Temporal trends and spatial variations of chlorinated paraffins and olefins in sewage sludge from eight Swiss wastewater treatment plants from 1993 to 2020

Jules Hutter; Oscar Mendo Diaz; Marco Knobloch; Markus Zennegg; Jean Claude Vogel; Edith Durisch; Urs Stalder; Laurent Bigler; Susanne Kern; Andreas M Buser; Norbert V Heeb

doi:10.1016/j.chemosphere.2025.144071

Temporal trends and spatial variations of chlorinated paraffins and olefins in sewage sludge from eight Swiss wastewater treatment plants from 1993 to 2020

Chemosphere. 2025 Jan 3:144071. doi: 10.1016/j.chemosphere.2025.144071. Online ahead of print.

Authors

Affiliations

¹ Swiss Federal Institute for Materials Science and Technology Empa, Laboratory for Advanced Analytical Technologies, Überlandstrasse 129, 8600, Dübendorf, Switzerland; Zurich University of Applied Sciences ZHAW, Einsiedlerstrasse 31, 8820, Wädenswil, Switzerland. Electronic address: jules.hutter@chem.uzh.ch.
² Swiss Federal Institute for Materials Science and Technology Empa, Laboratory for Advanced Analytical Technologies, Überlandstrasse 129, 8600, Dübendorf, Switzerland; University of Zurich, Department of Chemistry, Winterthurerstrasse 190, 8057, Zurich, Switzerland. Electronic address: oscar.mendodiaz@empa.ch.
³ Swiss Federal Institute for Materials Science and Technology Empa, Laboratory for Advanced Analytical Technologies, Überlandstrasse 129, 8600, Dübendorf, Switzerland; University of Zurich, Department of Chemistry, Winterthurerstrasse 190, 8057, Zurich, Switzerland. Electronic address: marco_knobloch@hotmail.com.
⁴ Swiss Federal Institute for Materials Science and Technology Empa, Laboratory for Advanced Analytical Technologies, Überlandstrasse 129, 8600, Dübendorf, Switzerland. Electronic address: markus.zennegg@empa.ch.
⁵ Office for Waste, Water, Energy and Air of the Canton of Zurich AWEL, Water Protection Department, Hardturmstrasse 105, 8090, Zurich, Switzerland. Electronic address: jean-claude.vogel@bd.zh.ch.
⁶ Office for Waste, Water, Energy and Air of the Canton of Zurich AWEL, Water Protection Department, Hardturmstrasse 105, 8090, Zurich, Switzerland. Electronic address: edith.durisch@bd.zh.ch.
⁷ University of Zurich, Department of Chemistry, Winterthurerstrasse 190, 8057, Zurich, Switzerland. Electronic address: urs.stalder@chem.uzh.ch.
⁸ University of Zurich, Department of Chemistry, Winterthurerstrasse 190, 8057, Zurich, Switzerland. Electronic address: laurent.bigler@chem.uzh.ch.
⁹ Zurich University of Applied Sciences ZHAW, Einsiedlerstrasse 31, 8820, Wädenswil, Switzerland. Electronic address: susanne.kern@zhaw.ch.
¹⁰ Swiss Federal Office for the Environment FOEN, 3003, Bern, Switzerland. Electronic address: andreas.buser@bafu.admin.ch.
¹¹ Swiss Federal Institute for Materials Science and Technology Empa, Laboratory for Advanced Analytical Technologies, Überlandstrasse 129, 8600, Dübendorf, Switzerland. Electronic address: norbert.heeb@empa.ch.

PMID: 39756702
DOI: 10.1016/j.chemosphere.2025.144071

Abstract

High production rates of chlorinated paraffins (CPs) and their widespread use resulted in a global contamination. Since 2017, short-chain CPs (SCCPs, C₁₀-C₁₃) are listed as persistent organic pollutants (POPs) in the Stockholm Convention. Technical CP mixtures contain hundreds of homologues and side products such as chlorinated olefins (COs), diolefins (CdiOs) and triolefins (CtriOs). Sewage sludge from wastewater treatment plants (WWTPs) is a suitable indicator to assess anthropogenic emissions of POPs. We studied 40 sewage sludge samples from eight WWTPs taken in 1993, 2002, 2007, 2012 and 2020. These samples represent effluents of households of ∼344000 inhabitants corresponding to 4% of the Swiss population. Extracts were studied by liquid chromatography high-resolution mass spectrometry (LC-MS, R>100000). Respective mass spectra contained more than 20000 m/z values which were evaluated with the R-based automated spectra evaluation routine (RASER). We assigned ∼4300 ions to 226 CP, 94 CO, 32 CdiO and 26 CtriO homologues. Proportions of olefinic material were on average 8%, 1% and <1%, respectively. Homologue distributions from 1993 sludge were rich in SCCPs (26%) and SCCOs (36%). Average SCCP levels dropped by 85% from 15600±14300 (1993) to 2370±840 ng/g dry matter (2020). Thus, SCCP emissions from Swiss households and industry were reduced successfully from 1993 to 2020. Levels of medium- (MCCPs, C₁₄-C₁₇), long- (LCCPs, C₁₈-C₂₁) and very long-chain CPs (vLCCPs, C_≥22) decreased by 67%, 11% and 11%. 2020 samples contained some (<1%) very short-chain CPs (vSCCPs, C_≤9). Spatial variations for different WWTPs are minor, except for one, which received high MCCP loads from 2002 to 2012. We assume that wastewater from a point source has reached this plant in those years. According to the levels of sludge from WWTPs, we conclude that the use of SCCPs in Swiss households and thus the exposure of people was reduced in the last three decades.

Keywords: Chlorinated paraffins (CPs); Orbitrap mass spectrometry; Persistent organic pollutants (POPs); RASER (R-based automated spectra evaluation routine); Sewage sludge.