CHAPTER 3

CONTEXT OF POLLUTION IN THE

3.1 Purpose

This chapter provides background information on the study area, discusses the sources and causes of pollution in the Buriganga River and critically reviews the findings of previous studies on water quality and pollution management for this river.

3.2 Study area

3.2.1 Hydrodynamic features

The Buriganga River system is located in the southern part of the North Central Region of , close to the confluence of the Padma () and upper Meghna rivers. The hydrology and the flow of this river are influenced by some upstream rivers and canals like Jamuna, Turag, Karnatali, Dhaleswari and khal (canal) (Figure 3.1). The Buriganga is an old river and there is a traditional story behind naming this river. Originally, one branch of the Ganges River flowed into the Bay of through the Dhaleswari River. Over time, this branch changed its course and eventually lost its connection with the primary flow of the Ganges River and was renamed as Buriganga (Old-Ganges) (Majumdar 2005). Previously, the upstream of the Buriganga, above the confluence of the Turag was a branch of the Dhaleswari, which used to contribute a substantial flow to the Buriganga. However, in recent times this portion of the river has dried up. At present, the flow of the is the main source of water into the Buriganga, particularly during the dry period (Kamal 1996; Alam 2003). Thus, originating from Dhaleswari and after meeting with Turag near Bosila, this river flows along the western border of City and finally reunites with the Dhaleswari River at Hariharpara (Rashid 1991; Gain et al. 1998).

33 The boundary of the Buriganga River is considered from Bosila (where the river Turag ends at a distance of about 11 km downstream from Aminbazar bridge at Mirpur) to Hariharpara (where Buriganga meets with Dhaleswari downstream) which is 17 km in length. The river reaches have general low gradient from north to south direction (BWDB 1996). Generally, the river experiences low tidal (back water) influence in downstream reaches during the wet (monsoon) season, where as during the dry periods semi-tidal influence occur (Magumdar 2005). The tidal effect during the dry season takes place when the upstream flow becomes very low or non-existent (SWMC 1996). The entire eastern bank of the river is enclosed by the Dhaka Integrated Flood Protection embankment with drainage structures to protect Dhaka City from flooding by Buriganga (Huq and Alam 2003).

Figure 3.1. The Buriganga River system (Inset: location of the study area is boxed in the map of Bangladesh) Image adapted and modified from: IWM 2004a Inset image source: http://www.physics.harvard.edu/~wilson/arsenic/countries/bangladesh/arsenic_project_maps.html

Rahman and Rana (1996) have reported the average flow of the river during May to October as 700 m3/sec and during November to April as 140 m3/sec. Camp and Mckee (1989) observed the flow rate in Buriganga on the order of 400 to 850 m3/sec during the

34 months from June to October. Moreover, it has been reported that during the dry months of the year, the net flow of the river becomes very low or non-existent (SWMC 1996). Kamal (1996) reported that the low flow rate of the river during the dry season causes little dilution capacity of pollutants in Buriganga. The average (considering both dry and wet season flow) width of this river has been recorded as 500 m (Rahman and Rana 1996). However, there is a possibility that because of morphological reason in the last two decades the flow rate of this river may have changed.

The Bangladesh Water Development Board (BWDB) regularly monitors and keeps record of the hydrological information of this river. Latest available data (during years 2005, 2006 and 2008) on water level, surface water velocity and discharge rate of Buriganga River at Millbarak, which is about 10.5 km downstream from Bosila were collected through personal communications from the BWDB. According to these data the river attains the maximum water level, surface water velocity and the discharge rate during the months from July to September, while the minimum values remain within the months of December to March (Figure 3.2). The average maximum flow of the river during May to October in last few years remained within 300 to 1,100 m3/sec, while the average minimum flow of the river during November to April remained within 60 to 90 m3/sec.

These data show a distinct difference of river flow characteristics during the different periods of the year, which is influenced by seasonal variation, rainfall and discharge from upstream rivers. This flow variation has direct impact on the pollution assimilation capacity of the river (Kamal 1996) and hence the temporal (seasonal) variation needs to be considered while studying the pollution impact and management alternatives. A substantial temporal difference for water level, discharge and velocity of the Buriganga River has been observed between two major periods of the year. The month-wise variations of these two periods are distinguished in two seasons which are dry (November to March) and wet (April to October). The distinction of the two seasons is further validated with the data on the climatic situation of the study area in the next section.

35 ) 6

5 D datum

W 4 P , 3 n m

(i 2 evel 1

0 Water l Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Months

(a) Water level 2005 2006 2008

1.2 sec) / 1 y (m t 0.8 oci 0.6

0.4

0.2 rface water vel

u 0 S Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Months

(b) Surface water velocity 2005 2006 2008

1800 1600

ec) 1400 1200 1000 800 scharge (cum 600 400 ver di

Ri 200 0 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Months

(c) Discharge rate 2005 2006 2008

Figure 3.2. Buriganga River (a) water level, (b) surface water velocity and (c) discharge rate measured at Millbarak during 2005, 2006 and 2008 (Data source: Bangladesh Water Development Board through personal communication)

36 3.2.2 Climatic condition

The climatic condition of the study area is classified as tropical monsoon type, which influences the hydrodynamic features of the Buriganga River. The temporal variations in climatic features such as rainfall intensity, duration, air temperature, relative humidity, evaporation and wind velocity affect the magnitude of discharge along hydrological pathways (Burgoa et al. 1993; DeWalle and Pionke 1994), which ultimately affect the quality of the river water.

The long term monthly average climatic data of the study area is presented in Table 3.1. It is observed that for the dry season, the monthly average values for rainfall (29.9 mm), rainy days (2.6), maximum temperature (28.4 0C), minimum temperature (16.4 0C), humidity (69.4 %), evaporation (88.8 mm) and wind velocity (3.3 km/hr) are lower than the corresponding values for rainfall (285.5 mm), rainy days (13.1), maximum temperature (32.1 0C), minimum temperature (25.2 0C), humidity (82.3 %), evaporation (97 mm) and wind velocity (7.1 km/hr) during the wet season.

Table: 3.1 Climatic condition of the study area Months Average No. Max. air Min. air Relative Evaporation Wind Seasons rainfall of temperature temperature humidity (mm) velocity considered (mm) rainy (0C) (0C) (%) (km/hr) for this days research Jan 7.7 2 25.4 12.7 70 104 3.7 Feb 28.9 3 28.1 15.5 66 79 3.7 Dry Mar 65.8 5 32.5 20.4 63 81 5.6 season Apr 156.3 10 33.7 23.6 71 77 9.2 May 339.4 15 32.9 24.5 79 78 9.2 Jun 340.4 14 32.1 26.1 86 83 7.4 Jul 373.1 17 31.4 26.2 87 87 7.4 Wet Aug 316.5 16 31.6 26.3 86 130 7.4 season Sep 300.4 13 31.6 25.9 86 118 5.6 Oct 172.3 7 31.6 23.8 81 106 3.7 Nov 34.4 2 29.6 19.2 74 75 1.8 Dry Dec 12.8 1 26.4 14.1 74 105 1.8 season

Source: Bangladesh Meteorological Department (http://www.bmd.gov.bd/)

37 3.2.3 Drainage system

The Buriganga River receives wastewater and storm water along its course through many point sources such as sluice gates, city drains and effluent outfall of the Pagla Treatment Plant (PSTP). Kamal (1996) and Magumdar (2005) have identified five sluice gates along the river which have the potential of discharging wastewater into this river. However, during the field visits conducted in this research, only the Rayerbazar sluice gate was found in operation. The previous studies by Kamal (1996) and Magumdar (2005) have also identified this particular sluice gate to be the most susceptible to discharge highly polluted wastewater from tanneries in Hazaribagh area along with municipal wastewater from the neighbouring areas of Katasur and Ramchandrapur khal. Kamal (1996) and Magumdar (2005) have identified 41 city drains including the Dholai khal along the Buriganga, which carry wastewater and storm water and directly discharge into the river. However, the Dholai khal which was identified as a major pollution route in Buriganga (Rahman and Rana 1996) does not exist any more, as it has been converted into a box culvert. Moreover, it was found during the field work that many of the city drains (including Dholai Khal box culvert) remain non-functional throughout most of the year as they are clogged up because of poor maintenance (New Nation 2009). The clogging of the city drains has caused overflowing of these previous pollution routes and are possibly diverted through other drainage routes which are currently functional.

Besides these point sources, there are numerous discharge pathways (diffused sources) of wastewater into the Buriganga River from adjoining urban to semi-urban areas and some low lying areas, originating either from industries or from domestic wastes. These are mostly located within very densely populated areas near the river like Islambagh, Shahidnagar and Kamrangir Char. Because of this scattered and unpredictable drainage pattern, the Buriganga River basin has been subdivided into a number of wastewater and storm water drainage zones by previous studies in order to compute wastewater flow rates and pollution loadings (JICA 1991; Browder 1992; Kamal 1996; Rahman and Rana 1996).

Each of the above mentioned studies had its own objectives and criteria in determining the drainage zones; and therefore, they do not match with one another. However, the information collected on different drainage zones for the Buriganga River facilitated to

38 charter the flow of wastewater generated from the surrounding areas of Buriganga. The Burignaga River basin drainage zone as identified by the JICA (1991) has been found to be the most relevant one to use for the purpose of this particular research. Accordingly, the information collected from JICA (1991) and Browder (1992) facilitated in identifying three major pollutant discharge routes into the Buriganga from three different drainage zones viz. Hazaribagh and Rayerbazar tanneries, City drains near Shahidnagar and PSTP outfall as described in Table 3.2. Ahmed et al. (2010) have also identified these as the three main pollutant discharge routes into the Buriganga River. Each zone accumulates pollution within a certain area from a number of sources (both point and diffuse) and ultimately drains wastewater through specific discharge points such as sluice gate, drainage outlet or effluent outfall. This drainage zoning pattern simplifies the computation of pollutant load and wastewater flow rate into the Buriganga River.

Table: 3.2 Three main drainage zones of Buriganga River basin Discharge Location Drainage zone Drainage point area (sq. km) A Rayerbazar Drains tannery waste of Hazaribagh along with 17.6 sluice gate municipal wastewater from Rayerbazar, Nimtala, Sultanganj, Zigatola, Nawabganj and west Dhanmondi

B Shahidnagar Discharges municipal waste water (untreated or 17.7 drainage partially treated) through City drains from outlet Pilkhana, Enayetganj, Azimpur, Kamrangir char, Islambagh and Nawabganj

C Pagla Sewage Discharges treated sewage from PSTP, 7.3 Treatment Industrial wastes from Pagla, Shyampur and Plant (PSTP) Postogola effluent outfall

Adapted from: JICA (1991) and Browder (1992)

3.2.4 Socio-economic condition

Dhaka, the capital of Bangladesh, has grown on the banks of the Buriganga River. It is the eighth largest city (the metropolitan area administered by Dhaka City Corporation) in the world, with a population of around 12.8 million (BBS 2009a) and an average density

39 of about 28,000 people per sq. km, which is one of the highest in the world (Morol 2009; Nabi 2009). Dhaka was established as a provincial capital of the Mughal rulers on the Northern bank of Buriganga in the year 1610. However, the city’s existence can be traced back to the seventh century when the township is known to have existed as a small riverside settlement (Alam 2008). The city has since developed gradually on the north and eastern banks of the Buriganga River.

At present, the major land use along the banks of the Buriganga River falls within the category of urban fringe areas. The areas are mainly used for residential and commercial purposes, e.g. housing, markets, small to medium enterprises (SMEs)/industries and warehouses (DWASA 1998). Hundreds of thousands of people and hundreds of industries depend on this river and its water on a daily basis for various socio-economic purposes. A survey on the bank side population of this river conducted by Alam (2003) found that about 71 percent of them were employed, while 29 percent were unemployed. The percentage distribution of occupation of the employed people is provided in Table 3.3.

Table 3.3: Occupation of the river bank side population

Occupation Percent (%)

Self employed and business 35

Household work 31

S ervice 29 In dustry 4.6 A griculture 0.4

Total 100

Modified from: Alam (2003)

The Buriganga River acts as the main navigational route for important commercial activities of Dhaka City and thus is an integral part of the city’s urban landscape, history, economy and ecology. Over the years and especially since the 1980s, unplanned urbanisation, industrialisation and population pressure along the river have adversely affected the river’s flow and ecological condition (Browder 1992; BKH 1995). The current population density within the river drainage area is extremely high, around 46,000 per sq. km (estimates based on population census-2001 and with 2.5 percent average

40 growth rate) (BBS 2001). The greater opportunities for business and trade and easy communication are the main reasons for the high population density along the river banks (Alam 2003). However, the massive urbanisation and population growth along the banks of the river has made it vulnerable from the discharge of industrial effluents, sewage, household and commercial wastes.

3.3 Usefulness of the Buriganga River

Unlike many other rivers in the world, the Buriganga River is not only important for providing vital ecological function (Mika et al. 2008), but also for various other purposes such as drinking water supply, transportation, cleaning, washing, recreation, ground water recharge, flood control and also as a means of disposing wastes within the assimilation capacity of the river. Currently, there is no establishment of any irrigation project which depends on the water of this river. The following sections will briefly discuss the utility of the Buriganga River to Dhaka City residents to further understand the importance of healthy existence of this particular river.

3.3.1 Water supply

The Buriganga River was once used as the main source of water supply for Dhaka's residents when the Chadnighat water treatment plant (located near Millbarak) was established in 1874, which is currently being operated by Dhaka Water Supply and Sewerage Authority (DWASA) (Alam 2003; IEDS 2003). The plant has a capacity to treat 39 Million Litre per Day (MLD) of water (about 2 percent of the present daily demand for water in Dhaka City) from this river for supplying it to the surrounding urban areas like in Lalbagh and Kotwali for drinking and other domestic usage (Grontmij 2009; Kamol 2009a). However, according to a recent statement of DWASA official, the plant currently uses excess chemicals to treat the river water and often cannot run at its full capacity (Bulbon 2008).

3.3.2 Inland water transportation

The Buriganga River provides an extensive network of inland waterways all over Bangladesh, particularly within the southern districts. Hundreds of launches and

41 thousands of country and engine boats ply on this river daily to transport goods and passengers. The Dhaka Port (locally known as Sadarghat Launch Terminal) located on this river is used by an average of 30,000 people per day (Kamol 2009b). Apart from this major port, there are also several other ports and landing stations on this river such as at Postogola, Pagla, Fatulla, Kholamura and Bosila. Thus the Buriganga River system has been playing an important mode of communication for hundreds of thousands of people everyday and has a great significance for the economic life and development activities of Dhaka.

Because of this widespread inland transportation network, the river has contributed in the establishment of hundreds of SMEs and factories, shops and business centres and residential houses at a close proximity of the river. This has resulted in economic growth and employment generation in the surrounding areas, but has also caused negative impact on the quality of the river water from discharge of uncontrolled wastes.

3.3.3 Cleaning and washing

There are about 1.2 million people who live within the catchment area of the river and directly use the water for washing, bathing and other domestic purposes on a daily basis (Plate A.1 a to d in Appendix A) (Ahmed et al. 2010). Besides these, many people utilise the river for commercial laundry services, washing animals, cleaning polythene bags and plastic containers (for recycling factories).

3.3.4 Recreation

During the British regime, the bank of the Buriganga River was considered to be the most scenic place in Dhaka for its natural beauty. An embankment named Buckland bandh (named after C.T. Buckland, the then Commissioner of Dhaka) was constructed in 1864 to protect Dhaka City from flooding of this river and also to create recreational facilities around the embankment. In course of time, these facilities were closed down because of pollution, encroachment and unplanned development in Buriganga and surrounding areas. However, many people still use the river for recreational purposes, such as walking along the river side, swimming and boating (Alam 2003). Moreover, still to date occasional cruises on this river take place for visiting dignitaries and for local residents.

42 3.4 Sources and causes of pollution in the Buriganga River

The various sources of pollution have been identified through reviewing previous studies, inspecting the river during the fieldwork and discussing with experts and officials from relevant agencies like Department of Environment (DOE), Dhaka Water and Sewage Authority (DWASA), Dhaka City Corporation (DCC), Bangladesh Inland Water Transport Authority (BIWTA), Institute of Water Modelling (IWM) and Bangladesh University of Engineering and Technology (BUET).

3.4.1 Point sources

The major point sources of pollution in the Buriganga River are a number of industrial installations, municipal wastewater and sewage treatment plants (Rahman and Rana 1996; Kamal et al. 1999). These are described as below:

Discharge of industrial effluent

Small to medium sized home-based industries started developing along or near the banks of the Buriganga River since the 1960s (Alam 2003). BKH (1995) reported that most of these industrial enterprises did not have any treatment facility since their establishments and discharged their effluent either directly into the river or into the nearby drains and canals which subsequently found their way into the river. The Department of Environment (DOE) conducted a survey in 1998 and identified 249 industries along the banks of the river responsible for (Alam 2003). These industrial installations and SMEs include tanneries, dyeing industries, aluminium, iron and steel workshops, plastic, pharmaceuticals, battery manufacturing, washing, hardware and cold storage units (Ali and Chowdhury 2001; Alam 2003).

Faisal et al. (2001) and Khan (2006) contended that the largest share of industrial pollution load into the river comes from the tanneries, which are located in a small area of 25 hectares (0.25 sq. km) in Hazaribagh, where nearly 10,000 people rely directly on this industrial cluster for their source of income. The pollutants from these industries are being generated through leather tanning process, which involves a series of chemical operations. Within the tanneries, 85 percent of the hides (mainly cow hides) are processed

43 by the chromium tanning process, while 15 percent (mainly goat hides) by the vegetable tanning process (Alam 2003). As a by product in this process, large quantities of wastewater is being generated, which is characterised by high pH, high suspended and dissolved solids, high BOD and COD, strong colour and potentially toxic substance, such as chromium (Rao and Datta 1987; Devnath 2000). The wastewater from the tanneries is discharged through open drains into a stagnant pond named ‘Nimtala ’, which is located between the Hazaribagh area and the flood protection embankment along the Buriganga River. Ultimately, this wastewater is released through Rayerbazar sluice gate into the river.

There are data inconsistencies regarding the volume of effluent and loads of pollutants (in terms of BOD) discharged from the tanneries into the Buriganga. Some previous studies showed that up to 15,000 cubic meters of liquid wastes and about 18 tons of BOD load entered into the Buriganga each day from these industries (BKH 1995; Gain et al. 1998; DWASA 1998), while a newspaper report (Khan 2005) claimed that at least 22,000 cubic meters of tannery wastes were being dumped directly into this river every day. Contrary to these, some other reports (Mitu 2006; Khan 2007) have indicated that the discharge rate was only 7,700 cubic meters per day during 2006-2007. In an earlier study Browder (1992) estimated the BOD load from the tanneries as 15 tons/day. Moreover, 3,500 cubic meters of liquid wastes were being discharged each day from other industrial installations into the Buriganga (Gain et al. 1998; Khan 2005; Hossain 2007).

Discharge of municipal wastewater and sewage

The Dhaka Water Supply and Sewerage Authority (DWASA) is responsible for collection, treatment and disposal of municipal wastewater, sewage and storm water in Dhaka City. However, the existing sewerage system of Dhaka City is quite old and inadequate to meet the present demand. Reports revealed that the current sewerage network covers only 110 sq. km of 360 sq. km of the city area, serving only 20 percent of the population (SWMC 1995; Amin 2006; RPMC 2008). As a result, particularly in areas that are not yet within the sewerage network of DWASA (like the areas adjacent to the Buriganga), there has been a tendency of having unauthorized connection of domestic sewer into the storm water pipes that end into the Buriganga River (RPMC 2008). This causes discharge of massive amount of untreated municipal wastewater and sewage

44 directly into the Buriganga through the city drains and sewers along the river. The unauthorized connection has also resulted in blockage of sewerage system in many areas because of disposal of solid wastes into the pipes. Moreover, thousands of people have illegally built hanging houses (Plate A.2 in Appendix A) on the river banks and they also cause discharge of wastewater and sewage directly into the river.

In early 1960s the PSTP was established near the Buriganga River to treat the sewage of Dhaka City. The plant was renovated and extended in 1990 to increase its capacity to treat a maximum flow of 0.12 million cubic meters per day, which is so far the only sewage treatment plant for entire Dhaka City (Amin et al. 1998). In the present situation, this capacity of the plant is still very low compared to the current generation of sewage, which is estimated as 1.3 million cubic meters per day (RPMC 2008). However, because of the blockage created in the city sewerage network system, the plant currently receives only about 30 percent of its maximum capacity to treat the effluent (DWASA, personal communication, 2009). As a result, the remainder of the sewage is being drained into the lowlands and natural streams in and around Dhaka City and a portion of it is entering into the Buriganga River without any treatment.

3.4.2 Non-point or diffuse sources

Besides the major point sources, there are some diffuse sources that also cause pollution into the Buriganga River. These include: dumping of solid wastes along the banks in a scattered manner by river side dwellers (Plate A.3 in Appendix A); leakage of oil from floating oil-seller boats; and direct disposal of wastes (like residue of food, human excreta) from thousands of water vessels that ply on the river.

Pollution also results from urban runoff caused mainly by rainfall. As the runoff moves on the land, it picks up and carries pollutants including polythene bags disposing them into the river. Recently, BIWTA has discovered a 3 m layer of garbage including discarded polythene bags on the bed of this river near Sadarghat Launch Terminal (Khan 2009a).

The entire north bank of the river has now become urbanised and very few agricultural practices take place on the south bank of the river, where some vegetables are only being

45 grown in a few spots, mostly with the use of organic manure (Alam 2003). Thus the impact of agricultural runoff in the Buriganga River could be considered insignificant compared to the other sources.

3.5 Water quality guideline values

Pollutants generated from anthropogenic sources put the aquatic ecosystems under serious threat as well as constrict the safe use of water for different purposes. To control and prevent the release of these pollutants into the water bodies, many countries and regions took steps to formulate and implement water management policies and strategies, based on water quality guidelines among other measures. These guidelines set standards to assess the acceptable levels of water quality for particular use (Lawrence et al. 1994).

Water quality guidelines are formulated to protect and restore the quality of the region’s waters, according to the regulatory standards of the country. These guidelines help to identify the causes of water quality problems such as inadequately treated wastewater discharges, runoff from urban or agricultural areas and industrial effluents. Moreover, such guidelines can help decision makers, especially in countries where rivers are severely affected by pollution, to plan and adopt control strategies to deal with the impacts of pollutants.

The guidelines are conventionally expressed in numerical concentrations or narrative statements; however, some countries (like USA) have introduced the pollution guidelines in terms of total maximum daily load (TMDL). The guidelines are usually set as law to enforce for compliance in a country, being termed as water quality standards (Liston and Maher 1997). Table 3.4 provides the standards for allowable concentrations of the selected water quality parameters for different uses as set by the Department of Environment (DOE), which is the authorised government agency to control the environmental pollution in Bangladesh (GOB 1997). In this research the assessment results on the state of water quality of the Buriganga River will be compared with these water quality standards.

46 Table 3.4. Water and effluent quality guidelines (standards) of selected parameters for different uses as set by the DOE in Bangladesh Parameters River water For discharge For using as For maintaining as effluent in drinking aquatic river water water supply ecosystems source

Temperature (0C) 20-30 20-30 30 pH 6.5-8.5 6.5-8.5 6.0-9.0 DO (mg/L) > 6 > 5 4.5-8.0

BOD5 (mg/L) < 2 < 6 40 COD (mg/L) 4 4 200

ECw (µS/cm) 350 350 1200 Pb (mg/L) 0.05 0.05 0.1 Cr (VI) (mg/L) 0.05 0.05 0.1

NH3-N (mg/L) 1.2 1.2 50 3⎯ PO4 -P (mg/L) 6 6 35 Source: GOB (1997)

3.6 Previous studies on the Buriganga River

Various organisations and individual researchers have carried out a number of water quality studies in the Buriganga River. As a result, large amount of information on water quality and pollution impact in this river are available from various sources. Yet, except for a few previous studies, detailed measurement and assessment work on the water quality was not conducted; and several previous studies mainly provided references to earlier measurements carried out by others. The previous studies had different objectives and methodologies, particularly in terms of selecting the river water quality measurement locations (receptor points).

The strategy of selecting the receptor points (which will be discussed in detail in Chapter 4) as sampling locations for this current research was quite different from the strategies which were adopted in earlier studies. One of the purposes of this present research was to look into the dynamics (spatial and temporal variation) of pollution along the full length

47 of the Buriganga River. This would provide a wider representation of pollution situation of this river. Thereby in this research the receptor points were selected longitudinally away (0.5 to 5.5 km) from upstream or downstream of the points of waste discharge, while in most cases the earlier studies selected the receptor points horizontally near (within 10 to 50 m) the points of waste discharge (DOE 1993; Kamal 1996; IWM 2004b; Magumdar 2005).

It was anticipated that a clear understanding on the dynamics and assimilation of pollution along the full length of the river could not be reached, if the receptor points for river water quality measurements for this study were selected according to the sampling strategy of previous studies. Hence, as the strategy for selecting the receptor points in this research was different from the earlier studies, consequently, the numerical results from the previous water quality measurement locations could not be fully compared with the present water quality measurement locations. However, it would be useful to review the major findings of the previous studies in order to obtain an understanding on the trend of prevailing water pollution problem of the Buriganga River.

3.6.1 Trend of water quality

The available literature showed that the quality of the river water of Buriganga was under investigation since 1968. An assessment of recorded water quality data at Chadnighat in terms of DO and BOD concentrations for the period of 1968 to 1980 was conducted by Mohammed (1988). This study established that the average DO level at Chadnighat decreased considerably from 6.7 mg/L in 1968 to 3.3 mg/L in 1980, while the average BOD level at that point increased almost fourfold during the same period. Moreover, the same study recorded the DO and the BOD levels at the PSTP outfalls respectively as 4.2 mg/L and 2.1 mg/L during a sampling period in February 1987. The study also investigated the water quality near Hariharpara and found the DO and the BOD concentrations as 7.8 mg/L and 1.4 mg/L respectively. In addition, Mohammed (1988) argued that the river had a capacity to quickly disperse any wastewater discharged into the river. However, during the last two decades apparently the situation of the river has changed considerably and the legitimacy of these findings and arguments for that location need to be re-examined.

48 Ahmed and Mohammed (1988) observed the effects of effluent discharges on DO and coliform density along the five different points of the river during the dry season of the year. They found that the DO concentration remained below 4 mg/L (minimum value was observed near Dholai Khal outfall as 3.0 mg/L) within a stretch of about 9 km (from Buriganga Chainage 4 km to 14 km) of the river, while at the upstream (near Bosila) the average DO concentration was 5.5 mg/L and at the downstream (near Hariharpara) it was 7.0 mg/L. Thus they computed an oxygen sag curve along the length of the river and recommended shifting of the tannery industries (located at Hazaribagh and Rayerbazar area) to improve the DO concentration at the critical section of the river. They calculated that this shifting would increase the DO level from 3.0 mg/L to 4.5 mg/L within this section of the river. In the present conditions, the conclusion of this study (nature of the DO sag curve) may still remain valid, provided the upstream and the downstream DO levels should remain above the DO levels within the critical section. Otherwise, mere relocation of the tanneries may not substantially improve the river water quality of the Buriganga.

Based on the data compiled from previous studies, Figure 3.3 summarises the historical trend of DO and BOD levels in the Buriganga River at three different locations, where the information signify a definite deterioration of the water quality over the years. Moreover, the cumulative data on water quality of the Buriganga available between 1981 and 1990 as published by DOE (1993) indicate that a considerable problem existed in river water especially due to high Cr concentration (0.01 to 0.63 mg/L).

Browder (1992) carried out a comprehensive study on the state of incoming pollution in terms of BOD into the Buriganga River. Four major pollution discharge routes for this river were identified in this study (estimates of the BOD loading shown within brackets) as: Hazaribagh tanneries near Rayerbazar area (15 tons/day); City drains along the river near Shahidnagar (10 tons/day); Dholai Khal (35 tons/day); and PSTP outfall (5 tons/day). Thus the total amount of BOD loading discharged into the Buriganga through these routes was estimated at 65 tons/day (Browder 1992). However, there has been increased urbanisation and industrial growth along the river since then. In addition, Dholai khal route is currently no more in existence (replaced by box culvert) and the wastewater is being diverted to other routes. Therefore, it is likely that the pollution load along the different discharge routes of the Buriganga has altered since the study was

49 conducted by Browder (1992), and this justifies the necessity for an updated study on estimation of pollution load (amount) in Buriganga.

7 DOE acceptable level > 5 mg/L 6 Mar-85

5 Feb-89 Mar-90

L) 4 Dec-94 g/

m Dec-97 3 Feb-98 DO ( Mar-02 2 Mar-04 1

0 Near Hazaribagh tanneries at Near Chadnighat water intake Near PSTP effluent discharge Kamrangirchar point point Stations downstream

(a)

60 DOE acceptable level < 6 mg/L

50 Mar-85 Feb-89 40 Mar-90 g/L) Dec-94 30 Dec-97

BOD (m Feb-98 20 Mar-02

10 Mar-04

0 Near Hazaribagh tanneries at Near Chadnighat water intake Near PSTP effluent discharge Kamrangirchar point point Stations downstream

(b)

Figure 3.3. The historical trend of (a) DO and (b) BOD levels in Buriganga River at three different locations (Data compiled from: DOE 1993; Kamal 1996; IWM 2004b; Magumdar 2005)

50 Kamal et al. (1999) reported the findings on the overall status (location wise result was not presented) of water quality of the Buriganga River for the dry period of 1994-95. The summary of water quality data from this study in terms of the selected parameters is shown in Table 3.5. The study found that the test results hardly satisfied the DOE standards. Kamal et al. (1999) commented that the occasional high concentrations of DO or low concentrations of other parameters (where they complied with the DOE standards) were mainly the result of freshwater inflow into the river, especially during the high tide period and local rainfall. Based on the test results, this study also established that the water quality of the Buriganga River system had been deteriorating at an alarming rate, inadequate to sustain aquatic life. However, absence of specific location wise water quality test results has limited further use of the findings of this study.

Table 3.5. Summary of water quality results for the Buriganga River during the dry period of 1994-95 for selected parameters Water Quality Observed values Parameters (in mg/L) minimum maximum

DO 0.1 17.2

BOD5 2.5 430 COD 8 540 Cr 0 0.014

NH3-N 0 15.2 3⎯ PO4 -P 0.4 15.2 Source: Kamal et al. (1999)

It is apparent from the previous studies that river water quality of Buriganga has been deteriorating over at least the last two decades. The socio-economic development and the land use pattern along the Buriganga River has made it susceptible to pollution. Yet, the river is playing a vital role in maintaining the daily activities of people who live in and around the river basin. The information from previous studies is useful to understand the trend of pollution in Buriganga; however updated and comprehensive information is required to comprehend the pollution dynamics along the full length of the river.

51 3.6.2 Suggested measures for pollution management

Rahman and Rana (1995) conducted a study on the management of Buriganga River water quality in terms of DO and BOD under alternative scenarios. They were convinced that either a treatment plant at Hazaribagh or relocating of tannery units to Savar (at a distance of about 20 km north of Dhaka) would provide considerable opportunity to improve and to properly manage the Buriganga River water quality. However, the major limitation of this study was that it did not include the technical and economic feasibility of the alternative measures; hence the applicability of those measures could not be evaluated by the decision makers. In an another study Rahman and Rana (1996) assessed the pollution assimilation capacity of the Buriganga River and concluded that if the tanneries are shifted to a new location, the additional pollution loads could be discharged through PSTP without violating water quality standards, while the river would still have considerable assimilative capacity. However, this kind of approach may not provide a sustainable solution to the problem and it may only transfer the pollution from one place to another.

Commissioned by the Government of Bangladesh, BKH (1995) conducted a study to estimate the costs required for setting up of combined effluent treatment plants (ETP) for tannery industries at the proposed site in Savar. During 1995, the total cost required for this purpose was estimated as US$ 32 million (revised in 2007 as US$ 77 million). However, the industry operators have been claiming about US$ 62 million (about 8 percent of their total relocation costs) from the government as compensation for transporting their equipments and rebuilding at the new tannery estate in Savar (Khan 2009b). This has caused dispute between the government and the industry owners association and has since identified as a barrier for the implementation of this relocation measure in its full scale. Currently a legal case is pending with the High Court to resolve this matter (Bdnews 2010).

Although the earlier studies have identified that the water pollution in the Buriganga River is caused by a variety of sources, they have argued that this pollution is generated primarily by point sources (Rahman and Rana 1995; DWASA 1998; Kamal et al. 1999; Karn and Harda 2001). These point sources of pollution mainly come from discharge of industrial effluents and municipal wastewater, which are either directly discharged into

52 the river through drains and sluicegates, or are discharged into the nearby low lands, which ultimately drains into the river through some specific pollution routes.

Kamal et al. (1999) estimated the finalised BOD loadings from the point sources which entered into the Buriganga River system as 68.5 tons/day. This estimated pollution load was very close to the value (65 tons/day) estimated by Browder (1992). Kamal et al. (1999) also developed a one-dimensional water quality model (using Mike 11) for the Buriganga River system for a dry period of 1994-95 to simulate different alternative scenarios for pollution control and to predict the most likely condition of the river. The major findings from this simulation exercise were as follows:

- discontinuation or relocation of any of the major point sources of pollution (such as Hazaribagh tannery area or Dholai Khal) may not be adequate for the improvement of the minimum DO level in the river; - establishments of the treatment plants at the sites of the major point sources of pollution may not be sufficient for the improvement of the DO level in the river; - a dramatic improvement of the minimum DO level (5.14 mg/L) in the river was observed if all the pollutants from the major point sources were diverted, treated (60 percent BOD reduction) and discharged at the confluence of Dhaleswari- Lakhya river (at a distance of about 14 km downstream of Hariharpara). However, this study recognised the impracticality of implementing such measures to restore the water quality of the Buriganga River.

IWM (2004a) performed a study on the possibility of setting up a 140 km long augmentation route along the Dhaleswari-Pungli-Bangshi-Turag-Buriganga Rivers in order to improve the water quality of the Buriganga River. The model results from this study indicated that a minimum diversion of 300 m3/sec of water from the off take at the Jamuna River during the dry season for this proposed route would ensure acceptable quality of the Buriganga River water after satisfying the hydraulic requirements along the route. The proposed augmentation was designed considering the projected pollution loading in Buriganga up to year 2020. The capital cost for this project was estimated at US$ 100 million, with another US$ 1 million per year for the maintenance cost of the route.

53 However, application of that project without the detailed Environmental Impact Assessment (EIA) may result in negative consequences in other areas especially at the source of the proposed water diversion (Rotmans and Asselt 2000). Moreover, this is an expensive approach which is quite difficult to implement in a developing country like Bangladesh, considering the financial constraints of the government. Also, this measure may fail to provide a sustainable solution to the problem, as et al. (2006) have pointed that if the pollution loading in the Buriganga increases more than its design value, it may result in significant reduction in the positive effect of augmented flow in the Buriganga.

Alam (2003) conducted a study on estimating the valuation of pollution cleanup of the Buriganga River. The major findings of this study that used economic methods of valuation showed that a significant proportion of the respondents were willing not only to pay for environmental improvements of this river, but that they are also willing to contribute to the clean-up efforts in terms of devoting their own time. In this investigation, the development and restoration benefits of cleanup of the Buriganga River were estimated to be about US$ 7 million per year. This study concluded that failure to consider such benefits in the decision making calculations could lead to gross under- estimation of the role that general public could play in environmental improvement activities of the river.

54