Steffen Heusch

Water quality-based assessment of urban drainage impacts in Europe - where do we stand today?

Traditionally, design and optimisation of urban drainage systems was mainly driven by cost efficiency, surface flood prevention, and later by emission reduction. More recent procedures explicitly include ecological conditions of the receiving water in the definition of acceptable pollutant discharges via sewer system and treatment plant outlets. An ambient Water Quality based impact Assessment (WQA) principle therefore requires an integrative system optimisation. However, a broad range of mostly national WQA protocols exist across Europe varying in structure and complexity, assessment concept, spatial and temporal scope and handling of uncertainty. This variety inherently implies a considerable risk of subjectivity in the impact assessment with highly variable outcomes. The present review identifies differences and similarities of WQA protocols in use and discusses their strengths and weaknesses through: (i) a systematic comparison of WQA protocols by selected attributes, (ii) a review of real-life cases reported in the literature and expert interviews, and (iii) an illustration of our main findings by applying selected WQA in an instructive example. The review discusses differences in structure and concept, which are mainly identified for simplistic WQA protocols. The application of selected protocols to an example case shows a wide variety of numerical results and conclusive decisions. It is found that existing protocols target different questions within the decision making process, which users should be more aware of. Generally, to make assessments more reliable, further fundamental research is required to fully understand the relationship between stressors and stream ecosystem responses which will make assessments more reliable. Technically, tools suggested in WQA protocols show severe deficiencies and an uncertainty assessment should be mandatory.

Simulation of wastewater treatment plant within integrated urban wastewater models.

In the federal state of Hesse in Germany the application of an integrated software modelling framework is becoming part of the planning process to attain legal approval for the operation of combined sewer systems. The software allows for parallel simulation of flow and water quality routing in the sewer system and in receiving rivers. It combines existing pollution load model approaches with a simplified version of the River Water Quality Model No. 1 (RWQM1). Comprehensive simulation of the wastewater treatment plant (WWTP) is not considered yet. The paper analyses alternatives for the implementation of a WWTP module to model activated sludge plants. For both primary and secondary clarifiers as well as for the activated sludge process concepts for the integration into the existing software framework were developed. The activated sludge concept which uses a linearized version of the well known ASM1 model is presented in detail.

Performance and Comparison of BlueM.MPC and Lamatto

We compare the quality and generation performance of the optimal control sequence produced by the software frameworks BlueM.MPC and Lamatto.

Optimal Control of Sewer Networks Engineers View

This chapter introduces a software tool for MPC of sewer networks with a dynamic process model which is based on an interative approach. A flexible optimizer, which implements local and global optimization methods, is connected to a dynamic sewer network model to evaluate the objective function values. Numerical results for a simple urban drainage network are presented, illustrating the functionality of the approach.

Model Predictive Control with SWMM

Real time control (RTC) is particularly promising in large, flat and heterogeneous sewer systems with a high in-line storage volume. For the simulation of such…

Optimal Control of Sewer Networks Problem Description

This chapter gives an overview of optimal control of sewer networks with dynamic process models. After introducing the method of model predictive control (MPC) and its requirements for optimization and process modeling a focus is set on practical applications and the industrial viewpoint. An up-to-date sewer management system is introduced and used to illustrate industrial requirements and the mathematical challenges involved in it.