Title page – – – i
        Declaration – – – – ii          
        Certification – iii
        Dedication – iv
        Acknowledgements – – – – – v
        Table of Contents – – viii
        List of Plates – – – xv
        List of Figures – – xvi
        List of Tables – xxiv
        Abbreviations and symbols – – – xxvii
        Abstract – – – – xxxii

Chapter 1

:  
Introduction – – 1
11     Background to the study – 1
12     Problem statement – – – – 5    
13     Aim of the research – 6
14     Objectives – 6
15     Scope of study – – – 6
16     Justification of study – 7
17     Limitation of the work – – – – 7
 

Chapter 2

: Literature review – 8
    21   The pressure on water demand 8
    22   Wastewater treatment systems in use – – – – 9
    23   Waste stabilization ponds – 11
231   Treatment units in Waste Stabilization Ponds – – – 12  
        232   Anaerobic ponds – 13
            232 1 Design approach for anaerobic pond15      
      233   Facultative ponds – – – – 17
            2

331 Design criteria for facultative pond – – – 17  
            2332 Surface BOD loading in facultative ponds – – – 19
        234 Model approaches for faecal coliform prediction in facultative pond – – 20
            2341 Continuous stirred reactor (CSTR) model approach21
                2342 Dispersed flow (DF) model approach – – – 23
        235 Maturation Pond24
    24 Waste Stabilization Ponds in Some Selected Institutions in Nigeria – 26
            241   Waste stabilization pond in University of Nssuka, Nigeria – 29
            242   Waste stabilization pond in Obafemi Awolowo University,  
                          Ile-Ife, Nigeria – 30
              243   Waste stabilization pond in Ahmadu Bello University, Zaria,  
                          Nigeria – 32
  25   Residence time-models in waste stabilization ponds – – – 35
                251 Plug flow pattern – 35
                252 Completely mixed flow pattern – – – – 37
                253 Dispersed hydraulic flow regime – – – – 39
  26 Wind effect and thermo-stratification on hydraulic flow regime – 42
  27 Tracer experiment43
  28 Effects of baffles on the performance of waste stabilization – – 44
  29 Computational Fluid Dynamics Approach to Waste Stabilization Ponds – – – 48
  210 Laboratory scale ponds – – – – 56
  211 Optimization of waste stabilization pond design – – – 59  
  212 Summary of literature review – – – – 61
   

Chapter 3

:
Methodology – – – 62
  31   Description of the study area – – – – 62
32   Collection of data on Water demand – – – – 65
  33   Estimation of wastewater generated – – – – 66
  34   Study of existing wastewater treatment system – – – 66
  35   Analysis of wastewater samples70
  36   Design of the laboratory-scale plant layout – – – – 70
                  361 Design Guidelines for the University, Ota – – – 73
                        3611 Temperature (T) – – – – 73
                        3612 Population (P) – – – – 73
                        3613 Wastewater generation (Q) and Design for 20 years period – 73
                        3614 BOD Contribution per capita per day (BOD) – – 73
                        3615 Total Organic Load (B) – – – 74
                        3616 Total Influent BOD Concentration (Li) – – – 74
                        3617 Volumetric organic loading (λv) – – – 74
                        3618 Influent Bacteria Concentration (Bi) – – 74
                        3619 Required effluent standards – – – 74
37   Waste stabilization pond design – 75
            371 Design of Anaerobic Pond – – – – 75
            372 Design of Facultative pond76
            373 Design of Maturation Pond77
38 Design of Laboratory scale model – – – – 79
            381 Modeling of the Anaerobic Laboratory-scale pond – – 79
                382 Modeling of the Facultative Laboratory-scale pond – – – 81
            383 Modeling of the Maturation Laboratory-scale pond – – – 82
 39 Laboratory Studies – – 85
            391 Construction of the laboratory-scale waste stabilization ponds – 85
            392 Materials used for the construction of the inlet and outlet structures – 86
            393 Design of inlet and outlet structures of the WSP – – – 91
            394 Operation of the Laboratory-Scale waste stabilization pond – – 94
            395 Sampling and data collection – – – 95
                3951 Water temperature – – – 95
                3952 Influent and effluent samples – – – 95
310   Laboratory methods – 95
          3101     Feacal coliform – 96
          3102     Chloride – 96
          3103     Sulphate – 96
          3104     Nitrate – – 96
          3105     Phosphate – 96
          3106     Total Dissolved Solids – – – – 96
          3107     Conductivity – 97
          3108     pH – 97
311   Tracer Experiment – – 97
              3111   Determination of First Order Kinetics (K value) for Residence time  
                        distribution (RTD) characterization – – – 99
              3112   The gamma extension to the N-tanks in series model approach – 101
312   Methodology and application of Computational Fluid Dynamics model – 103
          3121 Introduction 103
          3122 CFD Model Application – – – – 106
                      31221 Simulation of fluid mechanics fecal coliform inactivation 106
                      31222 Constants used in the application modes – – 109
                      31223 Mesh generation for the computational fluid dynamics model110
                          31224 Model test for the simulation of residence time distribution
                                    curve in the CFD – – – 113
                    31225 Model test for the simulation of faecal coliform inactivation in
                                    the unbaffled reactor – – – – 114
                    31226 Model test for the simulation of faecal coliform inactivation in
                                    the baffled reactors – – – 116
            3123 Application of segregated flow model to compare RTD prediction  
                      and the CFD predictions for feacal coliform reduction – 122  
          3124 Summary of the CFD model methodology – – – – 124
  3131 Optimization methodology and application – – – 125    
            31311 Integration of COMSOL Multiphysics (CFD) with  
                          ModeFRONTIER optimization tool – – – 125
31312 The workflow pattern – – – – 126
            31313 Building the process flow – – – 127
            31314 Creating the application script – – 128
            31315 Creating the data flow – – – – 129
            31316 Creating the template input – – – 130
            31317 Mining the output variables from the output files – 131
3132 Defining the goals – – – – 132
            31321 The Objective functions for the optimization loop – – 132
            31322 The constraints for the optimization loop – – – 133
            31323 Cost objective Optimization – – – – 133
            31324 The DOE and scheduler nodes set up136
            31325 Model parameterization of input variables – – – 137  
            31326 DOE Algorithm – 140
            31327 Simplex algorithm – 140
              31328 Multi-Objective Genetic Algorithm II (MOGA-II) – – – – 141
            31329 Faecal coliform log-removal for transverse and longitudinal  
                          baffle arrangements143
    3133 Sensitivity Analysis on the model parameters – – – 145      
    3134 Running of output results from modeFRONTIER with the CFD tool – – 146
    3135 Summary of the optimization methodology – – – – 146
 

Chapter 4

: Modeling results and Analysis  
    41 Model results for the RTD curve and FC inactivation for unbaffled reactors – 147  
    42 Initial Evaluation of baffled WSP designs in the absence of Cost using CFD151
        421 Application of segregated flow model to compare the result of RTD  
                prediction and the CFD predictions for feacal coliform reduction – 163  
  43 Results of the N-Tanks in series and CFD models – – – 166
      431 General discussion on the results of the N-Tanks in series and CFD
                Models – 173
  44 Results of some selected simulation of faecal coliform inactivation for 80%
            Pond-width baffle Laboratory- scale reactors – – – 176
45 Optimization model results – 181
      451 The single objective SIMPLEX optimization configuration results – 181
      452 The Multi-objective MOGA II optimization configuration results – 195  
      453 Scaling up of Optimized design configuration – – 216
                4531 Scaling up of Anaerobic Longitudinal baffle arrangement – – 216
                4532 Scaling up of Facultative Transverse baffle arrangement – 218
                4533 Scaling up of Maturation Longitudinal baffle arrangement – 219
                4534 Summary of results of scaling up of design configuration – 220
      454 Results of sensitivity analysis for Simplex design at upper and lower  
                boundary – 220
    455 Results of sensitivity analysis for MOGA II design at upper and lower  
                    boundary – 235
    456 Summary of the optimization model result – – – – 249
 

Chapter 5

: Laboratory-Scale WSP post-modeling results and verification of the  
                  Optimized models – – – – 250
51 Introduction – 250
52 Microbial and physico-chemical parameters – – – 251  
    521 Feacal coliform inactivation in the reactors – – – 251
    522 Phosphate removal256
    523 Chloride removal – – – – 258
    524 Nitrate removal – – – – 259
    525 Sulphate removal – – – – 260
    526 pH variation265
    527 Total dissolved solids removal – – – 266
    528 Conductivity variation – – – – 266
    529 Summary of laboratory experimentation – – – 267
 
Chapter 6: Discussion of results – – – – 269
        61 Experimental results of Laboratory-scale waste stabilization ponds  
              in series – 269
62 Hydraulic efficiency of CFD model laboratory-scale waste stabilization
              ponds in series – 270
        63 Optimization of laboratory-scale ponds by Simplex and MOGA II  
              Algorithms – 274
        64 Summary of discussion – – – – 275
 
Chapter 7: Conclusions and recommendations for further work – 277
        71 Conclusions277
        72 Contributions to knowledge – – – 278
        73 Recommendation for further work – – – 279
 
References – 280
   
Appendix A – 298
  A1     COMSOL Multiphysics Model M-file for Transverse baffle  
          anaerobic reactor – – – – , – 298
  A2     COMSOL Multiphysics Model M-file for longitudinal baffle  
          anaerobic reactor – 302
  A3     COMSOL Multiphysics Model M-file for Transverse baffle  
          facultative reactor306
  A4     COMSOL Multiphysics Model M-file for longitudinal baffle  
            facultative reactor – – – – 310
  A5     COMSOL Multiphysics Model M-file for Transverse  
          Maturation reactor – – – – 314
  A6     COMSOL Multiphysics Model M-file for longitudinal
          Maturation reactor – – – – 318
 
Appendix B322
B1     Transverse baffle arrangement scripting – – – 322
B2     Longitudinal baffle arrangement scripting – – 324

List of Plates
Plate 31       Tanker dislodging wastewater into the treatment chamber – – 67
Plate 32       The water hyacinth reed beds showing baffle arrangement  
                      at opposing edges68
Plate 33       The inlet compartment showing gate valve – – 68
Plate 34       The Outfall waterway leading into the valley below the cliff – 69
Plate 35       Effluent discharging through the outfall into the thick  
                    vegetation valley – – – – 69
Plate 36       Front view of the laboratory-scale pond – 88
Plate 37       Areal view of the laboratory-scale pond close to source of sunlight – – 88
Plate 38       An elevated tank serving as reservoir – 89
Plate 39       Inlet-outlet alternation of laboratory-scale WSP – – 89
Plate 310     Laboratory-scaled anaerobic ponds – – – 90
Plate 311     Laboratory-scaled facultative ponds – – – 90
Plate 312     Laboratory-scaled maturation ponds – – – 91
Plate 313       Inlet and outlet structure of the laboratory-scale  
                      waste stabilization pond – – – 92
Plate 314     Two 25-mm PVC hoses linked with the T-connector – – 92
Plate 315     Control valves screwed to position for wastewater flow – 93
Plate 316     Outlet structures connected to two pieces of ½ inch hoses  
                    for effluent Discharge – – – – 93
Plate 317     Tracer experiment with Sodium Aluminum Sulphosilicate – – 97
Plate 318     Tracer chemical diluting with the wastewater before  
                    getting to the outlet – – – – 98
Plate 319     Improvement in wastewater quality along the units – – 98

List of Figures
Figure 21     Waste stabilization pond configurations                                                   12
Figure 22     Operation of the Anaerobic Pond                                                               14
Figure 23     Operation of the facultative pond                                                               23
Figure 31     Bar chart of staff and student population trend                                         63
Figure 32     Template for calculating the per-capita water use                                     65
Figure 33     A sketch of the laboratory-scale WSP and operating conditions               72
Figure 34     Configuration of the designed WSP for Covenant University                 79
Figure 35     Different baffle arrangements with 70% pond width  
                        anaerobic pond                                                                                         99
Figure 36       Different baffle arrangements with 70% pond width  
                      facultative pond                                                                                       100
Figure 37       Different baffle arrangements with 70% pond width
                        maturation pond                                                                                     100
Figure 38     Data conversion for reactor length to width ratio to N for
                      N-tanks in series model                                                                         102
Figure 39     Description of length to width ratio for the laboratory-scale  
                      model                                                                                                     102
Figure 310     Triangular meshes for the model anaerobic reactor                               111
Figure 311     Triangular meshes for the model facultative reactor                             111
Figure 312     Triangular meshes for the model maturation reactor                           112
Figure 313   Model Navigator showing the application modes                                 113
Figure 314   Correlation data of the predicted-CFD and observed effluent Faecal  
                      coliform counts in baffled pilot-scale ponds                                         115
Figure 315   General arrangements of conventional longitudinal baffles of  
                    different lengths in the anaerobic pond                                                 117
Figure 316   General arrangements of conventional longitudinal baffles of  
                    different lengths in the facultative pond                                                 117
Figure 317   General arrangements of conventional longitudinal baffles of  
                    different lengths in the maturation pond                                                 118
Figure 318     Mesh structure in a 4 baffled 70% Transverse Anaerobic reactor           118    
Figure 319     Mesh structure in a 4 baffled 70% Longitudinal Anaerobic reactor         119
Figure 320     Mesh structure in a 4 baffled 70% Transverse Facultative                       119
Figure 321     Mesh structure in a 4 baffled 70% Longitudinal Facultative  
                        reactor                                                                                                       120
Figure 322     Mesh structure in a 4 baffled 70% Transverse Maturation  
                        reactor                                                                                                       120
Figure 323     Mesh structure in a 4 baffled 70% Longitudinal Maturation  
                        reactor                                                                                                       121
Figure 324     Workflow showing all links and nodes in the user application  
                        interface                                                                                                   127
Figure 325     Logic End properties dialogue interface                                                   128
Figure 326     Data variable carrying nodes and the input variable properties  
                        Dialogue interface                                                                                   129
Figure 327     Template for the calculator properties and JavaScript  
                        expression editor                                                                                     130
Figure 328     Output variable mining interface and input template editor                   131
Figure 329     DOS Batch properties and batch test editor for mined data                   132
Figure 330     Constraint properties dialogue in the workflow canvas                         135
Figure 331     Objective properties dialogue in the workflow canvas                           135
Figure 332     DOE properties dialog showing the initial population of designs           136
Figure 333     Scheduler properties dialog showing optimization wizards                   137
Figure 334     Designs table showing the outcomes of different reactor  
                      configurations                                                                                         144
Figure 335     History cost on designs table showing the optimized cost     &a