Related Experiment Video
Updated: Jun 19, 2026

Vegetated Treatment Systems for Removing Contaminants Associated with Surface Water Toxicity in Agriculture and Urban Runoff
Published on: May 15, 2017
Model-based comparison of two ways to enhance WWTP capacity under stormwater conditions
M Ahnert1, J Tränckner, N Günther
1Institute for Urban Water Management, Technische Universität Dresden, 01069, Dresden, Germany. Markus.Ahnert@tu-dresden.de
Abstract:
Two different approaches to increase the fraction of combined water treated in the wastewater treatment plant (WWTP) which would otherwise contribute to combined sewer overflows (CSO) are presented and compared based on modelling results with regard to their efficiencies during various rain events. The first option is to generally increase the WWTP inflow according to its actual capacity rather than pre-setting a maximum that applies to worst case loading. In the second option the WWTP inflow is also increased, however, the extra inflow of combined water is bypassing the activated sludge tank and directly discharged to the secondary clarifier. Both approaches have their advantages. For the simulated time series with various rain events, the reduction of total COD load from CSOs and WWTP effluent discharged to the receiving water was up to 20% for both approaches. The total ammonia load reduction was between 6% for the bypass and 11% for inflow increase. A combination of both approaches minimises the adverse effects and the overall emission to the receiving water.
Related Concept Videos
Design Example: Analyzing Capacity Contours for Flood Risk Assessment
Typical Model Studies
Conservation of Mass in Moving, Nondeforming Control Volume
In the context of a detention basin, the conservation of mass states that the total mass of water entering the basin must equal the mass leaving the basin plus any accumulation of...
Design Example: Creating a Hydraulic Model of a Dam Spillway
Modeling and Similitude
Design Example: Design of an Irrigation Channel

