Toxicity and pollutant impact analysis in an urban river due to combined sewer overflows loads

摘要

The Navile Channel (Bologna, Italy) is an ancient artificial water course derived from thenReno river. It is the main receiving water body for the urban catchment of Bologna sewernsystems and also for the Waste Water Treatment Plant (WWTP) main outlet. The aim of this worknis to evaluate the Combined Sewer Overflows (CSOs) impact on Navile Channel’s water quality.nIn order to collect Navile flow and water quality data in both dry and wet weather conditions,ntwo measuring and sampling stations were installed, right upstream and downstream thenWWTP outflow. The study shows that even in case of low intensity rain events, CSOs havena significant effect on both water quantity and quality, spilling a considerable amount ofnpollutants into the Navile Channel and presenting also acute toxicity effects. The collected datanshown a good correlations between the concentrations of TSS and of chemical compoundsnanalyzed, suggesting that the most part of such substances is attached to suspended solids.nResulting toxicity values are fairly high in both measuring points and seem to confirm synergisticninteractions between heavy metals.