Benchmark Simulation Model for Integrated Urban Wastewater Systems : Model Development and Control Strategy Evaluation

Abstract: The integrated urban wastewater system (UWS) consists of different sections that are interconnected. These include: i) catchment; ii) sewer network; iii) wastewater treatment plant (WWTP); and finally, iv) receiving water system. Traditionally, these sections are operated and evaluated individually. However, it is now well-established that all the sections of an UWS should be operated in a holistic manner in order to improve the receiving water quality. The thesis aims at developing an integrated model library that can be used to simulate the dynamics of flow rate and pollutant loads in all the sections of an UWS on a single simulation platform. It is further aimed at defining a hypothetical UWS using the model library, so that future users can use the pre-defined layout to study multiple control strategies and structural modifications. In order to facilitate an objective evaluation of the results, criteria for evaluating river water quality as well as the sewer network and WWTP performance are described.Firstly, the suitability of existing model libraries is assessed. The building blocks from the Dynamic Influent Pollutant Disturbance Scenario Generator (DIPDSG) are used as the starting point for the catchment and sewer network model library. Additional model blocks that are missing in the DIPDSG are developed. A modified version of the Benchmark Simulation Model No. 2 (BSM2) is used to simulate the WWTP. Model blocks for river water quality assessment are developed. Using the model library, a hypothetical UWS for an urban catchment with 80 000 population equivalents and an area of 540 hectares is described. The UWS layout is used to develop and evaluate different control strategies (local/integrated) and structural modifications. The case studies indicate that: i) the presented model library and the layout can be used to develop various control strategies and evaluate their impact on river water quality; and ii) improving the performance of an individual section does not necessarily lead to better river water quality. It is expected that the model library will be widely used as an open-source software toolbox for benchmarking purposes, integrated modelling studies as well as for modelling the individual sections.