Priority pollutants in urban stormwater: Part 2 – Case of combined sewers

Abstract

This study has evaluated the quality of combined sewer overflows (CSOs) in an urban watershed, such as Paris, by providing accurate data on the occurrence of priority pollutants (PPs) and additional substances, as well as on the significance of their concentrations in comparison with wastewater and stormwater. Of the 88 substances monitored, 49 PPs were detected, with most of these also being frequently encountered in wastewater and stormwater, thus confirming their ubiquity in urban settings. For the majority of organic substances, concentrations range between 0.01 and 1 μgl(-1), while metals tend to display concentrations above 10 μgl(-1). Despite this ubiquity, CSO, wastewater and stormwater feature a number of differences in both their concentration ranges and pollutant patterns. For most hydrophobic organic pollutants and some particulate-bound metals, CSOs exhibit higher concentrations than those found in stormwater and wastewater, due to the contribution of in-sewer deposit erosion. For pesticides and Zn, CSOs have shown concentrations close to those of stormwater, suggesting runoff as the major contributor, while wastewater appears to be the main source of volatile organic compounds. Surprisingly, similar concentration ranges have been found for DEHP and tributyltin compounds in CSOs, wastewater and stormwater. The last section of this article identifies substances for which CSO discharges might constitute a major risk of exceeding Environmental Quality Standards in receiving waters and moreover indicates a significant risk for PAHs, tributyltin compounds and chloroalkanes. The data generated during this survey can subsequently be used to identify PPs of potential significance that merit further investigation.

Assessment of floating plastic debris in surface water along the Seine River

“…The high percentage of plastic for boom no. 6 is correlated with its immediate proximity to the largest CSO outfall within the Paris metropolitan area (Gasperi et al, 2012) and with a CSO discharge of about 100,000 m 3 that occurred prior to sampling.…”

“…The Paris sewer network is a combined one, leading to discharges of combined sewer overflows (CSO) during wet weather periods (Gasperi et al, 2012). To avoid any visible pollution in rivers, the SIAAP has deployed a network of floating debris-retention booms since 1990.…”

Using rapid assessment of marine pollution (RAMP) techniques to assess the quality of marine sediments

“…That was expected since Ribeira is under direct influence of sewage, stormwater and especially marinas, whereas Itaguá is under influence of similar sources (mainly sewage and stormwater). Marinas (King et al, 2004;Neira et al, 2017), sewage (Nichols & Espey, 1991;Wlodarczyk-Makula, 2005;Gasperi et al, 2012) and stormwaters (Launay et al, 2016;Rogers, 2002) have been identified as local sources of PAHs. In addition, Itaguá waters are often considered by the State Environmental Agency as of poor quality for bathing (CETESB, 2008(CETESB, , 2013(CETESB, , 2016.…”

Analysis of the influence of rainfall variables on urban effluents concentrations and fluxes in wet weather

“…Bertrand-Krajewski (2006) reports TSS in the 176-2500 mg l À1 range for a combined sewer overflow compared to 21-2600 mg l À1 for a separated storm system, while COD values are in the reported ranges of 42-900 mg l À1 for a combined system overflow and 20-500 mg l À1 for a separated storm water system. Work by Lessard and Lavallée (1985) on five unitary catchment areas in Quebec City (Canada), produced mean values for the catchments of 276 mg l À1 TSS and 142 mg l À1 for the COD, while Gasperi et al (2011) obtained a mean value for TSS of 209 mg l À1 compared to 274 mg l À1 for COD for the Clichy, France, combined system. These results are similar to measurements obtained by Angerville (2009) for a storm overflow sample in Lyon, France (340 mg l À1 TSS and 390 mg l À1 COD).…”