Suspect and Nontarget Screening of Organic Micropollutants in Swiss Sewage Sludge: A Nationwide Survey

The increasing amount of sewage sludge generated during wastewater treatment poses both growing management challenge and environmental issues. Sludge with many co-occurring contaminants is often destined to land application which raises concern regarding human and environmental health. It is also a good integrator in time and space and can provide valuable information on consumption pattern and change over time. Here, we have conducted suspect and nontarget screening (SNTS) in sludge from 29 wastewater treatment plants (WWTPs) covering 30% of the Swiss population. Over 500 contaminants were identified and up to 382 quantified, with concentrations ranging from a few ng/g to several thousand ng/g, which translated into total annual loads of approximately 5 g of micropollutants per Swiss citizen. The distribution of detected substances was dominated by pharmaceuticals in terms of number of compounds (>250) and personal care products in terms of concentration (e.g., 75 μg/g for linoleic acid). Homologous series analysis revealed the presence of multiple classes of surfactants among those compounds with the highest signal intensities in sludge. Principal component analysis and hierarchical clustering showed that spatial distribution of contaminants across Switzerland was not homogeneous, while Pearson correlation indicated that changes can be attributed to different anaerobic digestion times in WWTPs.