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Municipal Wastewater Management in Developing Countries

Municipal Wastewater Management in Developing Countries

Zaini Ujang | Mogens Henze

(2006)

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Abstract

Municipal Wastewater Management in Developing Countries discusses various approaches to municipal wastewater management in order to protect both public health and the environment, with the major focus being on waterborne diseases. Developing countries can be divided into two main categories, i.e. countries in transition with higher growth rates where industrialisation and urbanisation are taking place rapidly, and countries with slower growth rates. It is important, therefore, that approaches should be tailor-made and site-specific. In general, the major trends of water pollution control have significantly contributed to the development of ?conventional sanitation? approaches in terms of legal and financial frameworks, as well as technological enhancement. Despite advances in the science, engineering and legal frameworks, 95 per cent of the wastewater in the world is released into the environment without treatment. Only five per cent of global wastewater is properly treated using the ?standard? sanitation facilities, mainly in developed countries. As a result, the majority of the world?s population is still exposed to waterborne diseases, and the quality of water resources has been rapidly degraded, particularly in poor developing countries. The challenge now is to provide the world?s population, especially the poor, with adequate water and sanitation facilities. Despite billions of dollars of investment spent every year, billions of poor people are still suffering and dying because of poor sanitation. At the beginning of this century, about 1.1 billion people lived without access to clean water (compared to about the same number in 1990), 2.4 billion without appropriate sanitation (compared to 2.3 billion in 1990) and four billion without sound wastewater disposal. The future scenario, that water resources will be further depleted by a growing world population, will be coupled with environmental degradation due to poor pollution control, particularly in most of the developing countries. In order to address the issue of water and wastewater management in developing countries it is necessary to take into consideration the segments of the society itself, particularly the types of housing areas. The segments will indicate the level of socio-economic, mentality and knowledge, which is important for any planned changes in their life style and social engineering. It is also important to segregate the funding framework of any proposed projects. High-income urban communities, for instance, are generally willing to pay for sewerage services and higher water supply tariffs, therefore a designated system can be accordingly provided. Over the past 10 years, serious criticism has been given to the ?conventional sanitation? approach, consequently many definitions, concepts and characteristics have been proposed on ?sustainable sanitation?. Sustainable sanitation is a relevant concept in order to achieve the  Millennium Development Goals by 2015 of providing water supply and adequate sanitation for developing countries. Sustainable sanitation is flexible in approach any community ? poor or rich, urban or rural, water-rich or water-poor country ? and requires lower investment costs compared to conventional sanitation approaches. It is also important to note that the framework of sustainable sanitation is much easier  to adopt in developing countries where water supply and sanitation infrastructures are still in the developing stages. In some developing countries, no public facilities are available therefore it is an ideal condition to start a new infrastructure with a new framework. This comprehensive reference, prepared by leading international authorities, will provide an invaluable reference for all those concerned with the management of sanitation services in developing countries worldwide.

Table of Contents

Section Title Page Action Price
Contents 6
Preface 15
1 Sustainable sanitation for developing countries 18
1.1\tINTRODUCTION 18
1.1.1\tMajor trends 19
1.1.2\tConventional sanitation approach 20
1.1.3 The challenge 22
1.1.4 Dilemma of developing countries 23
1.2\tPOOR DEVELOPING COUNTRIES 25
1.3 COUNTRIES WITH HIGH GROWTH RATES 26
1.4 SOCIO-ECONOMIC CATEGORIES 26
1.5\tSUSTAINABILITY AND SANITATION 28
1.6\tSUSTAINABLE SANITATION FOR DEVELOPING COUNTRIES 32
REFERENCES 33
2 Setting effluent quality standards 34
2.1\tINTRODUCTION 34
2.1.1\tCurrent conditions 36
2.1.2\tSetting realistic quality standards based on available resources 38
2.2\tWATER QUALITY 42
2.2.1\tWater quality criteria and standards 42
2.2.2\tScientific basis for development of criteria and standards 43
2.2.3\tClasses of water 44
2.3\tCRITERIA FOR DISCHARGE 45
2.3.1\tAssimilative capacity of receiving environments 46
2.3.2\tRelating discharges to assimilative capacity of receiving environments 47
2.3.3\tSetting effluent standards with multiple discharges 48
2.3.4\tDischarge licences for water quality control 49
2.4\tCRITERIA FOR REUSE 50
2.4.1\tReuse as a means of water quality control 51
2.4.2\tWater quality criteria for reuse 52
2.4.3 Reuse for forestry, agriculture (including hydroponic systems), horticulture, aquaculture, polyculture 54
2.4.3.1 An example of wastewater reuse for Aquaculture in a developing country 56
2.5\tCASE STUDIES OF A DEVELOPING COUNTRY 57
57
2.5.1.1 Standards 57
2.5.1.2 Governance 58
REFERENCES 59
3 Strategy and planning of sewerage infrastructures 63
3.1\tINTRODUCTION 63
64
3.1.1\tMalaysia in brief 64
3.1.2 Sewerage development in Malaysia 64
3.2\tSEWERAGE POLICY 69
3.2.1 National framework 71
3.2.1.1\tRegional and local authorities 72
3.2.1.2\tPrivatisation 72
3.3\tCAPITAL CONTRIBUTION 74
3.4\tCATCHMENT STRATEGY 81
3.4.1\tSewerage system 81
3.4.2\tBasic principles 82
3.4.3\tSewerage management alternatives 82
3.4.4\tFinancial analysis and options 84
3.5\tCONCLUSION 85
REFERENCES 85
4 Wastewater treatment technology 87
4.1\tINTRODUCTION 87
4.2\tBIOFILM SYSTEM 89
4.2.1\tMass balances for biofilters 89
4.2.1.1 Biofilters without recycle 89
4.2.1.2 Biofilters with recycle 90
4.2.2\tConcept and definitions for biofilters 91
4.2.3\tDesign of biofilters 92
4.2.3.1 Design of trickling filters 93
4.2.3.2 Design of rotating biological contactors or discs 95
4.2.3.3 Other type of filters 95
4.2.4\tTechnical conditions concerning biofilters 96
4.2.4.1 Aeration of biofilters 96
4.2.4.2 Growth and sloughing off the biofilm 96
4.3\tACTIVATED SLUDGE TREATMENT SYSTEM 98
4.3.1\tMass balance in activated sludge plant 98
4.3.2\tConcept and definitions of the activated sludge process 101
4.3.3\tDesign of the activated sludge processes 109
4.3.4\tDesign using volumetric loading 109
4.3.5\tThe design using sludge loading or sludge age 112
4.4\tHYBRID TECHNOLOGY 114
4.5\tCONCLUSION 114
REFERENCES 114
5 Collection systems - dry and wet weather performance 116
5.1\tINTRODUCTION 116
5.2\tTYPES OF COLLECTION SYSTEMS 118
5.3\tSOURCES AND QUANTITIES FOR DRY WEATHER WASTEWATER 120
5.3.1\tWastewater from households 120
5.3.2\tInstitutions, business areas and industries 122
5.3.3\tInfiltration and drainage of buildings 123
5.4\tSTORMWATER QUANTITIES 124
5.4.1\tPrecipitation and design storms 126
5.4.2\tChoosing return frequency and storm duration 128
5.4.3\tImpervious surfaces and runoff coefficients 129
5.4.4\tRunoff hydrographs 130
5.5\tROOTING OF DRY AND WET WEATHER FLOW 131
5.5.1\tDry weather flow 131
5.5.2\tWet weather flow 132
5.6\tWASTEWATER QUALITY 133
5.6.1\tTypes and concentrations of wastewater quality parameters 133
5.6.2\tCharacterization of wastewater organic matter 136
5.6.3\tVariability in wastewater composition 140
5.7\tSTORMWATER QUALITY 141
5.7.1\tSeparate systems 141
5.7.2\tCombined systems 142
5.7.3\tPollutants variability 143
5.8\tSTORMWATER IMPACT MITIGATION 144
5.9\tCHEMICAL, BIOLOGICAL AND PHYSICAL PROCESSES IN SEWERS 145
5.9.1\tWhy simulate sewer processes? 146
5.9.2\tCorrosion and odours 146
5.9.3\tTreatment plant impacts 147
5.9.4\tReceiving water impacts 147
5.9.5\tIntegrated urban wastewater management 147
5.10\tCONCLUDING REMARKS 149
REFERENCES 149
6 Conventional small and decentralised wastewater systems 151
6.1\tINTRODUCTION 151
6.1.1\tCurrent practices in developing countries 152
6.1.2\tConventional and decentralised wastewater systems 153
6.2.\tSMALL SYTEMS AND SUSTAINABILITY 154
6.2.1 Relationship between small systems and sustainability 154
6.2.2 Economic, social and cultural implications of small systems 157
6.3 SEWERAGE SYSTEMS 158
6.3.1 Settled sewerage (small bore sewerage) 158
6.3.2 Simplified sewerage (shallow sewerage, including condominial sewerage) 159
6.3.3 Low cost sewerage and community involvement 160
6.4 SMALL SYSTEMS 161
6.4.1 Ponds and lagoons 161
6.4.2 Constructed Wetlands 161
6.4.3 Land based treatment systems 162
6.4.4 Reuse 164
6.4.5 Aquaculture systems 165
6.4.6 Sludge management 165
6.5 ONSITE SYSTEMS 166
6.5.1 Ventilated improved pit (VIP) latrine 166
6.5.2 Vermicompost toilets 166
6.5.3 Composting toilets 168
6.5.4 Pour flush toilets 169
6.5.5 Septic tanks (including Imhoff tanks) 170
6.5.6 Leach drains 171
6.5.7 Evapotranspiration beds 171
6.5.8 Digesters (small anaerobic systems) 172
6.5.9 Reuse of wastewater and sludge 173
6.6 SELECTION OF SMALL AND ONSITE SYSTEMS 174
6.6.1 Decision support tools for selection of small and onsite systems 174
6.6.2 Computer based decision support tools 175
SANEX© 176
Sanitation alternatives considered in SANEX© 176
Two-Stage Evaluation 177
Multi-Level Amalgamation 177
Costing of Sanitation Alternatives 177
6.7 CASE STUDY FROM AFRICA 177
6.7.1 Onsite technologies employed in Africa 179
Septic Tanks 179
Reid’s Odourless Earth Closet (ROEC) 179
Double-vault VIP latrine 180
Composting Toilets 181
6.7.2 Onsite system application 181
REFERENCES 182
7 Waste stabilization ponds 185
7.1 Introduction 185
7.2 Water are waste stabilization ponds? 186
7.3 Advantages and disadvantages of WSP 187
7.4 Financial and economic aspects of WSP 188
7.5 Main types of WSP 189
7.6 Other WSP formats 190
7.7 Anaerobic ponds 191
7.8 Facultative ponds 193
7.9 Why ponds do not smell 196
7.10 Maturation ponds 196
7.11 Operation and maintenance of WSP 205
References 205
8 Design and operation of constructed wetlands for wastewater treatment and reuse 209
8.1\tINTRODUCTION 209
8.2\tTYPES AND FUNCTIONS OF CONSTRUCTED WETLANDS 210
8.2.1\tFree water surface (FWS) systems 210
8.2.2\tSubsurface flow (SF) systems 210
8.2.3\tAdvantages and disadvantages 211
8.3\tTYPES AND FUNCTIONS OF VEGETATION 212
8.4\tWASTEWATER TREATMENT MECHANISMS 212
8.4.1\tBOD removal 213
8.4.2\tSuspended solids removal 213
8.4.3\tNitrogen removal 213
8.4.4\tPhosphorus removal 215
8.4.5\tHeavy metals removal 215
8.4.6\tTrace organics removal 215
8.4.7\tPathogen removal 215
8.5\tDESIGN EQUATIONS 216
8.5.1\tFWS constructed wetlands 216
8.5.2\tSF constructed wetlands 221
8.6\tOTHER CONSIDERATIONS 224
8.6.1\tHydraulic budget 224
8.6.2\tSite selection 225
8.6.3\tFlow patterns 225
8.6.4\tSlope 226
8.6.5\tLiners 226
8.7\tOPERATION AND MAINTENANCE 226
8.7.1\tMosquito control 226
8.7.2\tPlant harvesting 227
8.7.3\tSystem perturbations and operation modifications 227
8.8\tCASE STUDIES 231
8.8.1\tCase Study A: Emmitsburg, Maryland, USA, SF Constructed Wetland 231
8.8.2\tCase Study B: The Eastern Seaboard Industrial Estate (ESIE), Rayong Province, Eastern Thailand, Vertical-flow Constructed Wetlands 231
8.8.3\tCase Study C: Vertical-flow Constructed Wetlands for Septage Dewatering and Stabilization, Asian Institute of Technology (AIT), Bangkok, Thailand 233
ACKNOWLEDGEMENT 235
REFERENCES 235
9 Innovation and technology for sustainability 236
9.1\tINTRODUCTION 236
9.1.1\tSustainability as a context 238
9.1.2\tDrivers for technology innovation 239
9.2\tCURRENT ADVANCES AND INNOVATIONS 241
9.2.1 Innovations in onsite systems 242
9.2.2. Innovations in sewerage systems 245
9.2.3 Innovations in treatment systems 246
9.2.4 Innovations in reuse systems 247
9.3 RESEARCH NEEDS 248
9.3.1 Technology 249
9.3.2 Technology management 250
9.3.3 Environmental health 251
REFERENCES 252
10 Sludge treatment and management 254
10.1\tINTRODUCTION 254
10.2 CHARACTERIZATION 255
10.2.1 Types of sludges 255
10.2.2 Sludge production 255
10.2.3 Quality 256
10.2.3.1 Physical characteristics 256
10.2.3.2 Chemical 258
10.2.3.3 Biological characteristics 258
10.3 TREATMENT 264
10.3.1 Degritting 264
10.3.2 Thickening 264
10.3.3 Conditioning 265
10.3.4 Dewatering 267
10.3.5 Stabilization 267
10.3.5.1 Alkaline stabilization 268
10.3.5.2 Composting 271
10.3.5.3 Anaerobic digestion 274
10.3.5.4 Acid treatment 275
10.3.6 Storage 276
10.3.7 Considerations for process selection 276
10.4 SLUDGE REDUCTION 279
10.5 SEPTIC TANKS 280
10.6 BENEFICIAL USES OF BIOSOLIDS 280
10.6.1 Agricultural application 281
10.6.2 Remediation 284
10.6.3 Desalinization of soils 285
10.6.4 Forest use 285
10.6.5 Non conventional uses of sludges 285
10.7\tCONFINEMENT 286
10.7.1 Monofills 286
10.7.2 Ponds and lagoons 286
10.7.3 Specific disposal sites 286
10.7.4 Municipal sanitary landfills 288
10.8\tLEGISLATION 291
10.8.1 South Africa 291
10.8.2 Mexico 291
10.8.3\tChile 292
10.8.4\tChina 294
10.8.5 \tBrazil 294
10.9 SAMPLING AND MONITORING ISSUES 295
10.9.1 Sampling 295
10.9.2 Vector attraction 297
10.10 COSTS 298
10.11 PRACTICAL EXPERIENCES 298
10.11.1 Mexico 298
10.11.2 Brazil 300
10.11.3 Argentina 300
10.11.4 Chile 301
10.11.5 China 301
10.11.6 Accra, Ghana 302
10.11.7 Alexandria, Egypt 303
10.11.8 Europe 303
10.12\tACTIVITIES NEEDED 304
REFERENCES 304
11.1\tINTRODUCTION 310
11.2\tMAJOR ISSUES 313
11.3\tPLANNING AND STRATEGY FOR SEWERAGE CATCHMENT 316
11.3.1\tInstitutional framework 316
Sewage Flow and Sludge Generation Estimate Estimation of sewage flow and associated pollutant loading and sludge generation rate are important considerations as they dictate the sizing of collection and conveyance systems, and the determination of treatm 323
Assess Existing Sewerage Deficiencies Constraints that exist within the current sewerage infrastructures to receive future sewage loads must be identified. Among the major factors that would be considered to propose alternatives in solving existing const 323
11.6\tDATABASE AND ZONING 333
11.6.1\tTypes of sewage plants 333
11.7\tINSPECTION AND EFFLUENT QUALITY MONITORING 338
11.8\tUPGRADING STRATEGY 340
11.9 RATIONALISATION STRATEGY 341
11.10\tFUTURE CHALLENGES FOR MALAYSIA 346
REFERENCES 348