Sewage sludge in a wastewater treatment plant in Berlin
Source: BAM
Per- and polyfluoroalkyl substances (PFAS) are synthetic chemicals and include more than 10 000 compounds. PFAS have been used extensively in a variety of products and industries due to their inert chemical stability and resistance to degradation by heat or acids. Due to the continuous use of PFAS containing industry and consumer products, effluents and sewage sludge from wastewater treatment plants (WWTPs) have been identified as a significant path of discharge for PFAS into the environment. In addition to direct entry discharge of PFAS through effluents and volatile PFAS into the air, sewage sludge has been observed to be an important pathway for PFAS release to agricultural soils. The German legislation banned sewage sludge application on agricultural land through the amendment of the German fertilizer ordinance and by 2029 sewage sludge will be totally prohibited from agricultural application. In addition, the European Union has proposed to ban the use of all (non-essential) PFAS to reduce pollutant entry to the environment. While environmental exposure of organic pollutants like PFAS and antibiotics is no longer desirable, phosphorus (P) from sewage sludge should still be recycled in WWTPs of cities with a population larger than 50 000 residents. Currently, plant-available P-fertilizers from recycled materials (e.g., sewage sludge, sewage sludge ash, wastewater precipitates) can be produced using a variety of treatment approaches including precipitation, leaching, and thermal treatment.
Currently, only the sum amount of the two PFAS perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) is monitored via the German fertilizer ordinance with a limit of 100 µg per kg dry matter. Due to the strong diversity of industrial PFAS usage this limitation is not adequate to ensure safe application of novel recycled P-fertilizers from WWTPs on agricultural fields. Therefore, we analyzed wastewater-based fertilizer using combustion ion chromatography (CIC) for “total” PFAS followed by comparing subset of results with classical liquid chromatography tandem mass spectrometry (LC-MS/MS) for target analysis, and high-resolution – mass spectrometry (HR-MS) suspect screening to unravel PFAS pollution in wastewater-based fertilizer for safe nutrient recovery from wastewater for a circular economy.
Elevated levels of per- and polyfluoroalkyl substances (PFAS) in wastewater derived fertilizers
Christian Vogel, Philipp Roesch, Philipp Wittwer, Christian Piechotta, Jan Lisec, Thomas Sommerfeld, Stephanie Kluge, Hannes Herzel, T. Huthwelker, C. Borca, Franz-Georg Simon
Environmental Science: Advances, 2023,2, 1436-1445