Vision-Based System for the Control and Measurement of Wastewater Flow Rate in Sewer Systems
L. Nguyen, D. Sage, S. Kayal, D. Jeanbourquin, M. Scherz, D.A. Barry, M. Unser, L. Rossi
Proceedings of the Tenth IWA Conference on Instrumentation, Control and Automation (ICA'09), Cairns QLD, Commonwealth of Australia, June 14-17, 2009, paper no. OP03-4.
Total pollutant mass carried by sewer systems is an important factor affecting the quality of receiving waters [Burton and Pitt 2002]. This is especially the case during sizable rain events, when the total amount of the wastewater/stormwater mixture cannot be treated in the wastewater treatment plant; the overflow water goes directly into the environment (streams, rivers, lakes, coastal seas) through combined sewer overflows (CSOs). This water is untreated and is recognized as an important source of pollution [e.g., Even et al. 2006, Chèvre et al. 2007, Rossi et al. 2009]. Reliable pollutant concentration data are often available via sampling and analysis. However, accurate estimation of the total pollutant mass is infeasible unless the total volumetric flow rate is known with precision and reliability, and so the environmental impact due to CSO's cannot be predicted.
Knowledge of volumetric water flow rate in sewer systems is a key environmental parameter. Robust monitoring of sewers is a challenging task as the environment within them is inherently harsh: constant humidity of 100%, rapid and large water level changes, corrosive atmosphere, presence of gas, difficult access and solid debris inside the flow are some of the usual problems. Accurate monitoring of the volumetric water flow is thus of crucial environmental importance. In this paper, a novel approach to the monitoring of flow in sewers based on video images is presented. Specifically, the method is based on image processing and computer vision techniques for water level and flow velocity estimation.
References
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N. Chèvre, N. Vallotton, L. Rossi, "Risk Assessment of Urban Runoff Pollution in Rivers: How to Deal with Time-Varying Concentrations?," Sixth International Conference (NOVATECH'07), Lyon, French Republic, June 24-29, 2007, 8 p.
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L. Rossi, N. Chèvre, R. Fankhauser, V. Krejci, "Probabilistic Environmental Risk Assessment of Urban Wet-Weather Discharges: An Approach Developed for Switzerland," Urban Water Journal, in press.
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