Constructed wetlands for combined sewer overflow treatment: Ecosystem services at Gorla Maggiore, Italy

摘要: Abstract Three sampling campaigns have been done in 2014–2015 order to temporally characterize CSOs quality and quantity during representative seasonal-specific rain events, estimate the ecosystem service of a CSO-CW located Northern Italy terms water improvement. The adoption an on-site treatment by Constructed Wetlands for Combined Sewer Overflows is example decentralized approach optimization existing sewer networks needed reduction their impacts on receiving bodies. CW system, that treating first flush overflows, joined with extended retention basin acting as tertiary effluents also storing whole second flush, slowing down throttle discharge river therefore playing role flooding risk control. During monitored time interval 69 events overflow discharges observed quantified; this quantification total volumes discharged specific CSO useful evaluating performances mass loads single year, author’s opinion more conservative evaluation than comparing only average concentrations removal rates. obtained results shown CWs can obtain appropriate performances, demonstrated about 87% 93% COD NH 4 + respectively 68% 94% year. A relevant analysis program secondary services provided artificial ecosystems are discussed paper, together unique characterization sources (washout, urban wastewater) reaching unit.