Suspected-target screening for the assessment of pollutants in sewage sludge and assessment of their environmental risk

Wastewater generated by human activities contains different organic pollutants from anthropogenic origin. During its depuration in the wastewater treatment plants (WWTPs) sewage sludge is generated, which also contains these pollutants. While water influents and effluents of WWTPs are widely studied, the studies focused in the analysis of sewage sludge are more limited. This is probably due to the complexity that involves the analysis of samples with a high percentage of organic matter. However, since sewage sludge is sometimes employed as fertilizer, its analysis is crucial to assess its possible impact in the environment and human health. Sludge samples analysed in this study were from 8 WWTPs with different treatments. They were extracted using ultrasound assisted extraction (UAE). Then, solid phase extraction (SPE) using StrataTMX cartridges was employed as clean-up. The suspected analytes were identified by liquid chromatography-quadrupole time-of-flight mass spectrometry (LC-QqTOF-MS). As overall results, 50 different compounds were identified with high degree of confidence belonging 31 of them to the group of the pharmaceuticals. Human metabolites were the most relevant, present in all samples, including nucleotides (adenosine triphosphate), amino acids (phenylalanine) or peptides (leucine-phenylalanine). Several human metabolites (nucleotides, amino acids, etc.) were also detected. A significant number of compound were tentative identified but more in depth study is needed to increase the degree of confidence in their identification. Further research is also needed to provide a complete profile of the organic pollutants present in sewage sludge and to obtain a full picture of their potential risk for humans and the environment. Acknowledgment: This work has been supported by the Spanish Ministry of Economy and Competitiveness and the ERDF (European Regional Development Fund) through the project CICLIC -subproject WETANPACK (RTI2018-097158-B-C31) and by the Generalitat Valenciana through the project ANTROPOCEN@ (PROMETEO/2018/155); R. Álvarez also knowledge the same institutions for his FPI grant BES-2016-078612.