Effluents discharged from Wastewater Treatment Plants (WWTPs) to surface waters and biosolids land-applied to agricultural fields for beneficial reuse have been identified as potential PFAS release pathways into the environment by the Interstate Technology and Regulatory Council.

WWTPs are not a source of PFAS, but they serve as a central collection point to control and mitigate release into the environment. Some regulatory bodies are beginning to establish or have already set limits that could significantly impact wastewater utilities and how they manage the effluent, sludge disposal through landfilling or incineration, and/or the beneficial reuse of biosolids through land application practices.

To better understand the current data gaps and improve the understanding of PFAS impacts on the WWTPs, including their fate and transport, AECOM implemented an internal national WWTP study regarding PFAS. Nineteen WWTPs from eight states across the US participated in the study, representing various sewer shed characteristics, sizes and treatment processes.

Phase 1 was an initial screening of influent, effluent and final biosolids products. A limited number of participants from Phase 1 were selected for Phase 2, based on initial results and site-specific process arrangements of the facility. Phase 2 included an in-depth evaluation of the PFAS fate within the WWTPs to understand the mass balance through the facility and the potential impacts to present end uses of the effluent or final treated solids from the facility. Additional samples were collected from both the liquid and solids management processes within the facilities. Based on the PFAS signature from various samples, the evaluation also investigated if there was potential precursor degradation or recirculation of PFAS within the WWTP through various treatment streams.

As an industry leader on PFAS worldwide, AECOM reviewed process flow diagrams and operational logic information to recommend facility-specific sampling and flow measurement plans to support the development of an understanding of PFAS transport through the individual facilities. The evaluation considered the physical-chemical properties of multiple PFAS “families” with various carbon chain lengths.

Study Benefits The study provides better insight into PFAS concentrations within WWTPs across the US and the potential fate within the WWTPs. The results from the study offers insight into the presence and speciation of PFAS within their facilities and potential liability that WWTPs may have to address for compliance with future surface water criteria or disposal of final treated solids, including beneficial reuse through the land application of biosolids. The study also provides insight into the nature of the PFAS loading at these facilities and potential sources where pretreatment mitigation strategies may be employed.

Read more about the study here.