Release of poly- and perfluoroalkyl substances from finished biosolids in soil mesocosms

Per- and Polyfluoroalkyl Substances in Toilet Paper and the Impact on Wastewater Systems

“…Furthermore, PFAS known as triPAPs and larger analogs have been detected in the environment . These compounds may also be present in toilet paper; however, determining the quantity of these species is difficult due to the lack of available standards and the limitations of the total oxidizable precursor (TOP) assay for diPAP-containing and/or high organic matter matrixes. , …”

Underestimation of Per- and Polyfluoroalkyl Substances in Biosolids: Precursor Transformation During Conventional Treatment

“…For example, transformation of 6:2 diPAP to PFHxA might increase the tendency for PFAS to partition from soil to water (i.e., the tendency to leach from biosolids into the surrounding environment) by a factor of 1000. The breakdown of PFAA precursors into terminal species has been demonstrated to take place during conventional treatment of biosolids and in soils that have had biosolids land applied to them. , If PFAS, and particularly short chain PFAAs, are to be regulated in biosolids, analytical protocols as well as when and where samples are taken will have an impact on the outcome of any monitoring program. For example, in this study, it was reported that aerobically composted biosolids increased in short chain PFCAs (i.e., PFHxA and PFPeA); if guidelines were in place to monitor the concentrations of these compounds, it would be theoretically possible to be below risk-based thresholds before treatment but exceed the same thresholds after treatment.…”

“…Based on previous studies, a fraction of the PFAS load will pass through the wastewater treatment plant and be released to the environment as effluent, while a significant portion (especially larger molecular weight PFAS) partition to the solid fraction (i.e., biosolids). − Data from multiple countries have identified significant concentrations of PFAS in biosolids, and as analytical capabilities have improved, the variety of PFAS identified by these analyses has increased as well. − While PFAS in biosolids have been well studied, we hypothesize that existing research may underestimate the magnitude of PFAS in this waste stream as a result of two factors: analytical limitations which do not capture a significant fraction of PFAA precursors and sample selection which may not capture transformations which result from standard biosolids treatment processes, predominantly comprised of perfluoroalkyl carboxylic acids (PFCAs) and perfluoroalkyl sulfonic acids (PFSAs), which are end products of the degradation of larger and less stable PFAA precursor species. , PFAA precursor species are susceptible to thermal and chemical decomposition and have been found to undergo biodegradation in standard environmental conditions . Though certain PFAA precursors have been identified in biosolids, − there are a limited number of compounds that have been quantified, and even further, their explicit transformation during conventional treatment of biosolids is relatively unknown. Quantifying these precursors before and after treatment is important to understanding the true environmental risk posed by PFAS in biosolids.…”

The analysis of per- and polyfluoroalkyl substances in wastewater sludges and biosolids: which adsorbents should be used for the cleanup of extracts?

“…Thus, once the solvent composition changed, they precipitated out of the solution. Schaefer et al 22 also observed that biosolid extracts consisting of 50/50 (v/v) methanol/water emulsified. To address this issue, Schaefer et al added isopropanol to the sample such that the final sample composition was 3/2/2 (v/v/v) methanol/isopropanol/ water.…”

“…21 While PFAAs are the PFAS that have been measured the most frequently, two recent studies reported that PFAA precursors, such as disubstituted polyfluorinated phosphate esters, were the dominant PFAS in the studied biosolids. 20,22 Some of these precursors could be transformed into PFAAs. Since it is a common practice around the world to use biosolids as fertilizer, there have been significant concerns that biosolidamended agricultural fields could be potential PFAS point sources, which could contaminate soil, crops, grazing animals, surface water, and groundwater.…”