State Water Resources Research Institute Program

Project ID: 2007DC87B
Title: Modeling of Integrated Urban Wastewater System in the District of Columbia
Project Type: Research
Start Date: 3/01/2007
End Date: 2/29/2008
Congressional District: DC
Focus Categories: Models, Wastewater, Water Quality
Keywords: modeling, water quality, urban wastewater
Principal Investigators: Deksissa, Tolessa; Behera, Pradeep K.
Federal Funds: $ 14,647
Non-Federal Matching Funds: $ 4,980
Abstract: The ultimate objective of this study is to develop a conceptual mathematical model that can assist water quality regulators as a tool for urban wastewater management. The scheme of modeling an integrated urban wastewater system includes three components: the sewer, the wastewater treatment plant and the river. In the traditional urban wastewater modeling, these three components are considered separately and their mutual interaction among the three components is missing. Urban wastewater system must, however, be considered as a single system, and all components need to be included in one model that simulates the three components simultaneously. Simultaneous or parallel simulation allows evaluation of system performance, and optimizing it in terms of environmentally and economically sound planning and management.

This study is a preliminary study towards a development of a conceptual integrated mathematical model of sewer, wastewater treatment plant and the river. In the integrated modeling of the wastewater treatment plant and the river, the main problem is that all of these components are not only complex, but also there is incompatibility between state variables, biochemical processes and parameters used in the different sub-models. In this study an appropriate method of model selection and building an interface between submodels will be investigated.

Approximately, one third of the District of Columbia is served by a combined sewer system, which was designed to convey sewage from homes, businesses and runoff from streets, parking lots, and rooftops to the wastewater treatment plant during dry weather flow. The capacity of the combined sewer system is limited and when it is exceeded during storms, the excess flow, which is a mixture of raw sewage and storm water runoff, is discharged to the receiving waters: Anacostia, Potomac Rivers, Rock Creek and tributary waters. Thus, Combined Sewer Overflow (CSO) allows discharging of a mixture of untreated sewage and storm water runoff to the receiving waters during high flow periods due to storms. Discharging such untreated wastewater may cause acute toxicity to the aquatic life, and if not controlled, it results in continuous deterioration of water quality of the receiving waters.

Integrated modeling helps to conduct different scenario analysis to overcome the water quality problems in the District of Columbia and other states where the receiving water quality is being adversely affected by Combined Sewer Overflows (CSOs). The proposed study is therefore helpful for a researcher or planner and regulator to detect the weak point of the system and to evaluate the efficiency of alternative action, e.g. using storm tank or sewer tunnel and low impact development.

In this preliminary study, appropriate sub model selection, model reduction, building interface, and implementation of the models will be carried out. Also, selected water quantity and quality parameters will be collected.

Progress/Completion Report, PDF

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