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Thermodynamic assessment of (semi-)volatile hydrophobic organic chemicals in WWTP sludge – combining Solid Phase Microextraction with non-target GC/MS

Abstract

Applying WWTP sludge on arable soil has clear benefits from a resource recycling point of view but can potentially also lead to contamination of soils, agricultural products and the environment. The sludge contains a complex mixture of particularly hydrophobic organic chemicals (HOCs) that sorb to the organic matter. Equilibrium sampling was recently applied to measure chemical activities of polycyclic aromatic hydrocarbons (PAHs) in secondary and digested sludge, and clear activity increases by the anaerobic digestion treatment were observed. In the present study we extend this work to a large number of (semi-)volatile HOCs by combining automated Head Space Solidphase Microextraction with non-targeted gas chromathography mass spectrometry. Chemical activity ratios were determined between sludge from the different stages of a WWTP and after co-composting with garden waste and sorbent amendment with activated carbon (AC) and biochar (BC). Generally, chemical activities increased from primary, to secondary, to digested sludge and the level in dewatered sludge was not significantly different from the level in the digested sludge. The cyclic siloxane D5 behaved differently as the level was similar until the dewatering step, where it increased 4-fold. The results confirmed the earlier observation that anaerobic digestion increased chemical activity, now for a broader range of chemicals and showed that co-composting was effective in reducing chemical activities for most of the tested (semi-)volatile organic chemicals. Decamethylcyclopentasiloxane (D5) and a musk fragrance were reduced the least of the studied compounds by co-composting.

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Publication details

The article was received on 03 Sep 2018, accepted on 02 Oct 2018 and first published on 03 Oct 2018


Article type: Paper
DOI: 10.1039/C8EM00407B
Citation: Environ. Sci.: Processes Impacts, 2018, Accepted Manuscript
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    Thermodynamic assessment of (semi-)volatile hydrophobic organic chemicals in WWTP sludge – combining Solid Phase Microextraction with non-target GC/MS

    K. Knudsmark Sjøholm, M. Flyckt-Nielsen, T. D. Bucheli and P. Mayer, Environ. Sci.: Processes Impacts, 2018, Accepted Manuscript , DOI: 10.1039/C8EM00407B

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