Waste Water Treatment
Fundamentals of Waste Water Treatment Processes
(Physical, Chemical and Biological)
,Preface
Waste-water treatment is becoming more important in the light of diminishing water
resources. The treatment of waste-water for reuse and disposal is particularly important
for water scarce countries. The municipal sector consumes significant volumes of water,
and consequently generates considerable amounts of waste-water discharge. Municipal
waste-water is a combination of water and water-carried wastes originating from homes,
commercial and industrial facilities, and institutions. Treatment of waste water is a
complex process. Selection of treatment process is based on type of waste water
composition and availability of resources. This module describes Fundamentals of
wastewater treatment processes
Learning Objectives
• To describe the typical composition of raw wastewater.
• To understand the effects of wastewater discharges on the receiving stream.
• To understand basics of wastewater treatment process used in various
wastewater techniques.
i
, Table of Contents
Preface ............................................................................................................................. i
1 INTRODUCTION TO FUNDAMENTALS OF WASTEWATER TREATMENT ........... 2
1.1 Characteristics of Wastewater ............................................................................ 2
1.2 Contaminants Typically Found in Untreated Wastewater.................................... 3
1.2.1 Organic Contaminants ................................................................................. 3
1.2.2 Inorganic Contaminants ............................................................................... 3
1.2.3 Pathogens.................................................................................................... 4
1.2.4 Solids ........................................................................................................... 4
1.3 Effects of Wastewater Discharges ...................................................................... 5
1.3.1 Oxygen Depletion and Odor Production....................................................... 6
1.3.2 Effects of Scum and Sludge Accumulation .................................................. 7
1.3.3 Other Effects ................................................................................................ 7
1.4 Wastewater Treatment Objective ....................................................................... 7
1.4.1 Wastewater Stabilization .............................................................................. 8
1.4.2 Disinfection .................................................................................................. 8
1.4.3 Removal of Accumulations of Scum and Sludge ......................................... 8
1.5 Wastewater Treatment Processes...................................................................... 8
2 PHYSICAL PROCESS IN WASTEWATER TREATMENT ..................................... 12
2.1 Introduction Physical Process........................................................................... 12
2.1.1 Screening................................................................................................... 12
2.2 Flow Equalization ............................................................................................. 15
2.3 Sedimentation................................................................................................... 15
2.3.1 Horizontal Flow .......................................................................................... 16
2.3.2 Solid Contact Clarifiers............................................................................... 16
2.3.3 Inclined Surface Basins ............................................................................. 17
2.4 Flotation............................................................................................................ 18
2.5 Granular Medium Filtration ............................................................................... 20
3 CHEMICAL PROCESSES...................................................................................... 23
ii
, 3.1 Chemical Coagulation and Precipitation ........................................................... 23
3.1.1 Chemical Treatment System ...................................................................... 24
3.2 Adsorption with Activated Carbon..................................................................... 25
3.3 Disinfection ....................................................................................................... 26
3.4 De-chlorination ................................................................................................. 27
4 BIOLOGICAL PROCESS IN WASTEWATER TREATMENT ................................. 32
4.1 Biological Process ............................................................................................ 32
4.1.1 Bacterial Growth Curve .............................................................................. 32
4.2 Biological Oxidation and Biosynthesis .............................................................. 33
4.3 Factors Effecting Bacterial Activity.................................................................... 34
4.3.1 Temperature .............................................................................................. 35
4.3.2 Dissolved Oxygen ...................................................................................... 35
4.3.3 Nutrient Concentration ............................................................................... 35
4.3.4 Toxic Material ............................................................................................ 35
4.3.5 Basic Biological Processes in Wastewater Treatment ............................... 35
4.3.6 Suspended Growth Processes................................................................... 36
4.3.7 Attached Growth Processes....................................................................... 37
4.4 Microbial Assisted Waste Water Treatments .................................................... 37
4.4.1 Aerobic Treatment ..................................................................................... 37
4.4.2 Anaerobic Treatment ................................................................................. 39
4.5 Membrane Bioreactor (MBR) ............................................................................ 40
4.5.1 Membrane Bioreactor Technology - An Overview ...................................... 41
4.5.2 STRUCTURE OF MEMBRANE UNIT ........................................................ 42
4.6 Biological Removal of Nitrogen ......................................................................... 43
5 PHYTOREMEDIATION OR CONSTRUCTED WETLANDS ................................... 45
5.1 Introduction to Phytoremediation ...................................................................... 45
5.2 Rhizofiltration .................................................................................................... 47
iii
Fundamentals of Waste Water Treatment Processes
(Physical, Chemical and Biological)
,Preface
Waste-water treatment is becoming more important in the light of diminishing water
resources. The treatment of waste-water for reuse and disposal is particularly important
for water scarce countries. The municipal sector consumes significant volumes of water,
and consequently generates considerable amounts of waste-water discharge. Municipal
waste-water is a combination of water and water-carried wastes originating from homes,
commercial and industrial facilities, and institutions. Treatment of waste water is a
complex process. Selection of treatment process is based on type of waste water
composition and availability of resources. This module describes Fundamentals of
wastewater treatment processes
Learning Objectives
• To describe the typical composition of raw wastewater.
• To understand the effects of wastewater discharges on the receiving stream.
• To understand basics of wastewater treatment process used in various
wastewater techniques.
i
, Table of Contents
Preface ............................................................................................................................. i
1 INTRODUCTION TO FUNDAMENTALS OF WASTEWATER TREATMENT ........... 2
1.1 Characteristics of Wastewater ............................................................................ 2
1.2 Contaminants Typically Found in Untreated Wastewater.................................... 3
1.2.1 Organic Contaminants ................................................................................. 3
1.2.2 Inorganic Contaminants ............................................................................... 3
1.2.3 Pathogens.................................................................................................... 4
1.2.4 Solids ........................................................................................................... 4
1.3 Effects of Wastewater Discharges ...................................................................... 5
1.3.1 Oxygen Depletion and Odor Production....................................................... 6
1.3.2 Effects of Scum and Sludge Accumulation .................................................. 7
1.3.3 Other Effects ................................................................................................ 7
1.4 Wastewater Treatment Objective ....................................................................... 7
1.4.1 Wastewater Stabilization .............................................................................. 8
1.4.2 Disinfection .................................................................................................. 8
1.4.3 Removal of Accumulations of Scum and Sludge ......................................... 8
1.5 Wastewater Treatment Processes...................................................................... 8
2 PHYSICAL PROCESS IN WASTEWATER TREATMENT ..................................... 12
2.1 Introduction Physical Process........................................................................... 12
2.1.1 Screening................................................................................................... 12
2.2 Flow Equalization ............................................................................................. 15
2.3 Sedimentation................................................................................................... 15
2.3.1 Horizontal Flow .......................................................................................... 16
2.3.2 Solid Contact Clarifiers............................................................................... 16
2.3.3 Inclined Surface Basins ............................................................................. 17
2.4 Flotation............................................................................................................ 18
2.5 Granular Medium Filtration ............................................................................... 20
3 CHEMICAL PROCESSES...................................................................................... 23
ii
, 3.1 Chemical Coagulation and Precipitation ........................................................... 23
3.1.1 Chemical Treatment System ...................................................................... 24
3.2 Adsorption with Activated Carbon..................................................................... 25
3.3 Disinfection ....................................................................................................... 26
3.4 De-chlorination ................................................................................................. 27
4 BIOLOGICAL PROCESS IN WASTEWATER TREATMENT ................................. 32
4.1 Biological Process ............................................................................................ 32
4.1.1 Bacterial Growth Curve .............................................................................. 32
4.2 Biological Oxidation and Biosynthesis .............................................................. 33
4.3 Factors Effecting Bacterial Activity.................................................................... 34
4.3.1 Temperature .............................................................................................. 35
4.3.2 Dissolved Oxygen ...................................................................................... 35
4.3.3 Nutrient Concentration ............................................................................... 35
4.3.4 Toxic Material ............................................................................................ 35
4.3.5 Basic Biological Processes in Wastewater Treatment ............................... 35
4.3.6 Suspended Growth Processes................................................................... 36
4.3.7 Attached Growth Processes....................................................................... 37
4.4 Microbial Assisted Waste Water Treatments .................................................... 37
4.4.1 Aerobic Treatment ..................................................................................... 37
4.4.2 Anaerobic Treatment ................................................................................. 39
4.5 Membrane Bioreactor (MBR) ............................................................................ 40
4.5.1 Membrane Bioreactor Technology - An Overview ...................................... 41
4.5.2 STRUCTURE OF MEMBRANE UNIT ........................................................ 42
4.6 Biological Removal of Nitrogen ......................................................................... 43
5 PHYTOREMEDIATION OR CONSTRUCTED WETLANDS ................................... 45
5.1 Introduction to Phytoremediation ...................................................................... 45
5.2 Rhizofiltration .................................................................................................... 47
iii
