Fate and persistence of emerging chemical contaminants after land application of biosolids: A screening-level risk assessment.

Abstract

The presence of emerging chemical contaminants embodied in wastewater treatment plant residuals represents a potential barrier to the continued land application of biosolids given concerns about diffuse and long-term contamination of agricultural lands. Their diverse physiochemical properties, and uncertain environmental fate and persistence constitute chemical contamination risk for the health of soils, especially due to accumulation after repeat applications. This study aimed to quantify the risk posed by 47 emerging contaminants from a range of sources (e.g., pharmaceuticals, personal care products, industrial chemicals, hormones and nitrosamines). Risk was characterized as a combination of persistence and ecotoxicological effect, using the half-life and the hazard quotient, respectively, as the key metrics. Chemicals identified to be persistent in the environment included several per- and polyfluorinated alkyl substances (PFAS), carbamazepine, galaxolide, tonalide, triclocarban and triclosan. Wastewater treatment plant operational and environmental conditions that resulted in faster degradation for particular chemicals have been identified, so practices to minimize their persistence could be implemented. This work has developed a framework for identification of chemicals likely to be highly persistent and thus accumulate following repeat biosolids application, facilitating prioritization of chemical concentration monitoring, targeted treatment, and quantification of repeat biosolids application frequency to minimize emerging contaminant accumulation.