable leads the way. [online] Belgium. Available from: http://ec.europa.eu/publications/booklets/move/70/en.pdf regarding the size of the case area. It can be said that the (Accessed 28 February 2012). hard infrastructure in the case area is excellent because Grimes, S. (2003) The digital economy challenge facing peripheral of existing heavy industry and working freight traffic rural areas. Progress in Human Geography 27(2), 174–193. solutions including shipping, rail traffic, and road Haverinen, K. (2011) Edellytyksiä Kajaanin datakeskus-klusterille, transport. MS thesis, University of Oulu, Oulu, Finland (in Finnish). Hossain, A., Iqbal, A.K.M.P., Rahman, A., Arifin, M. & Mazian, M. Therefore, the conditions for the emergence of a (2007) Design and development of a 1/3 scale vertical axis wind nationally significant wind power cluster are good. We turbine for electrical power generation. J. Urban Environm. think the next step would be to market the area and Engin. 2(2), 1–5. develop the best possible conditions for the core Hossain, A., Rahman, A., Rahman, M., Hasan, S.K. & Hossen, J. (2009) Prediction of power generation of small scale vertical axis companies of the wind energy business outside the case wind turbine using fuzzy logic. J. Urban Environm. Engin. 3(2), area. The missing core companies are especially wind 43–51. turbine (see Fig. 5) and part manufacturers, but a larger Jauhiainen, J. (2006) Multipolis: High-technology network in number of other core companies would also profit the Northern Finland. Europ. Plan. Studies 14(10), 1407–1428. area. In addition, it should be ensured that the education Keskinen, S. (2011) Olisiko tyvenen paikka? Raahen Seutu 14 June 2011 (In Finnish).
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Kitchenham, B. (2004) Procedures for performing systematic Tuikkala, K. (2010) Tuulivoimapääkaupungiksi. Raahen Seutu 23 reviews. Keele University Technical Report. November 2010 (in Finnish). Launhardt, W. (1885) Mathematische Begründung der Ministry of Employment and the Economy (2008) Climate Change Wolkwirtschaftslehre. B.G. Teubner, Leipzig (in German). and Energy Strategy 2008. Government Report to Parliament 6 Marshall, A. (1890) Principles of Economics. Macmillan, London. November 2008. Available from: Multipolis (2009) Welcome to Multipolis. Available from: http://www.tem.fi/index.phtml?l=en&s=2658 (Accessed 28 http://www.multipolis.com/index.php?189 (Accessed 4 March February 2012). 2012). Veräjänkorva, A. (2010) Jari Sillanpää sijoittaa Raahen Nousiainen, T. (2010) Raahe sai tukikohdan. Raahen Seutu 1 tuulivoimaan. Yle Oulu. Available from: December 2010 (in Finnish). http://yle.fi/alueet/oulu/2010/11/jari_sillanpaa_sijoittaa_raahen_t Nummi, J. & Lahenius, K. (2004) Medical devices innovation uulivoimaan_2162218.html (Accessed 6 March 2012). networks in Oulu Region as local innovation system. Frontiers of Villafafila, R., Sumper, A., Suwannarat, A., Bak-Jensen, B., e-Business Research 2003. Feb 2003. Conference proceedings, Ramirez, R., Gomis, O. & Sudria, A. (2007) On wind power September 24–25, 2003, Tampere, Finland. integration into electrical power system: Spain vs. Denmark. Porter, M. E. (1998) The competitive advantage of nations. Poster session presented at International Conference on MacMillan, London. Renewable Energies and Power Quality, ICREPQ'07, Sevilla, Sarja, J. & Halonen, V. (2012) A case study of a wind turbine Spain. sourcing: manufacturer selection criteria. Proceedings of the vom Hofe, R. & Chen, K. (2006) Whither or not industrial cluster: annual Electrical Power and Energy Conference. Oct 2012. pp: conclusions or confusions? The Industrial Geographer 4(1), 2– 266-271. 28. Sileń, T. (2001). Laatu, brändi ja kilpailukyky. WSOY, Helsinki (in Von Thünen, J.H. (1826) Der isolierte Staat in Beziehung auf Finnish). Landwirtschaft und Nationalökonomie. Perthes, Hamburg. Statistics Finland (2012) Standard Industrial Classification TOL Weber, A. (1909) Über den Standort der Industrien. J.C.B Mohr, 2008. Available in: Tübingen, Germany. http://www.stat.fi/meta/luokitukset/toimiala/0012008/index_en.ht ml. (Accessed 22 May 2012).
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Journal of Urban and Environmental Journal of Urban and E Engineering, v.7, n.1, p.151-156 Environmental Engineering ISSN 1982-3932 J E www.journal-uee.org U doi: 10.4090/juee.2013.v7n1.151156
FLOW PHYSICS OF 3-BLADED STRAIGHT CHORD H-DARRIEUS WIND TURBINE
Rajat Gupta¹ and Agnimitra Biswas² ¹Director, National Institute of Technology Srinagar, Srinagar, Jammu & Kashmir, India ²Assistent Professor, National Institute of Technology Silchar, Silchar, Assam, India
Received 30 March 2013; received in revised form 9 May 2013; accepted 30 May 2013
Abstract: Steady-state two-dimensional Computational Fluid Dynamics (CFD) simulations were performed using Fluent 6.0 software to analyze the flow physics of 3-bladed straight chord H-Darrieus wind turbine having blade twist of 300 for 10% of its chord at the trailing ends. The flow was simulated using finite volume method coupled with moving mesh technique to solve mass and momentum conservation equations. The standard k-ε turbulence model with enhanced wall condition was used. Second-order upwind discretization scheme was adopted for pressure-velocity coupling of the flow. Flow physics of the turbine was analyzed with the help of pressure and velocity contours. It was found that velocity magnitude decreases from upstream to downstream side across the turbine, which will cause overall lift for the turbine. Further, blade twist at the trailing ends creates circulations that interact with the blades in a direction opposite to the direction of rotation of the turbine which would enhance power production for the three bladed turbine.
Keywords: H-Darrieus turbine, straight chord blade, CFD analysis, contours
© 2013 Journal of Urban and Environmental Engineering (JUEE). All rights reserved.
Correspondence to: Agnimitra Biswas, Tel.: Fax: +091-3842-233797, Phone: +0091-3842-248308. E-mail: [email protected]
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INTRODUCTION attempt was made to study the performance of a three- bladed H-Darrieus turbine having blade twist of 300 for The straight-bladed Vertical Axis Wind Turbine 10% of its chord at the trailing ends. Two dimensional (VAWT), H-Darrieus turbine, is an invention included simulations were run using Fluent 6.0 CFD software. in the Darrieus patent (Darrieus, 1931). The H-Darrieus Pressure and velocity contours were analyzed and turbine, also known as H-rotor after its inventor, is a lift performance of the present turbine was predicted from type device, which has two to three blades designed as the analysis. airfoils. The blades are attached vertically to the central shaft through support arms. The support to the vertical Model Design axis helps the turbine maintain its shape. The H-
Darrieus turbine is normally placed on the top of a The height of the turbine was 20cm, and the chord tower in order to reach higher winds. Moreover, the H- length of the blades was 5 cm. An angular twist of 300 Darrieus turbine is the most suitable turbine in extreme was provided at the tips of the chords for 10% of chord wind conditions, like wind gusts, cyclone, and its length from the trailing end. The turbine is shown in the efficiency could be as high as Horizontal Axis Wind Fig.1 respectively. The blades were supported on bolts Turbine (HAWT) when placed on rooftops (Mertens, 5mm in diameter & 12 cm in length. The central shaft of 2003). the turbines was 1.5 cm in diameter and about 25 cm in Guy wires are generally used to support the shaft of length. By changing the overall turbine diameter but eggbeater Darrieus turbine since it gives a stiffer, more keeping the height constant, ten numbers of H/D ratios robust construction. However, guy wires are optional were obtained. The central shaft, base and the supports for H-Darrieus turbine, which is an advantage. It is self- were made from mild steel, and the blades were made regulating in all wind speeds reaching its optimal from lightweight aluminium. Ball bearings were used to rotational speed shortly after its cut-in wind speed support the shaft of the turbines at the base. The base (Islam et al., 2005). The blades of H-Darrieus turbine was 7cm wide and 2.4 cm thick. are much easier to manufacture than the blades of a HAWT or of an eggbeater Darrieus turbine. Light A Figura 1 dee vir aqui dentro desta caixa de texto weight, highly flexible turbines are usually two-bladed para ficar na 1a. página. turbines. Visual aesthetics and lower noise are the reasons for using three-bladed designs. Tangtonsakulwong & Chitsomboon (2006) did Computational Fluid Dynamics (CFD) simulation of wind flow over an untwisted three-bladed H-Darrieus turbine of NACA 0015 blade profile by using 3D unstructured-mesh finite volume method together with the sliding mesh technique to solve mass and momentum conservation equations. The maximum power coefficient of 0.20 was obtained at a tip speed ratio of 2.9. Jiang et al. (2007) developed 2D CFD models to study the effects of number of blades and tip speed ratio on the performance of multi-bladed H- Darrieus turbines. However, the highest power coefficient of their turbine was about 19%. Howell et al. (2010) studied the performances of two-bladed and three-bladed H-Darrieus turbines through wind tunnel experiments and also through CFD analyses. The two- bladed turbine had a higher peak power coefficient of 0.25 compared to about 0.22 for the three-bladed turbine. Twist blades could be a good field of research since such blades have the potential to be superior to the untwisted blades. Tip geometry can locally modify the angle of attack and the inflow dynamic pressure and hence can improve performance of the turbine. But experimental or computational works in this direction are very few. Keeping this in view, in this paper, an
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(triangular) meshing was done on the face external to the turbines. The computations were initially carried out with various levels of refinement for the mesh until the Grid Independent Limit (GIL) mesh Masson et al. (1997) was attained. Each refinement 7 cm level was solved in Fluent with the same set of input parameters. The unstructured triangular mesh around an airfoil blade of such turbine is shown in Fig. 3.
5 cm
300
1.5 cm
20 cm Fig. 2 Computational domain of the 3-bladed straight chord H- Darrieus turbine.
2.4 cm
Fig. 1 Three-bladed straight chord H-Darrieus turbine.
The Computational Approach
The CFD simulations were carried out using Fluent 6.0 software in which the meshing was done in Gambit. The computational models of the turbine along with the boundary conditions are shown in Fig. 2. Velocity inlet and outflow conditions were taken on the left and right boundaries respectively. The top and bottom boundaries of the computational domain, which signify the sidewalls Fig. 3 Computational mesh around straight chord H-Darrieus turbine. of the wind tunnel, had symmetry conditions on
them. The blades, central shaft and the support CFD Formulation arms were set to standard wall conditions. On the four surrounding edges of the computational The Navier-Stokes equation in finite difference form for domain, uniform grids were taken. The density of incompressible flow of constant viscosity is solved by the mesh was higher at the blade ends since sudden the in-built functions of the fluent CFD package. change in blade section at the ends requires more Similarly, the finite difference forms of continuity and turbulence equations are solved. The simplest and most dense nodes on them. The distance of the first row widely used two-equation turbulence model is the of grid points (i.e. nodes) in direction normal to the standard k-ε model that solves two separate transport solid boundary was 0.0001 cm. Unstructured
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equations to allow the turbulent kinetic energy and its For the convective terms of the momentum equations dissipation rate to be independently determined. The and also for the turbulence equations, the second order standard k– ε model is particularly suitable for flows upwind interpolating scheme Versteeg and though sharp corners, straight and curved edges like the Malalasekera (1995) was adopted in order to achieve turbine blades as the model uses wall functions based on accurate results. The iterations are continued until the the law of the wall. The k– ε can be represented as: residual values had dropped to 1×10-3.
k CFD Analysis of 3-bladed Straight Chord H- kku t i (1) Darrieus Turbine txijk x xj GYkM The contour plots of pressure and velocity magnitude are analysed. These plots are generated at the tip speed t ui ratios for which the power coefficients of the turbines tx x x ij j (2) were the highest. Figure 4 shows static pressure 0 0 0 2 contours at 5 , 125 and 245 . Figure 5 shows static 0 0 0 CGC12k pressure contours for blade angles: 90 , 210 and 330 . kk The blade angles are to be counted starting from the left, i.e. upstream side and then moving in the clockwise Equation 1 corresponds to turbulent kinetic energy direction. The pressure contour plots show a decrease of equation in which the first and second term on the left static pressure from the upstream side to the hand side represent local and convective turbulent downstream side across the turbine. For blade angles of kinetic energies per unit mass respectively; first term on 50, 1250 and 2450 of the straight chord turbine, i.e. for the right hand side is the stress tensor for turbulent the advancing blade at 50, Fig. 4 shows that the static kinetic energy, ‘Gk’ meaning generation of turbulence pressure decreases from 1.89×102 Pascal in the due to viscous forces, ‘ρε’ meaning turbulence upstream side to 9.63×101 Pascal in the downstream dissipation rate per unit specific volume and ‘YM’ n side across the turbine. Similarly, Fig. 5 of the straight meaning momentum source. Similarly eq 2 corresponds chord turbine for blade angles of 900, 2100 and 3300 to turbulence dissipation rate equation in which left shows that static pressure decreases from 6.38×102 hand side terms correspond to local and convective Pascal in the upstream side to 1.21×102 Pascal in the dissipation rates per unit mass; first term on right hand downstream sides. Thus, the amounts by which the side is the stress tensor for turbulent dissipation rate and static pressures decrease across the turbines increase the remaining terms correspond to source terms for with the increase of the blade angle of rotation. dissipation. The values of the five constants of the The static pressure contours further show that standard k- turbulence model are taken as: circulations or vortices are generated on the blade ends. These circulations are generated in areas very close to C 09.0 the blade ends, and there is a close interaction of these C1 44.1 C 2 44.1 k 0.1 3.1 circulations with the blades as well. Although these interactions are more for the turbine, such effects would simultaneously increase the drag on the three-bladed In this study, steady state, incompressible flow was turbine. Further, the static pressures are negative near considered. The numerical simulation was carried out the ends of the blades meaning circulations at the blade by solving the conservation equations for mass and ends were in a direction opposite to the direction of momentum and by using an unstructured-grid finite rotation of the turbine thereby would enhance power volume methodology coupled with moving mesh production for the three bladed turbine. However, the technique (FLUENT, 2005). The standard k- pressure at the exit of the computational domain is turbulence model with enhanced wall function was positive that means bulk flow is uniform throughout the utilized. The method of dynamic grid or rotating computational domain. The dynamic pressure contour reference frame was implemented in which the blade is of the turbine for blade angles of 900, 2100 and 3300 is fixed in the view of an observer who is moving with the shown in Fig. 6. It shows that the dynamic pressure is rotating frame of reference. Single rotating reference positive in the computational domain meaning the flow frame was considered, where the blades along with the physics are alright. Moreover, it further shows that the support arms and the central shaft rotate relative to the dynamic pressures are high and positive on the blade incoming fluid stream. The sequential algorithm, Semi- ends where static pressures are negative as the total Implicit Method for Pressure-Linked Equation pressure is constant for any location within the flow (SIMPLE), was used for solving all the scalar variables.
Journal of Urban and Environmental Engineering (JUEE), v.7, n.1, p.151-156, 2013 Gupta and Biswas 155
domain. Further, it can be observed from that the downstream of the blade, the velocity is around 13 m/s
3 dynamic pressure is very high (of the order 10 Pascal) to 15 m/s.
Fig. 4 Contour plot of static pressure of 3-bladed straight chord H- Darrieus turbine having Al blades for blade angle: 50, 1250 and 2450. Fig. 6 Contour plot of dynamic pressure of 3-bladed straight chord H-Darrieus turbine for blade angle: 900, 2100 and 3300.
CONCLUSIONS
Steady-state two-dimensional CFD simulations were performed using Fluent 6.0 software to analyze the flow physics of 3-bladed straight chord H-Darrieus wind turbine. From the present study, the following conclusions are summarized:
1. Static pressure decreases from upstream side to downstream side of the rotor. With increase in blade rotation, static pressure drop across the rotor increases thereby propelling the rotor in its power Fig. 5 Contour plot of static pressure of 3-bladed straight chord H- 0 0 stroke by creating useful pressure difference across Darrieus turbine having Al blades for blade angle: 90 , 210 and the blade. Static pressures are negative near the ends 3300. of the blades but the pressure at the exit of the computational domain is positive. Dynamic for the blades at 3300 positions (upstream side). This pressure is positive throughout the computational would have been caused due to the twisted shape of the domain as expected from the flow physics. blades. And it would result in the increased performance for the twist bladed turbines especially in the upstream side. Figure 7 shows velocity contour of the turbine for blade angles of 900, 2100 and 3300. The blade angles are to be counted starting from the left, i.e. upstream side and then moving in the clockwise direction. The velocity contour shows that there is a decrease of velocity magnitude from the upstream side to the downstream side across the turbine. The difference of velocity magnitude causes overall lift for the turbine. Figure 7 shows that velocity magnitude decreases from 17.7 m/s upstream to 8.97 m/s downstream. Now, for the blade at 3300 position, the velocity magnitude is very high on the immediate upstream of the blades due to high intensity of dynamic pressure. On the
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the turbine which would enhance power production for the three bladed turbine.
REFERENCES
Darrieus, G.J.M. (1931) Turbine having its rotating shaft transverse to the flow of the current, US Patent No 1 835 018. FLUENT. Fluent 6.2 documentation: user’s guide. 2005. Howell, R., Qin, N., Edwards, J. & Durrani, N. (2010) Wind tunnel and numerical study of a small vertical axis wind turbine. Renew. Ener. J. 35(4), 412–422 . Islam, M., Esfahanian, V., Ting, D.S.-K. & Fartaj, A. (2005) Applications of Vertical Axis Wind Turbines for Remote Areas. In: Proc. 5th Iran National Energy Conference, Tehran. Jiang, Z.-C., Doi, Y. & Zhang, S.-Y. (2007) Numerical investigation Fig. 7 Contour plot of velocity magnitude of 3-bladed straight chord on the flow and power of small-sized multi-bladed straight H-Darrieus turbine having Al blades for blade angle: 900, 2100 and Darrieus wind turbine. J. Zhejiang Univ. Sci. A 8(9), 1414–1421. 3300. Masson, C., Ammara, I. & Paraschivoiu, I. (1997) An aerodynamic method for the analysis of isolated horizontal-axis wind turbines, Int. J. of Rotating Machinery, 3(1), 21-32. Mertens, S. (2003) The energy yield of roof mounted wind turbines. 2. There is a decrease of velocity magnitude from J. Wind Engg. 27(6), 507–518. the upstream side to the downstream side across Tangtonsakulwong, J. & Chitsomboon, T. (2006) Simulation of flow over a 3-blade vertical axis wind turbine. In Proceedings: the 2nd the turbine as the energy from wind is extracted Thailand national energy conference, Thailand, July, 2006. by the turbine. Versteeg, H.K. & Malalasekera, W. (1995) An introduction to computational fluid Dynamics, the finite volume method. In: Longman Scientific & Technical, New York, 132. 3. The blade twist at the trailing ends creates circulations that interact with the blades in a direction opposite to the direction of rotation of
Journal of Urban and Environmental Engineering (JUEE), v.7, n.1, p.151-156, 2013 Journal of Urban and Environmental Journal of Urban and E Engineering, v.7, n.1, p.157-163 Environmental Engineering ISSN 1982-3932 J www.journal-uee.org E doi: 10.4090/juee.2013.v7n1.157163 U
ANAEROBIC EFFLUENT POST-TREATMENT APPLYING PHOTOLYTIC REACTOR PRIOR TO AGRICULTURAL USE IN BRAZILIAN SEMIARID REGION
José Tavares de Sousa¹, Geralda Gilvânea Cavalcante Lima¹, Wilton Silva Lopes¹, Eclésio Cavalcante Santo² and José Lima de Oliveira Júnior³
1 Department of Sanitary and Environmental Engineering of the State University of Paraíba ² Master in Science and Environmental Technology by the State University of Paraíba ³ Department of Environmental Engineering of the Federal Institute of Ceará
Received 21 August 2012; received in revised form 19 January 2013; accepted 24 June 2013
Abstract: This work applied a Compact System consisting of a Reactor Up flow Sludge Blanket (UASB) in conjunction with s Submerged Anaerobic Filter containing polyurethane cubes as support media, followed by a Solar Photolytic Reactor. The compact anaerobic system produced a clarified effluent with low concentration of organic matter, especially dissolved (20 mg.VSS/L), and free of helminthes eggs. These low concentrations of suspended solids facilitated photolytic disinfection process producing a good quality final effluent, of which 90% of the samples were thoroughly disinfected, while the other fraction showed concentration of Thermotolerant Coliform (TTC) at or below 100 . + . -3 CFU/100 mL and high concentrations of nutrients (48 mgNH4 -N/L and 6.4 mg PO4 - P/L) enabling the use of irrigation for productive purposes. Another advantages of the compact anaerobic treatment consisted of low sludge production, and relatively simple operation without energy consumption. These advantages results in a significant reduction in operational costs of sewage treatment, and, indeed, an outlet for developing countries in tropical climate.
Keywords: Anaerobic system; post-treatment; photolytic reactor; removal of pathogenic organisms.
Correspondence to: José Tavares de Sousa. E-mail: [email protected]
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INTRODUCTION When the destination is the reuse of wastewater in agriculture, necessarily, there is demand for removal or Access to sanitation can be understood as an indicator inactivation of pathogenic organisms like viruses, of a society development state. The universalization and bacteria, protozoa and helminthes, which create serious improvement in quality of sanitation services can be public health problems affecting workers in plantations considered as one of the biggest challenges of the as well as consumers of these cultures (Sousa et al., country, requiring an investment of 178 billion dollars 2009). over the next 20 years (UNDP, 2004). The microorganisms present in domestic wastewater Treating sewage properly, with secondary treatment are usually vulnerable to heat and ultraviolet radiation. followed by a tertiary one, like filtration and Once the sun is a free available source of heat and disinfection for production of sanitary quality effluent radiation it can be used as a source of UV disinfection required by the World Health Organization can be too processes. So, one can use photolysis process via UV expensive and difficult to implement, especially in for effluent disinfection, especially in semiarid region of developing countries. From a practical point of view Northeast Brazil, where the sunshine lasts an average of searching new technologies or adapt existing ones is a 2,800 h/year (Sousa et al., 2005). desirable goal in order to deal more economical and In this context, this study propose was to apply an environmentally with the large amount of sewage anaerobic treatment of domestic sewage using system generated by urban and suburban populations. composed by a compact anaerobic UASB combined The application of anaerobic treatment systems is of with anaerobic filter and effluent post-treatment in Solar great importance, as they allow the removal of organic Photolytic Reactor. It is understood as a low-cost matter without the need for energy consumption technology able to produce effluent of good sanitary required in aerobic processes. Other advantages include: quality, low organic load and considerable low production of solid methane formation (which can concentration of nutrients. be recovered) and disposing of equipment for aeration.
Among the major technological advances in the MATERIAL AND METHODS application of anaerobic digestion processes in wastewater treatment is the development of the UASB, The experiment took place at the station of Biological especially for application in tropical and subtropical Treatment of Sewage (EXTRABES) located in an area countries, where the temperature stays above 20oC. belonging both to the Company of Water and Sewers of Their efficiency is related to the flow direction and Paraíba state (CAGEPA) and the State University of configuration (presence of three phase separator), which Paraíba in Campina Grande, Paraíba State, with altitude allows longer cell retention, while providing an of 550 m. adequate stirring and mixing between the affluent and The municipal wastewater used during the the sludge blanket Foresti et al., 2006). experiment was captured by a submersible pump The UASB reactor consists of a low cost alternative installed in an inspection well from the CAGEPA’s in the treatment of domestic sewage, providing a sewer Interceptor Pipe. The sewage fed by gravity, removal of about 70% of BOD5 and low hydraulic through plastic hoses of 20 mm in diameter, a box of retention time (HRT) from 5 to 8 hours (Além 100 liters, where there was peristaltic metering pump Sobrinho; Kato, 1999). However, the disposal of with preset flow feeding system. effluents into water bodies requires post-treatment to The experimental system of wastewater treatment reduce or eliminate pathogens and reduce the illustrated in Fig. 1 was composed of two units. The concentration of nutrients like nitrogen and phosphorus.
Fig. 1 Schematic of anaerobic reactor followed by Solar Photocatalitic Reactor.
Journal of Urban and Environmental Engineering, v.7, n.1, p.157-163 Sousa, Lima, Lopes, Santo and Oliveira Júnior 159 first consisted of a compact system (hybrid) comprised (Amber type). The containers were removed from the of anaerobic coupled UASB and anaerobic submerged oven the same day of sampling, listed according to the filter with support medium made of cuboids plyurethane effluent collected and date of collection. The analysis synthetic fiber sponges, each cube with a volume of 2 was preceded immediately after collection. cm3, occupying 3% of the volume of filter media, built For helminthes eggs examination, it was used the in PVC with 20 cm diameter, effective height of 1.65 m modified method Bailenger (WHO, 1989). The and volume of 52 L, monitored with Hydraulic materials used for the analysis were: optical microscope Detention Time (HDT) of nine hours common objective with 10X and 40X brand MEIJI; The second unit consisted of a photolytic reactor, Centrifugal brand Sublime model BL 206; shaker-type solar parabolic cylindrical model (PTR, Parabolic Vortex brand Thermolyne Max Mix Plus model; Board through Reactor). The photolytic reactor consisted of a of McMaster; common pipettes; Volumetric pipettes, metal device about 70 cm by 180 cm in width and 76 Pasteur pipettes, tubes Nesseler; rack for Nesseler tubes; cm high, provided by a mobile adjustable aluminum buckets with capacity of 2 liters, and siphoning hose and rods manually adjusted to 15° every hour, so as to densimeter. The solutions used were: distilled water concentrate the sun’s rays by three half-parabolas of solution Triton X-100 and Tween 80, pH 4.5 buffer aluminum mounted below three glass tubes (Pyrex ®) solution; PA Ethyl acetate and zinc sulfate solution with with 1.50 m in length and 2.5 cm in diameter and density 1.18. volume of 2.205 L. The photolytic reactor operated in Alkalinity determinations were performed by the batch regime with a volume of 14.0 L during four hours method Kapp (1994) apud Buchau (1998), while all from 10:00 to 14:00 h, recognized as the period of other tests followed the recommendations of the highest incidence of solar radiation, and probably a Standard Analytical Methods (APHA, 1998) higher incidence of UV rays. The system was equipped Regarding the analysis of the photolytic reactor, with a container of equalization, and a centrifugal pump solar radiation intensity was measured with the aid of a with a flow rate of 11.620 L/min which recirculated the radiometer VLX Cole-Par Mer Instruments Co. 9811 effluent in batches of 4 hours. According to Eq. (1), the series with a photoelectric cell for direct measurement exposure time in the hydraulic photolytic process of UV radiation of 365 ± 2 nm, each 15minutes. For corresponded to 0.63 hours. Table 1 shows the main tests of photoreactivation the effluent was packaged in physical and operating of the system used: amber glass for 24 hours for subsequent analysis of Thermotolerant Coliforms (TTC).
(1)
hydraulic Exposure time in photolytic process Table 2. Efficiency average and standard deviation of the (hours); monitored parameters reactor volume (liters); Anaerobic system Parameters Efficiency wastewater volume treated (liters); Influent Effluent batch period (hours). (%) pH 7.2 ± 0.3 7.8 ± 0,3 - Raw COD (1): photolytic reactor was operated in batch, with a cycle of 4 h/d 380 ± 88 114 ± 48 70 The anaerobic system was powered by a pulse pump (mg O2/L) Filtrada COD with a flow rate of 5.8 L/h and hydraulic retention time 152 ± 50 85 ± 18 44 (HRT) of 9.00 hours, cell retention time of 90 d and (mg O2/L) TSS organic loading rate (OLR) applied of 1.52 kg COD/ m3 180 ± 88 22 ± 10 88 (mg/L) d. VSS 145 ± 58 20 ± 10 86 Samples for microbiological analysis of effluents (mg/L) (fecal coliform) were collected in sterile containers Turbidity - 21 ± 18 - (NTU) Table 1. Operational parameters of the studied systems Ammonium-N + 45 ± 12 48 ± 11 - Anaerobic Photolytic (mg NH4 -N/L) Parameters (1) Total Phosphorus system Reactor 8.4 ± 2.1 7.8 ± 2.1 - (mg P/L) Volume (L) 52.0 14.0 Orthophosphate 6.2 ± 1.7 6.4 ± 1.8 - (mg PO -3 –P/L) TDH (h) 9.0 4.0 4 Alkalinity 360 ± 58 400 ± 59 - Flow (L/d) 139.0 14.0 (mg.CaCO/L) C thermotolerant 3.4x106 2.1x105 93, 823 Volumetric organic (CFU/100mL) load (VOL) 1.52 (kg COD/m3 d) NTU: Nephelometric Turbidity Units.
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RESULTS AND DISCUSSION Table 3. Helminthes eggs Mean concentration and frequency found in affluent and effluent during the experimental period Anaerobic System Anaerobic System RW In Table 2 operational parameters of the anaerobic Species Effluent system are presented been acquired from 28 Eggs/L % Eggs/L Enterobius determinations for 210 d of operation including the 35 19,45 ND mean, standard deviation and removal efficiency. vermicularis The anaerobic compact system obtained removal of Ascaris lumbricoides 58 32,23 ND total COD and filtered of 70% and 44%, respectively Trichiuris sp 3 1,67 ND (Table 2). Santos (2010) using a similar support media, Entamoeba sp 8 4,45 ND Taenia sp 4 2,2 ND although applying separate operating reactors, UASB Ancilostoma sp 72 40 ND followed by anaerobic filter obtained removal of 72 and Total of eggs/L 180 100 ND 49% respectively. Busato and Pawlowsky (2005) ND: Not Detected obtained a removal efficiency in UASB followed by anaerobic filter of 72% been the complementary removal in the filter of 29%. Thus, the efficiencies Disinfection by Photolytic process presented by other researchers dealing with sewage in UASB anaerobic filter were similar. Table 4 shows values of 19 determinations of TTC Regarding the combined anaerobic filter, the limiting concentrations of the influent for four months operating factor for this technology has also been the choice of the photolytic reactor as well as data on the effluent alternatives for support media. In this case, the turbidity and variations of temperature, UV intensity polyurethane behaved as a promising material occurring and applied solar radiation dose. proliferation and fixation of microorganisms during the The average intensity of UV radiation applied in 19 monitoring process. However it was observed an initial batches monitored according to data presented in Table 2 accommodation of the support media during the system 4 ranged from 1.82 to 3.00 mW/cm . Elkarmi et al. feeding. The criteria and design parameters for hybrid (2008) confirmed that UV radiation ranging from 2.3 to 2 system (UASB and anaerobic filters in this setting are 2.7 mW/cm was sufficient to maintain an efficiency of not well defined, and still require further investigations. 99.9998% removal of E. coli present in water with high Despite all these difficulties, the fact is that the effluent turbidity of 16 NTU. The concentration of TTC in the 5 . -1 7 coming from the anaerobic system was free of influent ranged from 9.0×10 UFC 100 mL to 1.1. 10 . -1 helminthes eggs and presented a clarified appearance, CFU100 mL with removal efficiency of fecal coliform low concentration of organic matter, especially of 99.9999%. dissolved (20 mg VSS/L) and average turbidity of 21 The initial temperature of the influent varied from 25 NTU. These low concentrations of suspended solids to 28°C and the effluent after each batch of four hours facilitated the disinfection in photolytic process. per day with recirculation ranged from 34 to 49°C and an average turbidity of 21 NTU. The efficiency in the Helminthes Eggs Removal decay of pathogens to reduce turbidity exceeds 5 NTU (Elkarmi et al., 2008). With respect to helminthes eggs, 20 determinations The effluent presented good sanitary quality, with were performed for raw sewage and effluent from the 90% of the samples thoroughly disinfected while the anaerobic system. Table 3 shows the average other fraction showed a concentration of TTC concentration values (eggs/L) and frequency of organisms up to 100 CFU. 100 mL-1. It is worth helminthes eggs during the experimental period. mentioning that the variation in temperature was 25 to According to data from the effluent of the anaerobic 35°C (Table 4), less than the variations in the other system presented in Table 3, the removal of helminthes experiments (2549°C). According to some authors, the eggs in the anaerobic filter coupled to the UASB reactor temperature exerts a synergistic effect with UV, which was efficient because it is composed of a layer of alone seems unable to inactivate microorganisms support media made of polyurethane cubes with 2 cm (Elkarmi, et al., 2008). side, where has occurred the proliferation and Accordingly to data in Table 4, the penultimate attachment of microorganisms. The high surface area to experiment was submitted to the lower cumulative dose adherence, as well as the setup of polyurethane media 4 196 mWs.cm-2 and a higher standard deviation in was sufficient to provide good flow distribution, intensity (1.28), showing high variation in intensity performing filtering and percolation through the support compared to the others, probably because of media, allowing the removal of helminthes eggs also atmospheric attenuation periods with a lower stroke aided by decanting, because of the sizes and sufficient incidence, which led to a lower efficiency in eggs densities. disinfection, been, as Mamame (2008) affirmed, a disadvantage of using sunlight as a disinfectant agent.
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Only one from the 19 experiments presented in Disinfection Effect depending on the dose and Table 4 underwent to photoreactivation, was reactivated temperature by maintaining a population of surviving microorganisms to disinfection after 24 hours of rest Figures 3 and 4 were constructed from the geometric between 100 and 200 UFC/100 mL. This amount of mean of the determinations made during the experiment, reactivated TTC remained below the limit set by WHO dealing respectively with the bacterial decay in relation for unrestricted irrigation (WHO, 2006). This success to the applied dose of radiation and temperature can be attributed to the inactivation spectrum offered by occurred during the exposure time in the photolytic the sun in the disinfection process that damages not only reactor effluent. specifically the nucleus but other organelles and It is observed from Fig. 3 that the decay of bacteria proteins. Thermotolerant Coliforms was significant from a Figure 2 shows the behavior of TTC concentration applied dose around 3 000 m.W.s/cm2. The applied decay as a function of exposure time. It is observed that ultraviolet irradiation dose is a crucial parameter in during the first hour of exposure the same order of microorganism’s inactivation process. As the dose is the magnitude of 106 CFU/100 mL was maintained only product of radiation intensity by the exposure time, the occurring a significant decay after 140 minutes of inactivation can be achieved in the time interval smaller exposure time. This observation guided the exposure or larger depending on UV intensity (mW/cm2) at the time hydraulic for the effluent treated. exposure site.
Fig. 2 Bacterial inactivation with time variation from 10:00 am to 2:00 pm.
Fig. 3 Bacterial inactivation with the increase of solar radiation dose.
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Table 4. Thermo Tolerant Coliform (TTC) Influent and effluent Concentration and variation of temperature, radiation intensity and dose Radiation Intensity Temperature Influent Influent Turbidity (mW/cm2) Dose (CFU/100mL) (NTU) (mWs/cm2) Initial - Final Average Std. Dev. 9.0×106 10 28−49ºC 2.65 0.59 6010 1.1×107 14 26−45ºC 2.37 0.77 5365 9.9×106 9 25−46ºC 2.50 0.85 5670 9.2×106 14 26−48ºC 2.46 0.7 5579 9.0×105 8 25−49ºC 2.50 0.83 5670 8.0×106 33 26−48ºC 2.21 0.83 5012 9.0×106 18 25−48ºC 2.66 0.89 6032 4.8×106 14 26−47ºC 1.89 0.68 4268 9.0×105 15 25−46ºC 3.00 1.00 6804 4.3×106 18 26−47°C 2.22 1.00 5035 8.0×106 16 25−45ºC 1.85 0.86 5443 9.2×106 18 26−49ºC 2.16 0.66 4899 8.0×106 31 25−47ºC 1.82 0.63 4241 9.4×106 32 25−47ºC 2.58 0.89 5851 7.9×106 23 25−45ºC 2.48 0.78 5624 9.0×105 21 25−49ºC 2.26 0.80 5125 4.8×106 15 25−45ºC 2.43 0.91 5511 8.7×106 36 25−34ºC 1.85 1.28 4196 8.3×106 38 26−35°C 2.00 0.89 4536
Fig. 4 Bacterial inactivation with Temperature
The effect on the effluent disinfection by UV disappeared with the evolution of chlorination. radiation on microorganisms is a function of dose However, for semi-arid region, application of solar UV intensity, temperature and turbidity. Even with the disinfection of effluent with low concentration of monitoring of the samples batch time, the radiation suspended solids should be encouraged. Concerning the intensity varied significantly affecting the exposure photo reactor, the material must have high time, and therefore, influencing the dose. transmissivity of UV rays and durability. The ordinary As shown in Fig. 4 for temperature above 40°C was glass is not suited because of iron´s substance present in observed an increase in the inactivation rate, indicating its constitution and also UV rays absorbance. Therefore, a synergistic effect for TTC decay that, in turn, occurred a better suited glass should be those with low iron when the temperature reached 45°C. According to some content, for example, Borosilicate. authors, the temperature exerts a synergistic effect with UV, which means that alone, the UV is not able to CONCLUSIONS inactivate microorganisms, but its effect is amplified significantly for temperatures above 40°C (Abu- The compact anaerobic system produced a clarified Ghararah, 1997; Meierhof et al. 2002; Elkarmi, et al., effluent free of helminthes eggs, presenting also low 2008). concentration of organic matter, especially dissolved Although UV disinfection has been known since the (20 mg SSV/L). These low concentrations of suspended nineteenth century, its implementation has virtually solids facilitated the photolytic disinfection process,
Journal of Urban and Environmental Engineering, v.7, n.1, p.157-163 Sousa, Lima, Lopes, Santo and Oliveira Júnior 163 producing a good quality sanitary effluent, of which water and sludge treatment processes. Water Science. A.; n.24, v. 90% of the samples were thoroughly disinfected, while 1, p. 49 – 56. Busato, R., Pawlowsky, U. (2005). Desempenho de um filtro the other fraction showed TTC concentration equal or anaeróbio de fluxo ascendente como tratamento de efluente de less than 100 UFC/100 mL and high nutrient reator UASB: estudo de caso da ETE de Imbituva. (Performance . + -3 -1 concentration (48 mg NH4 -N/L and 6.4 mg PO4 -PL ) of an up flow anaerobic filter as a treatment of UASB reactor and can be used for irrigation for productive purposes. effluent: a case study of TEE Imbituva) Proc. Congresso The efficiency of solar disinfection of anaerobically Brasileiro de Engenharia Sanitária Ambiental, 23, 2005. Campo Grande-Brazil. pretreated sewage in the photolytic reactor can be Foresti, E., Zaiat, M., Vallero, M. (2006). Anaerobic processes as the affected by temperature, applied dose, turbidity and core technology for sustainable domestic wastewater treatment: local climatic factors, requiring longer time of exposure. Consolidated applications, new trends, perspectives, and The photoreactivation was insignificant, yet challenges. Reviews in Environmental Science and Biotechnology. v.5, p.3-19. remaining within the recommendations required by law. Elkarmi, A.;, Abu-Elteen, K., Al-Karmi, A. (2008). Disinfecting The temperature increase, in turn, positively affected the contaminated water with natural solar radiation utilizing a efficiency of disinfection. disinfection solar reactor in semi-arid region. Jordan Journal of The compact system with UASB conjugate with an Biological Sciences. Jordan, 1(2), 47-53. anaerobic filter followed by photolytic reactor requires Mamame, H. (2008). Impact of particles on UV disinfection of water and wastewater effluents: A review. Reviews in Chemical relatively simple operation without energy consumption, Engineering. Israel, 24,(2-3), 69- 111. resulting in a significant reduction in operational costs Meierhofer, R. et al. (2002). Solar water disinfection: A guide for of sewage treatment, and, indeed, a sustainable the application of sodis. SANDEC (Water & Sanitation in alternative for developing countries of tropical climate. Developing Countries) at EAWAG (Swiss Federal Institute for Environmental Science and Technology), Duebendorf – The times of exposure to ultraviolet radiation of 38 Switzerland: Ed. SKAT, n.6/ 02, 2002. minutes was sufficient to achieve the inactivation of Programa das Nações Unidas Para o Desenvolvimento – PNUD; TTC to 6 log units. It is noteworthy that the intensity of Relatório do Desenvolvimento Humano, 2004 (Human solar UV radiation ranged from 2.0 to 2.3 mW/cm². Development Report). Available at: Journal of Urban and Environmental Engineering, v.7, n.1, p.157-163 Journal of Urban and Environmental Journal of Urban and E Engineering, v.7, n.1, p.164-175 Environmental Engineering ISSN 1982-3932 J E www.journal-uee.org U doi: 10.4090/juee.2013.v7n1.164175 RETROFITTING OF REINFORCED CONCRETE BEAMS USING FIBRE REINFORCED POLYMER (FRP) COMPOSITES – A REVIEW Namasivayam Aravind1, Amiya K. Samanta2, D. K. Singha Roy2 and Joseph V. Thanikal1 1Department of Built and Natural Environment, Caledonian College of Engineering, Oman 2Department of Civil Engineering, National Institute of Technology Durgapur, India Received 6 February 2013; received in revised form 31 May 2013; accepted 06 June 2013 Abstract: Rehabilitation and strengthening of old structures using advanced materials is a contemporary research in the field of Structural Engineering. During past two decades, much research has been carried out on shear and flexural strengthening of reinforced concrete beams using different types of fibre reinforced polymers and adhesives. Strengthening of old structures is necessary to obtain an expected life span. Life span of Reinforced Concrete (RC) structures may be reduced due to many reasons, such as deterioration of concrete and development of surface cracks due to ingress of chemical agents, improper design and unexpected external lateral loads such as wind or seismic forces acting on a structure, which are also the reasons for failure of structural members. The superior properties of polymer composite materials like high corrosion resistance, high strength, high stiffness, excellent fatigue performance and good resistance to chemical attack etc., has motivated the researchers and practicing engineers to use the polymer composites in the field of rehabilitation of structures. This paper reviews fourteen articles on rehabilitation of reinforced concrete (RC) beams. The paper reviews the different properties of Glass Fibre Reinforced Polymer (GFRP) and Carbon Fibre Reinforced Polymer (CFRP) composites and adhesives, influence of dimensions of beams and loading rate causing failure. The paper proposes an enhanced retrofitting technique for flexural members and to develop a new mathematical model. Keywords: Flexural Strengthening; CFRP; GFRP; Epoxy Resins Correspondence to: N. Aravind, E-mail: [email protected] Journal of Urban and Environmental Engineering (JUEE), v.7, n.1, p.164-175, 2013 Aravind, Samanta, Singha Roy and Thanikal 165 INTRODUCTION Also to achieve expected load carrying capacity of FRP strengthened RC beam, premature failure, which occurs Externally bonded FRP composites may be laid on RC in a strengthened beam before reaching full composite structures using FRP and epoxy adhesives. FRP can be action, has to be avoided (Nadeem, 2009). retrofitted for any RC structural member like slab, beam, masonry wall or column. This paper deals with PREVIOUS RESEARCH WORK ON RC BEAMS an extensive review of literature on earlier work done in STRENGTHENED WITH FRP the light of different types of FRP composites, its dimensions, type of adhesives used, experimental Several investigations on strengthening of RC beams methodology conducted by various investigators so far. using different FRP composites and adhesives have been studied and discussed in this paper. Table 1 shows FRPC Properties and applications the summary of test results, types and dimensions of FRP and beams, types of loading and types of adhesives A polymer composite is a material which is composed used for RC beams modeling done by different of a polymer matrix or reinforcement and manufactured investigators. in the form of chopped strand or woven mat (Budinski, Hamid & Mohammad (1991) have studied 1998). Types of polymer composites are shown in Fig. experimentally the characteristics of five rectangular 1. beams, ‘A to E’ of cross section of size 205×455 mm and one Tee beam ‘F’ of web size 205×455 mm and Polymer composites flange of size 610×75 mm. All beams were retrofitted using GFRP plates of dimensions 150×6 mm cross Matrix Reinforcement section and a length of 4.26m at tension zone with epoxy resins. Beams were provided with different types Thermoplastic Thermosetting of tension and shear reinforcements. Beam ‘A’ designed as shear deficient beam according to American Concrete Institute (ACI) code, to study the effect of shear crack. Aramid Carbon fibres Glass fibres Ceramic Metal Two point load system at 610mm spacing was applied Low/High strength for all beams, to study the relationship between load and E-Glass S-Glass Carbon fibres deflection, load and strain in concrete, steel Fig. 1 Types of composites. reinforcement and GFRP plates for each beam. The FRP plate strengthened beams resist more loads and reduces During the year 1994, about 60% of the total crack width. An analytical model was developed based polymer composites consumption was used in the field on equilibrium of forces and compatibility of of aerospace constructions. Later on composite deformations to predict the strength of beam to compare materials were used for boat constructions and with the experimental values. It was suggested that the renovation works for buildings (Budinski, 1998). comparison study between analytical and theoretical At present, FRP composites are universally accepted values provide reasonable accuracy, however additional for repairs and rehabilitation of buildings due to the analytical study will be required to predict the strength availability of the same with superior mechanical of upgraded beams. properties. Also the Glass Fibre Reinforced Polymer Grace et al. (1999) has tested fourteen pre-cracked (GFRP) composites are easily available in the market beams including one control beam. GFRP and CFRP with less cost than Carbon Fibre Reinforced Polymer plates and three types of epoxy resins with different (CFRP) composites. tensile strengths were used for strengthening the beams. Although traditionally steel plates are used for Strength and ductility of FRP strengthened beams were retrofitting works despite its high density, corrosiveness, studied, both vertical and horizontal layers of FRP requirement of mechanical fasteners to get attached with plates were placed on bottom and sides of beams at concrete, FRP composites are popularly used. different orientations for experiments. Concentrated load was acting at mid span of the beam. Based on Failure modes of a strengthened beam experiments, the load carrying capacity has increased The failures modes of FRP strengthened RC beams are and deflection has reduced for strengthened beam over classified into four types such as, concrete crushing, control beam. For example, the load carrying capacity cover separation, debonding between FRP laminates of strengthened beam, ‘UG2-III’ with both horizontal and laminates separation (Au & Buyukozturk, 2013). and vertical layers of GFRP plates is almost two times Journal of Urban and Environmental Engineering (JUEE), v.7, n.1, p.164-175, 2013 Aravind, Samanta, Singha Roy and Thanikal 166 that of the control beam. Also it was mentioned that, strengthened beams. The progress of debonding started high value of factor of safety is to be taken in design, from the point of loading towards the supports. Analysis since all the FRP strengthened beams were subjected of interface relationship between concrete and laminates to brittle failure. Also the beam was strengthened with was done by finite element method. Moment-deflection vertical layers over entire span of the beam to resist relationships for strengthened beams calculated by FE diagonal cracks. analysis were moderately well, since during the Tarek & Al-Salloum (2001) have strengthened and analysis, the interfacial debonding of FRP from the tested the three beams with GFRP and two with CFRP beam is negligible. composites using epoxy resins and test results were Pannirselvam et al. (2008) tested nine beams out of compared with a control beam. One, 2 and 4 numbers of which six beams were strengthened with GFRP and layer of 1.3 mm GFRP and 1 and 2 layers of 1 mm three were controlled beams. A model was developed CFRP were used for externally strengthening beams. All with the data available from seven beams by General beams were reinforced with 310 mm diameter bars at Regression Neural Network (GRNN) technique using tension zone, 16 mm diameter bar at compression zone MATLAB and two beam results were used for testing and 2 legged 8 mm diameter stirrups at 100 mm c/c. The the model. Also varied tension reinforcement for beams developed equations based on ACI code for moment 1, 2 and 3 such as 0.419, 0.603 and 0.905 percent capacity of strengthened beams, thickness of FRP are respectively was studied. Two concentrated loads were theoretically verified with experimental values. Two applied on the beam at a spacing of 933 mm. Load and point loads with spacing 200 mm were applied for deflections at first crack, yield and ultimate levels are experiments. All beams were failed by concrete measured for all beams. 3 and 5 mm GFRP plates and crushing at compression zone. It was concluded that the epoxy adhesives were used for strengthening RC beams. flexural strength of strengthened beams using FRP First crack load was increased for beams by increasing laminates at tension zone, more than that of control thickness of plates. Yield strengths for strengthened beam. Outcome results based on computational model beams were increased by a maximum of 76.49 and which has been presented by the author were performed 111.79 percent for 3 and 5 mm thick plates. well in the prediction of experimental results. Jumaat & Alam (2008) also worked on three beams Abdelhady et al. (2006) has studied on the influence of dimensions 125×250×2000 mm such as A1, B1 & of hybrid FRP wrapping techniques on the reinforced C1. A1 was kept as control beam; B1 and C1 were concrete Tee beams. Seven beams were tested including strengthened by steel plate of dimensions one control specimen. CFRP, GFRP and both laminates 2.76×73×1900 mm and CFRP laminates of dimensions were provided at different locations, directions and 1.2×80×1900 mm respectively. Compression and shear connected with a beam by epoxy adhesives. The corners reinforcements were provided only on ends of a beam. of the beams are rounded at radius of 15 mm to fix ‘U’ Those dimensions were designed based on simplified wrap of thickness 0.117 and 0.135 mm for CFRP & stress block method of BS 8110. Steel plate and CFRP GFRP respectively. The beams were tested with two laminate (SikaCarboDur S812) were provided full point cyclic loads acting at a distance of 750 mm. The length off the beams to maximize the strengthening ultimate loads for strengthened beams are between 16.5 effects. From the experiments, it was found that the and 69.7 percent than controlled beam. Strain controlled beam A1 failed by flexure, while B1 failed compatibility approach was used for ultimate load by debonding followed by concrete cover separation predictions and integration of the curvature along the and the beam C1 failed by debonding. Experimental span for deflection calculations. Theoretical values were results were compared with the values obtained by finite compared with experimental values and it shows good element analysis. From the comparison study it was correlation. The characteristics of beams can be found that those two results were almost equal for determined by strain compatibility approach accurately. control beam, but failure loads for strengthened beams Chiew et al. (2007) focused on the experimental by finite element analysis were more than experimental work on two unstrengthened and ten flexurally results. The reason was, the FE analysis was done based strengthened beams using GFRP laminates. Total beams on assumption of bond between strengthening materials grouped into two, such as ‘A’ and ‘B’ based on points and concrete surface was perfect. of application of loads. Spacing between two point In another research Sundarraja et al. (2008) tested loads are 1000 mm and 400 mm for group A and B thirteen beams including five control beams. All beams respectively. Number of layers and length of GFRP were divided into three sets based on wrapping such as laminates were varied for strengthened beams. Epoxy five control beam ‘C’ without wrapping, four beams resin adhesive was used for attaching GFRP with beam. with vertical strips ‘V’ and four ‘U’ wrap strip beams. This experimental study shows that, two unstrengthened For ‘V’ group beams, strips were provided at a width of beams were failed by flexure and strengthened beams 15 mm and c/c spacing of 45 mm. The widths of these were failed by laminates debonding. The strength and GFRP strips were designed based on ACI stiffness were increased significantly for flexurally recommendations. GFRP composites were connected Journal of Urban and Environmental Engineering (JUEE), v.7, n.1, p.164-175, 2013 Aravind, Samanta, Singha Roy and Thanikal 167 with beams using epoxy resins and hardener. The plates were connected at sides and bottom of the beams. wrapped beams resist more load than controlled beams Multiple cracks were developed for group two beams by and the vertical GFRP strips prevent diagonal cracks preloaded technique (B5-B8). For beam B5 two shallow significantly. It was concluded that the notches were provided at bottom. B6 and B8 were un- recommendations provided by ACI code can be used for notched and GFRP plates were provided at bottom of design of strips for retrofitted works. the beams. B7 was un-notched but flexural or shear Amer & Mohammed (2009) analyzed theoretically cracks were developed. All beams were anchored with by finite elements methods by ANSYS package on FRP ‘U’ shaped FRP plates. A mathematical model has been retrofitted beams. Experiment investigated six shear developed for determination of stress strain distribution deficient rectangular beams of cross section along the FRP corresponding to number of secondary 150×250 mm including two control beams B1 and B2. cracks and major cracks. Beams were strengthened Epoxy resins were used to retrofit Carbon or Glass fiber using 0.22 mm thick GFRP composites with epoxy reinforced polymers with RC beams. For B1C-90 type, resins. Two point loading system is applied at a loading one layer of 1.6 mm CFRP laminates was provided span of 300 mm. All beams were failed by FRP perpendicular to the longitudinal axis of a beam. B1G- debonding. The average load carrying capacity of 90 beam was similar to previous type but two layers of second group beams are much more than that of beams 2.1 mm GFRP were used. For B2C-90 type, one layer of from first group. Developed mathematical model has 0.18 mm CFRP composites was wrapped perpendicular been validated by the data which are available from to the longitudinal axis of a beam. For B2C-90-0 type, experimental results, and it revealed that calculated two layers of 0.18 mm CFRP composites were wrapped stress and strain values using mathematical model were on two directions such as 90° and 0° to the longitudinal matched well with the experimental values. axis of a beam. Effect of directions of FRP composites Yasmeen et al. (2011) investigated twelve beams on RC beams were studied, since it is an orthotropic which were divided into two groups such as RF and RS. material. The ultimate shear strength values of In RF group beams, reinforcements were deficient in retrofitted beams by experimental values were good flexure and shear and the beams were flexurally agreement with shear strength analyzed by finite strengthened by 50 mm CFRP plates at soffit of the element model, concluding that the carbon fibres were beam by varying its lengths after preloading. In RS resisting more load than glass fibres retrofitted with group, the beams were shear strengthened by 50 mm beams. CFRP strips at sides of the beam at a spacing of 100 mm Nadeem (2009) experimentally investigated six c/c and it is not provided at middle third 520 mm beams on strengthening of RC beams in flexure and portion. Out of which four beams were tested as control shear using 1 mm thick CFRP sheet and epoxy resins. beams, two from RF and two from RS group. Thickness The beams were categorized into two groups such as 1 of CFRP used is 1.2 mm and number of layer is 1 for and 2. Group 1 beams were weak in flexure and strong both beam groups and epoxy resin is used to fix the in shear and group 2 beams were weak in shear and beam. Two point loads were applied at a distance of strong in flexure. BCF and BCS were control beams 520 mm. After loading, it has been noted that crack from each group. For BFS-1&2 beams, one layer of width of the strengthened beam has been decreased by CFRP was fixed at bottom and for BFS-2, additional comparing control specimen. All the strengthened ‘U’ wrap attached at ends of a beam. For BSS-1&2 beams were failed by brittle and followed by sudden beams, vertical and inclined CFRP strips were attached CFRP debonding from the concrete. Control beams RF on the sides of a beam. Concentrated loads at a distance and RS were failed by flexure and shear. Two equal of 500 mm were applied on all beams. It was found that, beams were casted in each set and the mean value has BCF, BCS and BFS-2 were failed by flexure, shear and been considered as maximum load. Also it was found concrete crushing at compression zone respectively. that load carrying capacity of strengthened beams was Remaining three beams were failed by debonding of increased from 7 upto 33 percent in flexure and about laminates. Also it was observed that beam with CFRP 23 percent in shear. sheets at bottom & ‘U’ shaped anchorages resisted more Recently, Heshmi & Al-Mahaidi (2012) have flexural load than BFS-1, and beam with inclined strips presented an experimental work on RC beams resisted more shear than vertical strips. retrofitted with CFRP textile and fabrics using cement Pan et al. (2010) examined eight beams to study the based adhesives at high temperature. Testing of seven effect of flexural and shear cracks on FRP debonding. beams at cross sectional area of 120×180 mm was done. The beams were grouped into two, on first group, The cement based adhesives consists of OPC, micro opening in the shape of notches developed at tension cement at ratio of 1:4, super plasticizer and silica fume. zone along the length of the beam to avoid the The beams were tested at two types such as beams secondary cracks in the shear or flexural portion (B1- subjected to high temperature at constant service load B4). Single notch for beams B1, B2 and double notches and failure load at constant temperature. The reinforced for beams B3, B4 were provided at bottom and GFRP concrete beams retrofitted using epoxy adhesives were Journal of Urban and Environmental Engineering (JUEE), v.7, n.1, p.164-175, 2013 Aravind, Samanta, Singha Roy and Thanikal 168 failed by CFRP delamination at a temperature of 462°C deformations, equations for moment capacity of and performed similar to normal beam. On the other strengthened beams. Also Sundarraja et al. (2008) has hand, beam retrofitted using cement based adhesives has designed thickness of FRP laminate based on ACI code, resisted 844°C and this value is almost equal to the while Abdelhady et al. (2006) has used strain failure temperature of RC beams. The performances of compatibility approach for ultimate load predictions and beams such as crack pattern and strain distribution were deflection calculations. theoretically determined by finite element analysis and values were compared with the test results, reveals that PROBLEMS OF STRENGTHENING RC BEAMS the two results are closely correlated. Most recently Dong et al. (2013) has conducted test The study indicates that researchers have used FRP on fourteen beams divided into two groups such as plane laminates at different number of layers. Authors flexural (CR) and flexural shear strengthening (SR) (Hamid & Mohammad, 1991; Pannirselvam et al., 2008; using FRP sheets. A study on the effect of beam size Jumaat & Alam, 2008; Sundarraja, 2008; Yasmeen et and concrete cover to the reinforcements on the flexural al., 2011; Heshmi & Al-Mahaidi, 2012) have used one strength of strengthened beam was conducted. Concrete layer of laminates, authors (Amer & Mohammed, 2009; grades are not specified for CR group beams and it is Jinlong et al., 2010; Jiangfeng et al., 2013) have tried up common for that group, since beams were tested with to two layers of laminates, while authors Abdelhady et varying cover thickness and reinforcement percentage. al. (2006) and Sing et al. (2007) has attached three 28 days compressive strength for five beams of SR layers and authors Grace et al. (1999) and Tarek & Al- group was 22.8 MPa and two beams of same group was Salloum (2001) used upto four layers. 31.3 MPa. One layer of GFRP sheet with size According to ACI code assumptions, the bond 1500×50×0.273 mm and two layers of CFRP sheets of between laminates and concrete surface is perfect (ACI same length and width and 0.111 mm thickness were 440.2R-08). But most of the cases discussed in failure applied on bottom and sides of the beams. Two point modes of a strengthened beam, the failure of beams load system were applied on beams at a spacing of occurred due to debonding of laminates from concrete 500 mm. While loading, three numbers of LVDT were surface. In those cases, the beams failed by premature fixed at bottom of beams at different locations to failure which means, beams failed under the initial load. measure deflections. Experimental results show that, Also it has been noticed that, failure due to debonding ultimate loads for flexural strengthened beams increased of laminates occurs for beams retrofitted only at the between 41 and 125 percent over control beam and bottom. shear capacity of strengthened beams increased by 31 From theoretical analysis, the researchers have used and 74 percent. Based on existing data from previous only one tool for model development such as either studies, theoretical values were calculated and finite element analysis or neural network. correlated with experimental values. PROPOSED METHOD OF STRENGTHENING COMMENTS ON THE PRESENT STATE OF THE RC BEAM ART. To overcome the problem discussed in this paper, in the The above review of literatures on the field of proposed work, FRP composites are used to develop a strengthening of RC beams show that the researchers new profile and investigations for its physical have tried GFRP, CFRP or hybrid laminates with dimensions and structural behaviors, in flexural different thicknesses and number of layers. Most of the members. FRP laminates will be provided with full research works have compared the experimental values length of the beam to take into account shear and with theoretical values. Out of fourteen papers, for bending. To avoid premature failure, FRP laminates are theoretical analysis, Pannirselvam et al. (2008) have provided at bottom and are extended to the sides also. used General Regression Neural Network (GRNN) Most of the authors have used epoxy resins for attaching technique using MATLAB neural network, (Amer & FRP laminates with concrete surface due to its superior Mohammed, 2009; Hashemi & Al-Mahaidi, 2012; property by comparing other adhesives. The same resins Jumaat & Alam, 2008) and Sing et al. (2007) have used will be used for proposed work. Thirteen authors out of finite element analysis, in which (Hamid & the reviewed literatures have used two point load system Mohammad, 1991) has developed analytical model for their experimental setup. based on equilibrium of forces and compatibility of Journal of Urban and Environmental Engineering (JUEE), v.7, n.1, p.164-175, 2013 Aravind, Samanta, Singha Roy and Thanikal 169 Table 1. Summary of test results, types & dimensions of FRP and beams, type of loading and type of adhesive used for RC beams Author (year) / numbers Load type Beam ID Type of No. of layers FRP Concrete Reinforcement details Adhesive Failure load & size of beam nos. x / load Fibers /type or thickness grade Zone-Nos.× mm ø and type (kN) Type of clear span x b x D (mm) spacing location tf (mm) (MPa) stirrups mm ø @ mm failure/Remarks (mm) c/c or Nos. Hamid & Mohammad, Two point A (R) GFRP 1/T 6 35 T–3×25&C–2×13 Epoxy 300/Concrete crushing (1991) / load/ 610 B (R) GFRP 1/T T–2×25&C–2×13 250/Debonding 5(Rect.)×4570×205×455 C (R) GFRP 1/T T–2×13&C–2×13 182/Concrete failure & 1(Tee-beam) D (R) GFRP 1/T T–2×25&C–2×13 270/Cover separation ×4570×(205×455 E (R) GFRP 1/T T - 0&C–2×13 64 /Premature failure overall web) ×(610×75 F (Tee) GFRP 1/T T–2×25&C–3×13 300/Debonding flange) Grace et al. (1999) / One point CF-I CFRP 1/H 5 48.26 T–2×16, C–2×16 Epoxy Type 104.5/FRP Rupture 14 × 2743 × 152 × 292 load at CFS-I CFRP 2/H&V 5 & stirrups 8 mm ø at I, II, III, IV 110.3/FRP Rupture mid span CFS-II CFRP 2/H&V 13 152 mm c/c for all with 108.9/FRP Rupture UG1-III GFRP 4/2H&2V 10 beams different 164.5/FRP Rupture UG2-III GFRP 4/2H&2V 10 tensile 177.9/Concrete crushing BG1-IV GFRP 1/T & sides 13 strength 80.0 / FRP Rupture BG2-IV GFRP 2/T & sides 13 94.7 / Bond failure BG3-IV GFRP 3/T & sides 13 92.5 / Bond failure BG2-IV- GFRP 2/T & sides 13 142.2 / FRP Rupture E4 BG2-IV- GFRP 2/T & sides 13 129.0 / FRP Rupture E1 CP1-V CFRP 1/T 13 110.3 / Shear failure CP2-V CFRP 1/T+(1/4) 13 120.1 / Shear failure sides CP3-V CFRP 1/T+(1/2) 13 131.2 / Shear failure sides Tarek & Al-Salloum Two point F0 Control - 0 - 37.5 T–3×10, C–1×6 Epoxy 35.31 (2001) / load/ 200 FG1 GFRP 1/’U’ wrap 1.3 & stirrups 8 mm ø at 70.4 All beams failed 6 × 2050 × 150 × 200 FG2 GFRP 2/’U’ wrap 1.3 100 mm c/c for all 82.4 by concrete FG4 GFRP 4/’U’ wrap 1.3 beams 105.9 crushing FC1 CFRP 1/’U’ wrap 1.0 81.9 at top FC2 CFRP 2/’U’ wrap 1.0 103.1 Abdelhady et al. Two point F00 Control - CFRP/0.117 25 T–2×16&C–2×10 Epoxy 100 /Ductile failure (2006) / 7 × 3000 × cyclic F01 CFRP 2/at bottom GFRP/0.135 6@150 for flanges 116.5/CFRP rupture (Tee-beam) load / 750 10@150 for web ×4570×(160×300 F02 CFRP+GFRP on sides + 127.2/GFRP debonding overall web) × 3/at bottom (460×60 flange) F03 CFRP+GFRP on sides +3/at 117.3/Rupture of CFRP bottom + GFRP F04 GFRP 3/at bottom 125.25/CFRP rupture F05 GFRP 2/different 169.7/GFRP debonding orientations F06 CFRP+GFRP at bottom + 110.25/Rupture of CFRP on sides + GFRP Journal of Urban and Environmental Engineering (JUEE), v.7, n.1, p.164-175, 2013 N.Aravind, Amiya K. Samanta, D. K. Singha Roy and Joseph V. Thanikal 170 Author (year) /numbers Load type / Beam ID Type of No. of layers FRP Concrete Reinforcement details Adhesive Failure load & size of beam nos. x load spacing Fibers /type or location thickness grade Zone-Nos.× mm ø type (kN)/Type of clear span x b x D (mm) tf (mm) (MPa) and stirrups mm ø @ failure/Remarks (mm) mm c/c or Nos. Sing-Ping Chiew et al. Two point load/ A1 GFRP 0 - 41.4 T–2×16 Epoxy 163 /Flexure (2007) / 12 × 2600 × A-1000 C–2×10 A2 GFRP 1/T, L – 2.5m 1.7 203.5 /Debonding 200 × 350 & B – 400 and stirrups 10 mm ø A3 GFRP 2/T, L – 2.5m 3.4 219.25/Debonding mild steel at 150 mm A4 GFRP 3/T, L – 2.5m 5.1 c/c 238.5 /Debonding A5 GFRP 1/T, L – 2.2m 1.7 196 /Debonding A6 GFRP 1/T, L – 1.9m 1.7 204.75 /Debonding B1 GFRP 0 - 167.75 / Flexure B2 GFRP 1/T, L – 2.5m 1.7 201 /Debonding B3 GFRP 2/T, L – 2.5m 3.4 209 /Debonding B4 GFRP 3/T, L – 2.5m 5.1 243.25 /Debonding B5 GFRP 1/T, L – 2.2m 1.7 198 /Debonding B6 GFRP 1/T, L – 1.9m 1.7 200.25/Debonding Pannirselvam et al. Two point load/ B1 GFRP 0 - 23.54 T-0.419% Epoxy 34.34 (2008) / 9 × 2800 × 933 B2 0 - T-0.603% 41.69 150 × 250 B3 0 - T-0.905% 63.77 Deflection at first B1F3 1/T 3 T-0.419% 58.86 crack, yield, B2F3 1/T 3 T-0.603% 73.58 ultimate B3F3 1/T 3 T-0.905% 78.48 deflections are noticed B1F5 1/T 5 T-0.419% 63.77 B2F5 1/T 5 T-0.603% 88.29 B3F5 1/T 5 T-0.905% 105.46 Jumaat & Alam Two point load/ A1 - 0 - 30 T–2×12, C–2×10 Sika-dur 80.59 / Flexure (2008) / 700 Control & stirrups 6 mm ø at 3 × 2000 × 125 × 250 B1 Steel 1/T 2.76 75 mm c/c for all 104.3/ Debonding + cover plate beams separation C1 CFRP 1/T 1.2 123.9/Cover separation Sundarraja et al. Two point load/ C1 - 0 1 20 T–2×10, Epoxy 49 / Shear (2008) / 300 C–2×8&6@75 13 × 1000 × 100 × 150 C2 GFRP 0 T–2×10&6@75 47.5/ Shear V2 GFRP 1/Wf-15/Sf-45 T–2×10&6@75 48.1/ Concrete crushing U2 - 1/Wf-15/Sf-45 T–2×10&6@75 50.2/ Concrete crushing C3 GFRP 0 T–2×10, 42 / Shear C–2×8&6@150 V3 GFRP 1/Wf-20/Sf-45 T–2×10, 49 / GFRP tearing C–2×8&6@150 U3 - 1/Wf-20/Sf-45 T–2×10, 50.5/ Concrete crushing + C–2×8&6@150 flexure C4 GFRP 0 T–2×10&–2×8 32 / Shear V4 GFRP 1/Wf-40/Sf-45 T–2×10&C–2×8 59 / GFRP tearing U4 - 1/Wf-40/Sf-45 T–2×10&C–2×8 52.3/ GFRP rupture + concrete crushing C5 GFRP 0 T–2×10, 37 / Shear C–2×8&6@75 V5 GFRP 1/Wf-20/Sf-45 T–2×10, 51 / Flexure C–2×8&6@75 U5 GFRP 1/Wf-20/Sf-45 T–2×10, 50.1/ Concrete crushing C–2×8&6@75 Journal of Urban and Environmental Engineering (JUEE), v.7, n.1, p.164-175, 2013 Aravind, Samanta, Singha Roy and Thanikal 171 Author (year) Load type / Beam ID Type No. of layers /type or FRP Concrete Reinforcement details Adhesive Failure load /numbers & size of load spacing of location thickness grade Zone-Nos.× mm ø and type (kN) / Type of beam nos. x clear span (mm) Fibers tf (mm) (MPa) stirrups mm ø @ mm failure/Remarks x b x D (mm) c/c or Nos. Amer & Mohammed, Two point B1 0 - 27.54 T–2×13&C–2×10 Epoxy 69 Experimental ultimate (2009) / 6 × 2440 × load/1700 loads have been B1C-90 CFRP 1/Uni directional 1.6 27.54 T–2×13&C–2×10 125 150 × 250 compare with numerical loads and BIG-90 GFRP 2/Uni directional 2.1 27.54 T–2×13&C–2×10 116 mode of failure not discussed. B2 - 0 - 31 T–2×25&C–2×9 416 Stirrups 10 mm ø at 600 mm c/c used for B2C-90 CFRP 1/90° to LA 0.18 31 T–2×25&C–2×9 435 B1 type beams & 9 mm ø at 300 mm c/c B2C-90-0 CFRP 2/1 layer at 90° & 1 0.18 31 T–2×25&C–2×9 445 used for B2 type layer on both sides of beams web 0° to the LA Nadeem (2009) / Two point BCF - 0 - 35 T–3×14&C–1×6 Epoxy 197.2 / Flexure 6 × 2000 × 200 × 300 load/ 500 Control BFS-1 CFRP 1/T 1 T–3×14&C–1×6 241.5 / Debonding BFS-2 CFRP 1/T+1/U wrap 1 T–3×14&C–1×6 255.2 / Concrete crushing at top BCS - 0 - T–3×20&C–1×6 81.98 / Shear Control BSS-1 CFRP 1/Vertical strips on 1 T–3×20&C–1×6 95.97 / Debonding sides BSS-2 CFRP 1/Inclined 1 T–3×20&C–1×6 111.01 / Debonding strips on sides and stirrups 10 mm ø at 100 mm c/c for first 3 beams & 6 mm ø at 150 mm c/c for remaining 3 beams Jinlong et al. (2010) / Two point B1 GFRP 2/T 0.22 42.9 T–2×10 Epoxy 28.43 8×1800×150 × 200 load/ 300 L-1.7 m 8@14Nos. B2 GFRP 27.69 For all beams B3 GFRP 27.71 All beams are failed B4 GFRP 27.52 by FRP debonding B5 GFRP 79.61 B6 GFRP 77.00 B7 GFRP 76.34 B8 GFRP 75.31 Yasmeen et al. (2011) Two point 2×RF Control 0 - 29 RF Epoxy 118 / flexure / 12×1560× 150 × 300 load/ 520 T–2×12, 2×RF1 CFRP 1/L-1.56m, b-50 1.2 C–2×10 & 6@100 166 / debonding 2×RF2 CFRP 1/L-1.04m, b-50 1.2 RS 142 / debonding T–2×18, 2×RF3 CFRP 1/L-0.52m, b-50 1.2 128 / debonding C–2×10 & 6@400 2×RS Control 0 - 220 / shear 2×RS1 CFRP 1/Wf-50/Sf-100 1.2 270 / debonding Journal of Urban and Environmental Engineering (JUEE), v.7, n.1, p.164-175, 2013 Aravind, Samanta, Singha Roy and Thanikal 172 Author (year) Load type / Beam ID Type of No. of layers /type FRP Concrete Reinforcement Adhesive Failure load /numbers & size of load Fibers or location thickness grade details type (kN) / Type of beam nos. x clear span spacing tf (mm) (MPa) Zone-Nos.× mm ø Failure / Remarks x b x D (mm) (mm) and stirrups mm ø @ mm c/c or Nos. Heshmi & Al-Mahaidi, Two point Control-27 - 1/T Not 57 T–2×10 - 65.7/Steel yielding at 876°C (2012) load/ 200 -HT & L-1.16m Specified C–2×8 & 10 @ 125 / 7 × 1300 × 120 × 180 ESF-38-HT CFRP For all beams Epoxy 90.7/Concrete crushing at 428°C Fabric ESF-38-HT CFRP Epoxy 90.7/Concrete crushing at 496°C Fabric MTF-38-HT CFRP Mortar 90.8 / FRP debonding & rupture at Textile 846°C MTF-38-HT CFRP Mortar 90.8 / FRP debonding & rupture at Textile 855°C MTR-39-HT CFRP Mortar 94.9 / FRP debonding & rupture at Textile 841°C MTR-39-HT CFRP Mortar 94.9 / FRP debonding & rupture at Textile 832°C Jiangfeng et al. (2013)/ Two point CR1 Control 0 - Cc-25 T–0.49% N 54.30 / Flexure / 14×1500× load/ 500 150×250 150×250 CR2 CFRP 1/T&U anchor at 0.111 Cc-25 T–0.49% 76.93 / FRP rupture + flexure supports 150×250 CR3 CFRP 2/T&U anchor at 0.111 Cc-25 T–0.49% 93.66 / CFRP rupture + flexure supports 150×250 CR4 CFRP 2/T&U anchor at 0.111 Cc-25 T–0.49% 84.39 / CFRP debonding supports +shear 150×250 CR5 CFRP 2/ T&U anchor at 0.111 Cc-25 T–0.95% 121.7 / CFRP debonding supports +flexure 150×300 CR6 CFRP 2/ T&U anchor at 0.111 Cc-25 T–0.40% 95.89 / CFRP rupture + flexure supports 150×250 CR7 CFRP 2/T&U anchor at 0.111 Cc-35 80.45/ CFRP debonding supports T–0.51% +flexure 150×300 SR1 Control 0 - 22.8 S–0.25% 111.49/ Shear 150×300 SR2 GFRP 1/’U’ shape 22.8 S–0.25% 146.20/ Flexure configuration 0.273 150×300 SR3 CFRP 2/ diagonal ’L’ 0.111 22.8 S–0.25% 187.12/ CFRP rupture + flexure shape configuration 150×300 SR4 CFRP 2/ diagonal ’L’ 0.111 22.8 S–0.38% 187.74/ CFRP rupture + flexure shape configuration 150×250 SR5 CFRP 2/ diagonal ’L’ 0.111 22.8 S–0.25% 158.49/ CFRP debonding shape +shear configuration 150×300 SR6 Control 0 - 31.3 S–0.25% 115.81/ Flexure 150×300 SR7 CFRP 2/ diagonal ’L’ 0.111 31.3 S–0.25% 193.35/ CFRP rupture + flexure shape configuration D: Overall depth; b: Width or breadth; R: Rectangular in cross section; T: Tension reinforcement; C: Compression reinforcement / Hanger bars; N: Not mentioned; H: Horizontal; V: Vertical; F is Flexure; S is Shear; L is Length of FRP; Wf : Width of strip; Sf : Spacing between strips; ESF: Epoxy+ Fabric; MTF: Mortar + Textile; MTR: Mortar + Textile; HT: High temperature; Cc: Concrete cover in mm; LA: Longitudinal axis; E: Epoxy. Journal of Urban and Environmental Engineering (JUEE), v.7, n.1, p.164-175, 2013 N.Aravind, Amiya K. Samanta, D. K. Singha Roy and Joseph V. Thanikal 173 But practically most of the beams are subjected to failure load for a RC beam with four layers of GFRP uniformly distributed load (UDL). It has been noticed was 200% more than control beam. that, UDL test on beam is difficult, since once the beam All the beams, FRP laminates were retrofitted at started to yield, the inner load application points will tension zone of the beams, but beam dimensions and detach from the beam. Hence the same two point load thickness of FRP laminates were different. setup will be maintained for experimental work. The experimental results given by (Jumaat & Alam, It is proposed to develop and test a mathematical 2008), Jiangfeng et al. (2013), Abdelhady et al. (2006) model for flexural strength in relation with the thickness and Tarek & Al-Salloum (2001) revealed that the of the FRP laminates. It is proposed to use Artificial failure load for RC beams strengthened with 1, 2, 3 and Neural Network (ANN) and Response Surface 4 layers of FRP composites were 53.7, 72.5, 25.25 and Methodology (RSM) to develop the mathematical 200% increased over control beam respectively. The model for flexural strength of beams with composite calculation shows that the load carrying capacity of laminates. Also the developed mathematical model will strengthened beam will be proportional to the number of be used for determining optimal thickness of FRP layers used for retrofitting works. But additional care material for various loads and beam dimensions. should be taken to avoid beam failure due to The following parameters are to be modified to get delamination or rupture of FRP laminates, since failure better experimental results. The parameters are profile load RC beam with three layers was very less due to of FRP composites, number of layers with different premature failure. thicknesses and preloading techniques. For the proposed work, one layer of corrugated profile will be used for strengthening the RC beam Effect of number of layers instead of many plain number of FRP layers. The The study describes that researchers have used FRP dimension of the corrugated profile was chosen with a plane laminates at different number of layers such as 1, view to improve the sectional properties and 2, 3 and 4. Due to composite action between concrete subsequently flexural strength of RC beams. To avoid and FRP composites, the strengthened beams have taken premature failure, another plain layer of GFRP laminate more loads by comparing normal beams. will be used for covering the corrugated profile and Jumaat & Alam (2008) have used one layer of CFRP extended to the sides upto 75% of overall depth. for flexural strengthening of RC beams and found that ultimate load for strengthened beam was 53.7% Effect of laminates thickness increased over control beam. Pannirselvam et al. (2008), has used one layer with 3 Jiangfeng et al. (2013) have taken one and two layers and 5 mm thickness GFRP laminates retrofitted at of CFRP laminates, for flexural strengthening of RC tension zone of RC beam. Ultimate load for control beam and ‘U’ anchors were provided at the supports for beam and beam retrofitted with two different beams CR2 and CR3respectively. Based on the thicknesses were studied. Three beams in each group experimental results, ultimate load for the beam was were tested and varied by tension reinforcements. Test based on the number of CFRP layers. Comparing the result shows that the average increase in ultimate load control beam, the beam strengthened with one and two for RC beam retrofitted with 3 and 5 mm thickness were layers were increased to 41.7% and 72.5% respectively. 56.98% and 87.62% respectively by comparing control Therefore, second layer of CFRP laminates over the beam. existing one was effective in improving the stiffness. Abdelhady et al. (2006) has attached three layers of Effect of preloaded beams GFRP laminates at tension zone of ‘T’ beam F04. Ultimate load capacity of RC beam with three layers Pan et al. (2010) investigated eight beams strengthened was 25.25% more than that of control beam and the with GFRP plates including pre-cracked beam (B7) and strengthened beam failed due to CFRP laminate rupture. the results were compared with that of normal beams. Also author has mentioned that U-shape FRP laminates Preloaded technique was used to develop multiple helps to prevent the rupture failure of longitudinal cracks for beam type B7. The beams B6 and B8 were CFRP laminates. normal beams without any cracks or notches. Based on the test results, average ultimate load for beams B6 and Tarek & Al-Salloum (2001) have used four layers B8 was 76.16% and this value was almost equal to that of 1.3 mm GFRP for FG4 group RC beams. Among all of B7. Also ultimate load for B7 was in between that of of them, two layers were attached at bottom of the beam B6 and B8. This result shows that an effect of FRP on and the remaining two layers were wrapped over the existing structures with multiple cracks is similar to a first two layers and subsequently extended to the sides new structure. upto 50% of overall depth. The test results show that the Journal of Urban and Environmental Engineering (JUEE), v.7, n.1, p.164-175, 2013 Aravind, Samanta, Singha Roy and Thanikal 174 Advantage of corrugated profile over plain layer An extensive study is chosen to apply modeling tools and use of standard code of practice for designs. Finally Before the commencement of experimental work, Finite a need for research in use of different GFRP profile can Element Analysis using ANSYS software was carried further enhance the strengthening of RC beams. The out to observe the extent to which the rectangular Artificial Neural Network and Response Surface profile helps to strengthen the RC beams over plain Methodology can be applied to develop a mathematical layer. 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(1999) Strengthening Reinforced Concrete Beams Using Fiber GFRP laminates. Also to get accurate theoretical results, Reinforced Polymer (FRP) Laminates. ACI Structural J. 96(5), ANN and RSM will be used. 865−871. Heshmi, S. & Al-Mahaidi, R. (2012) Flexural performance of CFRP CONCLUSIONS textile-retrofitted RC beams using cement-based adhesives at high temperature. Construc. Build. Mater. 28(7), 791−797. The critical review of literature revealed; strengthening Jumaat, M.Z. & Alam, A. (2008) Experimental and Analytical of RC beams using FRP composites, which are mainly Investigation on the Structural Behavior of Steel Plate and CFRP focused on type, dimensions, orientation, number of laminate Flexurally strengthened Reinforced Concrete beams. J. Applied Sci. 23(8), 4383−4389. layers of FRP composites and modeling techniques. Nadeem, A. & Siddiqui, K. (2009) Experimental investigation of RC There are no mention in IS code for design of FRP beams strengthened with externally bonded FRP composites. strengthened RC beam, as available in ACI guidelines. Latin Amer. J. Solids Struc. 6(4), 343−362. Pan, J., Christopher, K.Y.L., Luo, M. (2010) Effect of multiple secondary cracks on FRP debonding from the substrate of 60 54.95 reinforced concrete beams. Construc. Build. Mater. 24(6), 2507−2516. doi:10.1016/j.conbuildmat.2010.06.006 50 45.25 Pannirselvam, N., Raghunath, P.N. & Suguna, K. (2008) Neural 39.2 40 Network for Performance of Fibre Reinforced Polymer Plated RC (kN) Beams. American J. Engin. Applied Sci. 1(1), 82−88. Saadatmanesh, H. & Mohammad, R.E. (1991) RC Beams Load 30 Strengthened with GFRP Plates. I: Experimental Study, J. Struct. 20 Engin., 117(11), 3417−3433. Failure Sundarraja, M.C., Rajamohan, S. & Bhaskar, D. (2008) Shear 10 Strengthening of RC beams using GFRP Vertical Strips – An Experimental Study. J. 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(2011) Retrofitting of reinforced concrete beams doi.10.1016/j.conbuildmat.2010.06.082 Journal of Urban and Environmental Engineering (JUEE), v.7, n.1, p.164-175, 2013 Journal of Urban and Environmental Journal of Urban and E Engineering, v.7, n.1, p.176-182 Environmental Engineering ISSN 1982-3932 J E www.journal-uee.org U doi: 10.4090/juee.2013.v7n1.176182 KOHONEN NEURAL NETWORKS FOR RAINFALL-RUNOFF MODELING: CASE STUDY OF PIANCÓ RIVER BASIN Camilo A. S. Farias1; Celso A. G. Santos2; Artur M. G. Lourenço3 and Tatiane C. Carneiro4 1Academic Unit of Science and Technology, Federal University of Campina Grande, Brazil 2Department of Civil Engineering, Federal University of Paraíba, Brazil 3Civil and Environmental Engineering Graduate Program, Federal University of Campina Grande, Brazil 4Electrical Engineering Graduate Program, Federal University of Ceará, Brazil Received 3 January 2013; received in revised form 24 June 2013; accepted 30 June 2013 Abstract: The existence of long and reliable streamflow data records is essential to establishing strategies for the operation of water resources systems. In areas where streamflow data records are limited or present missing values, rainfall-runoff models are typically used for reconstruction and/or extension of river flow series. The main objective of this paper is to verify the application of Kohonen Neural Networks (KNN) for estimating streamflows in Piancó River. The Piancó River basin is located in the Brazilian semiarid region, an area devoid of hydrometeorological data and characterized by recurrent periods of water scarcity. The KNN are unsupervised neural networks that cluster data into groups according to their similarities. Such models are able to classify data vectors even when there are missing values in some of its components, a very common situation in rainfall-runoff modeling. Twenty two years of rainfall and streamflow monthly data were used in order to calibrate and test the proposed model. Statistical indexes were chose as criteria for evaluating the performance of the KNN model under four different scenarios of input data. The results show that the proposed model was able to provide reliable estimations even when there were missing values in the input data set. Keywords: Self-organizing maps; artificial neural networks; rainfall-runoff model; semiarid area © 2013 Journal of Urban and Environmental Engineering (JUEE). All rights reserved. Correspondence to: Camilo A.S. Farias, Tel.: +55 83 3431 4000; Fax: +55 83 3431 4009. E-mail: [email protected] Journal of Urban and Environmental Engineering (JUEE), v.7, n.1, p.176-182, 2013 Farias, Santos, Lourenço and Carneiro 177 INTRODUCTION Adeloye et al., 2011; Santos & Silva, 2013). The studies of Garcia & González (2004) and Adeloye et al. (2011) The northeast region of Brazil is characterized by high are examples of the few applications of KNN models in rates of evaporation and irregular and intense rainfall the area of water resources. through space and time. Such hydrological conditions, combined with the inadequate management of river CASE STUDY basins, contribute to the occurrence of various types of problems such as alternating episodes of floods and The watershed of the Piancó River is located in the droughts, and the entrainment of sediment into the southwest region of the state of Paraíba, northeastern riverbeds, reducing the ability of the water bodies and Brazil. With a drainage area of 9228 km², it has affecting the quality of its waters (Farias et al., 2010; semiarid climate and average annual values of Vanmaercke et al., 2010; Silva et al., 2013). The need precipitation and temperature around 821 mm and 24ºC, for a development that is compatible with the reality of respectively. In this basin, the largest water reserve of the Brazilian semiarid hydrology has encouraged the the state, is located the system Coremas–Mãe d’Água. study of strategies for a better management of existing The affluent outflows to the system come from three water systems, both in terms of quality and quantity. major tributaries: Aguiar Creek, Emas Creek and Piancó However, the difficulty in obtaining long and reliable River. The flows of the tributary Piancó are measured at streamflow series has hampered the establishment of the Piancó stream gauge station, which has a drainage superior rules for the operation of water systems. area of 4170 km². The data collection was done in eight In places where the data of flows are limited or rain gauge stations and in one stream gauge station flawed, processes like rainfall-runoff should be located in the basin of the Piancó River. Details of the investigated for the reconstruction and/or the extension studied stations are shown in Fig. 1 and Table 1. The of the series of flows. Over the years, several models data has been obtained on the website of the National have been developed with the intention to understand Water Agency (Agência Nacional de Águas – ANA, the processes of rainfall-runoff transformation in river 2010). The period of analysis, knowingly chosen for basins, such as Stanford Watershed Model IV presenting more complete information, comprises (Crawford & Lindsley, 1966), SSARR – Streamflow monthly data from January 1963 to December 1984, Syntesis and Reservoir Regulation (US Army Engineer totaling 22 years of observations. Division, 1972) and SMAP – Soil Moisture Accounting Model (Lopes et al., 1982). More recently, models based on artificial neural networks have been applied to the rainfall-runoff transformation, as shown in the work of Coulibaly et al. (2001), Jeong & Kim (2005), Farias et al. (2007), Wu & Chau (2011) and Santos et al. (2012 a,b). According to Haykin (1999) and Farias et al. (2010), artificial neural networks are mathematical models, inspired by the human nervous system, capable of detecting complex relationships between input and output variables. This paper has as main objective the development and the verification of the implementation of a monthly rainfall-runoff model based on Kohonen Neural Networks (KNN) in order to estimate flows in the Piancó River, which is an intermittent river that is located in the Brazilian semiarid region. Fig. 1 Location of the rain and stream studied gauge stations in the Piancó River basin. The KNN are unsupervised neural networks that group data into classes according to their similarities Table 1. Gauges that were employed in the present study through competitive learning (Kohonen, 1982; Haykin, Gauge code Gauge name Type City 1999; Silva et al., 2010). Also known as self-organizing 737006 (P1) Piancó Rainfall Piancó maps, the KNN were proposed by Kohonen (1982) and 738020 (P2) Conceição Rainfall Conceição 738015 (P3) Manaíra Rainfall Manaíra have mostly been applied in pattern classification and 738013 (P4) Princesa Isabel Rainfall Princesa Isabel data grouping. One of the main advantages of KNN is 738019 (P5) Santana dos Garrotes Rainfall Santana dos Garrotes the ability to reduce a set of multidimensional data to a 738012 (P6) Boa Ventura Rainfall Boa Ventura 738014 (P7) Nova Olinda Rainfall Nova Olinda two-dimensional array of features which can be used for 738018 (P8) Ibiara Rainfall Ibiara analysis and prediction purposes (Silva et al., 2010; 37340000 (Q) Piancó Stream Piancó Journal of Urban and Environmental Engineering (JUEE), v.7, n.1, p.176-182, 2013 Farias, Santos, Lourenço and Carneiro 178 KNN MODEL network is of the unsupervised type since there are no desired outputs. Architecture and training For purposes of determining the neighborhood, the The main objective of the Kohonen neural network distances between the neurons of the output layer can be consists of clustering vectors with similar characteristics defined in several ways (Beale et al., 2012). Commonly, in the same class (winner neuron) or similar classes in a two-dimensional output layer, neurons are thought (neighboring neurons). of as rectangular or hexagonal shapes and the distance The architectures of KNN contain a multi- are established by the number of steps between them. dimensional input layer and an output layer which is Figure 2 shows how the distances between hexagonal either typically one-dimensional or two-dimensional. In neurons are obtained for purposes of determining the the output layer, also known as competitive layer, the neighborhood. neurons compete among themselves and only one of The training takes place in two phases: ordering them is considered the winner or, in simplified form, the phase and tuning phase. In the first phase, training is class most suitable for a given input vector x. In these limited by a given number of presentations of the data networks, each element of the input vector is connected set and the radius of the neighborhood starts with a to all the elements of the output layer. The strength of given distance that decreases to the unit value. This the connections is measured through weight wij between measure allows the weights of the neurons to organize the input neurons j and the neurons of the output layer i. themselves in the input space consistent with their During the training of the KNN model, the Euclidean positions. The tuning phase lasts the remaining number distances DIi between the input vector and the weights of presentations for the training defined. At this stage, attached to each of the output neurons are calculated as the radius of the neighborhood is below unity, so that shown by Eq. (1). there is only update at the weight of the winner neuron. J During the tuning phase, it is expected that the weights 2 will modify themselves relatively evenly in the input DIi ijj to; ,1 ,2 ..., Miwx . (1) j1 space, while maintaining the topology defined in the ordering phase (Beale et al., 2012). in which xj is the j-th component of the input vector x; J is the dimension of the input vector x; and M is the total number of neurons in the output layer. Forecasting using the KNN model The output neuron i that has the smallest Once trained, the KNN model can be used as predictive Euclidean distance when compared to the input vector is tools. For this, one should consider the input vector with considered the winner neuron. The weights connected to the absence of the variable to be provided through the this neuron i* and the neurons within a certain following steps: neighborhood radius Vi* are then updated by the rule of (a) Calculate the Euclidean distances between the Kohonen (Beale et al., 2012), as shown by Eq. (2). input vectors and weights attached to output neurons disregarding the element j to be provided. 1 1 to; * and ,1 2, ..., JjVinwnxnwnw . (2) ij ij j ij i This can be done by including a Boolean variable in which α is the learning rate, and n is an index that mj, as shown by Eq. (3). The variable mj is used to represents the sequence of sample presentation to the include (mj = 1) or exclude (mj = 0) the network. contribution of a given element j of the input vector The Kohonen rule forces the weights attached to the in the calculation of Euclidean distances; winner neuron and its neighbors to move in the direction of the input vector presented to the network, causing the Euclidean distance to become smaller and ep that these neurons learn to classify similar vectors. st The presentation of input vectors to the network can 1 also be done using the entire data set before any weight 3 ste update. This form of presentation is known as batch ps mode. In this case, the search for the winner neuron is performed for each input vector and the weight vector is then moved to a specific position calculated by the average of input vectors for which the neuron was the winner or the winner’s neighbor. The weights tend to stabilize after multiple presentations of the set of input Fig. 2 Distances between neurons of a KNN model for the data. It is worth noting that the training of this neural determination of the neighborhood. Journal of Urban and Environmental Engineering (JUEE), v.7, n.1, p.176-182, 2013 Farias, Santos, Lourenço and Carneiro 179 (b) Determining the winner neuron based on the lowest Detection of similarities Euclidean distance; The detection of the similarities between the variables (c) Using the weight of the winner neuron connected involved in this modeling can be visually performed to the missing element j of the input vector as the through the plans of the components shown in Fig. 4. prediction. Those plans or maps represent the weights associated J with each input variable. In order to facilitate the 2 (3) DIi ijjj to; ,1 ,2 ..., Miwxm . interpretation of the results, a color scale was displayed j1 with the original dimensions of the weights, which are actually the values of the variables under study for APPLICATION AND RESULTS different neurons or classes. The highest values correspond to yellow zones, and the smallest to the Application of the KNN model zones in black. In this study, the vectors of the input layer have 18 Correlations may be identified through color neurons representing the past and current flow, Q(t–1) gradients on each plane component. Two variables with and Q(t), and rain, P1(t–1), ..., P8(t–1), P1(t), ..., P8(t) parallel gradients show a direct correlation while monthly values. A two-dimensional output layer with antiparallel gradients show an inverse correlation hexagonal neurons was chosen. Based on the guidelines (Garcia & González, 2004). The analysis of Fig. 4 suggested by Garcia & González (2004), a grid of 9 × 9 allows the extraction of different information. neurons was used, providing a total of 81 neurons. When analyzing the generated maps of rain data Figure 3 shows the structure of the KNN model of this from the eight rain gauges, considering the same time paper and an example with a winner neuron and its period, it is found that low and high rainfall values were neighbors. classified into similar categories for all the positions The input data have been properly scaled to improve studied. Based on this result, it is understood that it is efficiency in the KNN model training. The scheduling reasonable to use information from neighboring rain process consisted of normalizing the data so that the gauges for filling gaps in the series of rainfall in the average would be zero and the unit standard deviation region studied. (Beale et al., 2012). The model training took place in When comparing the flows with average (red cells) batch mode, and in order to ensure a consistent learning, and high (yellow cells) magnitudes, it is clear that the the dataset has been submitted 200 times to the KNN map of Q(t) has little similarity with the map of Q(t–1). model. In the ordering phase, it was opted for 100 The map of Q(t) has presented the higher flow rates at presentations of the dataset and an initial neighborhood the bottom right. The investigation of maps focusing on radius equal to three steps. The tuning phase included a comparison of the flow Q(t) with rainfall in the same the 100 remaining presentations. The KNN model was period of time suggests that the flow data are strongly implemented in MATLAB R2012a by using the Neural correlated with rainfall for the most rain gauges studied. Network Toolbox (Beale et al., 2012). Despite the lesser extent, the flow rates were also The data used for training and testing the KNN reasonably correlated with rainfall in the previous model comprise the periods of 1963–1980 and 1981– month. This is evidenced by the identification that the 1984, respectively. regions with low (black cells), medium and high flows have similar colors in most plans of rain at t–1. 73 Bidimensional Space 74 Rainfall-runoff modeling 9 × 9 The performance evaluation of the KNN model for 81 estimating the flow rates was based on the following 11 1 indexes: correlation (R), relative bias (RB) and Nash- 12 2 Sutcliffe efficiency (NASH). The correlation measures Winning neuron the degree of linear dependence between the predictions Neighboring neurons Output Layer 18 and the observed values of flow, actually expressing a 9 potential value of good fit. The relative bias, in turn, Vector = [P18(t-1), ... , P(t-1), P18(t), ... , P(t), Q(t-1); Q(t) ] shows that the streamflow forecasting system has a tendency to underestimate or overestimate the observed Multidimensional Input Layer flow. The NASH efficiency index, which can vary Fig. 3 Structure of KNN model and example with a winner neuron between –∞ and 1, is traditionally used to express and its neighbors. adhesion between simulated and observed flow rates. Journal of Urban and Environmental Engineering (JUEE), v.7, n.1, p.176-182, 2013 Farias, Santos, Lourenço and Carneiro 180 Fig. 4 Plans of the components obtained by the KNN model for rainfall data P (mm) and flow Q (m³/s) in the Piancó River basin. This index considers both the systematic errors and the Table 2. Input data for estimating flow rates by using the KNN random errors, indicating that the fit is even better as its model for four simulations value is close to the unit. High correlation values do not Simulation Input data mean, by itself, predictions with high accuracy. For SIM #1 P1(t–1), ..., P8(t–1), P1(t), ..., P8(t) and Q(t–1) example, a system with a very high bias, even if SIM #2 P1(t–1), ..., P8(t–1), P1(t), ..., P8(t) correlation is equal to the unit (r = 1), will give SIM #3 P1(t–1), ..., P8(t–1) and Q(t–1) streamflow forecasts of low precision, although it is SIM #4 P1(t), ..., P8(t) and Q(t–1) possible to remove this bias by statistic models. A perfect forecast system would have r = 1 and RB = 0. The correlation, relative bias and NASH results show The equations for calculating these indexes can be that the KNN model could classify with good quality found in Lettenmaier & Wood (1993). the flow rates of the training dataset. The KNN model Figure 5 shows a comparison between the monthly was also evaluated for a period of tests represented by a flow rate estimates obtained with the KNN model, series of data fully independent from those used for considering the steps described in section 3.2, and the training the model. For this, four sets of input variables observed flow rate in the stream gauge investigated for estimating flow rates in the Piancó River were during the period of model training. chosen and tested, as shown in Table 2. Figure 6 shows the results of estimation of the flow rates for all simulations. The simulation SIM #1 shows 500 Observed that the estimates of the KNN model and the observed 450 r = 0.90 Calculated values have high correlation and a fairly low value of 400 RB = -0.15 NASH = 0.75 relative bias. The value of NASH was also high, 350 indicating that the monthly flow rate estimates hold 300 good quality. The indexes obtained for simulation 250 SIM #2, in which some input variables have been 200 deleted, show that the KNN model is able to produce Streamflow (m³/s) Streamflow 150 reliable estimates even when there are failures in the 100 input data. These results are justified by the powerful 50 classification capabilities of the networks KNN, even in 0 1 25 49 73 97 121 145 169 193 cases where some of the elements of the input vector are Time (months) not present (Beale et al., 2012). Fig. 5 Comparison between the monthly flow rates obtained with the Also analyzing the flow rates estimated by the KNN model and the observed values at the Piancó streamflow simulation SIM #2, it is observed that the removal of the station during the 18 years of the training period (1963–1980). past flow from the set of input data did not impair the Journal of Urban and Environmental Engineering (JUEE), v.7, n.1, p.176-182, 2013 Farias, Santos, Lourenço and Carneiro 181 200 200 Observed Observed 180 180 SIM #1 SIM #2 160 160 R = 0.88 R = 0.92 140 RB = -0.20 140 RB = -0.20 NASH = 0.75 NASH = 0.81 120 120 100 100 80 80 Streamflow (m³/s) Streamflow 60 (m³/s) Streamflow 60 40 40 20 20 0 0 1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 1 3 5 7 9 11131517192123252729313335373941434547 Time (months) Time (months) 200 200 Observed Observed 180 180 SIM #3 SIM #4 160 160 R = 0.51 R = 0.86 140 RB = -0.59 140 RB = -0.54 NASH = 0.18 NASH = 0.34 120 120 100 100 80 80 Streamflow (m³/s) Streamflow 60 (m³/s) Streamflow 60 40 40 20 20 0 0 1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 1 3 5 7 9 11131517192123252729313335373941434547 Time (months) Time (months) Fig. 6 Comparison between the monthly flow rate estimates obtained with the KNN model and the observed values at the Piancó stream gauge for various configurations of input data during the four years of the test period (1981–1984). performance of the model. These results confirm the KNN model with the data observed in the region. This analysis performed for the detection of similarities, in comparison, by using a testing period regardless of the which the weak relationship among the streamflows data used in the model training, has shown that the Q(t) and Q(t–1) was verified. On the other hand, the KNN model had a good performance for estimating the simulation SIM #3, which had no rain data for the monthly flow rates. current period, showed the least significant results, The plans of the components generated by the KNN confirming the strong correlation identified by the maps model were shown to be powerful analytical tools by of components between the rainfall P(t) and the allowing the visual identification of similarities between streamflow Q(t) data. The indexes obtained from the the variables involved in modeling. Simulations using SIM #4, which did not contain rainfall data in P(t1), four different configurations of inputs also indicated outperformed the SIM #3, which in turn suppressed the that the KNN model is able to produce reliable rainfall data in P(t). This suggests that the rainfall data estimates even when there are faults in the input data, P(t) have more significant correlations with the which is a common situation when dealing with streamflow Q(t) than the rainfall P(t–1). hydrometeorological data. The good results obtained for the stream gauge in the CONCLUSION Piancó River suggest that this type of model can be used to reconstruct and/or extend streamflow series, This paper presented a model of Kohonen Neural especially in places where hydrometeorological data are Networks (KNN) for detecting similarities between limited or at fault. Further studies together with monthly rainfall and runoff data, and it verified its physically-based runoff-erosion models (e.g., Santos et applicability for estimating the monthly streamflow at a al., 1994, 2003, 2011a b, 2012a b, 2013; Zhang et al., stream gauge on the Piancó River, which is located in 2013) seems to be a promising tool for dealing with the semiarid region of Paraíba state, Brazil. erosion issues, as well as the use of wavelet transform The developed model was evaluated through a (e.g., Santos & Morais, 2013; Santos & Silva, 2013). comparative study relating flow rates estimated by the Journal of Urban and Environmental Engineering (JUEE), v.7, n.1, p.176-182, 2013 Farias, Santos, Lourenço and Carneiro 182 Acknowledgment The financial support provided by models. Hydrol. Sci. J. 2013. doi: 10.1080/02626667.2013. CNPq (National Council for Scientific and 800944 Santos, C.A.G., Freire, P.K.M.M. & Mishra, S.K. 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(2013) Daily streamflow forecasting z using a wavelet transform and artificial neural network hybrid Journal of Urban and Environmental Engineering (JUEE), v.7, n.1, p.176-182, 2013 Journal of Urban and Environmental Journal of Urban and E Engineering, v.7, n.1 p. 183-194, 2013 Environmental Engineering ISSN 1982-3932 J E www.journal-uee.org U doi: 10.4090/juee.2013.v7n1.183194 AN ANALYSIS OF REGIONAL DISPARITIES SITUATION IN THE EAST AZARBAIJAN PROVINCE Nader Zali1, Hassan Ahmadi2 and Seyed Mohammadreza Faroughi3 1 Assistant Professor, Department of Urban Planning, University of Guilan, Iran 2 Assistant Professor, Department of Urban Planning, University of Guilan, Iran 3 Department of Urban Planning, University of Guilan, Iran Abstract: The regional disparity in Iran is now a matter of serious concern. Measuring development has been a matter of debate for nearly half a century. The conventional way of assessing development by social and economic indicators only has been challenged many times during this period. Accelerated urbanization in developing countries and the concentration of activities and population in some regions, have led to regional imbalances. This is one of the important characteristics of the third world countries. This characteristics is affected by pole growth policies that have led to a concentration of facilities in one or more of several regions. In this case, regional planning science offers beneficial patterns to resolve problems. The first step is the identification of socio-economical disparities in these regions. However, this article attempts to survey development disparities in the East Azarbaijan province. In this survey 44 indicators were selected for the comparison of the counties, and the Numeric Taxonomic & Cluster Analysis methods were used to rank the regions. Finally this article presents priority of counties for investment in order to achieve social justice. According to the results of this research the west area of the province is prosperous and east area has a low degree of development. Keywords: Development Ranking, Foresight, Regional Disparities, East Azarbaijan © 2013 Journal of Urban and Environmental Engineering (JUEE). All rights reserved. Correspondence to: Nader zali, Tel.: +98 914 303 8588. E-mail: [email protected] Journal of Urban and Environmental Engineering (JUEE), v.7, n.1 p.183-194, 2013 184 Zali, Ahmadi and Faroughi INTRODUCTION is to assessment the regional development inequalities in Iran at sub-province scale. In this way, multi criteria In general, disparities between regions and inside them decision making methods were applied for evaluating occur as result of some concentration, agglomeration, regional development level of sub-provinces (Tagvaei, trends triggered by external phenomena, globalization, 2012). integration, or by internal ones, clustering, emergence of Plan and policy makers propose the necessity for growth/development poles, involvement of local equal development for different reasons: first, to institutions in various aspects of economic life, etc. As a establish social equality in order to be enjoyed of rule, regional disparities take the shape of differences facilities in equality and appropriate for many reasons. between the level of incomes per capita and determine, Second, political considerations serve as a parameter to at a given moment, a chain reaction of companies, decrease political unrests and third, social and authorities, inhabitants, etc., that attempt to counteract economical considerations prevent immigration and their escalation (Antonescu, 2012) over-concentration of people. Based on this, the Islamic One of the characteristics for third world countries is Republic of Iran's constitute enforces the government to a high concentration of population and activities, and structure for a correct and fair economy to regulate space disparity in the enjoyment of social conveniences. justice-based economical plans in order to establish This was found before the Revolution in Iran and in its welfare, resolve poverty, eliminate deprivation and effects after the Revolution in Iran. Based on this establish social justice. tendency, a main portion of facilities and the population It seems that despite executing some development concentrate in one or more places. Other regions act as plans for Azerbaijan, the Sharghi province's boundaries resulting in regional disparities. development, it is still remained subject to inequality Regional disparities derive from two main fields: and disparity in terms of facility distribution. Unequal first the natural conditions in any geographical region distribution of facilities inevitably result from a high and second the economical plan & policy makers' density of the population, activities and services in some decisions. It should ne mentioned that the first factor regions, incompatible with the weight of population, declines with technological development and the second activities and services in other regions that results in an factor is considered to be more important. The plan & increasing population flow so that officials face with policy makers' decisions play the most important role in considerable problems. This phenomenon causes current creating regional disparity. economical life of small towns and villages’ in these regions to be inactivated, with increasingly mobile small PROBLEM VIEW cities' population and incapability to restrain big cities' population growth. Inequality and its different dimensions are the It is natural that the above-mentioned increase of significant signs of underdevelopment. Regional centralization results in a wide variety of problems in inequalities represent a continuing development the performance phase for managers and decision- challenge in most countries, especially those with large makers. Based on this, it seems that no plan would be geographic areas under their jurisdictions. Large able to address this disparity or restrict its intensification regional disparities represent serious threats to countries unless it considered the suitable distribution of social as they create potential for disunity and, in extreme facilities and services (Zali, 2000). cases, for disintegration. Marginalized populations often In this direction, the consideration of regional are left excluded when important development and disparities based on indices is supposed to be one of the investment decisions are made. Regional disparities in most important planning tools by which plan makers Iran have been growing at an alarming rate leading to can assess the results of a plan’s execution in the serious problems including migration with its associated context of geographical boundaries. If considered by problems from backward provinces to the more affluent plan makers logically and scientifically, such ones. So that, the Human Development Report for Iran considerations can clearly reveal the strengths and in 1999 reflected such disparities and reiterated that one weaknesses of planning in various areas and determine of the major human development policies in the planning regions in aspect of enjoyment scale based on country’s Third Plan is to “pay attention to the spatial hierarchy and homogeneity of regions (Zali, 2000). The planning as a long-term framework for social justice and distribution of services and facilities can be evaluated regional balance”. In order to provide a scientific basis through a comparative examination of various skeletal, to decrease regional inequalities, it is very necessary to social and economical indices in different regions. comprehensively assess the status of regional Indices compare the status of various geographical development with regard to different indicators. Once regions, prioritizing them based on the quality of their this assessment is done and we get a clear idea of the facilities and general conditions. In this way, we may be backwardness of some regions, we can proceed to tackle able to propose the capabilities and conditions of the problems of backward regions. The aim of this study various geographical scopes in terms of theor enjoyment Journal of Urban and Environmental Engineering (JUEE), v.7, n.1 p.183-194, 2013 Zali, Ahmadi and Faroughi 185 of services, infrastructures, etc. and to provide the The neoclassical arguments for vanishing necessary tools for decision-making and other objective inequalities between nations or regions have been determinations. the basis for the convergence literature (e.g. Barro, This paper examines the Azrbaijan Sharghi counties’ 1991). The full equalisation of the prices of the access to social services and facilities, by compiling production factors is captured by the concept of different indices and measurements in social, absolute convergence. In case of technological production, and infrastructural fields, and examining how facilities are distributed. The information can then differences each region or country converges be used to formulate the plans and specific objectives to towards its own steady state, denoted by achieve social equality and reduce regional disparity. conditional convergence (Barro & Sala-i-Martin, 1995). REGIONAL INEQUALITY THEORETICAL These convergence concepts are in line with the ARGUMENTS classical trade theory (Feenstra, 2004). The arguments for absolute convergence rely usually on The interaction of inequality and growth has been a the Solow growth model (Solow, 1956) which topic with several questions but without clear predicts the long run growth rate to approach the answers. On the one hand, it is asked whether rate of technological progress in the long run. In inequality is good or bad for growth. On the other fact, this model was rather constructed for hand, the question is whether growth increases or analysing the growth path of one country than reduces inequalities. Thus, not only the direction of comparing the speed of growth across spatial units the relationship (positive or negative), but also the (Solow, 2001). Conditional convergence is direction of causality is of interest. None of those consistent with endogenous growth models questions has been answered unanimously in the (Romer, 1986, 1990; Lucas, 1988) in which theoretical and empirical literature.(Paas, 2009) technological progress is modelled as depending on The literature on inequality and growth the contributions to the research and development considers usually the effects of individual sector. inequality to economic growth (an overview is Another group of models discussing the Kanbur, 2000). There are a lot of empirical interaction of regional inequality and growth investigations (e.g. Barro, 2000; Forbes, 2000), belongs to the field of new economic geography delivering contradictory results. For example, Barro (NEG) models (Baldwin et al., 2003). These (2000) obtains only a weak relationship between models are characterised by increasing returns to income inequality and growth. He argues that this scale in production, monopolistic competition, is consistent with the mixed theoretical arguments: costly interregional trade and factor mobility. In the the forces working in opposite directions cancel out first paper of the field, Krugman (1991) showed each other. that regional inequalities might be persistent The theories touching most directly on regional because of the so called home market effect: it is inequality and economic growth are trade and beneficial to locate production close to a large growth theories, considering also the persistence of market as this enables to increase sales and profits. regional inequalities. The most well known As splitting production between several regions is arguments for decreasing regional inequalities not profitable due to increasing returns to scale, come from the neoclassical approach. In the each firm produces only in one region. Costly trade neoclassical world with free trade or free causes the prices of the products to be higher in movement of production factors and perfect regions that are served by exporting and, thus, the competition, regional inequalities should vanish. firms are able to sell smaller quantities of their The production factors are paid according to their products there than in the home region. Moreover, marginal products and these would equalise over the low prices carry over to high real wages that the space as the firms look for the location with attract mobile workers to the region with more lowest production costs. However, if regions are firms. The wages are additionally drawn up in that characterised by differences region due to the competition of the firms for in technological level or other factors that workers. The home market effect appears also if the influence the productivity of the production factors, workers are assumed to be immobile, but the the inequalities may be persistent. products of the firms are used by other firms as intermediate inputs (Krugman and Venables, 1995). Journal of Urban and Environmental Engineering (JUEE), v.7, n.1 p.183-194, 2013 186 Zali, Ahmadi and Faroughi As the result, in a two region setting the firms and difficult or impossible to move machines and workers concentrate in one of the regions (the core) buildings necessary for production. Thus, this if the trade costs are sufficiently low even if the crucial assumption of the model is not overly regions are initially identical in their technological unrealistic. level and resource endowments. In fact, the home In this constructed capital model growth and market effect was already present in Krugman’s inequality interact in both directions: inequality has (1980) trade model without labour mobility. growth effects (increases the disparities in the However, that model was unable to explain the growth rates of the regions) and growth in one and emergence of agglomerations of economic activity recession in the other region increases of course in case of symmetric regions, i.e. the inequalities regional inequality. Thus, differently from the that can be observed in space. (Paas, 2009) neoclassical growth theory in this model the richer Some further developments in the field have region grows faster as also described by Myrdal directly tackled the interplay of growth and (1957) with the concept of cumulative causation. regional inequality. The first paper to address this However, once full agglomeration in the core has question was Baldwin (1999). Abstracting from been achieved, its growth comes to a halt. If now factor mobility, he shows that growth can affect liberalisation of trade continues, there will be inequality. This is achieved by the assumption that gradual growth in terms of real income in the other, capital (utilised by the modern sector) depreciates peripheral region. The reason behind this result is a and has to be replaced. Also, investment into decrease in prices as less has to be paid for capital construction will be done only if the present transporting the goods from the core region. Still, value of its expected flow of return is at least as even when trade is fully liberalised, there remain large as the investment costs. Another assumption differences in the per capita incomes across the two is that the constructed capital can be utilised for regions though not as high as for a medium range producing the consumer goods only in the region of of trade costs. However, if capital mobility is construction. allowed, these effects vanish and convergence is The spatial equilibrium is achieved if the achieved. Considering the whole economy’s expected return from capital covers exactly its income per capita, the degree of regional inequality construction costs: in that case there will be no has according to the model no effect in the long run growth. However, if from one of the initially if trade costs do not change. (Paas, 2009). identical regions one modern firm decides to Also endogenous growth models have been relocate to the other region and the trade costs are developed in the context of the NEG. In these sufficiently low, there starts a growth process in the models the degree of inequality has also now larger region and economic contraction consequences for national growth. The most well process in the smaller region. The reason behind known endogenous NEG model is due to Martin this result is again the home market effect, enabling and Ottaviano (1999), the spillovers model. Their the firms in the larger region to earn higher profits model is an upgrade of the constructed capital than before the relocation, and vice versa in the model. For achieving endogeneity of growth, they now smaller region. Construction of capital is then assume spillovers in the capital construction sector: unprofitable in the smaller region as the firms are the more capital there is in the economy, the not able to earn sufficiently high profits to cover cheaper it is to construct new capital (global the capital construction costs. Thus, the initially spillovers). It can also be assumed that the small inequality increases gradually. If the two spillovers from the other region are not captured as regions of the economy were initially identical, this easily as those from the home region, i.e. the local agglomeration process lasts until the whole modern capital stock has a larger impact on the innovation sector has concentrated into the larger region. If the efficiency (local spillovers). The conclusions from regions are initially of different size, also partial the spillovers models coincide largely with those agglomeration is possible, but in case of very low from the constructed capital model (Baldwin et al. trade costs still full agglomeration occurs. 2003), but give also new insights to the interplay of Such an agglomeration process can occur only if regional inequality and growth. capital is immobile. Clearly, there are almost no Differently from the constructed capital model mobility restrictions to the flows of monetary there is a continuous growth in the national real per capital in the nowadays world. However, it is capita income also in the long run equilibrium. Journal of Urban and Environmental Engineering (JUEE), v.7, n.1 p.183-194, 2013 Zali, Ahmadi and Faroughi 187 However, as in the constructed capital model the Hirschman believes that developing countries do not income levels differ if the capital stock and modern possess enough capital to be able to perform such sector firms are distributed unevenly in the space, multilateral investments. These countries have to choose also in case of completely free trade. The most an area of focus in which to invest and thus pioneer important result reveals that the national growth development by establishing a growth pole until the growth rate of this area causes the growth of other areas rate is highest if the capital construction activity (Beheshti, 1983). and thus, the production of the increasing returns There are probably identical methods over regions goods are present only in one region given that the development. The concept of a growth pole was spillovers have local character and trade costs are proposed by François Pro (French) in the 1960s. He sufficiently low. Moreover, if the share of the believed that growth poles would include some modern goods is sufficiently high in the industries and high-functioning factories with a high consumption expenditures, the welfare level is growth rate. He identified that the advanced and basic higher in the peripheral region than it would be industrial growth was an engine for the growth of the under a symmetric distribution of firms. Once national economy, and that imbalanced growth would again, if gradual liberalisation of trade takes place, occur. New industries would inevitably be settled on the relative real incomes of the two regions change neighboring infrastructures, stimulating certain growth points. Such centralization would encourage similarly to those in the constructed capital model. backwardness of other regions and result in The above introduction of the NEG models geographically regional polarization and heterogeneous support positive correlation between regional development. Several seminal works will ensure the inequality and the speed of economic growth. correction of the imbalance (Harvy, 1997). It is possible However, the models have some drawbacks, that to detect those regions being far away from social might influence the outcomes of testing this equality standards via this method (Hakimi, 1992). conclusion empirically. First, the models are It is his belief, that if development is not constructed for a two region economy, but in the accompanied with a coherent social policy that directly reality countries consist of several regions and have addresses the reasons for poverty and under- interactions with regions from other countries. development, it will be impossible to attain a solution However, it has been shown for the simple NEG that will address the poverty and disparity in the various regions and communities. Regional development models that the occurrence of agglomerations of follows three objectives: productivity, society and economic activity holds also in multiregional biology. Regional development attempts to provide the context (Fujita et al., 1999). For the interaction best condition and facilities for comprehensive with a foreign region, Krugman and Livas Elizondo development, minimize life quality differences between (1996) have shown that integration with a region regional and inter-regional and finally resolve it from abroad motivates a relocation within the home (Mokhber, 1988). economy towards the border, especially if the In late 70s and early 80s, concern about increasingly foreign region has a large market. economical disparities in the third world resulted in new The second issue considers the negligence of approaches toward development policy that focused on congestion cost. If lots of economic activity resolving basic needs. These approaches derived from a concentrates in just one region, the housing and concern that even redistribution policies associated with growth would not be able to improve the welfare of the land prices are driven up, there can occur poorest classes of the society. In the 1980s, neoclassic environmental problems and the loss of efficiency theorists established neoclassic reciprocal revolution due to e.g. traffic jams. Adding such aspects to the theory. This notion focused more on privatization and model would motivate the firms to move out of the less on governmental interference, and emphasized a core regions, as shown for example by Helpman belief in the free market. Such theories advanced the (1998). ideas that disappointment in development gains Finally Economic theorists have proposed many originates from excessive government interference in ideas to revive structural development. Some, like economic affairs (Ardeshiri, 2000). Rosenstein Rodan and Narks have found that the Accordingly, a new theory of growth was outlined simultaneous growth of economic sectors is necessary in based on innate growth and constant development in order to achieve economic development. They believe this decade. Constant development is being followed multilateral and simultaneous investment in various seriously in the recent years, meaning not only economic sectors is necessary in order to beak the preservation of environment but the new concept of debilitating cycle of poverty in developing countries. economic growth which offers life facility and equality This is the balanced growth theory. In contrast, for all people in the world, not just for a few people. Journal of Urban and Environmental Engineering (JUEE), v.7, n.1 p.183-194, 2013 188 Zali, Ahmadi and Faroughi METHODOLOGY show as a quantity called Fi that represents the deprivation scale for any region ranging from zero to Comparing geographical regions based on one or more one, so that the higher the index, the higher the development index value might be possible in two deprivation on this scale. ways: first, instance comparison, i.e. to determine the The scale is arrived at by the cluster analysis method development scale of each region based on any index to determine the homogeneous groups after rating. This that is neither logical nor actually represents method divides counties based on their distance from development scale in each region. Second, through a the intended target with other counties in the same general comparison and selection of those indices that homogeneous classes. Under this method, the represent the development symptoms of the region we quantitative properties of the counties of each group specify a quantity from the indices scientific possess relative and close similarities toward one aggregation, and classify regions according to this another. quantity. It seems that the second method is especially suitable to detect quality of life statuses. It is essential to SELESTION AND CLASSIFICATION OF use statistical and analytical models to gauge and INDIXES compare these figures, by compiling a number of indices to obtain the status of any region against other In this study 44 indices among several indices as regions. There are several scientific methods in this field counties enjoyment scale were chosen, regarded as a including: Numeric taxonomy, factor analysis, base to rank counties in several regions. Among these, deprivation coefficient, cluster analysis, the Murris there were 8 basic indices,8 production indices, 15 method and the sum of standard data method. social indices and 13 infrastructure indices which Among these, the numeric taxonomy method is wholly listed separately as below: considered to be one of the most current methods for classification, well-regarded most by plan makers in BASIC INDIXED recent years. Nevertheless, this technique is not free from limitation. For instance, it does not encourage the Employment rate, family density, municipalities' per translation of indices into analysis and classification. capita income, per capita tax, the number of bank Those indices that usually define each other locate branches as for 10,000 people, high educated employed together, probably boosting each other to manipulate the percentage, population density, urbanism percentage. results of analysis. According to experts, despite such defects, it is more reliable to use the numeric taxonomy PRODUCTION INDIXES technique rather than any of the other techniques mentioned above. Cultivated area for each beneficiary, consumptive water Taxonomy as a general name refers to those methods coefficient in production section to total electric that separate similar cases from dissimilar ones. One of consumption, one hectare garden products turnover per the most important is numeric taxonomy which is hectare, cultivation products turnover per hectare, capable both of classifying a series as a scale and of utilization ratio of agricultural instruments per every 10 identifying the under-development status of regions hectare of agricultural field, the ratio of large industrial (Borzooyan, 1995). Taxonomy is regarded as a workshop workers per total workers, the number of statistical method to specify units or any homogeneous industrial active and cooperative co. workers per types into a latter N diagram space without the use of 100,000 people variance regression or correlation analysis (Bidabad, 1983). SOCIAL INDIXES This method was first offered by Adanson in 1984, and proposed by Prof. Zygmunt Hellwing from Rekla Literacy rate, student ratio to training cadre, sport fields economy premier college in UNESCO as a tool for the area per capita, public library books per capita, cinema classification of the under-development scale between capacity, number of printing office, number of various nations. This method is considered as a premier nurseries, number of students, number of health care method for the rating, classification and comparison of and treatment centers, number of hospital beds, general countries of different regions, regarding their practitioners, dentists, number with access to heath care development scale. In the taxonomy method, the indices and birth control centers per 100,000 people. maximum quantity is chosen as the target quantity for the region’s rating after indices harmonization and INFRASTRUCTURE INDIXES standardization, and measuring the distance of other resources with the target index. Those regions showing The asphalted village road ratio to total village roads, less distance from the intended target will be regarded the number of working cable phones, cell phones, the as more developed regions. The taxonomy output will percentage of households with gas pipes, villages Journal of Urban and Environmental Engineering (JUEE), v.7, n.1 p.183-194, 2013 Zali, Ahmadi and Faroughi 189 enjoying healthy drinking water, four-lined main roads 0/65 to 0/72. With exemption of Jolfa, Sarab and Miane, per county area, number of urban sewerage divergence which are located in the respective northwest and east to urban household, road density, mailed postage per parts of the province, other counties of this group are capita, post offices rendering Pishtaz services, electric situated by the connection road between Tabriz- power subscribers as a percentage of the population, Miandoab, and are neighboring each other. Southwest county center distances from the nearest airport, county parts of the province are also provided with appropriate center distance from the nearest railway station. These infrastructure, production and social facilities on top of two indices remain from a minus of county center basic indices. distance from relative facilities as maximum as the Third group contains Oscu, Marand, Ajabshir and distance between counties from relative facilities. Hashtrood counties which have deprivation on a scale ranging from 0/74 to 0/81. These counties differ in AN ANALYSIS OF REGIONAL DISPARITIES IN several ways from the previous counties of the province EAST AZARBAIJAN PROVINCE regarding the provision indices. This difference for counties situated in the 3rd group equals the half of As described in this paper, the counties’ comparative Tabriz index of provision, and this indicates severe indices have been compiled into 4 sections of disparity between the counties of the province. The 4th production, infrastructure, basic and social in the group of counties, which contains the most deprived statistical period of 2006, using the numeric taxonomy ones, includes 7 of them: Kalibar, Malekan, Ahar, and cluster analysis techniques to rank counties. The Varzaghan, Haris, Bostanabad and Charoymagh. The results of the analysis in various regions are as followed: important point here is that 6 out of 7 counties in this group are situated in the east part of the province and RANKING BASED ON BASIC INDIXES only one county is situated in the southwest part of the province. It’s worth looking into deprived and Basic indices are those that represent the county’s prosperous counties’ spatial distribution in reference to general image, according to dominant development the basic indices analysis and that should be well- criteria, for example: urbanism scale, literacy rate, regarded in planning. employment rate, tax payment per capita and other indices that show the general development level of the RANKING BASED ON PRODUCTION society. Based on analysis, Tabriz, Jolfa, Azarshahr, INDIXES Shabestar, and Maraghe are the five counties with the least deprivation compared to other cities of the In this chapter we discuss the production indices of the province. In contrast, Charoymagh, Bostanabad, Haris, counties in different fields of agriculture and industry, Varzaghan and Ahar show the highest levels of and we try to use the most appropriate index to deprivation and the lowest standards of living indices represent the production properties of the counties. compared to other counties. Based on this analysis, counties like Shabestar, An important matter for ranking and disparities analysis Azarshahr, Tabriz and Bostanabad stand at the first level is that it takes into account that differences between of production indices provision rating. Shabestar counties based on the deprivation scale index do not County, due to its numerous productive agricultural perfectly represent the county’s status in relationship to territories and because of its industrial centers; then other counties. There may be an inconsiderable Azarshahr, due to its industrial zone called Salimi with difference in the ranking of a county located at the high concentration of industries and also because of its middle of table with the ranking of a county located at existing valuable cultivation land and gardens; followed the end of table and reasons to set them at a similar by Tabriz due its concentration of the key industries level. In order to wholly represent the picture, the along the roads which go to Tabriz, and because of the calculated deprivation scale is divided into industrial zones in its surroundings; and Bostanabad, homogeneous groups through the numeric taxonomy due to its industrial centers and watered grounds with method and the cluster analysis method, to demonstrate high cultivation, take from 1st to 4th rank based on the relative similarity of counties in each group. production indices. Charoymagh, Kalibar, Ahar, In basic section, the results from cluster analysis Ajabshir, Hashtrood, Varzaghan and Haris counties are represent 4 homogeneous classes with similar considered as the deprived ones in terms of production properties. Tabriz as the capital of the proper county and properties, and apart from Ajabshir they are all situated the regional center of the northwestern Iran stands in the in the east part of the province. They also have first level of the basic indices provision, being at a unfavorable status in terms of other social, considerable distance from the second class of infrastructural and basic indices. deprivation scale. Jolfa, Azarshahr, Shabestar, Maraghe, Grading through hierarchy and Dendogram diagram Miane, Sarab and Bonab counties stand in the second points to 4 homogeneous classes of counties regarding level of provision, with deprivation scale ranging from the production indices’ level. Shabestar, Azarshahr, Journal of Urban and Environmental Engineering (JUEE), v.7, n.1 p.183-194, 2013 190 Zali, Ahmadi and Faroughi Tabriz and Bostanabad are in the 1st class of RANKING BASED ON SOCIAL INDIXES homogeneous counties. Bonab, Sarab, Miane and Marand are considered as 4 counties situated in The set of social indices includes level of education, productive plains, which also have some production culture, sports, health and care that all reveal the social industries by which they are listed in the second class. life level of the counties. Based on the results of Oscu, Maraghe, Jolfa, and Malekan counties are in the numerical Taxonomy, the provinces like Tabriz, 3rd class. Varzaghan, Hashtrood, Haris, Ahar, Kalibar, Azarshahr, Maraghe, Shabestar and Jolfa are the 5 Ajabshir and Charoymagh are deprived counties in counties with a low level of deprivation or the counties terms of production indices. which have a high level of facilities in the province, where the index of facilities provision ranges from 0.69 RANKING BASED ON INFRA- to 0.54. The counties like Charoumagh, Varzeghan, STRUCTURE INDIXES Malekan, Bostanabad and Haris are among the very deprived ones in the province since they have the lowest Infrastructure is one of the most important factors which social facilities and services provision. The deprivation plays an important role in the regional development. index of these counties is between 0.96 and 0.89, and Infrastructure is considered as a series of correlative that shows a very high level of deprivation, especially in networks, energy networks, and information networks, the counties like Charoumagh and Varzeghan. and various water pipelines and services. The research Ranking of social indices which was conducted by indicates counties’ infrastructure facilities and services cluster analysis reveals that there are four homogeneous provision level. Tabriz, Jolfa, Azarshahr and Bonab are groups from the viewpoint of social indices. The considered as the most privileged counties, whereas counties like Tabriz, Azarshahr, Maraghe, Shabestar, Charoymagh, Kalibar, Varzaghan and Haris are Jolfa and Sarab with indices ranging from 0.7 to 0.54 regarded as the deprived ones. Based on the ranking are at the first level of facilities provision. Among the results, the distance between the most deprived and counties that are at the first level, all apart from Sarab most privileged counties is approximately double. are located in the western part of the province. Counties Infrastructure indices rating show the predominance of like Ahar, Hashtroud, Marand, Asko, Banab and counties like Tabriz, Jolfa and Azarshahr in comparison Miyaneh are at the second level homogenous counties to other counties regarding the infrastructural facilities of the province and their index ranges from 0.77 to 0.64. provision. The deprivation scale of these counties Counties like Bostababad, Haris and Ajabshir are at the ranges from 0.5 to 0.56. Accessibility to better third level, and counties like Malekan, Varzeghan and correlative networks, provision of adequate energy Charoumagh are at the fourth level. The counties of networks, accessibility to telecommunication and third and fourth level are among the most deprived ones information lines, are considered as qualities of counties in the province from the viewpoint of social indices. situated in the 1st group. Bonab, Malekan, Shabestar, Oscu, Maraghe and Marand with deprivation scale REGIONAL DISPARITIES ANALYSIS ranging from 0.6 to 0.7 are situated at the 2nd level of ACCORDING TO ALL INDICATORS provision. These counties are located at the western correlative paths of the province. There is no county in Evaluation of total indices of development of the east part of the province with correlative networks status counties in the province shows a large correspondence in the 2nd group. to the individual index ratings for the counties. Counties An interesting point to be considered here is that the like Tabriz, Azarshahr, Shabestar, Jolfa and Banab are counties from the 1st and 2nd group are all in the west, the 5 counties with respectively highest levels of whereas other eastern counties stand in the next two development in the province, and their development groups with the least infrastructural facilities provision. index ranges between 0.6 and 0.74. Counties like Bostanabd, Ajabshir, Ahar, Hashtrood, Sarab and Miane Maraghe, Sarab, Marand, Asko and Miyaneh, with counties are in the 3rd group of infrastructural facilities development index between 0.75-0.81 are between the provision. As metioned before, all other counties in this 6th and 10th grade. Counties like Hashtroud, group are situated in the east, except from Ajabshir Bostanabad, Malekan, Ahar, Ajabshir, Haris, which is the only county located in the western part. Kalibr,Varzeghan and Charoumagh are between 11th Deprivation scale for these counties ranges from 0.73 to and 19th grade. The deprivation grade of the least 0.8. Haris, Varzaghan, Kalibar and Charoymagh are the performing counties is nearly equal in ratings for each counties which are at the lowest level of facility one of them. provision, ranging from 0.801 to 0.99 on the deprivation Total ranking of the counties of the province scale. according to the development indices shows that there are four rather homogenous groups of counties. Counties like Tabriz, Azarshahr, Shabestar and Jolfa take first to fourth grade of facility ranking which goes Journal of Urban and Environmental Engineering (JUEE), v.7, n.1 p.183-194, 2013 Zali, Ahmadi and Faroughi 191 between 0.6 and 0.7. Counties like Banab, Maraghe, deprived ones in the province, together with the Sarab, Marand, Osko and Miyaneh are between 5th to southeast part of the province with 4 counties and 10th grade of ranking with indices between 0.73 and average deprivation index of 0.86. 0.81, and they are at the second level of facilities provision. Counties like Hastroud, Bostanabad, Table 1. Geographical zoning of the province, status evaluation and Malekan, Ahar and Ajabshir are at the third level with average utilization index Develop Deprivati grades between 11th and 15th, and they have facility Number Region Province ment on index indices ranging from 0.82 to 0.87. Counties like Haris, of region regions average Kalibar, Varzaghan and Charoumagh are regarded as Jolfa – the most deprived ones in the province with indices North Marand- 3 3 0.72 west between 0.9 and 0.99, and are at the 4th level of Shabestar development , with grades ranking from 16th to 19th. Ahar- For better understanding of the deprived geographical East Kaleibar- 5 0 0.87 regions and those with facility provision, the counties of north Heris- Azarbayjansharghi province have been classified Sarab according to their proximity in four parts: northwest, Bostan Abad- northeast, southwest, and southeast, and the number of South Myane- 4 1 0.86 deprived counties and those with facility provision in west each part has been identified and the average indices for charouimag -Hashatrood them have been evaluated. Tabriz- The results of this classification for the northwest Azarshahr- part of the province, with an average index of Ouskou- South deprivation equaling 0.72, show the lowest grade of Ajabshir- 7 5 0.75 east deprivation. The southwest part with seven counties and Marageh- average derivation index equaling 0.75 is in the second Malekan- grade. The western part of the province has good quality Bonab- of facilities whereas the eastern part of the province is Province 19 9 0.8 deprived of them. The northeast part with 5 counties and average deprivation index of 0.87 is among the most Table 2. Provision level of East Azerbaijan provinces in different sections Foundational Production Basic (General) Social district All indices total section section Explanation Fi grade Fi grade Fi grade Fi grade Fi grade 1 Azarshahr 0.665 2 0.647 2 0.552 3 0.658 2 0.682 3 2 ouskou 0.786 9 0.760 11 0.665 7 0.838 11 0.775 10 3 Ahar 0.858 14 0.750 10 0.801 15 0.904 17 0.862 15 4 BostanAbad 0.851 12 0.903 16 0.739 10 0.681 4 0.899 18 5 Bonab 0.735 5 0.724 7 0.600 4 0.732 5 0.726 7 6 Tabriz 0.600 1 0.541 1 0.507 1 0.678 3 0.407 1 7 Jolfa 0.697 4 0.690 5 0.535 2 0.848 12 0.657 2 8 Charoumag 0.981 19 0.954 19 0.990 19 0.962 19 0.905 19 9 Sarab 0.774 7 0.694 6 0.764 12 0.769 8 0.726 6 10 Shabster 0.684 3 0.656 4 0.652 6 0.576 1 0.720 4 11 Ajabshir 0.868 15 0.878 14 0.739 11 0.896 16 0.794 11 12 Kalebar 0.924 17 0.826 13 0.979 18 0.910 18 0.838 13 13 Marageh 0.756 6 0.648 3 0.688 8 0.833 10 0.725 5 14 Marand 0.784 8 0.738 8 0.694 9 0.763 6 0.767 9 15 Malekan 0.855 13 0.921 17 0.632 5 0.822 9 0.842 14 16 Myaneh 0.800 10 0.779 12 0.777 13 0.763 7 0.742 8 17 Varzegan 0.933 18 0.940 18 0.894 17 0.871 14 0.890 16 18 Heris 0.909 16 0.893 15 0.861 16 0.867 13 0.897 17 19 Hashtrood 0.824 11 0.747 9 0.798 14 0.873 15 0.811 12 Journal of Urban and Environmental Engineering (JUEE), v.7, n.1 p.183-194, 2013 192 Zali, Ahmadi and Faroughi Table 3. Town’s exploitation levels according to expansion indices Foundational Basic (Genera) Level Social indices Production indices All indices indices indices Tabriz-Jolfa Azarshar-Tabriz – Tabriz-Jolfa- Tabriz-Jolfa 1 Azarshah SArab- BostanAba Tabriz Azarshahr Azarsha Shabestar- Maraghe Shabestar- Bonab-Malekan- Jolfa-Azarshar- Ahar-Hashtrood- Sarab- Marand- Shabestar – Marand- -Bonab- Sarab-Shabestar- 2 Marand-Ouskou- Ouskou Bonab- ouskou- Myaneh-Sarab Maraghe-Bonab- Bonab-Myaneh Myaneh Maraghe- marand Myaneh BostanAbad- Marand - Ouskou Ajabshir-Ahar- Bostan Abad- Ouskou -Maraghe- Malekan-Ajabshir 3 Ajabshir- - Sarsb-Hashtrood- Ajabshir Heris Jolfa Hashtrood - Hashtrood Myaneh -Kaleibar- Ahar -Ajabshir BostanAbad Heris-Varzegan- Hashtrood- Heris- Heris - Varzegan- Heris-Varzegan- Malekan- -Ahar 4 Charouimag- Varzegan- Kaleibar Charouimag Heris - Varzegan Malekan Charouimag- Charouimag- Charouimag- Maleka n Malekan CONCLUSION Based on the results of ranking the counties of the province in different sectors, the counties like Tabriz, Balanced development and policy making have Azarshahr, Shabestar and Jolfa have shown the first always been the main problems for planners and grade and the first level of development in the final managers, who attempt to prepare and execute suitable analysis. From the viewpoint of economical and programs for decreasing the imbalances and to reach the productive infrastructure, especially in the sector of balanced development by using different methods based industry because of concentration of big industrial on several models. According to methods that were used centers like tractor manufacturing, Eidem, here, the counties of Azarbaijansharghi province have petrochemical complex, automobile manufacturing, been ranked by different indices from the aspect of Tabriz refinery, Salimi industrial estate, industrial - having high level of facilities provision, thus the commercial free zone and other variable infrastructures, deprived counties and those with high facility provision these counties are regarded as the ones which have a have been distinguished. high level of facility provision in the western part of the The results of the analysis show that in reference to province. infrastructure, production, social and macro indices, the According to the ranking results of the counties, it is counties like Tabriz, Azarshahr and Shabestar always shown that counties like Tabriz, Azarshahr, Shabestar, are within high grades of ranking while counties like jolfa, Banab, Maraghe, Sarab, Marand and Oskou fall Charoymagh, Kalibar and Varzaghan are always within within first to ninth grade. With exemption of Sarab low grades of ranking. In relation to the balanced county in the east, all counties of this group are located development foresightedness, it seems that a long term in the western part of the province, thus it could be planning should be based on thought of social justice in inferred that the western part of the province is more attaining different indices of development. It seems that developed than its eastern part. Therefore, we can the important thing in planning is to pay due attention assume a linear developed axis for the western part of toward counties with the lowest grades of social, the province. economical and infrastructural facilities. The above mentioned counties that are on a Based on this graph, the difference between the most development axis have some common characteristics. deprived county and the county with the highest level of Firstly, they are located in the railway corridor or they facilities is very large and it is necessary that in future have easy access to the railway. Secondly, they are development programs a special care is put toward located in the vast plains of the western part of the counties like Charoumagh, Kalibar, Varzaghan, Haris, province, e.g. in Tabriz plain, Maraghe plain, Marand Ajabshir and Ahar, which are among the most deprived plain, or they are located near these plains. From the counties. For example, by policy making based on the viewpoint of their size and fertility, these plains are least index, during a time period of 4 years the deprived regarded as the biggest and the best plains of this counties or counties having low level of facility could province. Another characteristic of these counties is the be improved. high ratio of urbanism in comparison to other counties, Journal of Urban and Environmental Engineering (JUEE), v.7, n.1 p.183-194, 2013 Zali, Ahmadi and Faroughi 193 so that counties of the first rank, which are located in Ajabshir and Malekan are located in the western part of the western part of the province are 75% urbanized in the province. average. Even if we exclude the Tabriz county from this group, the average level of urbanization is again higher REFERENCES than 55%. On the other hand, other counties that are manly located in the eastern part of the province have in Amini, N. (2006) Ranking health in Iran province. Refah J. 5(1), 27– average 30% of urbanized population. By this analysis 48. Antonescu, D. (2012) Identifying regional disparities in Romania: a there is a direct correlation between the level of convergence process perspective in relation to European Unions urbanization and the degree of development. 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