CSO management from an operators perspective: a step-wise action plan

摘要

Combined sewer overflows (CSO) are the ‘‘ugly ducklings’’ of urban wastewater infrastructure,nrather unknown, rarely loved. Contrary to wastewater treatment plants (WWTP) where, commonly,nprocess parameters are carefully registered, still relatively little is known about the spillnbehaviour of CSOs. In spite of the considerable bandwidth of pollution magnitude reported innliterature, it can be generally accepted that CSO impact certainly is not negligible. As the solenwastewater utility in Flanders (6,100,000 inhabitants), Aquafin operates, next to 230 WWTP’s andnalmost 1,000 pumping stations, some 3,100 CSOs. In search for an optimum CSO managementnstrategy, Aquafin prospected several modelling and monitoring possibilities. As a result, anCSO action plan could be drawn up tailored to the estimated relevance of the CSO undernconsideration. In a further step a cost-benefit analysis of several static and dynamic remediationnmeasures was undertaken. Real Time Control (RTC) strategies turned out to be the most costnefficient solution for CSO impact mitigation.