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Activated Sludge Separation Problems

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Activated Sludge Separation Problems

Simona Rossetti | Valter Tandoi | Jiri Wanner

(2017)

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Additional Information

Book Details

ISBN
978-1-78040-864-4
Edition
2
Language
English
Pages
324
Subjects
The environment
Water supply & treatment
Mining technology & engineering

Abstract

Activated Sludge Separation Problems: Theory, Control Measures, Practical Experiences, Second Edition, describes the most common activated sludge separation problems and explains the main reasons for the growth of the different filamentous microorganisms in activated sludge. The book summarizes the identification techniques for important groups of activated sludge microorganisms both based on conventional microscopic analysis and using the biological molecular tools available today (FISH and PCR). This new edition, with 70% new and updated material, also provides explanation of basic activated sludge process principles and of parameters necessary for process control and operation. The theory of secondary clarifies is described to the extent necessary for understanding the construction and operation of secondary clarifiers. The activated sludge reactor and secondary clarifies are treated as one system and the interactions are explained. The wide range of experiences around the world is documented and the methods to avoid the proliferation of these organisms are presented and critically reviewed. Activated Sludge Separation Problems consists of six chapters, presenting up-to-date technical and scientific aspects of these processes. The new edition also features an extended list of literature references for further reading. The book will be a valuable help for students of environmental engineering, wastewater specialists, plant operators and designers of activated sludge plants. It is also useful for specialists in wastewater operation laboratories, especially for those studying activated sludge separation properties.

Table of Contents

Section Title Page Action Price
Cover Cover
Contents vii
Abbreviations xiii
List of Contributors xvii
Preface xxi
Chapter 1: Wastewater characterization 1
1.1 INTRODUCTION 1
1.2 GROSS PARAMETERS 2
1.3 PHYSICAL PROPERTIES 4
1.4 ORGANIC MATTER 5
1.5 INORGANIC MATTER 7
1.6 MICROPOLLUTANTS 8
1.7 BIODEGRADABILITY 11
1.7.1 COD, Nitrogen and phosphorus fractionation 11
1.7.2 Evaluation methods 14
1.7.2.1 Carbonaceous substrate (COD) 14
1.7.2.2 Nitrogen and phosphorus 16
1.7.2.3 Micropollutants 16
REFERENCES 17
Chapter 2: The microbiology of the activated sludge process 21
2.1 INTRODUCTION 21
2.2 MICROORGANISMS IN ACTIVATED SLUDGE 22
2.2.1 Bacteria: cell structure 22
2.2.2 Inclusions 24
2.3 THE IDENTIFICATION OF BACTERIA 24
2.3.1 Conventional taxonomy 25
2.3.2 Molecular taxonomy 26
2.3.3 Molecular characterization of mixed biomass 26
2.3.3.1 Polymerase Chain Reaction (PCR) 27
2.3.3.2 Fluorescence In Situ Hybridization (FISH) 27
2.4 FILAMENTOUS BACTERIA 28
2.5 MICROTHRIX PARVICELLA 36
2.5.1 Identification of M. parvicella 38
2.5.2 Physiology of ‘Candidatus M. parvicella’ 38
2.6 THIOTHRIX 39
2.7 NOSTOCOIDA LIMICOLA 40
2.8 POLYPHOSPHATE ACCUMULATING ORGANISMS (PAO) 40
2.9 GLYCOGEN ACCUMULATING ORGANISMS (GAO) 41
2.10 NITRIFIERS 42
2.11 DENITRIFIERS 42
REFERENCES 43
Chapter 3: Activated sludge separation problems 53
3.1 INTRODUCTION 53
3.2 ‘WELL-SETTLING’ ACTIVATED SLUDGE 54
3.2.1 Requirements 54
3.2.1.1 Measurement of settling and thickening properties 55
3.2.2 Microscopic features of well settling activated sludge 57
3.3 ACTIVATED SLUDGE SEPARATION PROBLEMS 57
3.3.1 Poor floc microstructure 58
3.3.1.1 Dispersed growth 58
3.3.1.2 Unsettleable microflocs 59
3.3.1.3 Viscous bulking 59
3.3.2 Poor floc macrostructure 61
3.3.2.1 Filamentous bulking 61
3.3.2.2 Foaming caused by filamentous microorganisms 62
3.3.3 Other reasons 64
3.3.3.1 Rising sludge 64
3.4 SUMMARY 65
ACKNOWLEDGMENT 65
REFERENCES 65
Chapter 4: Aeration tank and secondary clarifier as one system 67
4.1 INTRODUCTION 67
4.2 AERATION TANK AND SECONDARY CLARIFIER INTERACTIONS 68
4.2.1 Activated sludge process 68
4.2.2 Secondary clarifier 69
4.2.2.1 General performance, thickening function 69
4.2.2.1.1 Solids flow theory 70
4.2.2.1.2 State point analysis 72
4.2.3 Separation function 76
4.2.4 BOD5 76
4.2.5 COD 77
4.2.6 Nitrogen and phosphorus 77
4.3 THE IMPACT OF AERATION BASIN EQUIPMENT AND OPERATION ON THE PERFORMANCE OF SECONDARY CLARIFIERS 77
4.3.1 Mechanical vs. diffused-air aeration 77
4.3.2 Mixed liquor mixing 78
4.3.3 Degasification and reflocculation in aeration tanks 79
4.4 FEATURES OF SECONDARY CLARIFIER CONSTRUCTION 80
4.4.1 Inlet structure with a flocculation zone 81
4.4.1.1 Principles of a flocculation zone 81
4.4.1.2 Conventional flocculation zones with tangential flow regime 82
4.4.1.3 Novel flocculation zone with deflectors and a vertical flow regime 83
4.4.1.4 Flocculation zone with deflectors with variable profile 83
4.4.2 Outlet structure 84
4.4.2.1 Peripheral vs. internal effluent launders 84
4.4.2.1.1 Circular clarifier, peripheral effluent launder (with inboard weir) 84
4.4.2.1.2 Circular clarifier, internal effluent launder (with inset double-sided weirs) 85
4.4.2.1.3 Effluent launders in rectangular clarifiers with longitudinal flow 86
4.4.3 Scum baffles 86
4.5 EFFICIENT SCUM REMOVAL FROM THE SURFACE OF SECONDARY CLARIFIERS 87
4.5.1 Conventional scum boxes 87
4.5.2 ‘Travelling’ scum boxes 88
4.5.3 Pneumatic systems 88
4.6 REMOVAL OF SETTLED AND THICKENED SLUDGE 90
4.6.1 Effect on the final effluent quality 90
4.6.2 Mechanical scrapers 90
4.6.3 Vacuum sludge removal 91
4.7 OPERATION OF AERATION TANK – SECONDARY CLARIFIER SYSTEM FOR BULKING AND FOAMING CONTROL 91
4.7.1 Use of chemicals in activated sludge process 92
4.7.1.1 Use of iron salts 93
4.7.1.2 Use of aluminium salts 93
4.7.1.3 Oxidizing agents 94
4.7.1.4 Use of organic flocculants 95
4.7.2 Operation of secondary clarifiers 95
4.7.2.1 Automatic sludge blanket level detector 95
4.7.2.2 Suspended Solids Sensors 96
REFERENCES 96
Chapter 5: Bulking and foaming control methods 99
5.1 INTRODUCTION 99
5.1.1 Microscopic characterization of the activated sludge 100
5.1.2 Biological foam 101
5.1.3 Bulking 103
5.1.4 The problem of excess sludge production and its disposal 103
5.2 SPECIFIC CONTROL METHODS 105
5.2.1 Bulking due to low (F/M) ratio 105
5.2.1.1 Continuous plug-flow reactors 107
5.2.1.2 Selectors 109
(a) Design based on a biokinetic models 109
(b) Design based on empirical criteria 110
(c) Enhancing the selector effect: anoxic and anaerobic selectors 111
5.2.1.3 Sequencing batch reactors 112
5.2.1.4 Role of storage phenomena in microbial competition in substrate gradient processes 112
5.2.2 Bulking due to low dissolved oxygen concentrations 117
5.2.3 Bulking due to low nutrient concentration 118
5.2.4 Bulking due to fatty acids in the influent stream: control methods for Microthrix parvicella 120
5.2.5 Microbial and enzymatic preparations 121
5.3 NON-SPECIFIC CONTROL METHODS 122
5.3.1 Oxidizing agents 122
5.3.2 Weighting or flocculating agents 126
5.3.3 Specific biocide 127
5.4 CONTROL OF NON-FILAMENTOUS BULKING (‘VISCOUS BULKING’) 127
5.5 AVOIDING POOR SETTLING PROPERTIES: ALTERNATIVE SEPARATIONS OF ACTIVATED SLUDGE 128
REFERENCES 129
Chapter 6: Experiences in various countries 139
6.1 INTRODUCTION 139
6.2 AUSTRALIA 140
6.2.1 General situation 140
6.2.2 What do we know of these filamentous bacteria? 142
6.2.3 Bulking and foaming filamentous bacteria in Australian activated- sludge plants 143
6.2.3.1 The main foaming organisms 144
6.2.3.2 The main bulking filamentous bacteria 145
6.2.4 Do filamentous bacteria populations in the same treatment plant change over time and can we control them? 147
6.2.4.1 Case Study – Excessive biological foam accumulation trouble shooting 148
6.2.4.2 Summary of case study 150
6.2.5 The future 151
6.3 AUSTRIA 151
6.3.1 Intention of the investigation 151
6.3.2 Organization of the assessment 152
6.3.2.1 General 152
6.3.2.2 Carrying out the investigation 152
6.3.2.3 Questionnaire 153
6.3.2.4 Participation of WWTPs 154
6.3.2.5 Categorization of plants and sludges 154
6.3.3 Methodology 155
6.3.3.1 Microscopy 155
6.3.3.2 Parameters for analysis 155
6.3.3.3 Data plausibility 156
6.3.3.4 Data processing and statistical analysis 156
6.3.4 Results 157
6.3.4.1 F/M ratio of the treatment plants 157
6.3.4.2 Sludge volume index (SVI) 158
6.3.4.3 Sludge volume index and plant size 159
6.3.4.4 Occurrence of filament types 159
6.3.4.5 Seasonal appearance of bulking sludge 162
6.3.4.6 F/M ratio and SVI 162
6.3.4.7 Influence of filament types on SVI 163
6.3.5 Summary and conclusion 164
6.4 BELGIUM 165
6.4.1 General situation 165
6.4.2 The M. parvicella problem 166
6.4.2.1 The filamentous types in the activated sludge 166
6.4.2.2 The filamentous types in the foam 168
6.4.2.3 Conclusion 168
6.4.3 Polyaluminium chloride to tackle M. parvicella 168
6.4.3.1 Curative approach 168
6.4.3.2 Preventive approach 170
6.4.3.3 Conclusions 171
6.4.4 Microthrix parvicella monitoring: a revised methodology 171
6.4.4.1 The MICPARV method 171
6.4.4.2 The real-time PCR method 172
6.4.4.3 Novel methods in practice 173
6.4.5 Conclusion 174
6.5 CHINA 174
6.5.1 Introduction 174
6.5.2 Distribution of filamentous bacteria in activated sludge 176
6.5.3 Studies on sludge bulking processes and control strategy 177
6.5.3.1 Wastewater treatment performance and population dynamics over a sludge bulking cycle 177
6.5.3.2 Control strategy for M. parvicella overgrowth 179
6.6 CZECH REPUBLIK 180
6.6.1 Separation problems – situation up to the 1980s 180
6.6.2 Separation problems – situation up to the mid-1990s 181
6.6.3 WWTPs screening – 1995–2000 181
6.6.3.1 Methodology 181
6.6.3.2 Microscopic analysis and sedimentation properties evaluation 182
6.6.4 Results of separation problems and filamentous micro-organisms screening 182
6.6.4.1 Filamentous microorganism abundance 183
6.6.4.2 Dominant filamentous microorganisms in sludge and foam 183
6.6.5 Development of filamentous population in Czech activated sludge plants between 1997 and 1998 184
6.6.5.1 SVI and total abundance of filaments 184
6.6.5.2 Dominant filamentous microorganisms in activated sludge mixed liquor and foams 185
6.6.6 Screening of eight nutrient removal plants in 2000 187
6.6.6.1 Characterization of monitored WWTPs 187
6.6.6.2 Activated sludges and settling properties 188
6.6.6.3 Dominant filamentous microorganisms in activated sludge mixed liquor 188
6.6.6.4 Biological foams 189
6.6.7 FOAM CONTROL STRATEGIES 189
6.6.7.1 Water sprays 189
6.6.7.2 Skimming (mechanical removal) of foam 190
6.6.7.3 Return activated sludge manipulation 190
6.6.7.4 Manipulation of SRT 191
6.6.7.5 Additional installation of baffles 191
6.6.7.6 Initial contact zones (‘selectors’) 192
6.6.7.7 Chlorination of foam 192
6.6.8 Development in the last decade 193
6.6.8.1 Activated sludge bulking 194
6.6.8.2 Activated sludge foaming 195
6.7 DENMARK 197
6.7.1 General situation 197
6.7.2 MiDAS: Large-scale survey of the microbiology of Danish WWTPs 198
6.7.3 Wastewater and WWTP characteristics 199
6.7.4 Settling properties in Danish nutrient removal plants 199
6.7.5 Filamentous community composition 202
6.7.5.1 q-FISH based survey of Danish WWTPs (2008–2012) 202
6.7.5.2 16S rRNA gene amplicon sequencing-based survey of Danish WWTPs (2006–2014) 204
6.7.6 The future: surveillance and control by DNA analyses 208
6.8 FRANCE 209
6.8.1 General situation 209
6.8.1.1 Bulking and foaming situation before 2005 210
6.8.2 Current settling and foaming problems and control measures (2012 survey) 211
6.8.2.1 Characteristics of the surveyed WWTPs 212
6.8.2.2 Occurrence of settling and/or foaming problems 213
6.8.2.3 Factors influencing settling and/or foaming problems 214
6.8.2.4 Correlation between settling/foaming problems and the process configuration of the surveyed WWTPs 214
6.8.2.5 Control measures 215
6.8.3 A Case study: metallic salt addition in an industrial size pilot-plant subject to M. parvicella bulking and foaming 215
6.8.4 Conclusions 217
6.8.5 Acknowledgments 218
6.9 GREECE 218
6.9.1 General situation 218
6.9.2 Reason for dysfunctions and filamentous bacteria identified 218
6.9.3 Solution adopted 221
6.9.4 A Greek case study 222
6.9.4.1 Settling and foaming problems 222
6.9.4.2 Setting up and applying a control strategy 222
6.10 ITALY 225
6.10.1 General situation 225
6.10.2 Characterizing the activated sludge and the qualification circuit 225
6.10.3 Filament surveys 226
6.10.4 Control methods 227
6.10.4.1 Non-specific methods 228
6.10.4.2 Specific methods 228
6.10.4.3 Case studies with specific solutions 228
6.11 MALAYSIA 233
6.11.1 General situation 233
6.11.2 Causes of plant dysfunction 235
6.11.3 Implemented control strategies of filamentous sludge bulking in Malaysia 237
6.11.4 Future scenario of sludge bulking occurrences in Malaysia 238
6.12 SOUTH AFRICA 239
6.12.1 General situation 239
6.12.2 Overview of filamentous bulking and foaming in South African wastewater treatment works 241
6.12.3 Case study 241
6.12.3.1 Filamentous bacteria and sludge bulking in seven South African municipal works 241
6.12.3.2 Filamentous bacteria abundance and floc structures 241
6.12.3.3 Gauteng Province 245
6.12.3.4 KwaZulu-Natal Province 245
6.12.3.5 Western Cape Province 246
6.12.3.6 Prevalence of Type 0092 in South African biological nutrient removal works 247
6.12.4 Remedial methods to control filamentous bulking and foaming in South Africa 247
6.12.4.1 Physical and chemical treatment methods 247
6.12.4.2 The effect of anoxic–aerobic selectors on filamentous bacteria 248
6.13 SPAIN 248
6.13.1 General situation 248
6.13.1.1 Wastewater composition 249
6.13.1.2 Treatment level 249
6.13.1.3 Level of application of microbiological control: interlaboratory exercises 251
6.13.2 Separation problems and control methods applied 252
6.13.2.1 Major filaments responsible for problems in Spanish Activated Sludge Plants 252
6.13.2.2 Other solid separation problems 253
6.13.2.3 Reasons for dysfunctions in Spanish activated sludge plants 255
6.13.2.4 Control measures applied 256
6.13.3 Spain case study 257
6.13.3.1 Viscous bulking with Nocardioforms and Type 021N growth 258
6.13.3.2 Filamentous bulking caused by Sphaerotilus natans 261
6.13.4 Acknowledgement 263
6.14 USA 263
6.14.1 General situations 263
6.14.2 Control of filaments in activated sludge systems 264
6.14.3 Other solid separation problems 270
6.14.4 Foaming 270
6.14.5 Viscous bulking and dispersed growth 271
6.14.6 Conclusions 275
REFERENCES 275
Index 293

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