Msc Thesis MWI SE 2014-24

MANAGEMENT AND OPERATION OF ONSITE WASTEWATER TREATMENT SYSTEMS - AN ANALYSIS OF SUCCESS FACTORS

Herath Mudiyanselage Udayakantha Herath

MSc Thesis MWI SE 2014-24

April 2014

MANAGEMENT AND OPERATION OF ONSITE WASTEWATER TREATMENT SYSTEMS - AN ANALYSIS OF SUCCESS FACTORS

Master of Science Thesis by Herath Mudiyanselage Udayakantha Herath

Supervisors Prof. Damir Brdjanovic

Mentors Dr. M.Ronteltap Dr. M. Mulenga Dr. Christoph Luethi Mr. M.G. Sherpa

Examination committee Prof. D. Brdjanovic Dr. M. Ronteltap Dr. C. Luethi

This research is done for the partial fulfilment of requirements for the Master of Science degree at the UNESCO-IHE Institute for Water Education, Delft, the Netherlands

Delft April 2014

©2014by Herath Mudiyanselage Udayakantha Herath. All rights reserved. No part of this publication or the information contained herein may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, by photocopying, recording or otherwise, without the prior permission of the author. Although the author and UNESCO-IHE Institute for Water Education have made every effort to ensure that the information in this thesis was correct at press time, the author and UNESCO- IHE do not assume and hereby disclaim any liability to any party for any loss, damage, or disruption caused by errors or omissions, whether such errors or omissions result from negligence, accident, or any other cause.

Abstract

The main objectives of this research are to identify the main challenges and success factors of operation and management of the DEWATS system at Nala in Nepal; including analyse the performance of the system; and to make recommendations on how the system can be improved and how lesions can be applied to similar type of systems in peri-urban areas of Nepal.

In order to achieve the objectives; sampling and laboratory analysis of wastewater samples collected at various points were performed. Additionally, a household survey covering 20% of the total households in the area, semi structured interviews with key groups related to operation and management of the treatment system and data collection from grey literature were carried out.

Sampling was carried out in the coldest months of the year, after 6-9 months from the start of the operation in the treatment plant. According to the results, although the treatment system achieves considerable removal efficiencies (more than 80% for COD and more than 93% for TSS), effluent quality was below the required effluent standards, in case of organic matter and pathogen removal. Therefore, further treatment steps would be necessary, if treated effluent is discharged to the surface water. However, reuse of treated wastewater for irrigation is a viable option. High level of treatment may therefore not be needed and most of the farmers are already willing to use the treated wastewater in their fields. However, Ammonia concentration was high even in the effluent and therefore, precautions have to be taken to avoid ammonia toxicity for the crops.

Selecting minimum wastewater temperature has a large effect on design of anaerobic baffled reactors and constructed wetlands and that was a major factor to overestimate the quality of effluent in the design. Therefore, selecting a realistic minimum wastewater temperature is very important in design, when further applying this type of treatment systems. A well established community organization with high public participation, vibrant leadership and team spirit engaged in operation and management of the treatment system is vital. Successful community involvement activities including the success of Community Led Urban Environmental Sanitation (CLUES) approach were major success factors for institutional sustainability. Treatment system is financially sustainable, if it is possible to operate with limited staff and getting voluntary community participation for most of the activities.

Key words: DEWATS, Operation and management, Nepal, Anaerobic baffled reactor, Constructed wetlands

i MANAGEMENT AND OPERATION OF ONSITE WASTEWATER TREATMENT SYSTEMS - AN ANALYSIS OF SUCCESS FACTORS

Acknowledgements

First of all, I would like to thank Eawag-Sandec for giving me an opportunity to do this research.

Special thanks to my mentors Dr. Mariska Ronteltap and Dr. M. Mulenga from UNESCO- IHE, Dr. Christoph Luethi from Eawag and Mr. Mingma Sherpa from Nepal and my supervisor, Prof. Damir Brdjanovic, for their guidance and motivating me to make this research a success.

Thanks for all who helped in the field work at Nepal. Special thanks to Mr. Mingma Sherpa, who helped me lot from the first day, after I came to Nepal, Mr. Bipin Dangol, my research assistants; Mr. Buddha Bajracharya and Mr. Roshan Chaulagain. Also, ENPHO gave me all the facilities to work at their office and did all the hard work of testing samples in a limited time frame.

Lot of gratitude for the people in Nala, office bearers and staff of Nala Drinking Water and Sanitation Committee and CIUD project office and the operator of the treatment plant for their great support at the field work of my research. It was a nice experience for me to work with a group of very friendly people in a nice country.

I very much appreciate support of every one, who helped me for my research although I could not mention all the names here.

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Table of Contents

Abstract i

Acknowledgements iii

List of Figures vii

List of Tables viii

Abbreviations x

1. Introduction 1 1.1. Problem statement, Research objectives, Research questions and Hypothesis 1 1.1.1. Problem statement 1 1.1.2. Research objectives 3 1.1.3. Research questions 3 1.1.4. Hypothesis 3 1.2. Wastewater treatment in Nepal 3 1.2.1. Wastewater related legislation in Nepal 4 1.2.2. Centralized wastewater treatment in Nepal 5 1.2.3. Decentralized wastewater treatment in Nepal 5 1.3. The concept of Decentralized wastewater treatment systems (DEWATS) 6 1.4. Treatment modules used in DEWATS systems 7 1.4.1. Settler/ Septic tank 7 1.4.2. Biogas reactor 8 1.4.3. Anaerobic baffled reactor 8 1.4.4. Anaerobic filter 9 1.4.5. Horizontal subsurface flow constructed wetland 10 1.4.6. Vertical subsurface flow constructed wetland 11 1.4.7. Waste stabilization ponds 12

2. Materials and Methods 13 This chapter contains a description about DEWATS system at Nala, which was selected for this study and various methods used for collection of data required to achieve the objectives. 13 2.1. Decentralized wastewater treatment system at Nala 13 2.1.1. Location 13 2.1.2. Situation before implementation of the treatment system 13 2.1.3. Design of the treatment system at Nala 14 2.1.4. Treatment components 15 2.1.5. Sewer system 17 2.1.6. Implementation of the project of wastewater treatment 17 2.1.7. Community Led Urban Environmental Sanitation (CLUES) approach 18 2.1.8. Current situation of the system 18 2.2. Sampling and laboratory analysis 18 2.2.1. Sampling 18 2.2.2. In-situ measurements 21 2.2.3. Laboratory analysis 22

2.2.4. Climatic conditions at the sampling period 22 2.3. Semiformal interviews 22 2.3.1. Household survey 23 2.3.2. Semiformal interviews with operation and management staff 23 2.3.3. Semiformal interviews with office bearers of the community organization 23 2.4. Literature review 23 2.5. Data collection from grey literature 23 2.6. Evaluation of the existing design 23 2.7. Analysis of the results 24

3. Results 27 This chapter contains results of the study. It includes performance results of the treatment system obtained from sampling, in-situ measurements and laboratory analysis and also the results obtained from other methods like semi structured interviews and data collected from grey literature. However, the sampling was carried out 6-9 months after the commencement of the operation at the treatment system. Also, sampling was performed at the coldest months of the year. Therefore, microbial activity in ABR and constructed wetlands might not be well established and cold temperature might also reduce it. 27 3.1. Technical performance of the treatment system 27 3.1.1. Flow rate 27 3.1.2. pH 29 3.1.3. Wastewater temperature 30 3.1.4. Solids removal 31 3.1.5. Organic matter removal 32 3.1.6. Nutrient removal 35 3.1.7. Pathogen removal 39 3.1.8. Summary of the discharge water quality 41 3.1.9. Climatic conditions of the sampling period 42 3.2. Results for analysis of Institutional and social aspects 42 3.2.1. Household information 43 3.2.2. Current situation of sanitation in households 44 3.2.3. Public involvement and acceptance of the current treatment system 45 3.2.4. Sludge treatment system 47 3.2.5. Treated wastewater reuse potential 47 3.2.6. Sewer system 48 3.2.7. Results from semiformal interviews with operation and management staff and office bearers of the community organization 48 3.3. Results for financial analysis 49 3.3.1. Income for the community organization 49 3.3.2. Capital expenditure 49 3.3.3. Recurrent expenditure 50

4. Discussion 51 4.1. Comparison of performance results with similar studies 51 4.1.1. Settler 51 4.1.2. Anaerobic baffled reactor 52 4.1.3. Horizontal subsurface flow constructed wetlands 53 4.1.4. Treatment system as a whole 54 4.2. Comparison of results with the original design 55 4.3. Redesign of treatment system with measured data 56 4.3.1. Redesign of settlers 56 4.3.2. Redesign of Anaerobic baffled reactors 59

4.3.3. Redesign of Horizontal subsurface flow constructed wetlands 61 4.3.4. Redesign of Constructed wetlands with anaerobic filters 63 4.4. Comparison of measured effluent quality with theoretical values 66 4.4.1. Settler 66 4.4.2. ABR 67 4.4.3. Horizontal subsurface flow constructed wetlands 68 4.5. Institutional sustainability 68 4.6. Financial sustainability 69 4.6.1. Income 69 4.6.2. Expenditure 70

5. Conclusions 73 5.1. Main challenges of operation and management of the treatment system 73 5.1.1. Technical aspects 73 5.1.2. Institutional aspects 74 5.1.3. Financial aspects 75 5.2. Main success factors of operation and management of the treatment system 75 5.2.1. Technical aspects 75 5.2.2. Institutional aspects 75 5.2.3. Financial aspects 76 5.3. Sustainability of the treatment system 77

6. Recommendations 78 6.1. Recommendations for the improvements to the DEWATS system at Nala 78 6.2. Key recommendations for applying similar treatment systems in small peri-urban areas of Nepal 80 6.2.1. Technical recommendations 80 6.2.2. Institutional and financial recommendations 81 6.3. Recommendations for further research 83

References 84

Appendices 86 Appendix A :Influent flow measurements 86 Appendix B :Results of Laboratory Analysis 87 Appendix C : Questionnaire for Household Survey 92 Appendix D : Semiformal interviews with operation and management staff and Office bearers of community organization 95 Appendix D :Semiformal interviews with operation and management staff and office bearers of the community organization 95

List of Figures

Figure 1.1 Septic tank ...... 7 Figure 1.2 Biogas reactor ...... 8 Figure 1.3 Anaerobic baffled reactor ...... 9 Figure 1.4 Anaerobic filter ...... 10 Figure 1.5 Horizontal subsurface flow constructed wetland ...... 11 Figure 1.6 Vertical flow subsurface constructed wetland ...... 12 Figure 2.1 Layout of sewer lines with wastewater treatment plant ...... 14 Figure 2.2 Bar screen chamber of the treatment system ...... 15 Figure 2.3 Hrizontal subsurface flow constructed wetland at the treatment system ...... 16 Figure 2.4 Layout of the treatment system ...... 17 Figure 2.5 Layout of treatment sytem in Nala with locations of sample points...... 19 Figure 2.6 Measurement of influent flow rate ...... 21 Figure 2.7 Flow diagram showing the means of getting to objectives 25 Figure 3.1 Influent flow rates measured at last manhole of the sewer system between 17.12.2013 and 06.02.2014 ...... 28 Figure 3.2 pH value at various points of the treatment system at 6 days between 01.01.2014 and 06.02.2014 ...... 29 Figure 3.3 TSS removal at various points of the two wastewater lines ...... 31 Figure 3.4 TSS concentrations at various points of the treatment system ...... 32 Figure 3.5 Average COD removal in the two wastewater lines ...... 33 Figure 3.6 COD concentrations at various points of the treatment system ...... 34 Figure 3.7 Wastewater discharge point when thereis no flow at the stream ...... 42 Figure 3.8 Distribution of households in each ward ...... 43 Figure 3.9 Interviewed member's position in the household...... 43 Figure 3.10 Number of people in the household ...... 43 Figure 3.11 Occupation of the people in the household ...... 43 Figure 3.12 Monthly expenditure in the household ...... 44 Figure 3.13 Time duration after connecting to the sewer network ...... 44 Figure 3.14 Reason for not connecting to the sewer system ...... 44 Figure 3.15 Participation for community organization ...... 45 Figure 3.16 Usefulness of community organization in solving problems related to sanitation ...... 45 Figure 3.17 Acceptance of current wastewater charges ...... 47 Figure 3.18 Number of households willing to buy sludge products for their crops ...... 47 Figure 3.19 Availability of water shortage for crops ...... 48 Figure 3.20 Willingness to use treated wastewater for crops ...... 48

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List of Tables

Table 1.1 Some selected tolerence limits for wastewater to be discharged into inland surface waters from combined wastewater treatment plant according to Generic standard Part III ...... 4 Table 2.1 Locations and uses of smapling points ...... 20 Table 3.1 Wastewater temperature measured at 8 days between 17.12.2013 and 06.02.2014 ...... 30 Table 3.2 Total suspended solids concentration in samples measured at 8 days between 17.12.2014 and 06.02.2014 ...... 31 Table 3.3 TSS removal efficiencies for different components of the treatment system ...... 32 Table 3.4 Chemical Oxygen Demand (mg/L) measured at 8 days between 17.12.2013 and 02.06.2014 ...... 33 Table 3.5 COD removal efficiencies ...... 34 Table 3.6 Total Nitrogen concentrations of influent and effluent samples and removal efficiencies .... 35 Table 3.7 Total Nitrogen concentrations of influent and effluent to constructed wetlands and respective removal efficiencies ...... 35 Table 3.8 NH4-N concentrations of influent and effluent measured in 5 days between 17.12.2013 and 24.01.2014 ...... 36 Table 3.9 NO3-N concentrations of influent and effluent measured at 17 and 24 of December 2013 . 36 Table 3.10 NH4-N concentrations of influent and effluent to the constructed wetlands and removal efficiencies ...... 37 Table 3.11 NO3-N concentrations of influent and effluent samples in constructed wetlands ...... 37 Table 3.12 Total Phosphorous concentrations of influent and effluent samples and removal efficiencies ...... 38 Table 3.13 Total Phosphorous concentrations of influent and effluent to the constructed wetlands and removal efficiencies ...... 38 Table 3.14 TP and Orthophosphate-P concentrations of influent and effluent measured between17.12.2013 and 24.01.2014 ...... 39 Table 3.15 Faecal coliform measurements at the influent and effluent of the treatment system and removal efficiencies measured between 17.12.2013 and 30.01.2014 ...... 39 Table 3.16 Faecal coliform content of influent and effluent to the constructed wetlands and removal efficiencies measured between 20.01.2014 and 06.02.2014 ...... 40 Table 3.17 Effluent water quality measured between 17.12.2013 and 06.02.2014 ...... 41 Table 3.18 Water quality at discharge on 30.01.2014 ...... 41 Table 3.19 Summary of suggestions by people to improve treatment system ...... 46 Table 4.1 Removal efficiencies of settlers in DEWATS systems ...... 51 Table 4.2 Removal efficiencies achieved from ABR with 6 compartments and 8 compartments ...... 52 Table 4.3 Removal efficiencies of ABR in DEWATS system at Sunga ...... 52 Table 4.4 Removal efficiencies of ABR in some DEWATS systems at Nepal ...... 52 Table 4.5 Removal efficiencies of Horizontal flow wetland in DEWATS system at Sunga ...... 53 Table 4.6 Removal efficiencies of Horizontal flow wetland in DEWATS systems ...... 53 Table 4.7 Treatment efficiencies in some constructed wetlands in Kathmandu valley ...... 53 Table 4.8 Removal efficiencies of DEWATS system at Sunga ...... 54 Table 4.9 Removal efficiencies of DEWATS systems ...... 54 Table 4.10 Results from the study and parameters from the original design ...... 55 Table 4.11 Initial parameters used in design of settlers ...... 57 Table 4.12 Dimensions of the settlers in the original design and the redesign ...... 58 Table 4.13 Initial parameters used in design of ABR ...... 59 Table 4.14 Comparison of new design with existing design ...... 60 Table 4.15 Initial parameters used in design of constructed wetlands ...... 61 Table 4.16 Comparison of new design of the constructed wetlands with existing design ...... 62

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Table 4.17 Initial parameters for designing of anaerobic filters ...... 63 Table 4.18 Comparison of new design of the constructed wetlands with existing design (with anaerobic filter) ...... 65 Table A.1 Flow measurements at the last manhole of sewer system ...... 86 Table B.1 Results of Laboratory analysis of sample at the influent ...... 87 Table B.2 Results of Laboratory analysis of sample at the effluent from the settler1 ...... 87 Table B.3 Results of Laboratory analysis of sample at the effluent from the settler2 ...... 88 Table B.4 Results of Laboratory analysis of sample at the effluent from ABR 1 ...... 88 Table B.5 Results of Laboratory analysis of sample at the effluent from ABR 2 ...... 89 Table B.6 Results of Laboratory analysis of sample at the effluent from Constructed wetland 1 ...... 90 Table B.7 Results of Laboratory analysis of sample at the effluent from Constructed wetland 2 ...... 91

Abbreviations

ABR Anaerobic Baffled Reactor BOD Biochemical Oxygen Demand BORDA Bremen Overseas Research and Development Association CDD Consortium for DEWATS Dissemination Society CIUD Centre for Integrated Urban Development COD Chemical Oxygen Demand CW Constructed Wetland DEWATS Decentralized Wastewater Treatment System Eawag Swiss Federal Institute of Aquatic Science and Technology ENPHO Environmental and Public Health Organization FC Faecal Coliform HFCW Horizontal Subsurface Flow Constructed Wetland HRT Hydraulic Retention Time Lpcd Litres per capita per day NGO Non Governmental Organization NPR Nepal Rupee O&M Operation and Maintenance SD Standard Deviation TKN Total Kjeldhal Nitrogen TN Total Nitrogen TP Total Phosphorous TSS Total Suspended Solids UN United Nations USD United States Dollar USEPA United Nations Environmental Protection Agency VDC Village Development Committee WB World Bank WHO World Health Organization WWTP Wastewater Treatment Plant

CHAPTER 1

Introduction

This chapter gives an overview of the purpose of the study, current situation of wastewater treatment in Nepal and the treatment units used in Decentralized Wastewater Treatment Systems.

1.1. Problem statement, Research objectives, Research questions and Hypothesis

1.1.1. Problem statement

Water and sanitation are one of the key areas of concern in sustainable development. Non availability of improved sanitation is one the major causes of contamination of water bodies and spread of communicable diseases globally. According to the World Health Organization statistics, about 6,000 children die every day, from diseases associated with inadequate sanitation, poor hygiene, and unsafe water. In 2011, only 64% of the world's population had access to improved sanitation (WHO, 2013). That indicates 36% of the world's population are obliged to defecate in the open or use unsanitary facilities, with a serious risk of exposure to diseases.

Because of these reasons, in 2000, United Nations made a promise to halve the proportion of the population without sanitation by 2015 as one of the sub goals in goal 7 of their Millennium Development Goals (UN, 2010). Achieving this goal has an influence on other goals also, since there is evidence that sanitation provision is fundamental to personal dignity, security, social and psychological issues, public health, poverty reduction and gender equality. Improved sanitation prevents diseases like Diarrhoea and Cholera, which puts stress on the health of children. However, the Millennium Development Goals Report of 2012 shows that many countries are lagging behind the target for basic sanitation and if the trend continues the number of people worldwide who do not have access to basic sanitation will grow to 2.7 billion in 2015 (WHO, 2014).

As a result, providing improved sanitation facilities has become one of the main objectives in development of most countries in the global South. Commonly used sanitation systems include; pit sanitation which is a drop and store method and flush sanitation which is a flush and discharge method. Although pit sanitation is a simple inexpensive system, it fails to contain and sanitize excreta, since pathogens and nutrients may seep into the ground water. In flush sanitation, human excreta is flushed with water and transported away to a treatment system, if such a facility exists (Shrish, 2011). However, in many cases, the waste is discharged

MANAGEMENT AND OPERATION OF ONSITE WASTEWATER TREATMENT SYSTEMS - AN ANALYSIS OF SUCCESS FACTORS 1

into the environment without any treatment. Therefore, a proper treatment system is necessary to prevent pollution of the environment and health risk to the people.

Approaches used for treatment wastewater in flush sanitation can be classified into two forms as centralized treatment and decentralized treatment. The centralized system consists of a water-borne wastewater collection system leading to a central treatment plant, where the wastewater is treated. This has been successfully applied over many decades and contributed to a great extent to the improvement of hygienic conditions in the world. On the other hand, in decentralized treatment systems, wastewater is collected and treated at a treatment system in household or community level.

The decentralized wastewater management concept can effectively be used to reuse wastewater as a potential resource and can be used to solve sanitation issues as close as possible to the source of waste generation. Furthermore, the decentralized wastewater management concept: •broadens the technology options and permits tailoring the solutions to the prevailing conditions; •minimizes the freshwater requirements for waste transportation; •reduces the risks associated with system failure; •increases wastewater reuse opportunities; and •permits incremental development; and investment in the community wastewater systems (Shrish, 2008).

Currently, decentralized wastewater treatment systems (also called as DEWATS) are becoming more and more popular all over the world. The main reason for that is the low maintenance requirement after construction and applicability for small communities, industries and small organizations. Most of the experts and organizations working on wastewater treatment have realized the importance of decentralized wastewater treatment systems as an alternative for conventional centralized wastewater treatment. Therefore, the number of decentralized wastewater treatment systems is increasing rapidly both in the developed and developing countries.

In developing countries, both government organizations and non-governmental organizations are promoting the use of DEWATS as a technological approach for treating black water and gray water discharged by households. Since most of the governments are now enforcing legislation for effluent standards, institutional and industrial level motivation is also increasing for the use of DEWATS systems. Sometimes, although construction of the treatment system is performed properly, little attention is drawn to the operation and management of the system. This leads to the deterioration in the performance of the system gradually and may lead to complete failure at a certain point. Consequently, untreated or poorly treated effluent may end up being discharged into environment creating pollution problems. This may also result in increased exposure to the health hazards for the people living around. Therefore, sustainable operation and management is equally important as the installation of treatment systems.

Identifying factors that affect the successes and failures in operation and management is very important to improve the performance of existing treatment systems and to set-up operation and management programmes for new treatment systems. It will decrease the possible failures of DEWATS systems in future. There are limited researches that have been performed in this regard. Most of the studies are dealing only with performance analysis and technical aspects of operation and management of the DEWATS systems. Therefore, it is necessary to have more studies on operation and management of DEWATS systems, which take into consideration all technical, institutional and financial aspects.

Nepal, the selected country for case study in this research, is a low income Asian country with diverse ethnic groups, high variation in altitude and climatic conditions. It is one of the countries where DEWATS systems have been increasing in popularity over the last few decades. Several studies have been done which look into the performance analysis, technical aspects and community involvement in implementation in DEWATS systems. But, there are no studies integrating all technical, institutional and financial aspects in

operation and management of a DEWATS system operating in Nepal. Therefore, this study aims to fill this gap.

1.1.2. Research objectives

General objective of this research is to analyze the success factors of management and operation of onsite wastewater treatment systems.

Specific objectives that are to be achieved through this study are as follows:  To identify the main challenges and success factors of operation and management of the decentralized wastewater treatment system in Nala, Nepal  To evaluate technical aspects including treatment efficiency achieved with current operation and management practices  To analyze institutional aspects related operation and management of treatment system  To analyze the financial sustainability  To recommend operation and management measures to improve the performance of the decentralized wastewater treatment system in Nala  To give key recommendations for applying DEWATS in small, peri-urban towns similar to Nala in Nepal

1.1.3. Research questions

This research is aimed to answer following research questions. 1. What are the main challenges and success factors of operation and management of the decentralized wastewater treatment system at Nala, Nepal? 2. How can the management and operation of decentralized wastewater treatment system at Nala in Nepal be improved for better performance? 3. What are the key recommendations for applying DEWATS in small, peri urban towns similar to Nala in Nepal

1.1.4. Hypothesis

Proper management and operation practices with sustainable financial arrangements will improve the performance of decentralized wastewater treatment systems.

1.2. Wastewater treatment in Nepal

Nepal is a landlocked sovereign state located in South Asia. Its total land area is 147,181 square kilometres and the population is approximately 27 million (Central Bureau of Statistics, 2012). Nepal is the world's 93rd largest country by land mass and the 41st most populous country. It is boarded to the north by China and to the south, east and west by India. Nepal has eight of the world's ten tallest mountains, including the highest point on the Earth, Mount Everest (Wikipedia, nd). According to Census in 2011, Average annual population growth is 1.35% and the population density is 180 persons per square kilometre. Urban population is nearly 17 percent of the total population (Central Bureau of Statistics, 2012).

MANAGEMENT AND OPERATION OF ONSITE WASTEWATER TREATMENT SYSTEMS - AN ANALYSIS OF SUCCESS FACTORS 3

Nepal is currently experiencing rapid urbanization. People are moving from villages to nearby municipalities expecting better quality of life, better access to health, education facilities and employment opportunities. However, high level of poverty is still a major challenge for the country. According to UN (2013), per capita gross domestic product is 607USD. According to World Bank (2011), 25 percent of population is living below poverty line.

1.2.1. Wastewater related legislation in Nepal

For environmental protection, government of Nepal has imposed several legislations. Among them, following are the standards related to wastewater discharge.

Generic Standards: Part I : Tolerance Limits for Industrial Effluents to be discharged into Inland Surface Waters Part II : Tolerance Limits for Industrial Effluents to be discharged into Public Sewers Part III : Tolerance Limits for Wastewater to be discharged into Inland Surface Waters from Combined Wastewater Treatment Plant Industrial Effluents Standards – Tolerance Limits for Industrial Effluents Discharged into Inland Surface Waters

However, there is no any legislation specific for domestic or municipal wastewater discharge. But, Generic Standards Part III : Tolerance limits for Wastewater to be discharged into Inland Surface Waters from Combined Wastewater Treatment Plant can be applicable, although no industrial wastewater discharge is available in this case.

Some tolerance limits given in that standard are given in Table 1.1.

Table 1.1 Some selected tolerance limits for wastewater to be discharged into inland surface waters from combined wastewater treatment plant according to Generic standard Part III

Characteristics Tolerance Limit

Total Suspended solids Max. 50mg/L

Particle size of total suspended particles Shall pass 850-micron Sieve

pH 5.5 to 9.0

Temperature Shall not exceed 40°C in any section of the stream within 15m downstream from the effluent outlet

Biochemical Oxygen Demand for 5 days at 20°C Max. 50mg/L

Ammonia Nitrogen Max. 50mg/L

Chemical Oxygen Demand Max. 250mg/L

These limits are somewhat similar to the General standard for discharge of environmental pollutants in India. However, maximum limit for suspended solids is strict in Nepal than in India, where it is 100mg/L. Maximum BOD in 3 days at 27°C is 30mg/L in India. Other limits like pH, Ammonia Nitrogen and COD are almost similar in India and Nepal (CPCB, 1986).

1.2.2. Centralized wastewater treatment in Nepal

Some centralized wastewater treatment plants are available in Kathmandu valley. However, most of them are not functioning well and discharging untreated or partly treated wastewater to the streams. That is the main reason for pollution of some water bodies like river Bagmati, which is the main river in the valley. According to Shrish (2011), four out of five treatment plants in Kathmandu valley are out of operation. But, functioning treatment plant is serving only a 3% of the total households in the city. Main reason for failure of treatment plants is poor maintenance of the systems.

1.2.3. Decentralized wastewater treatment in Nepal

Approximately 30% of the households having toilets use septic tanks as the wastewater treatment method. But, most of the septic tanks are not working properly and discharging untreated wastewater to the surrounding environment. Deterioration of water quality in surface water and ground water sources due to discharge of untreated wastewater has created health impacts to the people living in the city and the surrounding area (ENPHO, 2011).

Several decentralized wastewater treatment systems have been built in Nepal by various groups to minimize public health and environmental problems associated with uncontrolled discharge of untreated or poorly treated wastewater. The first community scale treatment system in Nepal has been built by ENPHO in 1997 for Dhulikhel Hospital. Since then, more than 20 new community and institutional level on-site wastewater treatment systems have been built by ENPHO and other organizations in Kathmandu valley and other areas of Nepal (ENPHO, 2011).

Considering operation and management of on-site wastewater treatment systems, four types of systems can be recognized as follows: 1. Community based treatment systems 2. Municipality managed treatment systems 3. Institutional wastewater treatment systems 4. Privately owned and operated wastewater treatment systems

According to ENPHO (2011), most of the on-site treatment systems are operating moderately to well. However, most systems have some issues with operation and maintenance, often due to poor understanding of system operation or lack of funds. Community systems with biogas generation are more financially viable due to generation of income by selling biogas.

Asian development Bank has approved funding for Kathmandu valley wastewater management projects in April, 2013. This project will invest in rehabilitation and expansion of sewerage network, modernization and expansion of wastewater treatment plants and improvement of wastewater management in the Kathmandu Valley (ADB, 2013). This project is mainly concerned about centralized wastewater treatment plants. However, it indicates that decentralized wastewater treatment systems would be a suitable solution for peripheral areas of Kathmandu city. Although an expectation for large treatment plants capable of treating entire wastewater from the city is available, also there is a great opportunity for decentralized wastewater treatment for treating wastewater from areas that have lower priority in connecting to a central system (ENPHO, 2011).

MANAGEMENT AND OPERATION OF ONSITE WASTEWATER TREATMENT SYSTEMS - AN ANALYSIS OF SUCCESS FACTORS 5

1.3. The concept of Decentralized wastewater treatment systems (DEWATS)

DEWATS is an approach, rather than a technical hardware package, which is based on a set of treatment principles. The selection of which has been determined by their reliability, longevity, tolerance towards inflow fluctuation. It can be used to treat 1-500m3 of wastewater per day. It works without any energy input and guarantees permanent and continuous operation. However, fluctuations in effluent quality may occur temporarily (Sasse, 1998).

DEWATS are based on four treatment steps.  Sedimentation and primary treatment in sedimentation tanks, septic tanks or Imhoff tanks  Secondary anaerobic treatment in fixed bed filters or baffled septic tanks (baffled reactors)  Secondary and tertiary aerobic/anaerobic treatment in constructed wetlands  Secondary and tertiary aerobic/anaerobic treatment in ponds

These steps are combined in accordance with wastewater influent and the required effluent quality (Sasse, 1998).

According to Sasse (1998), quality of the treatment depends on the characteristics of the influent and the temperature. Generally, following BOD removal efficiencies can be achievable. 25-50% in septic tanks and imhoff tanks 70-90% in anaerobic filters and anaerobic baffled reactors 70-95% in constructed wetlands and pond systems Choice of the required treatment system is based on these values and required quality of effluent. Even long way open discharge channels also provide some additional treatment.

To achieve substantial removal of Nitrogen, it is necessary to have a mix of aerobic and anaerobic treatment which is normally taking place at constructed wetlands and ponds. In closed anaerobic tanks, Nitrogen is converted to Ammonia and effluent can be used for irrigation. But, when the effluent is discharged to a water body, algae growth will increase and it is toxic for fish. Removing of Phosphorous is limited in DEWATS systems. When constructed wetland contains media containing Aluminium or Iron compounds, it will remove some amount of Phosphates.

Pathogen removal has not been considered in DEWATS systems. Considerable amount of pathogen removal is achieved in constructed wetlands and aerobic ponds. This effect is attributed to longer retention times, exposure to ultraviolet radiation in ponds and various biochemical interactions in constructed wetlands. Some amount of helminth eggs are removed from effluent by sedimentation and will accumulate in the bottom sludge of the treatment components. Long sludge retention times of 1-3 years provide sufficient protection against helminth infections. When, sufficient removal of pathogen is not achieved in DEWATS, chlorination can be used as another means to remove pathogens (Sasse, 1998).

Sludge discharged from septic tanks or baffled reactors are also a valuable fertilizer for crops. However, care should be taken when handling it, because of the presence of helminth eggs. Composting is a good option in this case, since it reduces pathogens due to elevated temperatures.

1.4. Treatment modules used in DEWATS systems

The treatment modules generally used in DEWATS systems are explained in this section.

1.4.1. Settler/ Septic tank

Normally, a settler or a septic tank is the first treatment step in a DEWATS system. Settlers are primarily designed for removal of settlable solids whereas septic tanks are designed to have some anaerobic treatment also. Main difference between a settler and a septic tank is their hydraulic retention times. Settlers have low retention times and septic tanks have higher retention times. However, only moderate level of treatment can be achieved by a septic tank and further treatment are needed before discharging effluent to the environment.

Normally, a septic tank has two chambers. Length of the first chamber should be 2/3 of total length of the septic tank, when two cambers are used. If more than two chambers are used, first chamber should be at least half of the total length. Baffles are provided between chambers to prevent escaping of scum and solids with the effluent. Outlet pipe is used in T-shape for prevention of escaping solids and scum. Solid liquid separation has to be taken place in the septic tank by sinking the solid particles to the bottom and floating scum on the top. Normally, in a septic tank, accumulation of sludge is faster than degradation of solids. Then, the accumulated sludge has to be removed after several years. For that, septic tanks should be built at a place where empting trucks are accessible (Morel et al, 2006).

Figure 1.1 Septic tank (Source: Tilley et al, 2008)

The design of septic tank is mainly on number of users, per capita waste water generation (based on per capita water consumption), average annual temperature and the desludging frequency. Generally, 48 hours hydraulic retention time is used for moderate treatment. Removal efficiency for solids is generally around 50% and for BOD, it is about 30-40%. One log removal of pathogens can be expected from a well designed and maintained septic tank. Removal efficiencies are greatly varying according to operation, maintenance and climatic conditions. However, since the septic tank is constructed underground, people will not contact with pathogens, although the removal efficiencies are lower. Water tightness in septic tanks is very important to prevent ground water contamination (Tilley et al, 2008).

MANAGEMENT AND OPERATION OF ONSITE WASTEWATER TREATMENT SYSTEMS - AN ANALYSIS OF SUCCESS FACTORS 7

1.4.2. Biogas reactor

Figure 1.2 Biogas reactor (Source: Tilley et al, 2008)

The anaerobic biogas reactor is an anaerobic treatment technology that generates biogas which can be converted to electricity, light and heat. Digested sludge that is produced in the reactor as a by product can be used for soil improvement. This reactor is a chamber inside which anaerobic degradation of black water and sludge takes place. These reactors are available in the form of prefabricated tank or chamber constructed with brick. Variable sizes ranging from 1,000L to 100,000L of biogas reactors are available in DEWATS systems (Sasse, 1998).

Hydraulic retention time should be selected considering climatic conditions and influent pathogen content. HRT of 15 days will be sufficient in hot climates and 25 days in temperate climates. When pathogen content is higher at the influent, higher retention times may be required. Gas produced through fermentation process collects at the top of the reactor. Normally, biogas reactors are emptied at a frequency ranging from 6 months to 10 years depending on the condition. Gas production is depending on temperature and using this for biogas production at temperatures below 15° C is not economical (Sasse, 1998).

Since digested sludge is not completely disinfected, it should be handled carefully to prevent health risks to people. Also, care should be taken in using gas as it is flammable. Anaerobic reactors should be gas tight to prevent hazards from leakages. Active sludge seeding is needed to start the reactor. Manually stirring the content once a week will prevent uneven reactions. Gas equipments should be cleaned regularly to prevent leaks. Grit and sand settled in the bottom of the reactor should be removed once in every year to prevent increase dead volume in the reactor. Main advantage of biogas reactor is generation of biogas which is a valuable energy source. Even capital and operation costs are also low. Locally available materials can be used for construction in most of the cases. Once constructed, it can be used for a long time without high maintenance. Land use can be reduced by underground construction. Main disadvantage of biogas reactor is that digested sludge requires further treatment (Tilley et al, 2008).

1.4.3. Anaerobic baffled reactor

The anaerobic baffled reactor is a treatment system similar to septic tank, but it has several baffles under which wastewater is flowing. Improved treatment can be attended than septic tanks due to higher contact time with sludge. ABR can achieve about 90% of BOD removal and also better removal efficiencies for organic matter and solids, compared with septic tanks. Since sludge accumulation rate is higher than decomposition rate, desludging is required in 2-3 years in most of the cases (Tilley et al, 2008).

Since ABR is constructed underground, this technology is suitable even for areas with limited land availability. However, this is not suitable at locations where ground water level is high due to the contamination of ground water. Water tightness is very important in this case and also to prevent pollution of ground water from leakages. Anaerobic baffled reactors also have most of the advantages that septic tanks have.

Figure 1.3 Anaerobic baffled reactor (Source: Tilley et al, 2008)

However, organic matter removal efficiency is much higher than in septic tanks. Anaerobic baffled reactors are sufficiently resistant to organic and hydraulic shock loads. Since it can be constructed with locally available materials, capital cost is low to moderate. Electrical energy is not required for the operation of reactor and desludging requires some operation and maintenance cost. However, since desludging is done in several years, operation and maintenance cost is lower compared with other treatment methods. Once constructed properly, ABR can be used for a long time. If properly maintained, odour problems also do not occur due to underground construction (Sasse, 1998).

Main disadvantage of ABR is that effluent requires further treatment, because solid and pathogen removal is not sufficient in most of the cases. ABR also requires continuous supply of water for successful operation. Generally, pre-treatment is required to prevent clogging. Another disadvantage is ABR takes several months for full operation after installation (Tilley et al, 2008).

1.4.4. Anaerobic filter

The anaerobic filter is a fixed bed biological reactor. It removes solids by trapping in the filter media and organic matter by degrading of biomass attached to the filter media. Providing large surface area in the filter media for attachment of biomass increases the degradation of organic matter. Hydraulic retention time is the most important parameter influencing the performance of the anaerobic filter. Generally, 12 to 36 hours HRT is used for design. Less than 2.8m/d of surface loading is suitable for proper operation of the filter. Although higher suspended solids and BOD removal efficiency can be expected from anaerobic filters, nutrient removal efficiency is lower.

MANAGEMENT AND OPERATION OF ONSITE WASTEWATER TREATMENT SYSTEMS - AN ANALYSIS OF SUCCESS FACTORS 9

Figure 1.4 Anaerobic filter (Source: Tilley et al, 2008)

According to the situation, anaerobic filters can be built above or below ground level. It should be water tight for prevention of pollution from leakages. Still anaerobic filter effluent may also need further treatment due to insufficient removal of organic matter and nutrients. An anaerobic filter takes 6-9 months after start up for full operation. However, after working at full capacity, it will have stable operation. In operation, the water level above the filter media should be maintained at least 300mm for even flow through the filter media (Morel et al, 2006).

Generally, at the start up process, active bacteria from an existing septic tank have to be added. After that, flow has to be gradually increased over time, until it gets maximum capacity after 6-9 months. After some time of operation, solids may clog the pores and thick biomass will also break up and clog the pores. Then, it has to be cleaned and applying a reversing flow to clean the media is the method generally used in that case (Tilley et al, 2008).

1.4.5. Horizontal subsurface flow constructed wetland

The horizontal subsurface flow constructed wetland is a form of constructed wetland with wastewater is flowing underground through gravel and sand filled media and plants grown on the ground surface. As water flows though the filter material horizontally, solid particles are filtered and organic material is degraded by micro organisms attached to particles and the roots. High reduction of organic matter, suspended solids and pathogens can be expected from this method. Water flow of the wetland should be maintained below 5-15cm from the soil surface to maintain a subsurface flow throughout the wetland. The bed should be sufficiently wide and shallow with wide inlet zone for proper distribution of water in the bed. Pre treatment is essential for preventing frequent clogging of filter material. (Morel et al, 2006) However, since wetlands are used after some treatment stages in DEWATS systems, it will not be a common problem in case of DEWATS systems.

Figure 1.5 Horizontal flow subsurface constructed wetland (Source: Tilley et al, 2008)

Prevention of ground water contamination by wastewater is important in this case also. Therefore, an impermeable layer with clay or geotextiles is used at the bottom and sides of the bed. Removal efficiencies depend on the surface area and the cross-sectional area of the bed. Filter material acts in three different ways to treat wastewater. It acts as a filter media, holds biomass needed for organic matter removal and holds the vegetation. Facultative and anaerobic bacteria are the most predominant organisms used in organic matter removal. However, some aerobic bacteria are also available in the root zone due to supply of Oxygen from the plants. Main mechanisms in pathogen removal in wetlands are natural decay, predation and sedimentation. Considerable land area is required for this treatment and availability of land at a cheap price is a pre-requisite to construct this type of treatment. This is mostly suitable for warm climates due to higher microbial activity (Tilley et al, 2008).

Gravel media may clog due to accumulation of solid particles and biomass. Then, replacement of filter media is necessary at every 8-15 years intervals. Ensuring tree roots have not grown to damage the impermeable liner is essential to avoid contamination of ground water by leakages (Tilley et al, 2008).

1.4.6. Vertical subsurface flow constructed wetland

MANAGEMENT AND OPERATION OF ONSITE WASTEWATER TREATMENT SYSTEMS - AN ANALYSIS OF SUCCESS FACTORS 11

Figure 1.6 Vertical subsurface flow constructed wetland (Source: Tilley et al, 2008)

When vertical flow constructed wetlands are used, a trained staff is needed, because of usage of mechanical equipments. Most of the cases, effluent will be sufficient for discharge to the environment because higher reduction in organic matter, suspended solids and pathogens can be achieved. Filter material has to be replaced in every 8-15 years due to clogging of gravel media. Generally, vertical flow wetlands need higher maintenance than other types of wetlands (Morel et al, 2006).

Main advantages of vertical subsurface flow wetland over horizontal subsurface flow wetland are less clogging and higher reduction of organic matter, suspended solids and pathogens. Vertical flow wetlands require less area than horizontal subsurface flow wetlands also (Tilley et al, 2008)

1.4.7. Waste stabilization ponds

Waste stabilizing ponds also known as polishing ponds are large man-made water bodies that are used to treat partially treated wastewater with natural processes. Although anaerobic and facultative ponds are also used in wastewater treatment, generally aerobic ponds are used as polishing ponds in latter stages of treatment in DEWATS systems for pathogen removal. Generally, several ponds are built in series to provide higher level of pathogen removal. Usually, depth of the pond is kept between 0.5 - 1.5 m to allow sunlight to penetrate whole depth for photosynthesis (Tilley et al, 2008).

Polishing ponds are mostly appropriate in rural areas where enough land is available. They are more efficient in warmer and sunny climates than in colder climates. When it is used in cold climates, retention times have to be increased or loading rates have to be lowered. Care has to be taken to avoid people using ponds for recreational activities or for domestic use. Also, ensuring that plant material do not fall into the pond is important (Morel et al, 2006).

Main advantage of polishing ponds is the high reduction of pathogens. It can be built with locally available materials and operating costs are also low. Main disadvantage is the requirement of large land area. Capital cost will depend on the price of land.

CHAPTER 2

Materials and Methods

This chapter contains a description about DEWATS system at Nala, which was selected for this study and various methods used for collection of data required to achieve the objectives. 2.1. Decentralized wastewater treatment system at Nala

2.1.1. Location

Nala is situated at an end of the Kathmandu valley, 32km away from Kathmandu, which is the capital of Nepal. Location according administrative divisions is as follows:

Region : Central Zone : Bagmati District : Kavrepalanchok Village development committee : Nala Ugrachandi Wards : 1-4 (CIUD, 2011)

Nepal is divided into 5 development regions as Eastern, Central, Western, Mid-western and Far-western. Nala is situated at central development region. Development regions are also further divided to zones. Nepal has altogether 14 zones and Nala is situated at Bagmati zone, where Kathmandu city is also situated. Each zone is further divided to districts and altogether 75 districts are available in Nepal. (Wikipedia, 2013) Each district has several village development committees (VDC) and they are the lowest administrative bodies in the country. A VDC is further divided into wards depending on the population.

2.1.2. Situation before implementation of the treatment system

66 households out of total 388 in wards 1-4 in Nala were not having toilets, before commencement of the project. Although this was a low amount, sanitation situation was much poor in the community. Most of the households had toilet facilities with simple cess pits. Due to high ground water level, these pits had to be emptied frequently and the sludge was disposed to nearby fields and water bodies. Frequent filling of cess

MANAGEMENT AND OPERATION OF ONSITE WASTEWATER TREATMENT SYSTEMS - AN ANALYSIS OF SUCCESS FACTORS 13

pits made toilets unusable and people tend to open defecation. Because of that, improved sanitation facilities became a high priority for the community (Sherpa et al, 2013).

WWTP

Figure 2.1 Layout of sewer lines with wastewater treatment plant (Source: CIUD, 2011)

2.1.3. Design of the treatment system at Nala

Treatment plant has been designed by a local NGO called Environmental and Public Health Organization (ENPHO). During the design process, two options have been considered. One option is with biogas reactor after screening and other one without biogas reactor. However the option without biogas reactor has been selected for implementation.

According to the grey literature, wastewater treatment system was designed to serve 352 households out of 388 households in the area. Remaining households were not occupied. Number of people in a household has been considered as 6 persons, which is a somewhat higher than the value for household size in Nepal from 2011 census data, which is 4.7 (Central Bureau of Statistics, 2012). According to estimated household size, designed total population was 2112.

Only black water from toilets is treated in the treatment system. Grey water and kitchen wastewater are flowing in trenches to the water streams without any treatment. Designed wastewater flow to the system is 31.7m3/day. Characteristics of the wastewater have been estimated as follows for the design:

COD 4167 mg/L BOD 2083 mg/L TSS > 1200 mg/L

Community living in the area receives water from a piped water supply to communal taps. Average per capita water consumption has been estimated as 65L /day (CIUD, 2011).

2.1.4. Treatment components

Treatment system consists of bar screens, settlers, ABR and horizontal sub surface flow constructed wetlands.

Bar screens:

Bar screens has been used as preliminary treatment step to remove debris coming with the wastewater flow.

Figure 2.2 Bar screen chamber of the treatment system

Settlers:

After the bar screens, flow is divided into two streams and similar treatment units are used in both streams. Therefore, each settler has been designed for a flow of 15.8 m3/day. Features of each settler are given below.

Number of compartments 2 Length 4.0m (first compartment 2.5m, other 1.5m) Width 2.2m Depth at outlet 2.0m Hydraulic retention time 2 hrs Designed sludge removal One year intervals

For BOD and COD, removal efficiencies of 26% and 25% have been estimated in the design. According to that, effluent BOD and COD have been assumed as 2492 mg/L and 1221 mg/L respectively. Sludge volume at removal has been estimated as 10.16m3 (CIUD, 2011).

MANAGEMENT AND OPERATION OF ONSITE WASTEWATER TREATMENT SYSTEMS - AN ANALYSIS OF SUCCESS FACTORS 15

Anaerobic Baffled Reactors:

There are two separate ABR systems for separate streams. Features of one ABR are listed below.

Size 2.2m ×0.8m × 2.0m Designed up flow velocity 1.13 m/h Hydraulic retention time 35 hrs Number of compartments 7

BOD and COD removal efficiencies of 94.8% and 92% have been assumed in design. According to those values, effluent BOD and COD have been estimated as 63.8mg/L and 187.7 mg/L respectively (CIUD, 2011).

Horizontal Subsurface flow constructed wetlands:

Final treatment step in the DEWATS system is horizontal subsurface flow constructed wetlands. Features of them are given below.

Length 6.5m Breadth 14.0m Minimum media depth 0.5m Slope 1% Hydraulic retention time 2.85days

It has been designed to keep effluent BOD and COD at 50mg/L and 149mg/L respectively (CIUD, 2011).

Figure 2.3 Horizontal subsurface constructed wetlands at the treatment system

Figure 2.4 Layout of the treatment system

2.1.5. Sewer system

A simplified sewer system has been used to collect black water from the households and convey to the treatment system. Main differences of simplified sewer system with a conventional sewer system are use of smaller diameter pipes and lower depth excavation. Sewer connection points have been placed for a group of households and connection has been done by this group forming a community. Finally, the group connection was connected to the main sewer that conveys wastewater to the treatment system. Total length of sewer lines is 4.4 km and 21 manholes have been used for the sewer network (CIUD, 2011).

2.1.6. Implementation of the project of wastewater treatment

A community based organization called 'Nala Drinking water and Sanitation Committee' was the client of this project. It is a community organization established more than 25 years ago, to upgrade the drinking water and sanitation facilities for the community living in peri-urban areas of Nala. It has entrusted management of the project of constructing upgraded drinking water supply, wastewater treatment and storm water disposal facilities to a local NGO called 'Centre for Integrated Urban Development (CIUD)'. Then, CIUD has implemented a project of drinking water supply, wastewater treatment and storm water

MANAGEMENT AND OPERATION OF ONSITE WASTEWATER TREATMENT SYSTEMS - AN ANALYSIS OF SUCCESS FACTORS 17

drainage, with the support from other organizations. Some other local and international organizations like UNHabitat, WaterAid, Eawag has also contributed for this project, with technical and financial support.

2.1.7. Community Led Urban Environmental Sanitation (CLUES) approach

Community Led Urban Environmental Sanitation (CLUES) approach was used at the planning stage. In the planning phase, an environmental sanitation plan has been developed addressing all waste streams including black water, grey water, storm water and solid waste. The participatory multi stake holder process has been used with household mapping and surveys, user needs identification and prioritization and stakeholder assessment. Among various alternatives, people have chosen the option with simplified sewer network and DEWATS treatment system (Sherpa et al, 2013).

First step in the implementation phase was development of a detailed action plan. Community has actively involved in terms of labour and finance at the implementation. Priority identified by the community was addressing the issues of black water management. In order to support low income groups for constructing toilets and connecting to sewer network, micro finance scheme with revolving fund has also been established (Sherpa et al, 2013).

2.1.8. Current situation of the system

Currently, all other components of the treatment system are working. But, the inlet zone of one of the constructed wetlands is clogged and wastewater has been directed to other parts of the wetland, bypassing clogged area. At the discharge to the stream, some turbidity and a smell in the treated wastewater are available. When considerable amount of flow is available in the discharging stream, turbidity of the effluent is clearly visible.

A part time operator is assigned to look after and to perform minor maintenance works of the treatment system. Project office established by CIUD, for the Water supply and wastewater project is still functioning with its staff. However, from March 2014, CIUD will close their project office and community organization will have to look after all the operation and management activities themselves.

2.2. Sampling and laboratory analysis

2.2.1. Sampling

2.2.1.1 Sampling points

Layout of the DEWATS system at Nala is given in Figure 2.3.

Samples for the influent to the treatment system were collected at the last manhole of the sewer system, which is collecting wastewater from three sewers and discharging to DEWATS system. (Sampling point 1) However, the effluent quality from the settler was not possible to measure directly because it is connecting to anaerobic baffled reactors, with underground pipes. Therefore, the samples at first compartment of the ABR were used to analyze the quality of effluent from the settler and the influent to the ABR. Since the flow is separated into two streams after the settler, all parameters had to be analyzed at two streams separately.

Since the effluent from two ABRs are directed separately to two horizontal subsurface flow constructed wetlands, the samples were collected from the manhole between ABR and wetlands and those samples represent the effluent from ABR and the influent to the wetlands. (Sampling points 4 and 5)

Influent

Manhole a c

Screening

Settler

2 3

A A

B B

C C ABR

D D

E E

F F

G G

4 5

Horizontal Subsurface

Flow Constructed Wetlands 6 7

Figure 2.5 Layout of DEWATS system in Nala with locations of sampling points

MANAGEMENT AND OPERATION OF ONSITE WASTEWATER TREATMENT SYSTEMS - AN ANALYSIS OF SUCCESS FACTORS 19

Then, samples were collected at the discharge from the chamber collecting treated wastewater from the wetlands and those were representing the effluent from the constructed wetlands and the effluent from the whole treatment system also. (Sampling points 6 and 7)

Table 2.1 summarizes locations of sampling points and use for the analysis of samples.

Table 2.1 Locations and uses of sample points

Location No. Location Use of the sample 1 At the last manhole of sewer system Influent to the treatment system, Influent to the settler 2,3 At the first compartment of ABRs Influent to the ABR, Effluent from the settler 4,5 At the manhole between ABR and Influent to the wetland, constructed wetlands Effluent from the ABR 6,7 At the outlet chamber of constructed Effluent from the wetland, wetlands Effluent from the treatment system

2.2.1.2 Sampling procedure

Samples were taken representing various days of the week. Following day, the samples were analyzed at the ENPHO laboratory in Kathmandu, which is an accredited laboratory from the Nepal laboratory accreditation scheme.

Sample point 1 Influent flow is changing according to the time of the day. Not only the flow rate, but also the quality of the influent also varies with the time. Although this treatment system is treating only black water from the toilets, that may contain various components like faeces, flush water, anal cleansing water and urine. Compositions of these components are varying according to the time of the day. Then, the parameters of the influent to the treatment plant are also varying. Therefore, quality of the influent had to be measured considering variation of parameters with time.

First three sampling days, influent grab samples were collected at 4 hour time intervals, starting from 7.30am until 3.30pm. Flow proportionate average of the parameters for each day was used for analysis. However, after that, grab sampling was replaced with flow proportionate composite sampling. Every one hour interval, sample was collected and finally, they were mixed according to the flow rate.

Sampling points 2,3,4,5,6 and 7 Since all other sampling points except point 1 are located after the treatment units that have considerable retention times, parameters of the samples from those points will not considerably vary with the time of the day. Therefore, grab samples at those points were collected once in a sampling day.

Equipment used in sampling Beaker 1L Cooler box filled with ice cubes Ethanol 70% Grab sampler Latex gloves Notebook and pencil Thermometer

Portable pH meter Plastic bottles 1000ml Plastic bucket volume 10L Measuring cylinder

Procedure used in grab sampling Grab samples were collected with the grab sampler. Bottles used for collection of samples were first rinsed with respective wastewater itself. Then, wastewater sample was filled up to the top to eliminate entering air bubbles. Bottles were labelled with the time, date and the sampling point and were kept below 4°C at the cooler box.

Procedure used for flow proportionate composite sampling Every hour, one sample was collected from 1L beaker starting from 7.30am until 3.30pm and placed in the cooler box. After taking all samples, volumes proportionate to the flow rate at the respective hour were poured into the 10L bucket. Then, the content of the bucket was mixed and 1L bottle was collected from that. Then, the bottle was labelled with the time, date and the sampling point and was kept below 4°C at the cooler box.

2.2.1.3 Sampling period Sampling was performed in 8days, starting from 24.12.2013 until 06.02.2014. Various days of the week including holidays also selected for sampling.

2.2.2. In-situ measurements

Flow rate at the influent to the treatment system, wastewater temperature and the pH were measured at the site itself.

2.2.2.1 Influent flow rate Influent flow rate was measured at the last manhole of the sewer system. Since wastewater is coming there from three separate sewer lines, flow rate was measured in those three lines separately and add together to get total influent flow rate to the treatment system. Since the wastewater from the sewers is falling freely in the manhole, time to fill a fixed volume bucket was used to calculate the flow rate at each of the pipeline and added all three flow rates to get the total influent flow rate.

Figure 2.6 Measurement of the influent flow rate

MANAGEMENT AND OPERATION OF ONSITE WASTEWATER TREATMENT SYSTEMS - AN ANALYSIS OF SUCCESS FACTORS 21

2.2.2.2 Wastewater temperature Wastewater temperature was measured using a mercury thermometer. For influent, it was measured at 2 hour intervals and for the effluent, it was measured at the time effluent samples were taken.

2.2.2.3 pH pH value was measured using an electronic pH meter. For influent, it was measured at every 4 hour intervals and for the effluents from various components, it was measured, when the samples were taken.

2.2.3. Laboratory analysis

Following parameters were measured at the laboratory in the influent and the effluent samples of the treatment system.

Chemical Oxygen Demand Total suspended solids Total Nitrogen Total Phosphorous NH4-N NO3-N Orthophosphate - P Faecal coliforms

Other samples only Chemical Oxygen demand and total suspended solids were measured and last five sampling days, TN,TP, NH4-N, NO3-N, Orthophosphate - P and Faecal coliforms were also measured in influent to wetland samples to evaluate the nutrient and pathogen removal in constructed wetlands.

2.2.4. Climatic conditions at the sampling period

Weather data like maximum and minimum temperature of the day and precipitation were collected from meteorological forecasting division of Government of Nepal.

2.3. Semiformal interviews

Main purpose of the semiformal interviews is to identify current operation and management procedures and possible success and failure factors related to the operation and management of the treatment plant. Semiformal interviews were conducted with people living in households, operation and management staff of the treatment system and office bearers of the community organization.

Results of the semiformal interviews are used in the research for following purposes.  To identify current practices in operation and management of the treatment system  To identify day to day operational tasks and maintenance work carried out by the operator, operator's training and understanding of the system, main issues that he is facing in operation and maintenance of the system  To identify issues relation to operation and management of the system, possible successes and failures and possible improvements, from the view of community leaders and operation and management staff

 To identify acceptance of the system for the community, their view on operation and management, improvement of living standards due to treatment facility, their suggestions for improvements

2.3.1. Household survey

Since the total number of users in treatment system is a large number, random sample of household that representing all income levels, social and educational levels was used for the study. 70 households representing 20% of total households in the four wards connected to the treatment system was used for the survey. Interviews were conducted in local languages and help of a translator was used to translate questionnaire and the answers from local languages to English and vice versa.

2.3.2. Semiformal interviews with operation and management staff

Operator of the treatment plant, the staff working at the project office and officers assigned for the treatment system at Nala by CIUD were also interviewed. Details about current operation and management practices and issues related to operation and management of the treatment system were collected from these interviews.

2.3.3. Semiformal interviews with office bearers of the community organization

Office bearers of the community organization, which is in charge of operation and management of the treatment system, were also interviewed. Details about the operation and management issues, financial situation and community participation were collected from those interviews.

2.4. Literature review

Various literatures regarding performance analysis of similar DEWATS systems in Nepal and other developing countries, design, operation and management of the treatment systems were also referred for this study. Performance of studied DEWATS system was compared with other similar systems to identify successes or failures of the performance of the treatment system.

2.5. Data collection from grey literature

Data were collected about current operation and management practices and income and expenditure of the community organization, for operation and management of the treatment system from various grey literatures from community organization and CIUD.

2.6. Evaluation of the existing design

Revision of original design for treatment system at Nala was performed with redesigning of treatment components using influent parameters from sampling. Design has been performed according to the procedure for design of DEWATS given in CDD (2013). Theoretical effluent qualities were also calculated with existing influent parameters and those values were compared with actual effluent parameters.

MANAGEMENT AND OPERATION OF ONSITE WASTEWATER TREATMENT SYSTEMS - AN ANALYSIS OF SUCCESS FACTORS 23

2.7. Analysis of the results

Finally, successes and failures identified using laboratory analysis and field measurements, details of current operation and management practices and possible success and failure factors identified with literature review and with semi structured interviews were analysed to identify main challenges and success factors of the treatment systems. Then, that information was also used to identify possible suggestions for improvements. Financial sustainability of the treatment systems was accessed using available data from the agency that is operating treatment system.

As the final step, applicability of similar type of DEWATS systems in Nepal was analysed based on the results obtained from laboratory analysis, semi-formal interviews, grey literature and data from the documentation in management entity. According to that, key recommendations for applying similar type of treatment systems in small peri urban towns in Nepal were made.

A detailed flow diagram showing how objectives have been achieved is shown in Figure 2.7. It shows the link between the methodology and research objectives and describes various steps followed throughout the study, to reach objectives. As an example, literature review was used to identify the operation and management issues of DEWATS systems. Then, that was used as a guide to identify the possible operation and management issues in the treatment system that was studied. Also, semi structured interviews were used for this purpose. By analyzing the results of this step, with identified success and failure factors of components of treatment system and data about current operation and management practices collected from semi structured interviews, the objectives could be achieved.

- WASTEWATER TREATMENTSYSTEMS MANAGEMENTAND OPERATION ONSITEOF

ANANALYSIS OF SUCCESS FACTORS Method Details collected Research activities Objectives

Literature Operation and Review management issues of Checking with typical onsite wastewater efficiencies and effluent treatment in various qualities countries Analysis of data

Laboratory Influent, effluent and Calculation of treatment Objective 1

analysis intermediate flow qualities efficiencies Challenges and success factors Identifying success or failure of the Identifying possible component success and failure factors

Objective 2

Recommendations for

Semi-formal Current operation and Checking with design improvement

interviews management practices data and local standards

Objective 3 Key recommendations for applying Review of grey Details about Analysis of financial DEWATS literature and expenditures and sustainability other income documentation

25 Figure 2.7 Flow diagram showing means of achieving objectives

CHAPTER 3

Results

This chapter contains results of the study. It includes performance results of the treatment system obtained from sampling, in-situ measurements and laboratory analysis and also the results obtained from other methods like semi structured interviews and data collected from grey literature. However, the sampling was carried out 6-9 months after the commencement of the operation at the treatment system. Also, sampling was performed at the coldest months of the year. Therefore, microbial activity in ABR and constructed wetlands might not be well established and cold temperature might also reduce it.

3.1. Technical performance of the treatment system

Evaluation of current performance of the treatment system is important to find out successes and failures of the operation and management, in technical aspects. Therefore, this section describes technical performance of the treatment system as the results of sampling and laboratory analysis.

3.1.1. Flow rate

Results of the influent flow rate measured at the last manhole of the sewer system are shown in Figure 3.1

MANAGEMENT AND OPERATION OF ONSITE WASTEWATER TREATMENT SYSTEMS - AN ANALYSIS OF SUCCESS FACTORS 27

1.2

1 17.12.2013

0.8 24.12.2013

01.01.2014 0.6

20.01.2014 Flow (L/s) Flow 0.4 24.01.2014 27.01.2014 0.2 30.01.2014 0 06.02.2014 7.30 8.30 9.30 10.30 11.30 12.30 13.30 14.30 15.30 Time

Figure 3.1 Influent flow rates measured at the last manhole of sewer system at 8 days between 17.12.2013 and 06.02.2014

Most of the days, influent wastewater flow rate gives a similar pattern. Morning, it has a higher flow rate and after around 8.30am, it starts to decrease. That continues until around 12.30pm and after that, it comes to a somewhat stable value. After that, it has some little fluctuations until 3.30pm. After, 3.30pm, wastewater influent flow rate could not be measured, because samples had to brought to the laboratory before its closure. However, according to the discussions with the operator, flow is very low at the late night and the early morning.

Average wastewater flow was 0.32L/s according to the measurements. Then, the average flow between 7.30am-3.30pm accounts to 9.0m3. Although normally peak flows of the day occurs between 7.30am and 3.30pm, wastewater flow is much less than designed flow of 31.6m3/d. Main reason for that is the lower consumption of water for flushing the toilets than assumed in the design. Also, total number of households still has not connected to the system and number of people in the household may lower than assumed. In design, 352 households have been estimated to connect to the system. However, only 277 households were connected at the moment. Average people in a household have been assumed as 6 and per capita toilet wastewater generation has estimated as 15lpcd.

Only black water coming from toilets is treated in the treatment plant and people are discharging kitchen wastewater and other types of wastewaters to the storm water drainage system. At the household survey, one question was whether the household is discharging kitchen wastewater and wastewater from bath also to the sewer system. Everyone answered that they are discharging only black water from toilets to the sewer system. Since the people do not have household water supply connections and they use communal taps for bath and washing, entering of other types of wastewaters such as grey water to the sewer system is minimal.

During the research period, water supply to the communal taps was available only at the morning and limited time duration at the evening. Therefore, people tend to use toilets mostly at the time periods, when water supply is available. That is one of the reasons to have a higher wastewater influent flow rate at the morning. On the other hand, since most of the people are going outside for their farm lands, schools etc at the daytime, usage of toilets is mainly at the morning, before around 8.30am. Also, little peak around 11.30am- 2.00pm is available sometimes. That coincides with the time, when some people return back from farm lands to their homes for lunch.

3.1.2. pH

Wastewater pH values measured at various places of the treatment system on 6 days between 01.01.2014 and 06.02.2014 are shown in Figure 3.2.

influent at 7:30am 8.5 Influent at 11:30am

8 Influent at3:30pm Effluent from settler 1

pH value pH 7.5 Effluent from settler 2 Effluent from ABR 1 7 Effluent from ABR 2 Effluent from CW1 6.5 01.01 20.01 24.01 27.01 30.01 06.02 Effluent from CW2 Date

Figure 3.2 pH value at various points of the treatment system at 6 days between 01.01.2014 and 06.02.2014

Influent wastewater pH value is always higher than 8. Black water from toilets will contain faces, urine, flush water and anal cleansing water as major ingredients. Although urine is generally normal (pH close to 7) at the fresh state, it starts ureolysis, which is the hydrolysis of urea to ammonia, with time. Therefore, that will be the reason for high pH value in the influent wastewater.

Always, there is a considerable decrease in pH value after passing through the settlers. Anaerobic digestion has four steps: hydrolysis, acidogenesis, acetogenesis and methenogenesis. At the hydrolysis stage, organic polymers are hydrolyzed to mono and oligomers. Then, in acidogenesis, it is converted to volatile fatty acids. In that step, decrease in pH will happen due to formation of acids. Reason for decrease in pH at the settlers may be that acidogenesis step of anaerobic digestion is taking place at the settler itself, because of higher hydraulic retention time, due to low flow rates. After that, sometimes, there is further small decrease in pH, after passing through the ABR. However, that is not much significant than the reduction in pH at the settlers.

However, the pH value is always in the range which is suitable for biological treatment. Since influent wastewater is always somewhat alkaline, wastewater does not reach to acidic conditions throughout the treatment system. It is better for anaerobic treatment that should take place at the ABR.

MANAGEMENT AND OPERATION OF ONSITE WASTEWATER TREATMENT SYSTEMS - AN ANALYSIS OF SUCCESS FACTORS 29

3.1.3. Wastewater temperature

Table 3.1 Wastewater temperatures measured at 8 days between 17.12.2013 and 06.02.2014

Date Time Location Temperature /°C 17.12.2013 7.30am Influent 16 11.30am Influent 16 Effluent 16 3.30pm Influent 17 24.12.2013 7.30am Influent 15 11.30am Influent 16 3.30pm Influent 16 Effluent 16 01.01.2014 7.30am Influent 15 Effluent 15 11.30am Influent 15 3.30pm Influent 16 20.01.2014 7.30am Influent 14 11.30am Influent 15 1.30pm Effluent 15 3.30pm Influent 16 24.01.2014 7.30am Influent 14 10.30am Effluent 16 11.30am Influent 16 3.30pm Influent 16 27.01.2014 7.30am Influent 14 8.30am Effluent 16 11.30am Influent 16 3.30pm Influent 16 30.01.2014 7.30am Influent 14 11.30am Influent 18 1.30pm Effluent 16 3.30pm Influent 16 02.06.2014 7.30am Influent 14 11.30am Influent 18 2.30pm Effluent 16 3.30pm Influent 16

Influent and effluent wastewater temperatures were always between 14-16°C in sampling days, except after 11.30am, on 06.02.2014. On that day, it was measured as 18°C at 11.30am and 3.30pm at the influent. These temperature measurements are always lower than the assumed minimum temperature in the design, which is 20°C. Wastewater temperature did not vary much with the change in atmospheric temperature and fluctuations were very low. High thermal capacity of water is the reason for that.

3.1.4. Solids removal

Total suspended solids measurements in samples are given in Table 3.2.

Table 3.2 Total suspended solids concentration (mg/L) in samples measured at 8 days between 17.12.2013 and 06.02.2014

Date Influent Effluent Effluent Effluent Effluent Effluent Effluent from from from from from CW from CW settler 1 settler 2 ABR 1 ABR 2 1 2 17.12.2013 1242 524 448 174 143 - - 24.12.2013 1229 531 354 94 80 49 55 01.01.2014 521 425 497 110 112 - 56 20.01.2014 1205 815 660 210 175 72 64 24.01.2014 1180 680 480 188 172 58 64 27.01.2014 790 435 431 109 94 42 43 30.01.2014 1020 680 736 170 118 70 70 06.02.2014 850 520 534 160 94 67 48 Mean 1005 576 518 152 124 60 57 SD 262 136 125 42 36 12 10 NB: Effluent TSS was not measured for both constructed wetlands on 17.12.2013 and for constructed wetland 1 on 01.01.2014

Although the results have somewhat higher variation, other similar studies in performance analysis of DEWATS systems also had similar type of results. (Lars, nd ; Shrish, 2008)

Total suspended solids removal in two wastewater lines is represented in Figure 3.3.

1200 1005 1005 1000

800 576 600 518

TSS (mg/L) TSS 400

152 200 94 60 48 Discharge limit 0 < 50mg/L Line 1 Line 2 Influent Effluent from settler Effluent from ABR Effluent from Wetland

Figure 3.3 TSS removal at various points of the two wastewater lines

Mean TSS results at various points of the treatment system are shown in figure 3.4

MANAGEMENT AND OPERATION OF ONSITE WASTEWATER TREATMENT SYSTEMS - AN ANALYSIS OF SUCCESS FACTORS 31

576±136 152±42 60±12

Settler 1 ABR 1 CW 1

Influent

1005±262 Settler 2 ABR 2 CW 2

518±125 124±36 57±10

Figure 3.4 TSS concentrations at various points of the treatment system (mg/L)

According to the results, influent wastewater has TSS concentration of 1005±262mg/L. Then, at the settlers, it is reduced to 576±136mg/L in line 1 and 518±125mg/L in line 2. After that, anaerobic baffled reactors reduce it to 152±42mg/L in line 1 and 124±36mg/L in line 2. Finally, after the constructed wetlands, it reduces to 60±12mg/L in line 1 and 57±10mg/L in line 2.

Then, the removal efficiencies of TSS were calculated for each of the component and for entire wastewater lines. These results are given in Table 3.3.

Table 3.3 TSS removal efficiencies for different components of the treatment system (in %)

Date Settler 1 Settler 2 ABR 1 ABR 2 CW1 CW 2 Line 1 Line 2 17.12.2013 57.8 63.9 66.8 68.1 - - - - 24.12.2013 56.8 71.6 82.3 77.4 47.9 31.2 96.0 95.5 01.01.2014 18.4* 4.6* 74.1 77.5 - 50.0 - 89.3 20.01.2014 32.4 45.2 74.2 73.5 65.7 63.4 94.0 94.7 24.01.2014 42.4 59.3 72.4 64.2 69.1 62.8 95.1 94.6 27.01.2014 44.9 45.4 74.9 78.2 61.5 54.3 94.7 94.6 30.01.2014 33.3 27.8 75.0 84.0 58.8 40.7 93.1 93.1 06.02.2014 38.8 37.2 69.2 82.4 58.1 48.9 92.1 94.4 Mean 43.8 50.0 73.6 75.6 60.2 50.2 94.2 93.7 SD 10.3 15.4 4.6 6.8 7.4 11.6 1.4 2.1 (* Since according to Dixon's Q test, this is an outlier from other results, it was not included in the calculation of mean)

Total average removal efficiency in wastewater line 1 is 94.2% and line 2 is 93.7%. Since influent flow is equally divided between two wastewater lines and all the components in two separate lines are similar, treatment efficiency also had nearly similar values for both of the wastewater lines.

3.1.5. Organic matter removal

Organic matter removal was evaluated using COD measurements. Results of COD measurements are shown in Table 3.4.

Table 3.4 Chemical Oxygen Demand (mg/L) measured at 8 days between 17.12.2013 and 02.06.2014

Date Influent Effluent Effluent Effluent Effluent Effluent Effluent from from from from from CW from CW settler 1 settler 2 ABR 1 ABR 2 1 2 17.12.2013 2573 1333 1320 554 533 501 517 24.12.2013 1993 600 500 395 360 160 160 01.01.2014 1117 1256 1232 512 439 - 448 20.01.2014 2020 1270 1420 740 730 332 345 24.01.2014 1930 1240 1330 780 810 465 505 27.01.2014 1780 1200 1280 690 650 288 293 30.01.2014 2150 1270 1090 860 650 410 410 06.02.2014 1872 1208 1163 748 863 490 529 Mean 1929 1172 1167 660 629 378 400 SD 407 235 288 157 176 125 128

NB: COD could not be measured at constructed wetland 1 on 01.01.2014, due to clogging.

COD removal in the two separate wastewater lines is represented in Figure 3.5.

2500

2000

1500 Influent Effluent from Settler

1000 Effluent from ABR COD (mg/L) COD Effluent from Wetland 500 Discharge limit <250mg/L 0 Line 1 Line 2

Figure 3.5 Average COD removal in the two wastewater lines

Mean COD results at various points of the treatment system are shown in figure 3.6.

MANAGEMENT AND OPERATION OF ONSITE WASTEWATER TREATMENT SYSTEMS - AN ANALYSIS OF SUCCESS FACTORS 33

1172±235 660±157 378±125

Settler 1 ABR 1 CW 1

Influent

ABR 2 CW 2 1929±407 Settler 2

1167±288 629±176 400±128

Figure 3.6 COD concentrations at various points of the treatment system (mg/L)

Influent has COD concentration of 1929±407mg/L. At the settlers, it is reduced to 1172±235mg/L in line 1 and 1167±288mg/L in line 2. After the ABR, it reduces to 660±157mg/L in line 1 and 629±176mg/L in line 2. Finally, the effluents from the constructed wetlands contain 378±125mg/L of COD in line 1 and 400±128mg/L of COD in line 2.

Removal efficiencies of COD in all components were also calculated and results are given in Table 3.5.

Table 3.5 COD removal efficiencies (in %)

Date Settler 1 Settler 2 ABR 1 ABR 2 CW 1 CW 2 Line 1 Line 2 17.12.2013 48.2 48.7 58.4 59.6 9.6 3.0* 80.5 79.9 24.12.2013 69.9 74.9 34.2 28.0 59.5 55.6 92.0 92.0 01.01.2014 -12.4* -10.3* 59.2 64.4 - -2.1* - 59.9 20.01.2014 37.1 29.7 41.7 48.6 55.1 52.7 83.6 82.9 24.01.2014 35.8 31.1 37.1 39.1 40.4 37.7 75.9 73.8 27.01.2014 32.6 28.1 42.5 49.2 58.3 54.9 83.8 83.5 30.01.2014 40.9 49.3 32.3 40.4 52.3 36.9 80.9 80.9 06.02.2014 35.5 37.9 38.1 25.8 34.5 38.7 73.8 71.7* Mean 42.8 42.8 42.9 44.4 50.0 46.1 81.5 80.7 SD 13.0 16.6 10.4 13.8 10.2 9.2 5.9 6.7 (* Since according to Dixon's Q test, this is an outlier from other results, it was not included in the calculation of mean)

COD removal efficiencies in both settlers are 42.8%, which is somewhat higher than the designed value of 25%. For ABR, it is 42.9% and 44.4%, which is considerably lower than the designed value of 92%. For wetlands, removal efficiencies are 50.0% and 46.1%, which is higher than the designed value of 20%. Total COD removal efficiencies of two wastewater lines are 81.5% and 80.7% and those values are somewhat lower than 95%, which is the designed value.

3.1.6. Nutrient removal

3.1.6.1 Nitrogen removal

Total Nitrogen concentrations were measured in influent and effluent samples for analysis of Nitrogen removal in the system. Results of those values are shown in the Table 3.6.

Table 3.6 Total Nitrogen concentrations of influent and effluent samples and removal efficiencies Date TN concentration (mg/L) Removal efficiency (in %) Influent Effluent-Line 1 Effluent-Line 2 Line 1 Line 2 17.12.2013 317 370 189 -16.7 40.4 24.12.2013 332 328 410 1.2 -23.5 01.01.2014 247 - 286 - -15.8 20.01.2014 270 152 257 43.7 4.8 24.01.2014 406 213 228 47.5 43.8 NB: TN was not measured at effluent of line 1 on 01.01.2014, due to clogging of the constructed wetland.

Large variation in efficiency values can be identified. Similar type of results with large variation in Nitrogen removal efficiencies were obtained by a study for Sunga wastewater treatment system in Kathmandu valley (Shrish, 2008).

According to the results, hardly any Nitrogen removal can be identified in the treatment system. Since anaerobic baffled reactors are treating wastewater with anaerobic digestion, Nitrogen removal with nitrification followed by denitrification cannot be expected. Some Nitrogen removal can be expected in the constructed wetlands only. Therefore, influent and effluent Total Nitrogen concentrations were measured at constructed wetlands and the results are shown in Table 3.7.

Table 3.7 Total Nitrogen concentrations of influent and effluent to constructed wetlands and respective removal efficiencies

Date TN concentration (mg/L) Removal efficiency Influent Effluent (in %) CW 1 CW 2 CW 1 CW 2 CW 1 CW 2 20.01.2014 308 331 152 257 50.6 22.4 24.01.2014 270 251 213 228 21.1 9.2 27.01.2014 282 245 230 202 18.4 17.6 30.01.2014 252 230 194 194 23.0 15.7 06.02.2014 270 280 85 220 68.5 21.4 Mean 276 267 175 220 36.3 19.3 SD 21 40 58 25 22.2 3.2

Not much higher variation in Nitrogen removal efficiencies is available, when compared with efficiencies of the whole treatment system. Relatively high variation in Nitrogen removal efficiency is available in constructed wetland 1. Around 1/3 of filter material in wetland 2 has been removed, washed and replaced, about 2-3 months before taking samples. Due to that, microbial film may have not much developed in the surface of the filter material. That may be the reason for lower removal of Nitrogen in the constructed wetland 2.

High amount of Nitrogen is in the form of NH4-N. That was also measured separately and results of influent and effluent to the treatment system is given in Table 3.8.

MANAGEMENT AND OPERATION OF ONSITE WASTEWATER TREATMENT SYSTEMS - AN ANALYSIS OF SUCCESS FACTORS 35

Table 3.8 NH4-N concentrations of influent and effluent measured in 5 days between 17.12.2013 and 24.01.2014

Date NH4-N concentration (mg/L) Influent Effluent-Line 1 Effluent-Line 2 17.12.2013 228 348 134 24.12.2013 252 309 388 01.01.2014 195 - 270 20.01.2014 122 131 248 24.01.2014 336 194 206 NB: Concentration was not measured at effluent of line 1 on 01.01.2014, due to clogging of constructed wetland.

Influent NH4-N concentrations are much higher than in most of the similar studies. (As examples, Lars (nd), Shrish (2008) Main reason for that is this treatment system is only treating wastewater from toilets and even the usage of flush water may be low. Results do not show much NH4-N reduction and sometimes even an increase is available. Some Ammonification may take place in anaerobic treatment steps also. Nitrate concentrations of the samples are also very low and do not show much sign of nitrification. Table 3.9 shows NO3-N concentrations of the influent and effluent samples from the treatment system.

Table 3.9 NO3-N concentrations of influent and effluent measured at 17th and 24th December 2013

Date NO3-N concentration (mg/L) Influent Effluent-Line Effluent-Line 1 2 17.12.2013 0.3 0.6 0.6 24.12.2013 <0.05 0.5 0.5 01.01.2014 0.05 - 0.7 20.01.2014 0.1 0.3 0.4 24.01.2014 <0.05 0.9 0.9 NB: Concentration was not measured at effluent of line 1 on 01.01.2014, due to clogging of constructed wetland.

NH4-N concentration of influent and effluent samples to the wetlands were also measured to identify whether there is reduction in NH4-N concentration in wetlands. Results of those measurements are given in Table 3.10.

Table 3.10 NH4-N concentrations of influent and effluent to the constructed wetlands and removal efficiencies

Date NH4-N concentration (mg/L) Removal efficiency (in %) Influent Effluent CW 1 CW 2 CW 1 CW 2 CW1 CW 2 20.01.2014 280 304 131 248 53.2 18.4 24.01.2014 258 220 194 206 24.8 6.4 27.01.2014 256 222 220 193 14.1 12.9 30.01.2014 226 204 185 185 18.1 9.3 06.02.2014 243 258 68 194 72.0 24.8 Mean 253 242 160 205 36.4 14.4 SD 20 40 61 25 25.1 7.4

NH4-N removal in constructed wetlands also follow similar pattern to Total Nitrogen removal. Lesser microbial growth in granular media in wetland 2 may be the reason for lesser NH4-N removal. Considerable part of granular media in constructed wetland 2 has been replaced recently, after washing. NO3-N concentrations were also measured at the influent and effluent of the constructed wetlands and the results are shown in Table 3.11.

Table 3.11 NO3-N concentrations of influent and effluent samples in constructed wetlands

Date NO3-N concentration (mg/L) Influent Effluent CW 1 CW 2 CW 1 CW 2 20.01.2014 0.2 0.6 0.3 0.4 24.01.2014 0.7 0.3 0.9 0.9 27.01.2014 0.7 0.7 0.7 0.8 30.01.2014 0.2 0.5 0.7 0.7 06.02.2014 0.4 0.7 0.6 0.6

Very small concentration of NO3-N is available in the samples, when compared with Total Nitrogen. However, that can be expected in influent to the wetlands, because wastewater has followed an anaerobic treatment step. Even much difference of NO3-N concentrations cannot be identified in influent and effluent samples to the constructed wetlands also.

Nitrogen removal mechanisms in the constructed wetlands are mainly in following forms. 1. Nitrification followed by denitrification 2. Plant uptake 3. Uptake by the microbes attached to the filter media 4. Volatilization as Ammonia

Although higher concentration of Nitrate is not available in the effluent, nitrification followed by dentrification may be the main mechanism of Nitrogen removal in these constructed wetlands. Since plant growth is very low in constructed wetlands, significant amount of Nitrogen removal with plant uptake cannot be expected.

MANAGEMENT AND OPERATION OF ONSITE WASTEWATER TREATMENT SYSTEMS - AN ANALYSIS OF SUCCESS FACTORS 37

3.1.6.2 Phosphorous Removal

Total Phosphorous concentrations were measured at the influent and effluent of the treatment system and the results are shown in Table 3.12.

Table 3.12 Total Phosphorous concentrations of influent and effluent samples and removal efficiencies

Date TP concentration (mg/L) Removal efficiency (in %) Influent Effluent-Line 1 Effluent-Line 2 Line 1 Line 2 17.12.2013 30 37 37 -23.3 -23.3 24..12.2013 28 39 35 -39.3 -25.0 01.01.2014 23 - 36 - -56.5 20.01.2014 24 23 30 3.7 -25.7 24.01.2014 30 27 34 9.4 -12.7 NB: Concentration was not measured at effluent of line 1 on 01.01.2014, due to clogging of constructed wetland.

According to the results, Phosphorous removal is very low and sometimes even increase is available also. Similar type of study done by Shrish (2008) for Sunga treatment system in Kathmandu valley also had results with increase in Total Phosphorous concentration in ABR. Further, influent and effluent Total Phosphorous concentrations were measured for constructed wetlands also and the results are given in Table 3.13.

Table 3.13 Total Phosphorous concentrations of influent and effluent to the constructed wetlands and removal efficiencies Date TP concentration (mg/L) Removal efficiency Influent Effluent (in %) CW 1 CW 2 CW 1 CW 2 CW 1 CW 2 20.01.2014 25.9 40.9 23.2 30.3 10.4 25.9 24.01.2014 26.2 27.1 27.1 33.7 -3.4 -24.4 27.01.2014 33.2 28.8 30.9 22.9 6.9 20.5 30.01.2014 30.2 36.1 30.6 31.6 -1.3 12.5 06.02.2014 30.3 32.5 29.3 31.4 3.3 3.4 Mean 29.2 33.1 28.2 30.0 3.2 7.6 SD 3.1 5.6 3.2 4.1 19.8 3.2

Not much Phosphorous removal is available in the constructed wetlands as well. Phosphorous uptake by plants may very low due to lower growth of vegetation in the wetlands. Also, the adsorption to the filter particles may be reduced due to formation of thick sludge layers in the surface of particles.

Most of the Phosphorous entering and leaving to the treatment plant is in the form of Orthophosphate -P and much transformation cannot be seen in the treatment process. Table 3.14 shows the Total Phosphorous and Orthophosphorous- P concentrations in the samples.

Table 3.14 TP and Orthophosphate-P concentrations of influent and effluent measured between17.12.2013 and 24.01.2014

Date Concentration (mgP/L) Influent Effluent-Line 1 Effluent-Line 2 TP Ortho-P TP Ortho-P TP Ortho-P 17.12.2013 30 25 37 37 37 36 24.12.2013 28 27 39 34 35 33 01.01.2014 23 22 - - 36 35 20.01.2014 24 20 23 20 30 20 24.01.2014 30 29 27 21 34 28 NB: Concentration was not measured at effluent of line 1 on 01.01.2014, due to clogging of constructed wetland.

3.1.7. Pathogen removal

Pathogen removal is also an important aspect of a wastewater treatment system. If pathogen removal is not successful in a treatment system, the effluent will contain high concentrations of pathogens that cause various diseases to the people. Then, the downstream water users will dispose to high risk of health hazards.

In this research, faecal coliform was measured as an indication for pathogens. Faecal coliform measurements in the influent and effluent samples between 17.12.2013 and 30.01.2014 are given in Table 3.15.

Table 3.15 Faecal coliform measurements at the influent and effluent of the treatment system and removal efficiencies measured between 17.12.2013 and 30.01.2014

Date Faecal coliform (CFU/1ml) Removal efficiency (in %) Influent Effluent-Line 1 Effluent-Line 2 Line 1 Line 2 17.12.2013 6.46×105 1.90×104 1.20×104 97.1 98.1 24.12.2013 3.30×105 1.63×104 1.21×104 95.1 96.3 01.01.2014 5.72×105 - 2.52×104 - 95.6 20.01.2014 2.20×105 1.40×104 5.00×104 99.4 77.3 24.01.2014 7.20×105 3.60×104 4.90×104 95.0 93.2 27.01.2014 2.22×105 6.30×104 8.40×103 71.6 96.2 30.01.2014 2.78×105 4.00×104 4.00×104 85.6 85.6 Mean 4.27×105 3.14×104 3.89×104 90.6 91.8 SD 2.13×105 1.89×104 2.55×104 10.4 7.57 NB: Concentration was not measured at effluent of line 1 on 01.01.2014, due to clogging of constructed wetland.

According to the results more than 90% removal of faecal coliform has been achieved with the treatment system. However, the effluent also contained high amounts of faecal coliforms and it is an indication of contamination with pathogens.

Since other treatment steps like settlers and ABR are not removing much faecal coliforms, only effective treatment step in removal of pathogens is wetlands. Therefore, faecal coliform removal efficiency of wetlands was also calculated using influent and effluent faecal coliform contents of the wetlands. Table 3.16 shows the results. MANAGEMENT AND OPERATION OF ONSITE WASTEWATER TREATMENT SYSTEMS - AN ANALYSIS OF SUCCESS FACTORS 39

Table 3.16 Faecal coliform content of influent and effluent to the constructed wetlands and removal efficiencies measured between 20.01.2014 and 06.02.2014

Date Faecal coliform (CFU/1ml) Removal efficiency Influent Effluent (in %) CW 1 CW 2 CW 1 CW 2 CW 1 CW 2 20.01.2014 2.22×105 7.00×105 1.40×103 5.00×104 99.4 92.9 24.01.2014 4.98×105 2.95×105 3.60×104 4.90×104 92.8 83.4 27.01.2014 2.51×105 2.88×105 6.30×104 8.40×104 74.9 97.1 30.01.2014 3.10×105 7.20×105 4.00×104 4.00×104 87.1 94.4 06.02.2014 1.24×105 7.92×105 1.40×104 4.88×104 88.7 93.8 Mean 2.81×105 5.59×105 3.09×104 3.92×104 88.6 92.3 SD 1.39×105 2.47×105 2.40×104 1.77×104 9.0 5.2

According to the results, constructed wetlands have nearly 90% faecal coliform removal efficiencies (one- log removal). That indicates a considerable reduction of pathogens relative to the influent concentrations. However, effluent still has high amount of faecal coliforms.

3.1.8. Summary of the discharge water quality

Effluent water qualities at the two different streams are summarized in Table 3.17.

Table 3.17 Effluent water quality measured between 17.12.2013 and 06.02.2014

Date BOD COD TSS TN TP NH4-N Faecal (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) coliform (CFU/1ml) Wastewater line1 17.12.2013 - 501 370 37 348 1.90×104 24.12.2013 - 160 49 328 39 328 1.63×104 01.01.2014 ------20.01.2014 - 332 72 152 23 131 1.40×103 24.01.2014 - 465 58 213 27 194 3.60×104 27.01.2014 - 288 42 230 31 220 6.30×104 30.01.2014 - 410 70 194 31 185 4.00×104 06.02.2014 210 529 67 85 29 68 1.40×104 Wastewater line 2 17.12.2013 - 517 - 189 37 134 1.20×104 24.12.2013 - 160 55 410 35 388 1.21×104 01.01.2014 120 448 56 286 36 270 2.52×104 20.01.2014 - 345 64 257 30 248 5.00×104 24.01.2014 - 505 64 228 34 206 4.90×104 27.01.2014 - 293 43 202 23 193 8.40×103 30.01.2014 - 410 70 194 32 185 4.00×104 06.02.2014 190 529 48 220 31 194 4.88×104 Discharge 50 250 50 - - 50 0 standard

Measured two days BOD are much higher than the tolerance limit given in the Generic standard for wastewater to be discharged into inland surface waters from combined wastewater treatment plants. Even COD are also higher, except on 24.12.2013. However, TSS concentration is close to the tolerance limit and it is fluctuating around the limit. There is no standard available for TN and TP. However, a tolerance standard for NH4-N is available and effluent is always much higher than that limit. Also, higher amount of faecal coliforms are available at the effluent.

Discharge wastewater quality at the point of discharge was not able to measure, because discharge point is below the water level of the stream in most of the times. However, on 30.01.2014, a sample could be collected from discharge point, since there was no flow at the stream because of diversion to the fields. The results of that are given in Table 3.18.

Table 3.18 Water quality at discharge on 30.01.2014

Parameter Measured value Tolerance limit COD 278mg/L 250mg/L TSS 62mg/L 50mg/L Faecal coliforms 3.00×102 FCU/1ml 0 Turbidity 121NTU -

MANAGEMENT AND OPERATION OF ONSITE WASTEWATER TREATMENT SYSTEMS - AN ANALYSIS OF SUCCESS FACTORS 41

According to the COD measurements at the discharge point, COD has only 11.2% increase than the maximum tolerable limit. However, the effluent from wetlands normally had much higher COD than at discharge point. Even faecal coliforms had considerably lower concentration than in the effluent from wetlands. Since treated effluent is flowing in a considerable distance before discharge to the stream, self purification may reduce amount of contaminant concentrations.

Figure 3.7 Wastewater discharge point when there is no flow at the stream

3.1.9. Climatic conditions of the sampling period

Temperature of the area as measured from Kathmandu airport was between 1.5°C - 21.0°C , during the sampling periods (between 17.12.2013- 06.02.2014). Sampling period was almost dry, having only 4.2mm total rainfall for the whole period. Highest rainfall of 3.5mm was available on 18.01.2014. However, that amount also was not significant for generating storm water.

3.2. Results for analysis of Institutional and social aspects

Household survey was conducted to identify public perception about the treatment system, its operation and management, wastewater reuse, use of sludge, wastewater discharge charges and community organization. Total 70 households were interviewed, which is nearly 20 % of the total households in the area (352 households). Random sampling was used in selecting households for the interviews. However, households representing all 4 wards connected to the sewer system were evenly selected for the survey.

Figure 3.8 shows the distribution of households interviewed within each ward of Nala. That is nearly similar to the pattern of connected households in each ward. Always, I tried to contact the head of the household for the interview. But, most of the cases, it was not possible, because normally they are working outside the house during the day time. Therefore, an adult (more than 18 years old) was interviewed from

the household. Similar to other Asian countries, extended families with children and grandchildren were commonly available in most households. Figure 3.9 shows the relationship of the interviewed member with the head of the household.

1 2

Head 25 Spouse 25 Son or doughter Brother or sister 17 Grandson or daughter

Figure 3.8 Distribution of households in each ward Figure 3.9 Interviewed member's position in the household

3.2.1. Household information

Number of people in the household Numbers of people in the interviewed households vary from 2 to 14. Distribution of number of people is indicated in Figure 3.10.

18 3% 2%

16 Farmer 14 12 Skilled labourer 10 8 24% Businessman 44% 6 4 Farmer & Number of households of Number 2 21% businessman 0 Farmer & self 1 2 3 4 5 6 7 8 9 10 11 12 13 14 6% employed Number of people in household Other

Figure 3.10 Number of people in the household Figure 3.11 Occupation of people in households

Employment

Most of the people were farmers and another considerable amount of people were running a small business. Considerable amount of households with either some members are farmers and some are running a business or one member is doing both farming and business were also available. No any unskilled labourer or person doing executive job could be found among interviewed households. Figure 3.11 shows the distribution of employment among households.

MANAGEMENT AND OPERATION OF ONSITE WASTEWATER TREATMENT SYSTEMS - AN ANALYSIS OF SUCCESS FACTORS 43

Economic situation

Monthly expenditure of total household was used as an indication for economic situation of the household. 62 households out of 70 were replied to that. According to the results, considerable amount of households are spending less than 10,000NPR (less than 100USD) per month for their needs. Distribution of monthly expenditure is shown in Figure 3.12.

Below 10,000NRs 11% Between 10,000- 11% 39% 20,000NRs Between 20,000- 39% 30,000NRs Not replied

Figure 3.12 Monthly expenditure in household

3.2.2. Current situation of sanitation in households

Every household interviewed has their own toilet. That is a good achievement, in case of health and hygiene of the community. Nala has been declared as an open defecation free zone. A successful campaign has been carried out to build toilet at every household.

Almost all the houses are using pour flush toilets. Only one household interviewed had a cistern flush toilet. 64 households out of 70 had a toilet, before connecting to the sewer system. Only 6 households built toilets after the start of the treatment system.

Connection to the sewer system

53 households out of 70 were connected to the sewer system. That is 76% of total households. Time duration after connection to the sewer system is shown in Figure 3.13.

Financial Less than 3 problems 6% months 6% Technical 24% 3 -6 months 29% limitation of the 33% system More than 6 47% Technical 37% months 18% problems in household Not connected Waiting for connection

Figure 3.13 Time duration after connecting to the Figure 3.14 Reason for not connecting to sewer sewer network system

5 households out of 17 not connected had already applied for a new connection and waiting for the connection. Other 12 houses had various reasons for still not having a sewer connection. Situation of households not connected is shown in Figure 3.14. No any household were available that is not interested in connection to the sewer system. That indicates highly successful awareness creation among the community, at the early stages of the project.

Most of the households had cesspits before connecting to the sewer network. 7 households were using pit latrines. All people answered that the connecting to the sewer system was beneficial for them.

3.2.3. Public involvement and acceptance of the current treatment system

Public participation for the community organization

Figure 3.14 shows the participation situation for the community organization among people in interviewed households.

4% Participate for meetings Actively involved in 9% Very much useful 26% discussion 40% Involved in 40% Useful commitees 6% Just participate to Somewhat useful 47% 8% hold membership No idea 20% Do not participate

Figure 3.15 Participation for community Figure 3.16 Usefulness of community organization organization in solving problems related to sanitation

Usefulness of community organization in solving problems related to sanitation

Figure 3.16 shows the percentages of answers from people about usefulness of community organization for solving their problems related to sanitation. Although one option of the answers was 'not useful', no one answered for that option. That indicates acceptance of community organization among people, as a useful forum to discuss and solve their problems related to sanitation.

Acceptance of current treatment system among community

Almost all the people, except one person interviewed think that current treatment system is a good solution for their wastewater treatment. That remaining one person thinks that this treatment system is not a good solution for their wastewater treatment, because some households are unable to connect for the sewer system.

MANAGEMENT AND OPERATION OF ONSITE WASTEWATER TREATMENT SYSTEMS - AN ANALYSIS OF SUCCESS FACTORS 45

Suggestions for improvements in the treatment system

22 people interviewed gave suggestions for improvement of the treatment system. Summary of their suggestions is given in Table 3.19.

Table 3.19 Summary of suggestions by people to improve treatment system No. Suggestion Frequency of suggestion

1 Biogas production 1

2 Another DEWATS system to cover unserved area 1

3 Discharge quality should be improved 3

4 Sustainability of the system should be improved 3

5 Size of main pipe in the sewer system is not enough. It 5 should be replaced.

6 Cover unserved area also 5

7 Time to time supervision of the system should be improved 1

8 Space is not enough for treatment plant. Increase the space 1

9 Sewer pipes are not in good quality. Replace with good pipes 1

10 There may be problems in rainy seasons. Get ready for that. 1

These suggestions were also considered carefully, when the improvement measures are suggested for the treatment system, in this study.

Willingness to pay for wastewater discharge

Almost all the people except 2 persons interviewed were willing to pay for wastewater discharge. Even 10 people out of 70 were willing to pay higher amount than current price, if it would necessary for successful operation and maintenance of the system. That is a very good situation for financial sustainability of the treatment system.

64 households have paid standard fee for wastewater discharge which is 8000NPR (80USD) at the beginning and 500NPR (5USD) annually. Although some households are not connected to the treatment system, most of them have paid initial amount. 3 households have paid different amounts due to various reasons. Only 3 households had not paid any amount for wastewater treatment system.

Acceptance of current wastewater charges

Figure 3.16 shows the acceptance of current wastewater discharge fees among people. Main reason for unacceptance among some people was that the initial charge of 8000NPR is too high according to their

view. 11 people out of 12, who answered as this amount is not reasonable, told that the amount is too high, according to their income levels. One person's idea was that there were enough funds from various organizations for the treatment system and people do not want to pay.

17% Reasonable Not reasonable 79% No idea

Figure 3.17 Acceptance of current wastewater charges

3.2.4. Sludge treatment system

Although no any sludge treatment or disposal is available at the moment, after one year of operation, sludge has to be removed from settlers in treatment system. Currently, there were two options discussing for sludge treatment; drying and composting. During the household survey, willingness to buy these products for their agriculture was also investigated.

61 households out of total 70 interviewed were growing some crops. 58 households out of 61 households growing crops were willing to buy dried sludge or compost for their crops. Details of number of households willing to buy compost or dried sludge for their crops are given in Figure 3.18.

Compost 14% 24% Dried sludge Any of two 57% No idea

Figure 3.18 Number of households willing to buy sludge products for their crops

3.2.5. Treated wastewater reuse potential

Possibility of reusing treated wastewater was also investigated during household survey. 21 households out of 61 growing crops had shortages of water for their crops. 48 households were willing to use treated

MANAGEMENT AND OPERATION OF ONSITE WASTEWATER TREATMENT SYSTEMS - AN ANALYSIS OF SUCCESS FACTORS 47

wastewater for their crops. Another 7 households were also willing, but their fields were far away from the treatment plant.

8% Willing to use treated Shortage of wastewater 2% 11% water Not willing to use 35% No shortage Willing to use. But, 62% No idea 79% farm land is far away No idea

Figure 3.19 Availability of water shortage for crops Figure 3.20 Willingness to use treated wastewater for crops

3.2.6. Sewer system

All the households interviewed were releasing only black water from toilets to the sewer system. Most of the houses were connected to the system, through an interceptor. Only 9 houses were connected directly without an interceptor.

During the household survey, problems in connecting to the sewer system from households were also investigated. 4 people told that not having proper cover for interceptor is a problem for them. If a precast cover can be provided, it will be beneficial for most of the households. That will reduce entering storm water with lot of suspended solids into the system at rainy season.

3.2.7. Results from semiformal interviews with operation and management staff and office bearers of the community organization

Main information collected from semiformal interviews with operation and management staff and office bearers of the community organization are listed below.  Nala drinking water and sanitation committee, which is the community organization in charge of operation and management of the treatment system, is involved in water supply, wastewater discharge and drainage of Nala.  It is operating for more than 25 years and currently having 452 members, who are living in ward no. 1-4 0f Nala. General assemblies are held at once a month or as needed. Committee with 15 people including chairman, vice chairman, secretary, vice secretary and treasurer is engaged in executive activities of the organization.  Currently, a project office is maintained by CIUD for their staff and also officers in community organization. Rent for the project is 3000/= NPR (30 USD) per month. Currently it is paid by CIUD.  CIUD has 3 employees for the water supply and wastewater project. Another 2 part time employees are paid by community organization. (One person for water supply system and one person for wastewater system)

 Project office will be closed after March 2014. Then, all the operation and management activities of the treatment system have to be maintained by the community organization. However, some possibilities are available to have technical or financial support from other organizations.  The operator of the wastewater treatment plant is employed part time and community organization is paying 4,500NPR (45USD) per month as his salary.  Collection of wastewater discharge fees is not having much problems. A micro finance scheme with concessionary loans with 6% interest rate is available for people to have new connections for sewer network.  Good participation is available for the meetings and activities of the community organization.  Currently, only 35 communal taps are available for water supply for the community. No household connections are available at the moment. Water supply is continuous in most of the time. But, in dry periods, water supply is available only 2 hours at the morning and 2 hours at the evening.  There are not much complaints about the treatment system from people. Sanitation situation of the community has improved lot after implementing the treatment system.  Inlet zone in one of the constructed wetlands had to be washed and replaced, before SaquaSan conference, held at October 2013. Other constructed wetland will also be washed recently. Frequent clogging is a major problem for wetlands. High amount of mud is entering to the system at rainy seasons. It will be a major reason for this situation.  Only vegetation planted at the beginning is available in the constructed wetlands. No increase in number of plants, but there are some green leaves in the plants at rainy seasons.

3.3. Results for financial analysis

Data collected from grey literature were used to analyse financial sustainability of the system.

3.3.1. Income for the community organization

Main income source to the community organization is water supply fees, sewer connection fees and annual water supply and wastewater discharge fees. Sewer connection fees and annual wastewater discharge fees are directly for wastewater treatment and discharge services and that has to be used for financing operation and maintenance activities of the wastewater collection and treatment system. However, according to the information from the treasurer of community organization, initial sewer connection fee is spent for the costs for materials and labour costs of the new connection. Therefore, the major source for financing recurrent expenditures of wastewater collection and treatment system is the annual wastewater discharge fee, which is 500NPR (5USD). Since 273 households have already connected to the system, total income from that source is 136,500NPR (1365 USD) per year.

3.3.2. Capital expenditure

According to the information from CIUD, which is the project management organization for the wastewater treatment project, total capital expenditure was 8,973,989NPR (89,740USD). That has been financed by various parties as below.

MANAGEMENT AND OPERATION OF ONSITE WASTEWATER TREATMENT SYSTEMS - AN ANALYSIS OF SUCCESS FACTORS 49

Eawag 2,370,662NPR (23,707USD) WaterAid Nepal 2,795,518NPR (27,955USD) Village Development Committee 687,415NPR (6,874USD) Other donors 55,555NPR (555 USD) Community 3,064,839NPR (30,648 USD) Total expenditure 8,973,989NPR (89,740 USD)

Since the system has been designed to connect 352 households, capital expenditure per one household is 25,494NPR (255USD). Currently 273 households are connected to the system and capital expenditure per one household connected to the system is 32,872NPR (329USD).

3.3.3. Recurrent expenditure

Main recurrent expenditures are: Salary for the operator (monthly) 4,500NPR (45USD) Rent for the office (monthly) 3,000NPR (30USD) For washing of the filter material in the constructed wetland, 25,000NPR (250USD) is needed.

CHAPTER 4

Discussion

This chapter contains a discussion about the results. Results of performance of the treatment system are compared with the results of similar studies conducted in Nepal and other developing countries. Also, the results are compared with expected effluent quality and treatment efficiencies that has been considered in the original design. Then, whole treatment system is redesigned, with measured parameters during the study. It is compared with the original design and if there are considerable differences, the reasons for them are further discussed. Finally, theoretical effluent qualities and efficiencies are compared with actual performance, to identify the reasons for changes.

4.1. Comparison of performance results with similar studies

In this section, results of the performance of the treatment system are compared with the results of similar studies conducted in Nepal and other developing countries.

4.1.1. Settler

According to a study performed by ENPHO, for 5 DEWATS systems in Kathmandu valley, following removal efficiencies have been obtained for settlers.

Table 4.1 Removal efficiencies of settlers in DEWATS systems (ENPHO, 2011)

Treatment plant TSS removal BOD removal COD removal efficiency (%) efficiency (%) efficiency (%) Sushma Koirala Hospital 75 11 -17 ENPHO office 56 35 36 ICIMOD 17 -36 -41 Private house at Dalu 74 98 98 Bhushan House, Kirtipur - 43 82

MANAGEMENT AND OPERATION OF ONSITE WASTEWATER TREATMENT SYSTEMS - AN ANALYSIS OF SUCCESS FACTORS 51

However, these removal efficiencies are doubtful. Large variation in the removal efficiency is available and there are some negative BOD and COD removal efficiencies also.

According to another study, average of BOD removal in 8 DEWATS systems in Nepal were more than 40% and the COD removal was more than 25%. (Mills et al, nd) COD removal efficiency of 42.8% calculated in this study is comparable with these results.

4.1.2. Anaerobic baffled reactor

According to Shrish (2008), following removal efficiencies have been achieved from a pilot scale 6 compartments ABR with average retention time of 33.7hours and an 8 compartment ABR with average retention time of 38.6horrs.

Table 4.2 Removal efficiencies achieved from ABR with 6 compartments and 8 compartments (Shrish, 2008)

Parameter Removal efficiency in 6 chamber Removal efficiency in 8 chamber ABR ABR Average Max Average Max TSS 77.1 82.9 75.6 87.5

BOD5 53.3 74.5 55.5 81.8 COD 45.9 71.3 56.0 86.2 TKN 32.9 - 12.9 - TP 16.2 - 27.7 -

That study has further extended to a full scale DEWATS system at Sunga in Nepal, treating wastewater from 80 households and comprising with a settler, ABR, Horizontal flow constructed wetland and vertical flow constructed wetland respectively. Removal efficiencies achieved from that study for ABR is given below.

Table 4.3 Removal efficiencies of ABR in DEWATS system at Sunga (Shrish, 2008)

Parameter TSS BOD COD NH4-N TP Faecal coliform Removal efficiency 68.3 45.3 47.2 -47.5 -30.5 -268.8

Results show that considerable organic matter and particles removal can be achieved with ABR. However, Ammonia N and total Phosphorous content will increase inside the ABR. The NH4-N increase in the ABR could be due to ammonification of the organic N and transformation of urea to ammonia and increase of total Phosphorous is due to release of stored intracellular polyphosphates by decomposition to simple orthophosphates.

However, the study performed by ENPHO gives following removal efficiencies in ABR for DEWATS systems in Kathmandu valley.

Table 4.4 Removal efficiencies of ABR in some DEWATS systems at Nepal (ENPHO, 2011)

Treatment plant TSS removal BOD removal COD removal efficiency efficiency efficiency Sunga 58 34 49 Dhulikhel Hospital -20 50 -5

ABR should remove considerable amount of suspended solids. The reason for showing increase in total suspended solids content in Dhulikhel treatment plant may sometimes be sampling errors. (Probably taking effluent samples with scum)

According to another study, average of BOD removal in 8 DEWATS systems in Nepal was nearly 40% and the COD removal was nearly 20%. (Mills et al, nd) Therefore, the removal efficiencies around 75% and 43% obtained in this research for TSS and COD respectively are comparable with the results of similar studies.

4.1.3. Horizontal subsurface flow constructed wetlands

According to Shrish (2008), following efficiencies have been achieved at horizontal flow constructed wetland in DEWATS system at Sunga.

Table 4.5 Removal efficiencies of Horizontal flow wetland in DEWATS system at Sunga (Shrish,2008)

Parameter TSS BOD COD NH4-N TP Faecal coliform Removal 69.3 57.5 51.4 23.8 27.3 68.8 efficiency (in %)

According to the study of ENPHO, following removal efficiencies have been achieved for horizontal flow constructed wetlands used in DEWATS systems.

Table 4.6 Removal efficiencies of Horizontal flow constructed wetland in DEWATS systems (ENPHO, 2011)

Treatment plant TSS removal BOD removal COD removal efficiency efficiency efficiency Sunga 51 64 54 Srikhandapur 74 76 48 Dhulikhel Hospital 77 0 52 Sushma Koirala Hospital 51 35 52

According to Shrestha et al (2003), following treatment efficiencies have been achieved in constructed wetlands situated in Kathmandu valley.

Table 4.7 Treatment efficiencies in some constructed wetlands in Kathmandu valley (Shrestha et al, 2003)

Location TSS removal BOD removal COD removal NH4-N removal efficiency efficiency efficiency efficiency Dhulikhel 98.6 98.9 83.7 57 Hospital Dallu house 98.6 99.5 96.8 97 Malpi school 99.1 99.5 99.5 98 SKM Hospital 98.1 99.2 95.4 98 Kathmandu 97.9 98.9 99.1 99 University ENPHO 92.1 99.7 97.8 91 MANAGEMENT AND OPERATION OF ONSITE WASTEWATER TREATMENT SYSTEMS - AN ANALYSIS OF SUCCESS FACTORS 53

In a similar type of study for performance analysis of three constructed wetlands in Thailand, more than 80% faecal coliform removal, TKN removal of 38-85% and Total Phosphorous removal of 15-60% have been measured. (Moller et al, 2012)

Although different studies give different type of removal efficiencies, more than 50% removal efficiencies have been achieved for organic matter and particles removal. For NH4-N and total Phosphorous removal also considerable removal efficiencies have been achieved. The study by Shrestha et al. (2003) reveals much better removal efficiencies.

4.1.4. Treatment system as a whole

According to Shrish (2008), DEWATS system at Sunga containing settler, ABR, horizontal and vertical flow constructed wetlands has achieved following removal efficiencies.

Table 4.8 Removal efficiencies of DEWATS system at Sunga (Shrish, 2008)

Parameter TSS BOD COD NH4-N TP Feacal coliform Removal 95.9 90.1 90.0 69.5 26.1 97.5 efficiency (in %)

The study performed by ENPHO gives following results for removal efficiencies.

Table 4.9 Removal efficiencies (in %) of DEWATS systems (ENPHO, 2011)

Treatment plant Components TSS removal BOD removal COD removal efficiency efficiency efficiency Sunga Settler, ABR, HFCW, 96 94 93 VFCW Srikhandapur Biogas chamber, 83 83 48 HFCW Dhulikhel Hospital Settler, ABR, HFCW, 91 90 48 VFCW Sushma Koirala Settler, HFCW, VFCW 97 84 81 Hospital ENPHO office Settler, VFCW 95 98 91 ICIMOD office Settler, VFCW 91 81 77 Private house at Settler, VFCW 99 100 99 Dalu Bhushan House, Settler, VFCW 57 83 82 Kirthipur

According to another study of the DEWATS system at Srikandapur in Nepal, more than 80% removal of BOD and TSS has been achieved. (Mills et al, nd)

According to the above results, in most of the cases, more than 80% removal efficiencies have been achieved for TSS, BOD and COD removal. In this study also, more than 93% removal of TSS and more

than 80% of COD removal have been achieved. Therefore, performance results of the constructed wetlands in this study are also comparable with other studies.

4.2. Comparison of results with the original design

Table 4.10 compare the results from this study with the original design of the DEWATS system.

Table 4.10 Results from the study and parameters from original design

Parameter Average value from the research Value assumed or calculated in the original design Influent Flow rate 9.0m3 between 7.30am-3.30pm 31.7 m3/d COD concentration 1929mg/L 3300 mg/L Lowest temperature 14°C 20°C

Settler COD removal efficiency 42.8% 25% Effluent COD concentration 1170mg/L 2492mg/L ABR COD removal efficiency 43.6% 92% Effluent COD concentration 645mg/L 187.7mg/L Horizontal flow subsurface constructed wetlands COD removal efficiency 48.0% 20% Effluent COD concentration 389mg/L 149mg/L

Flow rate is considerably lower than the assumed value in the design. Measured flow is between 6.6 - 11.6m3, with average of 9.0 m3, in 8 hours, from 7.30am until 3.30pm. Since this treatment system only treat black water from toilets and water supply is only available at morning and evening on sampling days, peak wastewater hours was within the time period, when flow rate was measured. Therefore, daily flow rate will be in the range of 8-20m3/d. Then, assumed wastewater flow rate in design is higher than the actual wastewater flow rate. However, in rainy seasons, storm water entering into the sewer system is a major problem. Then, the flow rate may be sometimes higher than the assumed flow rate in the design. Design flow rate has been calculated considering 15Lpcd black water discharge from toilets and population of 2112. At the population calculations, 6 people per household have been considered. Also, number of households has been considered as 352. However, only 273 households are currently connected to the sewer system and even the average number of people in a household may also less than 6.

COD concentration is also lower than the assumed value in design. In design, COD concentration of 3300mg/L has been assumed. However, actual measured values range between 1117-2513mg/L, with an average value of 1929mg/L. Sampling period was a dry period and no dilution from storm water could be expected. However, at the rainy seasons, COD concentration may be further reduced with storm water entering into the sewer system.

In design of ABR, minimum temperature of 20°C has been considered. But, at the sampling, wastewater temperature did not reach to that temperature. At some days, early in the morning, it was 14°C. If a minimum wastewater temperature around 15°C was considered in the design, it would be better suited for the conditions in coldest months.

MANAGEMENT AND OPERATION OF ONSITE WASTEWATER TREATMENT SYSTEMS - AN ANALYSIS OF SUCCESS FACTORS 55

Average COD removal efficiency measured for settlers is 42.8% and this value is higher than the expected COD removal efficiency in the design, which is 25%. This may be due to the increase of hydraulic retention time in the settlers. Since wastewater flow rate is lower than expected, hydraulic retention time is increased. Then, higher proportion of solid particles will settle. Another reason is that the effluent samples of the settler were taken from the first chamber of ABR. Then, some amount of settlement of solid particles and some amount of anaerobic treatment will have taken place at the first chamber of ABR itself, when samples were taken. That COD removal will also account as a COD removal in the settler. Since settlers and the ABR were connected with an underground pipe, actual discharge from the settlers could not be collected.

Since influent COD concentration is lower and the treatment efficiency in the settler is higher than expected in the design, effluent COD concentration is also lower than calculated in the design. However, COD removal efficiency in ABR is lower than expected in the design. Influent samples for the ABR were collected from the first chamber of ABR and that may include some treatment from that chamber also. Then, actual treatment efficiency should be higher than the calculated value from the sample results. Other main reason for having a lower treatment efficiency is that the effect of temperature. In design, minimum wastewater temperature was considered as 20°C. But, in sampling periods, it was between 14- 18°C. According to the design formula, used in design of ABR, considerable effect is available due to the change in temperature. That aspect is further discussed in next section.

In horizontal subsurface flow constructed wetlands, higher COD removal efficiency than in the design was achieved. Surface of the filter material was covered with a thick layer of sludge. That may contain a well grown bio film also. That may be the reason for higher removal efficiency of COD than expected. However, plant growth in the wetland is very low and available plants also do not have much green leaves. Then, the COD removal due to plants may be lower than expected. Other reason for higher removal efficiencies is the higher retention times in the constructed wetlands, due to lower flow rates than design.

Finally, the effluent COD concentration is higher than expected. That is considerably higher than the tolerance limit given in the standard. Temperature has considerable effect on treatment and thus on effluent quality. However, in warm climatic conditions, effluent quality may be better and COD concentration may reach to tolerance limit given in the standard and also to the designed value.

4.3. Redesign of treatment system with measured data

In this section, redesign of the treatment system with measured data has been performed. Main aim of this was to check whether current treatment components are arequate for treatment, acoording to measured data. Generally, design of DEWATS systems is based on organic matter removal. (BOD and COD)

4.3.1. Redesign of settlers

Two settlers have been used, separating influent wastewater to two similar streams.

Table 4.11 Initial parameters used in design of settlers

Parameter Value used in Value used Reasons original in redesign design Daily wastewater 15.8m3/d This is based on population and per capita flow wastewater generation. In redesign, time of most wastewater flow was considered as the highest flow rate measured between 7.30am-3.30pm. Therefore, no daily wastewater flow was considered. Time of most 8 hours 8 hours That is the value used in common practice (In wastewater flow redesign, 7.30am-3.30pm was considered as time of most wastewater flow.)

BODin 1650mg/L 1200mg/L Assuming COD:BOD ratio of 2 CODin 3300mg/L 2400mg/L Values received from laboratory analysis are in the range of 1929±407mg/L. Settlable 0.42 0.42 Typical value for domestic wastewater SS:COD ratio Hydraulic 2 hours 2 hours Typical value retention time Desludging 12 months 12 months Typical values are between 18-24 months. However, interval this system is having problems with entering high amount of suspended solids at the rainy seasons. Surface load 0.6m3/m2 0.6m3/m2 Typical value Water depth at 2.0m 2.0m Typical values between 1.8m-2.2m outlet point Inner width of 2.2m 2.2m Typical value settler

Calculation based on new values: a) Organic matter removal Maximum flow at peak hours = 11.6/8/2 = 0.72m3/h (11.6m3 is the maximum flow occurred between 7.30am-3.30pm on sampling period. That time period was considered as the time of most wastewater flow) COD/BOD ratio = 2400/1200 = 2 Factor COD removal to HRT = [(2-1)×0.1/2]+0.3 = 0.35 COD removal rate = (0.42/0.6)×0.35×100 = 24.5% COD out = (1-0.245)×2400 = 1812mg/L Factor efficiency ratio of BOD to COD removal = 1.06 BOD removal rate = 24.5×1.06 = 26.0% BOD out = (1-0.26)×1200 = 888mg/L

MANAGEMENT AND OPERATION OF ONSITE WASTEWATER TREATMENT SYSTEMS - AN ANALYSIS OF SUCCESS FACTORS 57

b) Determination of sludge volume Factor reduction of sludge during storage = (1-12×0.014)×100 = 83.2% Sludge volume per BOD removal = 0.005×0.832 = 0.0042L/g BOD rem BOD removed = 1200-888 = 312mg/L Sludge volume from BOD reduction = 0.0042×312/1000 = 0.0013m3/m3 Sludge volume = 0.0013×12×30×15.8 = 7.45m3 c) Determination of total volume of settler Water volume = 2×0.72 = 1.44m3 Water volume + Sludge volume = 1.44+7.45 = 8.89 m3 Settler surface area = 8.89/2.0 = 4.44m2 Scum volume = 4.44×0.2 = 0.88m3 Total settler volume = 8.89+0.88 = 9.78 m3 d) Determination of chamber sizes First chamber inner length = (2/3)×9.78/(2.2×2.0) = 1.48m Second chamber inner length = 1.48/2 = 0.74m Volume of settler = (1.48+0.74)×2.0×2.2 = 9.77 m3 Constructed settlers are having lengths of chambers 1.50m and 0.75m respectively, 2.2m width and 2.4m height with 0.2m free board.

Table 4.12 shows the dimensions of settler in original design and redesign with measured values.

Table 4.12 Dimensions of settlers in original design and redesign

Parameter Original design Redesign Length of the first chamber 2.5m 1.5m Length of the second chamber 1.5m 0.75m width 2.2m 2.2m Depth 2.4m 2.4m Free board 0.2m 0.2m COD out 2492mg/L 1812mg/L BOD out 1221mg/L 888mg/L

According to the redesign, sizes of the settlers are smaller than in original design. However, in rainy seasons, high amount of storm water is entering into the system. Therefore, values used in original design are suitable for that situation. Therefore, the settlers are adequate to give sufficient treatment at the coldest months of the year also.

4.3.2. Redesign of Anaerobic baffled reactors

Two ABR for two different streams are being used.

Table 4.13 Initial parameters used in design of ABR

Parameter Value used in Value used Reasons original design in redesign Daily wastewater 15.8m3/d 8.7m3/d Maximum wastewater flow measured is 11.6 m3 for flow time between 7.30am-3.30pm. Since black water only from toilets are entering, peak factor of 2.0 for this period was assumed. Time of most 8 hours 8 hours That is the value used in common practice (In wastewater flow redesign, 7.30am-3.30pm was considered as time of most wastewater flow.)

BODin 1221mg/L 735mg/L Considering ratio COD/BOD 2.04, which is the ratio at effluent according to the design

CODin 2492mg/L 1500mg/L According to measured values of BOD out from the settler (1172±235mg/L and 1167±288mg/L) Settlable 0.42 0.42 Typical value for domestic wastewater SS:COD ratio Average 20°C 15°C According to measurements, wastewater temperature temperature is around 15°C in December- January Water depth at 2.0m 2.0m Typical value outlet point Up flow velocity 1.2m/h 0.9m/h Typically between 0.9-1.2m/h SS/COD ratio 0.42 0.42 Typical value HRT 35.5h 20h Above 20h is not effective and economically viable Length to height 0.4 0.4 Typical value ratio Distance between 25cm Should not exceed 30cm pipes Number of 7 6 Typically 4-6. According to Shirish (2008), the chambers number of chambers does not have significant improvement in pollution removal. Organic load 6kg/m3.d BOD 5kg/ m3.d That should be <6kg/m3.d BOD BOD

Calculation based on new values: a) Determination of chamber size BOD in = 735mg/L COD in = 1500mg/L Maximum flow at peak hours = 11.6/8/2 = 0.72m3/h (11.6m3 is the maximum flow occurred between 7.30am-3.30pm on sampling period. That time period was considered as the time of most wastewater flow) Maximum length of chamber = 2.0×0.4 = 0.8m Chosen length of chamber = 0.8m

MANAGEMENT AND OPERATION OF ONSITE WASTEWATER TREATMENT SYSTEMS - AN ANALYSIS OF SUCCESS FACTORS 59

Required min. width of chamber = 0.72/[0.9×0.80] = 1.0m Chosen width of chamber = 1.0m Actual up flow velocity = 0.72/ [0.8×1.0] = 0.9m/h <1.2m/h b) Determination of sludge storage volume Actual volume of ABR = 0.9×1.0×2.0×6 = 10.8m3 Sludge volume = 5×10.8/100 = 0.54 m3 Water volume = 10.8-0.54 = 10.26m3 HRT = 10.26×24/8.7 = 28h > 8h c) Removal of organic pollutants Organic BOD load = 735×0.72×24/(10.8×1000) = 1.18kg/m3.d BOD <6 kg/m3.d BOD Factor strength = (735-500)×0.1/500+0.95 = 1.00 Factor temperature = (15-10)×0.39/20+0.47 = 0.57 Factor number of chambers = (6-3)×0.06+0.9 = 1.08 Factor HRT = 1.0 Factor organic overload = 1.00 BOD removal rate by factors = 1.00×0.57×1.08×1.0×1.00×100 = 61.6% Applied BOD removal rate = 61.6% BOD out = (1-0.616)×735 = 282mg/L Factor efficiency COD removal to BOD removal = (0.616-0.5)×0.065/0.25+1.06 = 1.09 Total COD removal rate = 61.6/1.09 = 56.5% COD out = (1-0.565)×1500 = 652mg/L

Table 4.14 Comparison of new design with existing design

Parameter Existing design New design Length of a chamber 0.8m 0.8m Width 2.2m 1.0m Depth 2.0m 2.0m Number of chambers 7 6 BOD out 64mg/L 282mg/L COD out 188mg/L 652mg/L

According to new design, ABR sizes are smaller than the original design. However, then the effluent quality is lower. Main reason to have a low BOD and COD out in the original design is considering minimum temperature as 20°C, which is not realistic.

Therefore, the size of the ABR is adequate. But, effluent concentrations calculated in design are not able to achieve.

4.3.3. Redesign of Horizontal subsurface flow constructed wetlands

Table 4.15 Initial parameters used in design of constructed wetlands

Parameter Value used in Value used Reasons original in redesign design Daily wastewater 15.8m3/d 8.7m3/d Maximum wastewater flow measured is 11.6 m3 for flow time between 7.30am-3.30pm. Since black water only from toilets is collected, peak factor of 2.0 for this period was assumed.

BODin 64mg/L 273mg/L Considering ratio COD/BOD 2.2, which is the ratio at effluent according to the redesign

CODin 188mg/L 600mg/L According to measured values of BOD out from the ABR (378±125mg/L and 400±128mg/L) Minimum 20°C 15°C According to measurements, wastewater temperature temperature is around 15°C in December- January Hydraulic 372m/d 372m/d Typical value conductivity

Expected BODout 50mg/L 50mg/L According to local standards Bottom slope 1% 1% Typical value Depth of filter 0.5m 0.6m To ensure aerobic conditions bed BOD on inlet 150g/m2.d 150g/m2.d Typical value cross sectional area BOD max load 10g/m2.d 10g/m2.d Typical value on chosen surface Voids of gravel 35% 35% Typical value Chosen surface 5m2/m3 5m2/m3 Typical value area

Calculation based on new values: a) Biological design requirements COD/BOD ratio = 2.20 BOD removal rate = (273-50)×100/273 = 82% Efficiency factor of BOD removal to COD removal l = 1.025 COD removal rate = 82/1.025 = 80% COD out = (1-0.80)×600 = 120mg/L MANAGEMENT AND OPERATION OF ONSITE WASTEWATER TREATMENT SYSTEMS - AN ANALYSIS OF SUCCESS FACTORS 61

b) Hydraulic design requirements Hydraulic conductivity = 372m/d Factor BOD removal to HRT = [(0.82-0.75)×9.5/5]+0.605 = 0.738 Factor HRT on temperature = 82-[(15-10)×37]/5 = 45 HRT = 45×0.738 = 33 days HRT in 35% pore space = 33×0.35 = 11.6days c) Determination of chamber sizes Cross section area 1 = 8.7/(372×0.01) = 2.34m2 Cross section area 2 = 8.7×273/150 = 15.8m2 Chosen cross section area = 15.8 m2 Required width = 15.8/0.6 = 26.3m Required surface area 1 = 8.7×(273-50)/10 = 194 m2 Required surface area 2 = 8.7×33/0.6 = 478 m2 Chosen surface area = 478 m2 Required length = 478/26.3 = 18.2m Chosen length = 18.2m Actual surface area = 18.2×26.3 = 479 m2 d) Cross check Hydraulic load on chosen surface area = 8.7/479 = 0.018m/d <0.1m/d BOD load on chosen surface area = 0.018×273 = 4.96g/m2.d <10 g/m2.d

Table 4.16 Comparison of new design of the constructed wetlands with existing design

Parameter Existing design New design Length 6.5m 18.2m Width 14.0m 26.3m Min. media depth 0.5m 0.5m BOD out 50mg/L 50mg/L COD out 149mg/L 120mg/L

However, new dimensions are much higher than original design values. Then, large amount of land area is needed for that. Therefore, if anaerobic filter is included between the ABR and constructed wetlands, it will be economical.

4.3.4. Redesign of Constructed wetlands with anaerobic filters

Since redesigned constructed wetlands require large amount of land area, then, redesign with anaerobic filter between ABR and constructed wetlands was also considered.

Table 4.17 Initial parameters for designing of anaerobic filters

Parameter Suggested Reason for selection value Daily wastewater 8.7m3/d Same value used in ABR flow Time of most 8 hours Typical value wastewater flow

BODin 273mg/L Considering ratio COD/BOD 2.2, which is the ratio at effluent according to the redesign

CODin 600mg/L According to measured values of BOD out from the ABR (378±125mg/L and 400±128mg/L) SS/COD ratio 0.42 Typical value Average 15°C According to measurements, wastewater temperature is temperature around 15°C in December- January Specific surface 120m2/m3 Typical value (Range is 80-120m2/m3) area of filter medium Voids in filter 40% Typical value (Range is 30-45%) mass Depth of filter 1.8m Selected value (Range 1.8-2.2m) chamber Length of filter 1m Selected value chamber Width of the 2.8m Same as ABR, for construction reasons filter chamber Number of filter 1 Typically 1 or 2 chambers

Calculation a. Determination of chamber sizes and numbers BODin = 273mg/L CODin = 600mg/L Maximum peak flow per hour = 8.7/8 = 1.1m3/h Filter height = 0.75m No. of chambers = 1 Effective filter chamber height = 1.8-[0.75×(1-0.4)] = 1.35m Net volume of AF reactor = 1×2.8×1.35 = 3.375m3 HRT inside AF reactor = 3.375/ (8.7/24) = 9.3h

MANAGEMENT AND OPERATION OF ONSITE WASTEWATER TREATMENT SYSTEMS - AN ANALYSIS OF SUCCESS FACTORS 63

Max. up flow velocity in filter voids = 1.1/(2.8×1×0.4) = 0.98m/h Max. up flow velocity recommended is up to 2m/h. b. Removal of organic pollutants Organic load on AF = 8.7×273/3.375/1000 = 0.70 kg BOD/m3/d This should be <4 kg BOD/m3/d Factor temperature = [(15-10)×0.39/20]+0.47 = 0.57 Factor strength = [600×0.17/2000]+0.87 = 0.92 Factor surface = [(120-100)×0.06/100]+1 = 1.012 Factor HRT = (9.3×0.16/12)+0.44 = 0.56 Factor organic load = 1 Factor chamber = 1+(1×0.04) = 1.04 COD removal rate = (0.57×0.92×1.012×0.56×1×1.04) = 0.31 COD out = (1-0.31)×600 = 414mg/L Factor efficiency BOD removal to COD removal = 1.06 BOD removal rate = 0.31×1.06 = 0.33 BOD out = (1-0.33)×273 = 183mg/L

Design of Horizontal flow subsurface wetland (after treatment with an anaerobic baffled reactor) a) Biological design requirements BOD in = 183mg/L COD in = 414mg/L COD/BOD ratio = 414/183 = 2.26 BOD removal rate = (183-50)×100/183 = 73% Efficiency factor of BOD removal to COD removal = 1.025 COD removal rate = 73/1.025 = 71% COD out = (1-0.71)×414 = 120mg/L b) Hydraulic design requirements

Hydraulic conductivity = 372m/d Factor BOD removal to HRT = [(0.73-0.4)×31/35]+0.22 = 0.51 Factor HRT on temperature = 82-[(15-10)×37]/5 = 45 HRT = 45×0.51 = 23 days

HRT in 35% pore space = 23×0.35 = 8 days c) Determination of chamber sizes Cross section area 1 = 8.7/(372×0.01) = 2.34m2 Cross section area 2 = 8.7×183/150 = 10.6m2 Chosen cross section area = 10.6 m2 Required width = 10.6/0.6 = 17.7m Required surface area 1 = 8.7×(183-50)/10 = 116 m2 Required surface area 2 = 8.7×23/0.6 = 334 m2 Chosen surface area = 334 m2 Required length = 334/17.7 = 18.9m Actual surface area = 18.9×17.7 = 335 m2 d) Cross check Hydraulic load on chosen surface area = 8.7/335 = 0.026m/d <0.1m/d BOD load on chosen surface area = 0.026×183 = 4.75g/m2.d <10 g/m2.d

Table 4.17 Comparison of new design of the constructed wetlands with existing design (with anaerobic filter)

Parameter Existing design New design without New design with anaerobic filter anaerobic filter Length 6.5m 18.2m 18.9m Width 14.0m 26.3m 17.7m Area 91m2 479m2 334m2 Min. media depth 0.5m 0.5m 0.5m BOD out 50mg/L 50mg/L 50mg/L COD out 149mg/L 120mg/L 120mg/L

Although anaerobic filter was used between the ABR and constructed wetlands, there would not be much decrease in required size of the constructed wetlands. Since treatment of wastewater in an anaerobic filter is also with anaerobic treatment, much NH4-N removal cannot be expected. Therefore, including a vertical subsurface flow constructed wetland or a polishing pond, as final treatment step of the treatment will improve the quality of discharge in case of NH4-N.

MANAGEMENT AND OPERATION OF ONSITE WASTEWATER TREATMENT SYSTEMS - AN ANALYSIS OF SUCCESS FACTORS 65

4.4. Comparison of measured effluent quality with theoretical values

Effluent COD concentrations were calculated according to the equations used in design of treatment system as given in Sasse (1998) and CDD (2013), in this section. Then, the measured values are compared with those theoretical values and that is used to identify the reasons for variations.

4.4.1. Settler

Average influent wastewater flow = 1.12m3/h (measured between 7.30am-3.30pm) Average inflow to one settler = 1.12/2 = 0.56m3/h Average influent COD concentration = 1929 mg/L According to the original design, sludge volume after 12months sludge collection = 10.16 m3 Time duration after commencement of the operation = 8months (Commencement of the operation of the treatment system was May, 2013. Then, nearly 8 months has lapsed, when the sampling was conducted. Assuming an uniform sludge filling rate, Sludge volume in the settler = 10.16×8/12 = 6.77m3 According to the original design, Scum volume after 12 months = 1.14m3 Assuming an uniform scum collection over time, Scum volume at the sampling period = 1.14×8/12 = 0.76m3 Total volume of the settler (from design) = 15.54m3 Then, water volume = 15.54 - 6.77 - 0.76 = 8.01 m3 Hydraulic retention time = 8.01/0.56 = 14.3 h This is very much higher than the designed HRT, which is 2 hours. This result is based on wastewater flow rate between 7.30am-3.30pm, when high flow rate is available. At the night, when low flow rate available, HRT will be much higher than this value. Factor COD removal to HRT = [(14.3-1)×0.15/27]+0.4 = 0.47 Assuming SS/COD ratio of 0.42 and surface load of 0.6m3/m2 (Typical values used in the design) COD removal rate = 0.42×0.47/0.6 = 0.33 Then, theoretical COD out = (1-0.33)×1929 = 1292mg/L Average COD concentration of the effluent from settlers was measured as 1170mg/L, which is considerably closer to the theoretical value. Actual effluent COD concentration is lower than theoretical value calculated considering assumptions used in the original design. In this calculation, HRT was calculated based on influent wastewater flow rate between 7.30am- 3.30pm. However, at the night, there will be much less flow than in measured time duration. Therefore, the hydraulic retention time will increase and more solids will settle. That will be the reason for lower effluent COD measurement than calculated.

4.4.2. ABR

Influent wastewater flow rate = 0.56m3/h (Same as for settlers) Influent COD concentration = 1170mg/L (Effluent from settlers, measured) From the design, Length of ABR = 0.8m Width = 2.2m Then, up flow velocity = 0.56/(0.8×2.2) = 0.32m/h Water volume assumed in the design = 23.4m3 Assuming an daily peak factor of 2 for the time period between 7.30am-3.30pm (for black water flow from toilets) Daily wastewater flow = 0.56×24/2 = 6.72m3/d Then, HRT = 23.4×24/6.72 = 83.6h This is much higher than the designed HRT, which is 35.5h. Lower influent flow rate than assumed in the design is the reason for that. Assuming an COD:BOD ratio of 2.04 (same ratio in the effluent of settler calculated in the original design) Influent BOD concentration = 1170/2.04 = 574mg/L Organic load of the ABR = 574×0.56×24/(24.6×1000) = 0.31kg/m3.d BOD Factor strength = [(574-500)×0.1/500]+0.95 = 0.96 Average wastewater temperature during the sampling = 16°C Factor temperature = [(16-10)×0.39/20]+0.47 = 0.59 Factor chamber = 1.14 (similar to the design) Factor HRT = 1 Factor for organic overloading = 1 BOD removal by factors = 0.96×0.59×1.14×1×1 = 0.65 Then, BOD removal efficiency = 65% Theoretical BOD out = (1-0.65)×574 = 201mg/L Factor for BOD to COD removal = [(0.65-0.5)×0.065/0.25]+1.06 = 1.10 COD removal efficiency = 1.10×65 = 71% Theoretical COD out = (1-0.71)×1170 = 339mg/L Average COD concentration measured at the effluent of ABR is 644mg/L, which is much higher than the calculated value.

Sludge volume of the ABR has been estimated as 5% of the total volume of the ABR, in calculation of water volume of the reactor. However, higher sludge deposition than that can be seen in the ABR and therefore, the hydraulic retention time will be lower than estimated. Then, COD removal due to settling of suspended solids may be lower than expected. Main reason for high sludge deposition in the ABR is entering of large amount of storm water, with high amount of suspended solids at the rainy seasons. Then, most of the suspended solids deposited in the ABR at that time are silts and clay particles. Since they are

MANAGEMENT AND OPERATION OF ONSITE WASTEWATER TREATMENT SYSTEMS - AN ANALYSIS OF SUCCESS FACTORS 67

inorganic particle, they will not have contribution for the anaerobic digestion which is expected to occur at the ABR.

4.4.3. Horizontal subsurface flow constructed wetlands

Influent daily wastewater flow rate = 6.72m3/d (Same as ABR) Influent COD concentration = 644mg/L (Effluent COD at ABR) Assuming an COD:BOD ratio of 1.7 (as in the previous calculation and from the measurements) Influent BOD concentration = 644/1.7 = 379mg/L According to design, Volume of the wetland filter media = 14×6.5×0.5 = 45.5m3 Hydraulic retention time = 45.5/6.72 = 6.8 days

Then, calculated hydraulic retention time is much higher than the designed HRT, which is 2.85 days. However, actual retention time in constructed wetlands depend on the porosity of filter media also. In clogged wetland, porosity will be reduced and then, hydraulic retention time may also have decreased.

4.5. Institutional sustainability

Sustainability of the operation and management of the treatment system largely depend on the sustainability of the organization, which is engaged in operation and management of the treatment system. Operation and management of DEWATS system at Nala is entrusted to a community organization called Nala drinking water and sanitation committee. This community organization has been started more than 25 years ago. Therefore, it had sustained for a long period, before the commencement of current water supply and sewer system. Residents in peri-urban areas of wards 1-4 in Nala Ugrachandi village development committee are the members of this community organization.

Community participation is one of the most important factors for the sustainability of this type of organization. Participation for the meetings and other activities of the community organization is high, according to the information from community itself and from the office bearers of the organization. Most of the people in this community are farmers and they have their farm lands around the area. Therefore, most of them are living and working in same area and they do not need to have much effort to attend for meetings and other activities. They can participate for those events, without spending much of their time and income.

On the other hand, earlier, this area had lot of environmental problems due to open discharge of faecal sludge emptied from septic tanks. Therefore, people have much experience about the nuisance caused from this situation. So, they accept that new treatment system is a good solution for their health and well being and also for preventing pollution to the environment. Almost all the people have answered that the current treatment system is a good solution for their wastewater discharge. This situation has created motivation for people to attend and involve in activities of the community organization.

According to Sherpa et al. (2012), this community organization has been registered in the local authority. Then, it is legal entity and has permission from the government to carry out its duties. Then, it has power to sign agreements with other organizations and to maintain bank accounts at its name. That is also important for the sustainability of an organization.

Strong leadership is also necessary for the sustainability of an organization. This community organization has a vibrant leadership and team spirit. Their dedication for the activities in the organization has been a major factor to implementing this project successfully.

Strong partnership with other organizations like Swiss Federal Institute for Aquatic science and Technology (Eawag) and Centre for Integrated Urban Development (CIUD) has played a vital role in the institutional sustainability of the system. They have facilitated for various activities like training programmes, discussions, community events at the project period. That also contributes for the sustainability of the system.

Financial sustainability also influence to the institutional sustainability. Although, all other factors like strong community participation, support from other organizations and vibrant leadership is available, organization cannot withstand without financial sustainability. Next section discusses the financial sustainability of the system.

4.6. Financial sustainability

For successful operation and management of the system, financial sustainability is an important factor. In this section, financial sustainability of the treatment system is analyzed, considering various elements of financial sources and expenditure.

4.6.1. Income

Main income for the community organization for operation and management of the wastewater treatment system is wastewater charges collected from households. Since 273 households are currently connected to the sewer system, 136,500NPR (1365USD) is collected annually. (with current rate of 500NPR per household) This is an affordable amount for the community, according to the results of household survey. Also, staff at project office told in the semiformal interviews, that they have not much problem in collecting wastewater charges from households. This will somewhat increase, when other households still do not have sewer connection also joined to the system.

Other source of income is selling compost or dried sludge for use in agricultural lands. This income will generate once in a year, at desludging. Currently, it is not possible to estimate this income, because most of the people are waiting to see how it is useful for their crops. However, most of the farmers were willing to buy sludge products for their crops and even before commencement of the treatment plant; most of them were using faecal sludge from empting septic tanks for their agriculture. Therefore, some income will definitely generate from this also.

Another source of income is the interest for the amount of 400,000NPR (4,000USD) granted by Eawag for major repairs. Generally, interest rates for the long term fixed deposits in commercial banks in the Nepal are around 5% per year. Then, interest income from that is around 20,000NPR (200USD) per year. Then, annual income of more than 156,500NPR (1,565USD) can be expected for the community organization for operation and management of the wastewater collection and treatment system. Some increase of this amount will occur due to increase of households connecting to the sewer system and from income generation by selling sludge for farmers.

According to World Bank (2013), inflation rate in Nepal for year 2013 is 9.9%. Therefore, considerable increase of expenditures may occur in near future. When current income is not enough for expenditures, new income sources or increase in current income sources is necessary, for financial sustainability of the system. However possibility for new sources of income is very limited. Although treated wastewater can be MANAGEMENT AND OPERATION OF ONSITE WASTEWATER TREATMENT SYSTEMS - AN ANALYSIS OF SUCCESS FACTORS 69

used for irrigation, collecting some income from selling treated wastewater will not be possible. According to the results of the household survey, farmers are not experiencing much shortages of water for their crops and currently, they are using water from stream, which is freely available.

Then, the only option for increase in income is increasing wastewater charges. According to the results of the household survey, 14% of people were willing to pay even a higher amount than current wastewater discharge fees. Due to increase of income levels from economic growth, increasing of wastewater charges will be possible, when it is necessary.

4.6.2. Expenditure

First, various types of expenditures have to be considered for this. Then, categorizing of expenditure gives better understanding about all the expenditures that will incur in the life time of the system.

Capital expenditure

Initial costs needed for develop the system include into the capital expenditure. Now, the sewer and treatment system has been built and all the payments have been settled. Therefore, further impact on sustainability from capital expenditure will not occur. However, still the sludge drying bed has not been constructed and still discussions are going on how it is made and financing for that. A suggestion to have a composting facility instead of a drying bed is also being discussed.

Cost of capital

Cost of capital is the cost for interest payments. However, loans have not been used to finance for this treatment system. Therefore, no any cost of capital involved in this case.

Operating and minor maintenance expenditure

Regular expenditure for operation and maintenance include in this category. For this treatment plant, salary for the operator and rent for the office is paid monthly and those have to be included as regular costs. Estimation for this type of costs was prepared in the following way.

Salary for the operator 4,500NPR (45USD) Rent for the office 2,000NPR (20USD) (Rent for the office is 3,000NPR per month. It can be distributed to pay 2,000NPR from wastewater income and 1,000NPR from water supply income) Other expenses 1,500NPR (15USD) Monthly expenditure 8,000NPR (80USD) Then, total expenditure per year 96,000NPR (960USD)

When new connections are applied to the sewer system, some amount of expenditure has to be spent by the community organization. However, according to the information from the treasurer, that amount can be totally compensated by the initial payment from household for new connection. Therefore, the impact of that can be neglected for this analysis. However, when expenditure for new connections increases due to inflation, initial payment from households has to be increased to compensate expenditure for community organization for that connection.

Another expenditure that will incur annually is the expenditure for desludging. High proportion of this expenditure will consist with labour costs. Generally, daily wage for an unskilled labourer is around 300- 500NPR in that area. Therefore, cost for desludging will be not much considerable, when compared with other costs. It can compensate with the income generated from selling sludge for farm lands. If operation

and maintenance expenditures can be limited to above mentioned amounts, annual saving of more than 60,000NPR (600USD) will be able to make for future major repairs. That is a considerable amount which will accumulate with the time.

Until end of March 2014, project office of CIUD will also operate and their staff is also supporting for the operation and management activities of the system. However, after April, all the expenses have to be barred by the community organization and according to the financial situation, community organization do not have enough strength to have more employees than one part time operator. The operator of the treatment plant is currently also working part time and he can manage all activities as a part time employee. Most of the other activities like collection of wastewater charges have to be performed by office bearers of the community organizations themselves.

Capital maintenance expenditure

Asset renewal and replacement costs include into this category. These are occasional and lumpy costs that seek to restore the functionality of the system.

Currently, the inlet zone of one of the constructed wetlands is clogged and filter material at that area has to be removed, washed and placed again. For other wetland, that type of operation has been done 4 months ago and according to the information from CIUD, its cost was 25,000NPR (250USD). Therefore, similar amount of expenditure has to be spent recently.

Still only less than one year has lapsed after starting the operation of the treatment system. Therefore, clogging of constructed wetlands is occurring at an unacceptable frequency. Main reason for this is entering high amount of suspended solids with storm water at rainy seasons. Therefore, preventive measures have to be taken to avoid this situation. Most of the interceptors, which connect toilet at the household to the sewer line, do not have proper cover. Then, storm water is entering into the sewer system, at rainy seasons. Precast concrete or metal covers have to be provided for households to cover their interceptors. Then, frequent washing of filter material at the constructed wetlands is not necessary and quality of the effluent will also improve.

Apart from that, there is no other capital maintenance expenditure was identified for recent years. When, need for a capital maintenance expenditure arises, if there are enough savings from income, financial difficulties will not occur. According to semiformal interview with the treasurer, possibility for financial support from District Development Committee is also available.

If these two ways are not sufficient to finance for capital maintenance expenditure that has to be incurred, then, part of the donation from Eawag has to be spent. However, that is not advisable, because assets for future major expenditures reduces and the income from interest of deposit also reduces. Then, the other way to finance in such type of situation is borrowing money from a financial institution or from an individual. Then additional expenditure will create due to the interest payments. Therefore, avoiding from these situations and saving enough amount for future capital maintenance expenditures is vital for financial sustainability of the system.

Expenditure on direct support Cost for support activities for service providers, users not directly related to implementation include into this category. As an example, cost for training community is in this category.

Various training programmes and capacity building actives have been conducted by CIUD, at the project period. Therefore, much expenditure will not be needed to finance for these type of expenditures in near future.

MANAGEMENT AND OPERATION OF ONSITE WASTEWATER TREATMENT SYSTEMS - AN ANALYSIS OF SUCCESS FACTORS 71

Expenditure on indirect support Cost for macro-level support, planning, policy making and capacity building includes in this category. For this system, that type of expenditure was not identified for near future.

CHAPTER 5

Conclusions

This chapter contains a description about main challenges and success factors of operation and management of the DEWATS system at Nala. That was the first objective of this research. Then, this also includes a description about sustainability of the treatment system.

5.1. Main challenges of operation and management of the treatment system

One of the main objectives of this research is finding main challenges and success factors for the operation and management of the treatment system at Nala. Therefore, this section describes main challenges categorized under technical, institutional and financial aspects.

5.1.1. Technical aspects

Several challenges have been identified for the operation and management of the treatment system, relating to technical aspects.  Failure of the effluent wastewater quality to meet local standards According to the results discussed in section 3.1, effluent wastewater does not meet the local standards in case of BOD, COD and Ammonia N, during the sampling period. Therefore, treatment is not sufficient for discharge into the atmosphere in winter seasons. In warmer climatic conditions, microbial activity will be higher and high amount of contaminant removal can be expected. Then, effluent concentration may be possible to reach below tolerable limits in the local standards. However, effluent should comply with the local standards at all the times. Also, the treatment system has started its operation 6-9 months ago, when the sampling was carried out. Therefore, microbial activities might not have well established at the treatment components like anaerobic baffled reactors.

 Excessive influx of storm water in rainy seasons According to the information gathered in semi structured interviews, at rainy seasons, high amount of storm water is entering into the sewer system. Generally, it contains lots of suspended solids including silt and clay particles. That is one of the major reasons for frequent clogging of the wetlands and depositing higher amount of sludge at the settlers and anaerobic baffled reactors than expected. When high flow rate is entering in to the system, hydraulic retention times of the components reduce. Then, MANAGEMENT AND OPERATION OF ONSITE WASTEWATER TREATMENT SYSTEMS - AN ANALYSIS OF SUCCESS FACTORS 73

settlement of solid particles is lower than expected and also digestion of organic matter and removal of other pollutants are also lower. Therefore, entering high amount of storm water with high content of suspended solids lower the quality of effluent and also removal efficiencies. However, this situation may change after completion of the storm water drainage system.

 Frequent clogging of constructed wetlands Although operation of the treatment system has started less than one year ago, already clogging of the filter media has happened in the inlet zones of both constructed wetlands. Then, filter material has to be removed, washed and placed again. That needs considerable expenditure. Treatment efficiency is also affected by clogging. However after completion of the construction of drainage system, reduction in storm water entrance can be expected.

 Health risk for downstream water users due to contamination of effluent with pathogens Although considerable efficiency is achieved for removal of faecal coliforms, effluent still have large concentrations of faecal coliforms, according to the results of the laboratory analysis described in section 3.1.7. Since faecal coliform is an indication for possible presence of pathogens, effluent may have considerable amount of pathogens causing diseases to the people. Since water in the stream, to which effluent from the treatment plant is discharged, may be used by downstream communities, health risk is available.

 Low growth of plants in constructed wetlands As observations in the sampling periods, plant growth in the constructed wetlands is very low. Low growth of plants will reduce the treatment in constructed wetlands. According to the information from plant operator, only planted vegetation at the beginning is available and only number of green leaves is increased in rainy seasons. Since the plant type used in the wetlands is well grown outside the treatment plant, that plant type will be suitable to local conditions. Then, the main reason may be the high concentration of NH4-N. Influent to the wetlands contains higher concentration of NH4-N and that amount may be toxic for the plants there.

5.1.2. Institutional aspects

Challenges identified regarding institutional aspects of the treatment system are listed below.

 Maintaining current level of service with limited number of staff According to the semi structured interviews, currently, most of the work related to management, collection of wastewater charges, maintaining records and community mobilization is performed by project staff employed by CIUD. However, after the end of the project period, those staff will not be available at the project office in Nala. Then, the community organization has to arrange alternative measures to have these services. However, according to the financial situation, hiring some other employees for these works will also not be possible. Therefore, office bearers or some other volunteers from the community have to do these works.

 Maintaining public perception and motivation at current level Since the sanitation situation in the community before implementation of the current wastewater treatment system was poor and environmental pollution due to open discharge of faecal sludge was common, people know the importance of the treatment system. Also, at the first stages of the wastewater treatment project, people were educated about importance of proper discharge of wastewater. Therefore, public perception of wastewater treatment system and their motivation for activities related to improved sanitation is high. However, if proper attention was not drawn continuously to improve this situation, people's motivation may reduce gradually. Therefore,

maintaining current public perception and motivation for treatment of wastewater is a challenge for community organization.

5.1.3. Financial aspects

Several challenges have been identified for the operation and management of the treatment system, relating to financial aspects also.

 Increase in operation and maintenance costs due to inflation Because of inflation, material and service costs are increasing with time. That will depend on economic and socio-political situation of the country and it cannot be totally predicted. Therefore, available income may not be sufficient to bear total costs in future. Then, it will be a challenge to maintain a successful operation and maintenance level with available financial resources.

 Financing for future improvements of the treatment system Currently, strict monitoring of the effluent discharge by regulatory authorities is not available in treated effluent discharges from domestic or municipal wastewater treatment systems in Nepal. However, with increased pollution of water bodies, enforcement of legislation may become strict and current legislation may be amended with more strict effluent standards. Since discharge of treatment system is not complying with current standards also, then, there will be high necessity for improvements. Then, further treatment steps also have to be included and some additional land area may also be required. It will need considerable amount of capital investment. Then, available financial resources of the community organization will not be sufficient for that. Therefore, funding for such type of major improvement will be a challenge for the system.

5.2. Main success factors of operation and management of the treatment system

This section describes main challenges categorized under technical, institutional and financial aspects.

5.2.1. Technical aspects

Main success factor related to technical aspects is the success of simplified sewer network used in conveying wastewater from households to the treatment plant. This sewer system is the first simplified sewer system in the area and it is functioning properly. According to the results from household survey, any problem related to sewer system has not identified by the community. Since simplified sewer systems are less expensive for construction and maintenance, it is beneficial in economic aspects also. Machinery is not needed for laying and repairing of pipelines and local labour can be used for construction and repairs.

5.2.2. Institutional aspects

Several success factors have been identified for the operation and management of the treatment system, relating to institutional aspects.

 Well established community organization for operation and management of the treatment system Operation and management of the treatment system is carried out by a community organization called 'Nala drinking water and sanitation committee'. According to the information from semi structured interviews, it has been continuously operating more than 25 years, well before starting of current pipe MANAGEMENT AND OPERATION OF ONSITE WASTEWATER TREATMENT SYSTEMS - AN ANALYSIS OF SUCCESS FACTORS 75

borne water supply system and current DEWATS system. It is a registered community organization and so they have legal provision to conduct its operations. All users of the treatment facility are members of that organization.

 Strong community participation Strong community participation is a major success factor for the system. According to the results from household survey and semiformal interviews with office bearers of the community organization, participation of people for meetings and other activities is high and almost all the people think that the community organization is a better entity to deal with, for solving their drinking water and sanitation issues. Community has contributed around 48% of the capital expenditure for the wastewater project also.

 Successful community involvement at the initial stages of the project At the implementation of this project, the Community Led Urban Environmental Sanitation (CLUES) approach has been used to develop and implement an environmental sanitation improvement plan. It is encouraging community involvement at every stages. Therefore, community was well aware about the benefits of treatment system and they had a change to present their suggestions at the initial stages of the project. Then, the public perception of the treatment system is also good.

 Strong local leadership Strong leadership is another success factor for this treatment system. The community organization has a vibrant leadership and it has a good team spirit.

 Strong partnership with local and international agencies Strong partnership with local agencies like Centre for Integrated Urban Development (CIUD) and international organizations like Swiss Federal Institute for Aquatic Science and Technology (Eawag) is also another success factor. These organizations have facilitated for various activities of the project.

5.2.3. Financial aspects

Following success factors have been identified in case of financial aspects.

 Successful base of income Initial charge for sewer connection has already paid by most of the households, including considerable amount of households who had not still connected to the sewer system. A revolving fund to grant concessionary financial facilities for the people who cannot bear the costs for a new connection is also available. Even annual wastewater discharge fee is 500NPR (5USD) which is only 0.4% of their total expenditure for a household with 10,000NPR monthly expenditure. Almost all the people think that they receive a service worth for that payment, according to the results from the household survey. Currently, collection of wastewater charges is very much successful. Therefore, this successful base of income is one of the major success factors for operation and management of the treatment system.

 Possible financial support from other organizations at major repairs According to the information from office bearers of community organization, at a major repair, there is a possibility to have some financial support from government through District Development Committee. Some part of the initial capital expenditure was contributed by Village Development Committee also. Village Development Committee is the main governmental organization operating at village level. Then, it will be easier to have some support from government funds.

 Voluntary labour contribution from community due to strong community involvement As well as strong community involvement is a major success factor, in case of institutional aspects, it also contributes positively for financial aspects also. Due to strong public involvement, it is easier to have voluntary labour contributions from community for the repair and maintenance activities. Currently, expenditure for community organization in connecting new sewer connection to the system has been considerably reduced due to involvement of community for that operation.

5.3. Sustainability of the treatment system

Institutional sustainability of the system depends mainly on the sustainability of the Nala Drinking Water and Sanitation Committee, which is the community organization in charge of operation and management of the treatment system. However, strong community participation is available for activities of that organization and it is the main factor for sustainability of a community organization. Also, that organization is a well established long lasting community organization with more than 25 years of history. Partnership with local and international organizations is also another factor that contributes to the institutional sustainability. Therefore, it can be predicted that institutional sustainability of the system will be successful. Current base of income is successful and community organization has sufficient financial resources for current operation and management. However, that income is sufficient only to have one part time operator for the treatment plant, maintaining an office and some other maintenance activities. Since increasing revenue at current situation is also not much possible, most of the other activities have to be carried out with voluntary community participation.

Technical sustainability of the system has the major drawback, because effluent is not complying with local standards at winter season. However, only a generic standard for discharging effluent from combined wastewater treatment plant which is treating both industrial and domestic wastewaters is currently available in Nepal. Since this treatment plant is only treating domestic wastewater, applicability of that standard is also questionable. However, more strict regulations regarding domestic wastewater discharge may also be implemented near future. Then, further improvements will need for technical sustainability of the system.

MANAGEMENT AND OPERATION OF ONSITE WASTEWATER TREATMENT SYSTEMS - AN ANALYSIS OF SUCCESS FACTORS 77

CHAPTER 6

Recommendations

This chapter contains a description about recommendations for improvements to the DEWATS system at Nala. Then, this also contains key recommendations for applying similar type of DEWATS systems in small peri-urban areas of Nepal. Therefore, this chapter covers the second and third objectives of the research. Finally, this also contains some recommendations for further research.

6.1. Recommendations for the improvements to the DEWATS system at Nala

Several recommendations are suggested in this section to improve the technical performance, operation and management of the treatment system at Nala.

 Reuse of treated wastewater for irrigation DEWATS system at Nala is situated in an area with lot of farm lands around. Currently, these farm lands are using water either from Punya Matha River, which is also the discharging river of treated effluent or from drainage streams flowing from the higher elevations. According to the results of household survey, most of the farmers like to use treated wastewater for their crops. Therefore, without much effort for public awareness, treated wastewater can be used for irrigation. Although much shortage of water for crops is not available in most of the times, reusing wastewater for irrigation has the benefit of recovery of nutrients. Since this treatment system is not removing much Nitrogen and Phosphorus, effluent is rich in nutrients, which should otherwise be supplied with fertilizers. Therefore, reuse of treated effluent will reduce needs for fertilizer also. However, to comply with WHO guidelines, further reduction of coliforms is needed. Also, current Ammonia concentration may be toxic for some crops. Therefore, further treatment will be needed for reusing of treated effluent for some crops.

 Improving effluent quality by adding further treatment steps Effluent from the treatment plant does not meet the required standards during winter season, in case of BOD, COD, Ammonia Nitrogen and Faecal coliforms. Therefore, if wastewater is discharged to surface water, further treatment steps are necessary to make effluent compatible with local standards. If anaerobic filters were used between the ABR and constructed wetlands, some improvement in the quality of the effluent can be achieved. However, if vertical flow constructed wetlands and/or polishing ponds were added to the system, after the current horizontal flow constructed wetlands, considerable removal of organic matter, solids, Ammonia Nitrogen and Faecal coliforms can be expected. But, it

requires considerable amount of land. According to the situation, there is not much possibility to acquire more land for the treatment system.

 Introducing urine separating toilets for households and reuse urine for agriculture (to reduce high Ammonia concentration to the DEWATS system) According to the laboratory results of the sampling, influent wastewater has a high concentration of Ammonia Nitrogen (section 3.1.6). That may be the main reason for reduced growth of plants in constructed wetlands. Although some aerobic treatment steps will remove considerable amount of Ammonia Nitrogen, much space is not available in the treatment plant premises to built new treatment units. Use of treated wastewater for some crops may not be suitable due to high Ammonia Nitrogen concentration. Therefore, reducing Ammonia Nitrogen concentration at the influent will be beneficial for the treatment system also. Urine is the main source of Ammonia at the influent wastewater. Therefore, separating urine at the source will be beneficial for the treatment system and stored urine can be used as a fertilizer for crops. Since most of the people in this community are having farm lands, this can be implemented successfully. Even at the household survey, one of the households was found which separates urine at the source and uses for their agriculture. But, for introducing urine separation toilets, some further investment is needed. Since people have contributed considerable amount of expenditure for treatment system and some people have renovated their toilets for connecting to the sewer system also, it will be not much possible in this stage itself. But, after few years, that can be applied as a new improvement.

 Reducing operation and management expenses with reduction of staff and replacing community involvement for operation and management activities According to the section 5.3, current revenue from wastewater is enough to pay salaries for one part time operator for the treatment plant, maintaining an office and other minor maintenance works. However, several employees will not be able to maintain with current level of income. Further increase of income will also not be possible in near future. Therefore, some operation and management activities including collection of wastewater charges, maintaining records, community mobilization have to be performed without creating much expenses to the community organization. Therefore, reducing operation and management expenses with reduction of staff and replacing community involvement for operation and management activities is necessary for financial sustainability.

 Selling of dried sludge or compost made out from sludge for farmers According to the design, sludge of the settlers has to be removed once in every year. Then, those sludge has to be treated and disposed or reused. Since lot of farm lands are available around the treatment plant, using dried sludge or compost for crops is a viable option. According to the results of household survey, most of the farmers are willing to buy dried sludge or compost made with sludge, for their crops. Some farmers had the experience of using faecal sludge for agricultural lands earlier also. Therefore, dried sludge or compost made using sludge can be sold to farmers and that income can be used to compensate for expenditure of desluding. However, sludge may contain pathogens, especially helminth eggs. Therefore, care should be exerted avoid contamination of foods.

MANAGEMENT AND OPERATION OF ONSITE WASTEWATER TREATMENT SYSTEMS - AN ANALYSIS OF SUCCESS FACTORS 79

6.2. Key recommendations for applying similar treatment systems in small peri-urban areas of Nepal

Most of the peri-urban areas in Nepal do not have any wastewater treatment facility now. Therefore, environmental pollution and health risks due to open discharge of wastewater and faecal sludge is a major problem in most of the peri-urban areas. Since people do not have sufficient income to finance for centralized treatment systems and this type of treatment systems needs high operational costs and high maintenance, DEWATS is one of the alternative becoming popularize in recent years. Now, DEWATS systems are constructing in many peri-urban areas for treatment of their wastewater, especially black water from toilets. Therefore, it is important to have some recommendations, based on findings of existing treatment facilities. Then, this section gives some key recommendations for applying DEWATS systems similar to Nala in other peri-urban areas in Nepal.

6.2.1. Technical recommendations

 Include vertical flow constructed wetlands or polishing ponds for removal of Ammonia, if treated effluent is discharged to surface water When treated wastewater is discharged to surface water, it should comply with the local discharge standards. Generally, design of DEWATS systems are based on organic matter removal. Then, solids removal also satisfied in most of the cases. However, nutrient removal is not normally considered in the design. However, local standards contain maximum tolerable limit for Ammonia Nitrogen also. Therefore, wastewater treatment system has to adhere to that limit. Generally, incoming wastewater to the treatment system contain high concentration of Ammonia, from hydrolysis of urine. However, treatment steps like anaerobic baffled reactors are only performing anaerobic treatment. Then, they are not effective in removal of Ammonia Nitrogen. For removal of Ammonia Nitrogen, some aerobic treatment steps are necessary. Then, nitrification will take place and Ammonia Nitrogen will convert to Nitrate Nitrogen.

According to the results, some NH4-N removal will take place at horizontal subsurface flow constructed wetlands. However, that amount is not sufficient to meet the discharge standards. Therefore, some other treatment step like vertical flow constructed wetlands or polishing ponds will need to remove further amount of NH4-N.

 Reuse treated effluent for irrigation

Domestic wastewater contain considerable amount of nutrients. Since sources of some essential nutrient for plant growth, like Phosphorous are depleting in the world, recovery of them from wastewater will be an essential step of wastewater treatment in future. Therefore, when wastewater treatment systems are designed in future, that should also be considered. Since Nepal is mainly an agricultural country with lot of farm lands even around cities also, reuse of treated effluent is a viable option. Similar type of treatment with setter, ABR and horizontal flow constructed wetland does not remove much nutrients and effluent from such type of treatment system is good for reuse in irrigation. Then, it will reduce the need for fertilizer also.

 Collect and sell biogas

Biogas is generated from anaerobic treatment steps and that can be used for energy. A biogas reactor can be included in DEWATS systems and collected biogas can be sold for households energy needs.

 Consider realistic lowest wastewater temperatures for the design Minimum wastewater temperature considered in the design of ABR and construct wetlands has a large effect. In design of ABR according to the method given in Sasse (1998) and CDD(2013), temperature factor for calculation of BOD removal efficiency is 0.57 for 15°C and 0.86 in 20°C. If minimum wastewater temperature is assumed as 20°C, when actual value is 15°C, error in calculating expected BOD removal efficiency is 51%, which is significantly higher value. Then, effluent BOD and COD concentrations will also be calculated with high errors. Then, it will affect for the design of next treatment steps also because of using lower influent BOD and COD concentrations than actual value. That will lead to under design the dimensions of treatment system and after construction with that design, system will not have required performance. This was the case in DEWATS system in Nala also. On the hand, if treatment system was designed assuming lower minimum temperature than actual value, treatment system will over design and costs will increase.

In design of horizontal flow subsurface constructed wetlands also, there is a large impact of minimum temperature. According to the method given in Sasse (1998) and CDD (2013), factor temperature for HRT is 45 at 15°C whereas it is 24 at 20°C. If minimum temperature is assumed as 20°C, when actual value is 15°C, there will be an error of 47% in calculation of HRT. Then, the dimensions of the wetland will be under designed and effluent quality will not reach to required standards. Therefore, considering realistic minimum wastewater temperature from past data around the area is very important.

 Take measures to prevent excessive influx of storm water at rainy seasons Design and construction of sewer system to prevent excessive influx of storm water at rainy seasons is also very important. Special attention should be drawn to cover manholes and interceptors properly and to prevent entering groundwater from joints and damages of pipe lines. If high amount of storm water is entering to the system, hydraulic retention times of the components will reduce and setting of suspended solids will be lower than expected. Even sufficient time for degradation of organic matter will not be available. It will reduce the nutrient removal with processes like nitrification, denitrification and adsorption, because of nonavailability of sufficient time. Further, storm water flowing through the land may contain high concentrations of suspended solids and sludge formation in settlers and ABR will increase. Then, desludging will have to be performed frequently and due to that, costs will be higher. Even constructed wetlands may clog frequently. On the other hand, effluent quality will also deteriorate with high effluent concentrations of suspended solids.

 Consider land availability for future improvements, at early stages Land availability is a major problem for further improvements to this treatment system. Therefore when new treatment systems are planned, land availability for further improvements should be considered, at early stages.

6.2.2. Institutional and financial recommendations

 Follow a structured planning procedure like CLUES (Community Led Urban Environmental Sanitation) for planning process Proper planning is vital for successful implementation of any type of project. Since implementation of a wastewater treatment project like this has several steps, a structured procedure will be very useful. Therefore, a structured planning procedure like CLUES developed by Eawag can be used at the planning stages. One of the main reasons for success of wastewater treatment system in Nala was also the successful implementation of CLUES approach.

MANAGEMENT AND OPERATION OF ONSITE WASTEWATER TREATMENT SYSTEMS - AN ANALYSIS OF SUCCESS FACTORS 81

 Involve public from the beginning of the project For successful operation of a similar type of treatment system, good public perception is necessary. If community has no enough knowledge about the importance of the system, considerable amount of people will not connect to the system. Then, the goals of treating wastewater will not be able to achieve. Therefore, from the beginning of the project, public involvement should be encouraged. Then, public have better understanding about the benefits of wastewater treatment and they will have a sense of ownership.

 Entrust operation and management to a community organization with better community participation When a DEWATS system is used for wastewater treatment of a community in a peri-urban area in a developing country similar to Nepal, it is better to entrust operation and management activities of the treatment system for a community organization. Since community organizations are operating at the area itself, it can operate and manage the treatment system than another outside organization. Also, it is difficult to get all the services for operation and management of a DEWATS system treating wastewater for a community with low income, with payment. Therefore, voluntary community contributions are also necessary to achieve financial sustainability. Then, a strong community organization is the solution for such a situation. However, that organization should be first empowered with necessary resources. Community participation, leadership and team spirit should also be at a high level to successfully operate the organization.

 Integrate the concept of 'Open defecation free zone' to the implementation of DEWATS systems Government and various NGO in Nepal is currently promoting the concept of 'Open defecation free zone' to their cities, peri-urban areas and villages. For implementation of this concept, education and public awareness are highly important. Financial aids also sometimes given to the poor, for constructing toilets at their households. This concept can be integrated, when new DEWATS system is implemented for a community. Even Nala has been declared as an open defecation free zone with the implementation of wastewater treatment system. Then, better improvement in sanitation can be achieved.

 Charge realistic wastewater charges to compensate operation and management expenses It is difficult to continue operation with a subsidised low wastewater charge or without having any wastewater charge. Then, the operation and management of the treatment system has to depend on financial support from another organization. Then, sometimes, necessary operation and maintenance activities will have to be delayed or cancelled, due to delays or insufficient financial allocations. Therefore, collection of sufficient income that is sufficient to cover operation and maintenance costs is important.

 Implement concessionary loan schemes to finance for wastewater connections of poor people as the model in Nala If a considerable amount of people are not connecting to the system and using unhygienic practices for wastewater removal, then, the goals of having a wastewater treatment will not be able to achieve. Therefore, people with low income also should have means to access for the system. A concessionary micro finance solutions are necessary for this case. A revolving fund can be established to grant concessionary loans for the poor, similar to that used in Nala.

6.3. Recommendations for further research

 This research was performed 6-9 months after the commencement of operation of the treatment system. However, microbial activity may not be well established in the system yet. Therefore, performance analysis after at least one year of operation will give better approximation of the performance in future.

 Also, during the research period, storm events were not be available. According to the results of semi structured interviews, at rainy seasons, high amount of storm water is entering to the system and influent has also high amount of suspended solids. Therefore, further analysis at rainy periods will be useful to understand the performance of the treatment system at storm events.

 Temperature has a considerable effect on performance of treatment components like anaerobic baffled reactors and constructed wetlands. Since Nepal has higher variation in climatic conditions with the season of the year, performance analysis at various seasons of the year is very useful to understand the variation of the treatment performance with climatic conditions.

 Also, further research on simple, cost effective methods that can be used in DEWATS for removal of nutrients, especially Ammonia Nitrogen is very much useful. Although current treatment units in DEWATS like, vertical flow constructed wetlands and polishing ponds remove considerable amount of NH4-N, they require considerable amount of land area. Therefore, it is not economical to use them in urban and peri-urban areas with high land prices.

 This treatment system is managed by a community organization. However, there are other types of managements like private service contract approach. Therefore, another research can focus on whether a community managed approach to DEWATS a sustainable mode of operation for small and emerging town. Then, that can be compared with a private service contract approach and its potential implications on the users.

 Looking into the various financing modalities to build and operate a DEWATS will be another main area that could be focused on further research.

MANAGEMENT AND OPERATION OF ONSITE WASTEWATER TREATMENT SYSTEMS - AN ANALYSIS OF SUCCESS FACTORS 83

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MANAGEMENT AND OPERATION OF ONSITE WASTEWATER TREATMENT SYSTEMS - AN ANALYSIS OF SUCCESS FACTORS 85

Appendices

Appendix A :Influent flow measurements

Table A.1 Flow measurements at the last manhole of sewer system (L/s)

Date/Time 17.12. 24.12. 01.01. 20.01. 24.01. 27.01. 30.01. 02.02. 2013 2013 2014 2014 2014 2014 2014 2014

7.30am 0.76 0.44 0.63 0.65 0.67 0.76 1.04 0.48

8.30am 0.66 0.59 0.56 0.85 0.85 0.86 0.76 0.62

9.30am 0.45 0.27 0.22 0.38 0.80 0.70 0.72 0.50

10.30am 0.22 0.14 0.14 0.15 0.26 0.32 0.41 0.25

11.30am 0.16 0.15 0.11 0.12 0.26 0.35 0.31 0.21

12.30am 0.19 0.17 0.14 0.15 0.17 0.22 0.16 0.13

1.30pm 0.17 0.10 0.19 0.14 0.15 0.20 0.14 0.12

2.30pm 0.11 0.08 0.08 0.20 0.12 0.15 0.14 0.09

3.30pm 0.14 0.06 0.08 0.11 0.11 0.12 0.13 0.10

Appendix B :Results of Laboratory Analysis

Table B.1 Results of Laboratory analysis of sample at the influent

Date/ Unit 17.12. 24.12. 01.01. 20.01. 24.01. 27.01. 30.01. 06.02. Parameter 2013 2013 2014 2014 2014 2014 2014 2014

BOD mg/L - - 394 - - - 750 775

COD mg/L 2573 1993 1117 2020 1930 1780 2150 1872

TS mg/L 2124 1864 1341 - - - - -

TSS mg/L 1242 1229 521 1205 1180 790 1020 850

TN mg/L 317 332 247 270 406 - - -

NH4-N mg/L 228 252 195 122 336 - - -

NO3-N mg/L 0.3 <0.05 0.05 0.1 <0.05 - - -

TP mg/L 30 28 23 24.1 29.9 - - -

Orthophosphate mg/L 78 84 66 60.4 90.3 - - -

Faecal coliform CFU/ 6.46E+05 3.30E+05 5.72E+05 2.20E+05 7.20E+05 2.22E+05 2.78E+05 - 1 ml

Table B.2 Results of Laboratory analysis of sample at the effluent from the settler1

Date/ Unit 17.12. 24.12. 01.01. 20.01. 24.01. 27.01. 30.01. 06.02. Parameter 2013 2013 2014 2014 2014 2014 2014 2014

BOD mg/L - - 635 - - - - 510

COD mg/L 1333 600 1256 1270 1240 1200 1270 1208

TSS mg/L 524 531 425 815 680 435 680 520

MANAGEMENT AND OPERATION OF ONSITE WASTEWATER TREATMENT SYSTEMS - AN ANALYSIS OF SUCCESS FACTORS 87

Table B.3 Results of Laboratory analysis of sample at the effluent from the settler 2

Date/ Unit 17.12. 24.12. 01.01. 20.01. 24.01. 27.01. 30.01. 06.02. Parameter 2013 2013 2014 2014 2014 2014 2014 2014

BOD mg/L - - 632 - - - - 500

COD mg/L 1320 500 1232 1420 1330 1280 1090 1163

TSS mg/L 448 354 497 660 480 431 736 534

Table B.4 Results of Laboratory analysis of sample at the effluent from ABR 1

Date/ Unit 17.12. 24.12. 01.01. 20.01. 24.01. 27.01. 30.01. 06.02. Parameter 2013 2013 2014 2014 2014 2014 2014 2014

BOD mg/L - - 320 - - - - 498

COD mg/L 554 395 512 740 780 690 860 748

TS mg/L ------

TSS mg/L 174 94 110 210 188 109 170 160

TN mg/L - - - 308 270 282 252 270

NH4-N mg/L - - - 280 258 256 226 243

NO3-N mg/L - - - 0.2 0.7 0.7 0.2 0.4

TP mg/L - - - 25.9 26.2 33.2 30.2 30.3

Orthophosphate mg/L - - - 68.4 63.1 83.9 80.3 75.4

Faecal coliform CFU/ - - - 222000 498000 251000 310000 124000 1 ml

Table B.5 Results of Laboratory analysis of sample at the effluent from ABR 2

Date/ Unit 17.12. 24.12. 01.01. 20.01. 24.01. 27.01. 30.01. 06.02. Parameter 2013 2013 2014 2014 2014 2014 2014 2014

BOD mg/L - - 130 - - - - 496

COD mg/L 533 360 439 730 810 650 650 863

TS mg/L ------

TSS mg/L 143 80 112 175 172 94 118 94

TN mg/L - - - 331 251 245 230 280

NH4-N mg/L - - - 304 220 221.5 204 258

NO3-N mg/L - - - 0.6 0.3 0.7 0.5 0.7

TP mg/L - - - 40.9 27.1 28.8 36.1 32.5

Orthophosphate mg/L - - - 56.7 59.4 87.7 86.2 92.4

Faecal coliform CFU/ - - - 7.00E+05 2.95E+05 2.88E+05 7.20E+05 7.92E+05 1 ml

MANAGEMENT AND OPERATION OF ONSITE WASTEWATER TREATMENT SYSTEMS - AN ANALYSIS OF SUCCESS FACTORS 89

Table B.6 Results of Laboratory analysis of sample at the effluent from Constructed wetland 1

Date/ Unit 17.12. 24.12. 01.01. 20.01. 24.01. 27.01. 30.01. 06.02. Parameter 2013 2013 2014 2014 2014 2014 2014 2014

BOD mg/L ------210

COD mg/L 501 160 - 332 465 288 410 490

TS mg/L 954 982 ------

TSS mg/L - 49 - 72 58 42 70 67

TN mg/L 370 328 - 152 213 230 194 85

NH4-N mg/L 348 309 - 131 194 220 185 68

NO3-N mg/L 0.6 0.5 - 0.3 0.9 0.7 0.7 0.6

TP mg/L 37 39 - 23.2 27.1 30.9 30.6 29.3

Orthophosphate mg/L 112 105 - 59.8 64.4 85.1 80.6 82.1

Faecal coliform CFU/ 19000 16300 - 1.40E+03 3.60E+04 6.30E+04 4.00E+04 1.40E+04 1 ml

Table B.7 Results of Laboratory analysis of sample at the effluent from Constructed wetland 2

Date/ Unit 17.12. 24.12. 01.01. 20.01. 24.01. 27.01. 30.01. 06.02. Parameter 2013 2013 2014 2014 2014 2014 2014 2014

BOD mg/L - - 120 - - - - 190

COD mg/L 517 160 448 345 505 293 410 529

TS mg/L 976 960 1027 - - - - -

TSS mg/L - 55 56 64 64 43 70 48

TN mg/L 189 410 286 257 228 202 194 220

NH4-N mg/L 134 388 270 248 206 193 185 194

NO3-N mg/L 0.6 0.5 0.7 0.4 0.9 0.8 0.7 0.6

TP mg/L 37 35 36 30.3 33.7 22.9 31.6 31.4

Orthophosphate mg/L 112 100 108 60.1 86.2 62.7 80.6 87

Faecal coliform CFU/ 12000 12100 25200 5.00E+04 4.90E+04 8.40E+03 4.00E+04 4.88E+04 1 ml

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Appendix C : Questionnaire for Household Survey

Question Categories of Answer

Household information

1 How many people are in your house?

2 What are the relationships of them with you? 1-Head of the family, 2-Spouse of the head, 3- Parents of the head, 4-Son, daughter, son in law, daughter in law, 5-Brother or sister, 6-Other

3 Who are the employed members of 1-Farmer, 2-Un skilled labourer, 3-Skilled household and what are their jobs? labourer, 4-Businessman, 5-Self employed, 6- Middle level employee, 7-Executive

4 How much is the monthly expenditure of 1-Below 10000NRs, 2-10000-20000NRs, 3- total household? 20000-30000NRs, 4-30000-50000NRs, 5- 50000-100000NRs, 6- Above 100000NRs

Details of current sanitation situation at household

1 Do you have a toilet at your household? Yes /No

2 If yes, what type of toilet do you have? (pour 1-Pit latrine, 2-Pour flush, 3-Cistern flush flush / cistern flush etc)

3 When did you start to use a toilet at your 1-Before start of sewer system, 2-After the household? sewer system

4 Have you connected to the sewer network? Yes /No

5 If the answer for Q.4 is yes, when did you 1-Less than 3 months, 2- 4-6 months, 3-7-12 connect to the sewer system? months

6 If the answer for Q.4 is no, what is the reason 1-Financial problems, 2-Technical limitations for not connecting to the sewer? of system, 3-Technical problems in household, 4-Having not interested

7 If the answer for Q.4 is yes, what was your 1-Cess pit, 2-Septic tank and soak away, 3-Other black water collection and treatment system before connecting to sewer system?

8 Do you think that you had benefits of 1-Very much beneficial, 2-Beneficial, 3- connecting to the sewer? Somewhat beneficial, 4-No benefit

Question Categories of Answer

Public involvement and acceptability of current O&M

1 How are you involved in community 1-Participate for meetings, 2-Actively involve in organization related to sanitation? discussion, 3-Involved in comities, 4-Just participate to hold membership, 5-Do not participate

2 Do you think that community organization is 1-Very much useful, 2-Useful, 3-Somewhat useful to solve problems related to useful, 4-Not useful sanitation?

3 If the answer for Q2 is not useful, what are the reasons for that?

4 Do you think that current wastewater Yes/ No treatment system is a good solution for your wastewater treatment?

5 If the answer for Q4 is no, what are the reasons for that?

6 What are your suggestions for improvement operation and management of treatment system, if any?

7 Are you willing to pay for wastewater Yes / No discharge?

8 If the answer for Q7 is yes, how much would 1- Below 500NRs, 2- Between 500-1000NRs, 3- you like to pay annually? Between 1000-2000NRs, 4- Above 2000NRs

9 If you already pay for wastewater discharge, 1-Standard (8000NRs at beginning, 500NRs how much do you pay for wastewater annually), 2-Other discharge?

10 Do you think that amount is reasonable for Yes /No the service that you receive?

11 If the answer for Q10 is no, what are the reasons for that?

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Question Categories of Answer

Possibility of reusing treated wastewater

1 If answer for Q1 in above section is yes, Do Yes /No you have shortages for your crops?

2 If answer for Q1 is yes, would you like to use Yes /No treated wastewater for crops?

Sewer System

1 What type of wastewater do you release to 1 - Wastewater from toilet, 2- Wastewater the sewer system? from bath, 3- wastewater from kitchen, 4- Other

2 Are you connecting to the sewer system with Yes / No an interceptor?

3 Do you have any problem regarding connection to the sewer system?

Appendix D : Semiformal interviews with operation and management staff and Office bearers of community organization

Date : 08.01.2014 Place : CIUD project office, Nala Interviewer: Udayakantha Herath Translator : Buddha Bajracharya

Sandya Ranjitkar Community mobilizer, CIUD How long are you working in this office? 1 1/2 years When was this office established? 3 years ago Who is paying your salary and other remuneration? CIUD project Are you working full time or part time? Full time What is your area of work? Community sanitation What is your post at this office? Community mobilizer At the household survey, I saw some houses especially in ward 1, are not connected to the sewer system, due to geographical condition. Is there any plan for them? Household sanitation will be promoted in non served areas What are your day-to-day works of the job? Awareness creation among people, convincing people, reporting How many people are working under this office? Altogether 5 people. 3 people are paid by CIUD and 2 people by drinking water committee. Are there any problems regarding collection of wastewater charges from people? No Some people told that they have problems in paying initial cost for a connection. Is there any loan scheme for that? Yes. SEED Nepal is giving loans for initial cost for connection. That is having only 6% interest rate and repayment in instalments. Do you have complaints from people regarding wastewater treatment system? No. Are there any problems regarding wastewater treatment system? When there are floods, there are some problems What is the normal procedure that you follow after having an application for a new sewer connection? First, applicant should submit the filled application. Then, initial payment has to be made.

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After that, he will have to dig the pit for interceptor and all the work related to connection will be done by members of community organization, who works as workers. Who pays the rental for office building? CIUD

Yadav Krishna Shrestha Treasurer, Nala drinking water and sanitation committee What are the posts available in the community organization? Chairman, Vice chairman, Secretary, Vice secretary, Treasurer With all these posts, altogether, there are 15 committee members. What is the name of community organization, engaged in operation and management of wastewater treatment system? Nala drinking water and sanitation committee How many members in that organization? 452 members (All households in peri-urban parts of wards 1-4 are members) How long are you maintaining this office? 3 years Do you have household water connections or community taps? Community taps only How many households use one tap? Altogether, there are 35 taps What is the source of water? Spring (A surface water source) Do you treat water, before distribute to the community? No. Since quality of water is good, no treatment is needed. However, sometimes, there is some turbidity in rainy seasons. Are you supplying water throughout the day? Yes. But in 3 months of a year, only 4 hours per day. (2 hours in morning and 2 hours in evening) Are you the treasurer of this community organization, from the beginning of wastewater treatment project? Yes. This community organization has started about 20 years ago. I am involving in organization from 12-13 years ago. When operation of this treatment plant started? One year ago. Construction started 3 years ago. How many paid employees in the community organization? 2 Are they involved in water supply or wastewater system? One for water supply and one for wastewater. But, both work together in water supply or wastewater, when it is necessary. Are office bearers also paid? No Do you receive any complaints about wastewater treatment system? No. Before starting the treatment plant, there were lots of problems. But, now, there are no problems.

What are your normal tasks as the treasurer? Salary payments, budget management, presenting income and expenditure to the general assembly Are you collecting wastewater charges from people? No. Kanchan is doing that. For what collected wastewater charges are utilized? Maintenance work, salaries How much do you collect from one household? 500NRS for wastewater and 200NRS for water supply. Households connected to sewer system only pay wastewater charge. However, every household pays charge for water supply. After collection, they are deposited in the bank. Is it enough for operation and maintenance expenditures? Yes How is the involvement of VDC for this treatment system? Community organization coordinated with VDC at construction. Even VDC gave some amount of money for construction of treatment plant. What is the role of CIUD in this wastewater treatment system? Project management How long they will involve in this project? Until March. We have requested for an extension. If you have large maintenance in sewer system or treatment plant, what is the arrangement that you have? We will coordinate that with VDC, Kavre district committee. They will coordinate and help for Major repairs. How much is the salary for operator of treatment plant? 3000NRS per month What are the income sources for community organization? Charges from household What is your arrangement for sludge removal and treatment? Still discussing about the matter.

Date : 15.01.2014 Place : CIUD project office, Nala Interviewer: Udayakantha Herath Translator : Buddha Bajracharya

Kanchan Shrestha Field mobilizer, CIUD When did you start to work for this office? At the beginning of 2011 What are your duties? Accounting, financial work, working supervision of field staff, collecting water and wastewater charges Is it difficult to collect wastewater charges from people? Only some people are difficult to pay. But, not much problem.

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For what the collected wastewater charges are spent? Operation and maintenance activities of wastewater system How many people are working for operation and maintenance? Two people. (One operator and a worker) This project is going to be finished soon. Then, how will your work carry out? Committee will look after that. Were you working from the beginning of the project? Yes Do you have any mechanism to support for people who cannot pay initial amount at once? Yes. We have a revolving fund. Up to Rs.8000/= anyone can have from that. Payment is within 8 months and 6% interest will be charged. For what initial charge is used? That is used for connection What are the maintenance tasks done in last period? Smaller size stones in the wetland were washed, before SaquaSan conference. Which stones in the wetland were washed? Upper 1/4 of inlet zone What is the plan for sludge removal? Still the discussions are going on When the treatment plant was started operation? From May 2013 Do all houses have interceptors to connect for the sewer system? Some houses do not have Do you have any problems in treatment plant or sewer system? No Do you have any complaints about treatment plant from people? No. But, in rainy season, more water is coming to the treatment system. What are the problems do you have in rainy season? Overflow of the interceptors. Mud is entering to the sewer system. Are people using discharge wastewater for their day-to-day work? Not much According to household survey, most of the people in this area are farmers. Is that true? Yes. Most people in this village are farmers. Are there any institutional wastewater dischargers also? Yes. 3 schools. How much is their wastewater discharge fee? Same amount as households.

Bishwanath Shrestha Field coordinator, CIUD How long you are working in this project? 2 1/2 years Before you join for this project, where were you working at? I worked as an engineer of water supply company. When will your work in Nala will finish? Project will end up in April, 2014. But, post monitoring will continue.

Which organization coordinated all the organizations involved in this project? CIUD Are there any plans for sludge removal? We are considering about composting or having an organic fertilizer from it. Do you think that the community organization is having enough funds for operation and maintenance of the treatment system? Yes. They have 400,000NPR from EAWAG for that purpose Do you think that this treatment system will also be sustainable after finishing the project support? Yes. Community involvement is good. Therefore, it will be sustainable. What is the reason for high turbidity in the treated wastewater discharge? Mud entering from the interceptors. Was this community organization prevailed before start of the project? Yes. Who supervised the construction work of the treatment plant? Some staff from CIUD Who designed the treatment plant at Nala? Rajendra Shrestha at ENPHO Is the effluent from treatment plant is similar in other times also? Effluent is highly turbid in rainy seasons. Who were involved in construction work of the treatment plant? People from the community How much is the expenses to community organization for new connections? Since community is not much paid, it is not a big amount. Do people have to build interceptor and other connection work by themselves? Yes. 12m long pipe is provided by community organization.

Ram Gopal Karmacharya Secretary, Nala drinking water and sanitation committee When did you join for this organization? 8 years How long this community organization was continuing in operation? 28 years Before start of the treatment plant, what was the duty of the organization? Earlier, it was involved in drinking water When this concept of having a treatment plant was originated? From an individual. 10 years ago, a person called P.S. Joshi in UN-habitat developed a drainage system. He studied about this whole area. How frequently do you have meetings in your organization? Monthly. According to need also. How is the participation of the community for those meetings? Participation is good. Are there sub committees available in your organization? Yes. Currently, there is a subcommittee for paving roads How much is the rent for this office? 3000/= NRs per month

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After the end of project period, what will you do for staff working in the office? They will continue. What are your normal duties as secretary of this organization? Dispatching letters, preparing minutes, planning and implementation Are you doing another job also? Yes. I am a veterinary technician, also I am doing agriculture If there is a major repair, how is the arrangement for that? Other organizations will support. Do you think that wastewater treatment system will be sustainable, after the end of project support? Yes. It will be sustainable. How long do you having this post? Three years Do you have any complaints from people regarding the sewer system or treatment plant? No. But, seepage of storm water to the system is a problem. Did you have to buy land for treatment plant? Yes. Its cost is 2.2Million. How much is the land for treatment plant? 1 Roppani 6 Anna

Badrai Narayan Shrestha Vice Chairman, Nala drinking water and sanitation committee How long do you involved in this community organization? 25 years Are you involved in the committee from the beginning? Yes. From early times. When did you have vice chairman post? 5 years ago Who had this concept of a wastewater treatment system first? CIUD gave this idea. How was the sanitation situation before start of this treatment system? Nearly 50% of the people had latrines. Most of them were pit latrines and sludge was used as manure. Is that CIUD first involved for this wastewater treatment project in Nala? No. They first came for a drainage project. Who did the finding of funds and negotiations for this project? CIUD did those things Do you think that having this treatment system is a good achievement for the community? Yes. It is a vast achievement. Do you think that initial cost for a new connection is affordable for people? Yes Do you have problems to convince people for a treatment system and for wastewater charges? Not much. First we decided to collect 10,000NRs at new connections. But, then we reduced from it, 2000NRs. Then, people were happy about that. What are the future plans of this organization? Buying a motor to pump wastewater from unserved areas with lower elevation.

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What are the people's suggestions that you received for improvement of the treatment system? Requesting to have biogas and compost

Date : 20.01.2014 Place : CIUD project office, Nala Interviewer: Udayakantha Herath Translator : Buddha Bajracharya

Luxmi Prasad Deula Operator of the treatment plant When did you start your job as the operator of the treatment plant? June or July in last year Are you working as the operator from the beginning of the treatment plant? No. After sometime. Was there other operator working for the treatment plant, before you start your work? No. I was the first operator. Are you doing this job as part time or full time? I am working as a helper in a school also. Normally, in a day, at what time do you start your work as the operator? At 11.00-12.00am What are your normal duties? Looking after the treatment plant. Helping for other tasks at the office. Was there any repair or major maintenance activity during your period? 1/4 of the wetland material was removed, washed and again kept. Are you working for other works of community organization, like water supply and sewer connections? No. Only for treatment work. We saw one day that the first wetland was blocked. What did you do to prevent that? Dug some channels on the wetland to convey wastewater bypassing blocked area. Is wastewater flow similar in other seasons also? In rainy season, it has higher flow and wastewater is highly turbid. Was the growth of plants in wetlands is similar from beginning? Yes. Growth of plants is very low. Only in rainy seasons, they have some green leaves. Did you also involved in construction work of the treatment plant? No. Did you have complaints regarding treatment plant from people? There were some complaints regarding smell problem. For what purposes water in discharging river is used? Irrigation. For agriculture. Do people use water from that river for bathing and washing also? No Do you think that downstream people use this water for their needs? There are no residential areas in downstream. So, there are no usages. Are you satisfied with your job as the operator of the treatment plant? It is OK.

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Did you have any training as the operator of the treatment plant? No. (According to Kanchan, there was a training programme on O&M of treatment plant for whole people. But, he did not participate for that and he was not working as the operator at that time.) Are people using the treated effluent for their agriculture? Because of high Ammonia content, they are not directly using. But, after going to the river, since it is diluted, it is used for irrigation. We saw that the flow of the discharging river is very low now. How is the flow in other seasons? Until March-April not much flow. But, after that, it has high flow. Even flooding can happen. Are the treatment plant also inundated with flood water? No. That will never happen.

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