CONTENTS Commonwealth of Learning xi Indian Institute of Science xii Preface xiii Unit 1: Water as a Resource: Some Related Issues 1 Overview 1 Learning Objectives 2 1.1Water as a Resource 3 1.1.1 Availability of Water and Hydrologic Cycle 3 1.1.2 Water in our Daily Life 5 1.1.3 Water Demand 8 1.1.4 Water Pollution 9 1.2Water Characteristics and its Classification 12 1.2.1 Physical 13 1.2.2 Chemical 13 1.2.3 Microbiological 15 1.3Water Quality 15 1.3.1 Drinking Water 16 1.3.2 Bathing and Recreational Water 20 1.3.3 Fisheries and other Sensitive Areas 20 1.3.4 Water Quality Index 22 1.4 Municipal Water Supply System 27 1.4.1 Source of Water 28 1.4.2 Selection of Water Treatment Processes 30 1.4.3 Water Distribution System 31 1.4.4 Water Leakage and its Impact 33 Summary 34 Suggested Readings 34 References 35 Unit 2: Municipal Wastewater Generation, Conveyance and Disposal 36 Overview 36 Learning Objectives 37 2.1 Municipal Wastewater Disposal Systems37 2.1.1 Sewerage Systems 39 2.1.2 Characteristics of Wastewater 41 2.1.3 Wastewater Treatment Processes 41 2.2 Pollution Control Measures 46 2.2.1 Types of Pollutants 48 2.2.2 Mass Balance Approach 49 2.2.3 Biochemical Oxygen Demand (BOD) 50 2.2.4 Nitrification 52 2.2.5 Reaeration 52 2.2.6 Dissolved Oxygen Sag 53 Summary 55 Suggested Readings 55 References 55 Unit 3: Water Treatment Processes 56 Overview 56 Learning Objectives 57 3.1 Basic Concepts of Treatment 57 3.2 Physical Treatment Process 58 3.2.1 Screening 58 3.2.2 Sedimentation 59 3.2.3 Flocculation 60 3.2.4 Filtration 61 3.3 Chemical Treatment Processes 65 3.3.1 Types of Chemical Reactions 66 3.3.2 Reaction Kinetics 66 3.3.3 Coagulation 67 3.4 Water Hardness and Softening 68 3.4.1 Hardness 68 3.4.2 Methods of Softening 68 3.4.3 Disinfection 71 3.5 Other Physical and Chemical Treatment Processes 73 Summary 75 Suggested Readings 75 References 76 Unit 4: Wastewater Treatment: Physical and Chemical Processes 77 Overview 77 Learning Objectives 78 4.1Basic Concepts 78 4.2Physical Treatment Processes 80 4.3Advanced Physical Processes 86 4.4Chemical Treatment Processes 90 4.4.1 Chemical Precipitation 90 4.4.2 Coagulation 90 4.5Advanced Chemical Processes 93 Summary 95 Suggested Readings 96 References 96 Unit 5: Wastewater Treatment: Biological Methods 97 Overview 97 Learning Objectives 98 5.1Biochemical Reactions 98 5.1.1 Basic Concepts of Biological Growth 99 5.1.2 Concepts of Biological Treatment 101 5.1.3 Kinetics of Biological Treatment 104 5.2Treatment Systems 108 5.2.1 Aerobic Fixed Film Systems 108 5.2.2 Anaerobic Systems 114 5.2.3 Waste Stabilisation Pond Systems 118 5.3Nutrient Removal 124 5.4Practical Aspects of Biological Treatment Processes 125 Summary 127 Suggested Readings 127 References 127 Unit 6: Wastewater Reuse 128 Overview 128 Learning Objectives 128 6.1Introduction to Wastewater Reuse 129 6.2Wastewater Reuse 133 6.2.1 Municipal Reuse 133 6.2.2 Industrial Reuse 134 6.2.3 Agricultural Reuse 138 6.2.4 Recreational Reuse 141 6.2.5 Groundwater Recharge 142 Summary 143 Suggested Readings 143 References 143 Unit 7: Sludge and Septage: Treatment and Disposal 144 Overview 144 Learning Objectives 145 7.1Sludge Sources and Characteristics 145 7.2Sludge Treatment Concepts and Processes 149 7.2.1 Sludge Thickening 153 7.2.2 Sludge Stabilisation 156 7.2.3 Anaerobic and Aerobic Digestion 159 7.2.4 Sludge Conditioning 160 7.2.5 Dewatering 161 7.3Sludge Treatment and Disposal 165 7.4Septage Treatment and Disposal 169 7.5Sludge Treatment Status in Developing Countries 170 Summary 171 Suggested Readings 171 References 172 Unit 8: Wastewater Disposal into Natural Waterbodies 173 Overview 173 Learning Objectives 174 8.1 Effluent Disposal Standards 174 8.2 Effluent Disposal by Dilution 177 8.2.1 Disposal into Lakes 177 8.2.2 Disposal into Rivers 181 8.2.3 Disposal into Estuaries 185 8.2.4 Disposal in Ocean 187 Summary 193 Suggested Readings 193 References 193 Unit 9: Wastewater Disposal on Land-Land Application 194 Overview 194 Learning Objectives 195 9.1Wetland Treatment 195 9.1.1 Natural Wetland 195 9.1.2 Constructed Wetland 197 9.2Effluent Disposal on Land 202 9.2.1 Spraying Method 203 9.2.2 Drip Method 204 9.2.3 Ponding Method 204 9.3Domestic Waste Disposal: Septic Tank 205 9.4 Sludge and Ash Disposal 209 9.4.1 Some Common Methods 209 9.4.2 Soil Conditioning or Fertiliser 210 Summary 212 Suggested Readings 213 References 213 Unit 10: Selection, Planning and Implementation Guidelines for Water and Wastewater Treatment Systems 214 Overview 214 Learning Objectives 215 10.1Site Survey and Investigation 215 10.1.1 Site Selection 217 10.1.2 Data Requirement 218 10.2Configurations and Types of Treatment Processes 220 10.2.1 Water Treatment Processes 221 10.2.2 Wastewater Treatment Processes 225 10.3Treatment Plant Operation and Control 229 10.3.1 Plant Operation and Maintenance 229 10.3.2 Process Control and Instrumentation 230 10.3.3 Plant Monitoring and Performance Evaluation 231 10.4Other Requirements 233 Summary 234 Suggested Readings 234 References 235 Model Answers to Learning Activities 237 Distance Learning in Environment Engineering 249 Index 265