A quantitative assessment of plastic residues in Australian biosolids

The extent and scope of how plastics may be introduced into soil systems is not fully understood, however it has been recognised worldwide that they can be introduced into soils through the practice of applying biosolids (treated sewage sludge) to agricultural land. In Australia, about 443,000 tonnes of biosolids were produced in 2016, with about 80% applied for agricultural purposes. The widespread use of biosolids for agricultural purposes could therefore be a potential opportunity for the release of plastics into receiving Australian agricultural soils, which could pose a greater risk to the soil ecosystem and humans. Nevertheless, we currently do not know how much plastics are in biosolids intended to be applied to agricultural lands across Australia. Accordingly, this study aims to determine the composition and per capita mass release loads of common plastics through biosolids in Australia using our novel pressurized liquid extraction combined with pyrolysis gas chromatography–mass spectrometry technique, to have a more comprehensive understanding of their fate.

Please note this is a PhD student’s thesis review.