Modelling, Simulation and Control of Urban Wastewater Systems

1. Introduction.- 1.1 Motivation of this Book.- 1.1.1 Administrative Responsibilities.- 1.1.2 Standards.- 1.1.3 Computer Software.- 1.1.4 Design and Operation.- 1.2 Outline of Chapters.- 2. The State of the Art.- 2.1 Components of the Urban Wastewater System: Basic Processes and Modelling Concepts.- 2.1.1 Urban Catchment Runoff and Sewer System.- 2.1.1.1 Surface Runoff in Urban Areas.- 2.1.1.2 Flow in the Sewer System.- 2.1.1.3 Pollutant Transport in the Sewer System.- 2.1.1.4 Biochemical Transformations in the Sewer System.- 2.1.1.5 Storage Tanks.- 2.1.2 The Wastewater Treatment Plant.- 2.1.2.1 Storm Tank.- 2.1.2.2 Primary Clarification.- 2.1.2.3 The Activated Sludge Process.- 2.1.2.4 Secondary Clarification.- 2.1.3 Rivers.- 2.1.3.1 River Flow.- 2.1.3.2 Pollutant Transport in the River.- 2.1.3.3 Biochemical Transformations in the River.- 2.2 Impact of Storm Events on the Urban Wastewater System.- 2.2.1 Impacts on Sewer Systems.- 2.2.2 Impacts on Treatment Plant Performance.- 2.2.3 Impacts on the Receiving River.- 2.2.4 Criteria for the Assessment of River Water Quality.- 2.2.5 The Dilemma of Control of the Urban Wastewater System.- 2.3 Integrated Modelling Approaches.- 2.4 Operational Management of Wastewater Infrastructure.- 2.4.1 General Concepts.- 2.4.2 Real-time Control of Sewer Systems.- 2.4.3 Development of Control Strategies - Exemplified for Sewer Systems.- 2.4.3.1 Off-line Development of Strategies.- 2.4.3.2 On-line Development of Strategies.- 2.4.4 Operation of Wastewater Treatment Plants.- 2.4.5 Real-time Control of Receiving Rivers.- 2.4.6 Integrated Real-time Control.- 2.4.7 Concluding Remarks.- 2.5 Mathematical Optimisation Techniques.- 2.5.1 Definition of the Optimisation Problem.- 2.5.2 A Review of Optimisation Methods.- 2.5.2.1 Local Optimisation.- 2.5.2.2 Global Optimisation.- 2.6 Conclusion.- 3. Development of the Integrated Simulation and Optimisation Tool SYNOPSIS.- 3.1 Requirements on the Simulation Tool.- 3.2 Modules Simulating the Parts of the Urban Wastewater System.- 3.2.1 Implementation of the Sewer System Module.- 3.2.2 Implementation of the Treatment Plant Module.- 3.2.2.1 The Original Implementation of Lessard and Beck's Treatment Plant Model.- 3.2.2.2 Modifications of the Treatment Plant Model.- 3.2.3 Implementation of the River Module.- 3.3 Assembling the Integrated Simulation Tool.- 3.3.1 Integration of the Simulation Software.- 3.3.2 Variables in SYNOPSIS.- 3.3.3 Auxiliary Routines Necessary for Simulation.- 3.4 Implementation of Control in SYNOPSIS.- 3.5 Optimisation Algorithms in SYNOPSIS.- 3.5.1 Controlled Random Search.- 3.5.2 A Genetic Algorithm.- 3.5.3 Powell's Local Optimisation Method.- 3.5.4 Interfacing the Simulation Tool with the Optimisation Routines.- 3.6 Summary: Overview of the Integrated Simulation and Optimisation Tool SYNOPSIS.- 4. Simulation of the Urban Wastewater System Using SYNOPSIS.- 4.1 Definition of a Case Study Site.- 4.1.1 Existing Data Sets.- 4.1.2 Definition of the Sewer System.- 4.1.3 Definition of the Wastewater Treatment Plant.- 4.1.4 Definition of the River.- 4.1.5 Overview of the Case Study Site Defined.- 4.2 Simulation of Dry-weather Flow.- 4.3 Simulation of a Rainfall Time Series.- 4.4 Analysis of the Control Devices of the Urban Wastewater System.- 4.5 Potential of Reduction in Simulation Time by Selective Simulation.- 4.5.1 Separation of Rainfall Events.- 4.5.2 Potential Savings in Simulation Time.- 4.5.3 Selective Versus Continuous Simulation.- 4.5.4 Conclusions.- 5. Analysis of Control Scenarios by Simulation and Optimisation.- 5.1 Definitions and Methodology.- 5.2 Analysis of Strategy Parameters - an Example.- 5.2.1 Definition of a Strategy Framework.- 5.2.2 Exploring the Parameter Space by Gridding.- 5.2.3 Optimisation of Strategy Parameters.- 5.3 A Top-down Approach to the Definition of Control Strategies.- 5.3.1 Definition of Various Frameworks.- 5.3.2 Evaluation of the Optimisation Algorithms.- 5.3.3 Conclusions.- 5.4 A Bottom-up Approach to the Definition of Control Strategies.- 5.4.1 Towards a Systematic Definition of Frameworks.- 5.4.2 Analysis of Frameworks Involving Several Controllers.- 5.5 Integrated Versus Local Control.- 5.6 Further Aspects.- 5.6.1 Sensitivity of Solutions.- 5.6.2 Multi-objective Optimisation.- 5.6.3 Simulation Period Required for Optimisation.- 5.6.4 Control Potential of Various Case Study Sites.- 6. Conclusions and Further Research.- 6.1 Summary.- 6.2 Suggestions for Further Research.- Appendix A. Overview of Existing Software.- A.1 Software for Simulation of Sewer Systems.- A.2 Software for Simulation of Activated Sludge Wastewater Treatment Plants.- A.3 Software for Simulation of Rivers.- Appendix B. Parameters of the Treatment Plant Model.- Appendix C. Rainfall Data Used in This Study.- Appendix D. Detailed Results of Optimisation Runs Presented in Chapter 5.- References.