Pharmaceuticals in hospital sewage effluents: Long-term surveillance & WWTP removal effectiveness

Sammendrag

Background The proposed EU Urban Wastewater Treatment Directive (UWWTD) requires monitoring of micropollutants in wastewater entering and leaving wastewater treatment plants (WWTP) that serve more than 100.000 pe, and at WWTPs treating wastewater from urban agglomerations >10.000 pe if the concentration or accumulation of micropollution poses a risk to human health or the environment. In anticipation of such legal requirements, the Ahus University Hospital in collaboration with the receiving WWTP and the municipality started already twelve years ago a monitoring campaign to document their discharges of up to 160 different pharmaceuticals to the public sewerage system and their fate at the WWTP. To our knowledge, this represents the most consistent and largest existing dataset for pharmaceutical residuals in Norwegian wastewaters. However, currently the dataset has not been exploited and interpreted. Despite of the upcoming EU regulation, knowledge about typical discharge concentrations from hospitals to the public wastewater system and from WWTPs to recipients, is currently lacking in Norway. Thus, our data set might be very valuable to provide knowledge on trends of the investigated compounds from long-term surveillance. Approach Three to four sampling events were conducted during 2019-2021. Hospital effluent and WWTP influent and effluent samples were collected as weeklong flow-proportional composite samples, while sludge samples at the WWTP were collected s composite grab samples over the same periods. The samples were analyzed for 130 - 160 pharmaceutical compounds. Environmental risk quotients, RQ (= predicted environmental concentration divided by predicted no-effect concentration), were determined for each individual compound, and the RQ of compounds with similar toxic effect were summed to consider the assumed cocktail effect. If RQ < 1, the effluent is assumed to pose no environmental harm. Results & Discussion Results from the last three years monitoring campaigns will be presented and discussed. This includes the quantitative and relative contribution of individual compounds in the hospital effluent to the observed levels in the inlet to the WWTP, where the compounds ended up (in the effluent, in the sludge or degraded/evaporated). In addition, we present whether the removal effectiveness was sufficient to comply with the requirements of the UWWTD. Furthermore, the results from an ecotoxicity risk assessment caused by the residual levels of the pharmaceutical residues in the effluent will be shown.