CONTENTS
1.Introduction 12
2.Towards comprehensive wastewater
and sanitation strategies 14
2.1 World water resources under threat 14
2.2 The protection of water resources- achievements and challenges 17
2.3 A short assessment of the sanitation and wastewater sectors
in developing countries 20
2.4 Signs of change- elements of efficient and sustainable
sanitation programmes 27
2.5 Towards service orientation- the conceptual framework
of basic needs sanitation programmes 29
2.6 The increasing demand for efficient and reliable decentralised wastewater-treatment solutions 31
3 DEWATS- Sustainable treatment of waste water
at the local level 32
3.1 DEWATS - a modular system approach to ensure efficient
wastewater treatment performance 33
3.2 DEWATS- a brief insight into technical configuration 35
3.3 DEWATS- good practice examples/applications 37
3.31 DEWATS/CBS- Community-Based Sanitation programme
in Alam Jaya, Tangerang, Java, Indonesia 37
3.3.2 DEWATS/CBS- Community-Based Sanitation programme
in Ullalu Upanagara, Bangalore, India 40
3.3.3 DEWATS at public institutions- Sino-German College of
Technology, Shanghai, China 43
3.3.4 DEWATS at public institutions- Aravind Eye Hospital
in Thavalakuppam, Pondicherry, India 46
3.3.5 DEWATS/SME-Ciuster approach- Kelempok Mekarsari
Jaya small-scale industry cluster, Denpasar, Bali, Indonesia 49
3.3.6 DEWATS/SME -Alternative Food Process Private Ltd. Bangalore, Karnataka, India 52
3.3.7 lnfrastructural development in rural China- Longtan Village,
Danleng County, Szechuan Province, China 54
3.3.8 DEWATS in integrated municipal planning- Wenzhou University,
Zheijang Province, China 56
4 Mainstreaming DEWATS - strategic planning and
implementation of sustainable infrastructure 58
4.1 Strategic planning of sanitation programmes 58
4.2 Legal framework and effic ient law enforcement 62
4.3 Target-oriented local and municipal planning 66
4.3.1 Features of urban infrastructu re development 66
4.3 Sanitat ion mapping as a tool for eff icient urban-infrastructure
deve lopment 68
4.4 Financ ial ana lysis 74
4.4.1 Comparative cost analys is for infrastructure development 74
4.4.2 Economic ana lysis in times of global warm ing and energy scarcity 77
4.4.3 Econom ic cons iderat ions for point-source polluters 80
4.4.4 Parameters f or economic calculation 82
4.4.5 Susta inable f inancing schemes for sanitat ion programmes-
multi-source f inancing and w illingness to pay 88
5 CBS programme planning and implementation 92
5.1 Stakeho lders in CBS programmes 92
5.2 Responding to basic needs- active involvement of beneficiaries
and residents 96
5.3 Local government and municipality bodies 97
5.4 Non-governmental organisations 99
5.5 Private sector 99
6 CBS Programme - detailed procedure for implementation 100
6.1 First planning activities 100
6.2 The pilot project 103
6.3 Preparation phase 105
6.3.1 Krck-off wo rkshop ,. 105
6.3.2 Planning workshop 106
6.3.3 Community pre-selection and community assessment 108
6.4 Planning phase 110
6.4.1 Site assessment 110
6.4.2 Informed techno logy choice 112
6.4.3 Detailed engineering design 114
6.4.4 Economic planning 116
6.4.5 Agreement on implementation and landholding 117
6.5 Implementation phase 118
6.5.1 Task planning 118
6.5.2 Quality management 120
6.5.3 Construction 121
6.5.4 Pre-commissioning test 123
6.5.5 Parallel training measures 123
6.6 Operation phase 124
6.6.1 Start operation 124
6.6.2 Operation & maintenance 126
6.6.3 Use of biogas 129
6.6.4 Monitoring and evaluation 131
7 DEWATS components & design principles 132
7.1 Basics of wastewater treatment 132
7.1.1 Definitions : pollution & treatment 132
7.1.2 Biological treatment 133
7.1.3 Aerobic - anaerobic 135
7.1.4 Physical treatment processes 136
7.1.5 Elimination of pollutants 141
7.1.6 Ecology and self-purification in nature 145
8 Treat ment in DEWATS 150
8.1 Parameters for wastewater-treatment design 152
8.1.1 Control parameters 153
8.1.2 Dimensioning parameters 163
9 Technical component s 168
9.1 Overview of DEWATS components 168
9.2 DEWATS modules 176
9.2.1 Grease trap and grit chamber 176
9.2.2 Septic tank 177
9.2.3 Fully mixed digester 182
9.2.4 Imhoff tank 184
9.2.5 Anaerobic baffled reactor 187
9.2.6 Anaerobic filter 191
9.2.7 Planted soil filters 195
9.2 7 1 Horizontal gravel filter 197
9.2 7 2 Vertical sand filter 207
9.2 8 Ponds 211
9.2.8 1 Anaerobic ponds 212
9.2.82 Aerobic ponds 216
9.2 Hybrid and combined systems 221
9.3 Non-DEWATS technolog ies 223
9.31 UASB 223
9.3 2 Trickling filter 225
9.3.3 Aquatic-plant systems 228
10 Designing DEWATS 230
10.1 Technical spreadsheets- background 230
10.1.1 Usefulness of computer calculation 230
10.1.2 Risks of using simplified formulas 231
10.1.3 About the spreadsheets 233
10.2 Technical spreadsheets- application 236
10.21 Assumed COD/BOD ratio 236
10.2.2 Domestic wastewater quantity and quality 237
10.2.3 Septic tank 238
10.2.4 Fully mixed digester 241
10.2.5 Imhoff tank 247
10.2.6 Anaerobic baffled reactor 250
10.2.7 Anaerobic filter 255
10.2.8 Horizontal gravel filter 261
10.2.9 Aerobic pond 264
10.2.10 Aerobic pond 270
10.3 Spreadsheets for castings 274
10.4 Using spreadsheets without a computer 278