Treating Wastewater
Developing Data-Driven Strategies to Mitigate PFAS in Wastewater Treatment Plants
Wastewater treatment plants (WWTPs) play a central role in the environmental cycling of PFAS, acting as both receivers and redistributors of these persistent compounds. Despite significant technological advancements over the years, conventional treatment systems remain largely ineffective in removing PFAS, resulting in continued discharge into surface waters and accumulation in biosolids.
PFAS in Wastewater Systems
PFAS are uniquely resistant to many biological and physical processes commonly used in wastewater treatment. To better understand their behavior, a comprehensive meta-analysis was conducted using data from over 1,500 WWTPs across more than 100 peer-reviewed studies worldwide. The analysis was synthesized into a global interactive map illustrating PFAS concentrations in influent, effluent, and residual treatment streams.1
The findings confirm that PFAS persist globally across all stages of wastewater treatment. Conventional systems that rely on biological degradation, sedimentation, or filtration show limited removal of well-known, commonly regulated compounds. More often, conventional wastewater treatments increase the concentration of perfluoroalkyl acids, including PFOA and PFOS, due to the transformation of precursor compounds.
Limitations of Conventional and Advanced Treatment Systems
Even WWTPs equipped with tertiary treatment processes, such as advanced filtration or oxidation, demonstrated limited PFAS removal. While PFAS can be treated with widely used adsorptive media (e.g., granular activated carbon or ion-exchange resins), these media are not typically used at WWTPs. The resulting median effluent concentrations for several PFAS compounds often exceeded 10 nanograms per liter, reinforcing the limitations of even advanced treatment configurations. These findings underscore a critical reality: no single treatment solution is universally effective for managing PFAS.
Instead, effective strategies must be tailored to site-specific influent characteristics, treatment configurations, and end-use objectives.
Implications for Utilities and Remediation Planning
While drinking water systems have made measurable progress in PFAS treatment, WWTPs remain a substantial source of environmental PFAS release. Understanding PFAS behavior through each treatment stage enables project teams to anticipate where removal challenges will arise and to design targeted, cost-effective interventions.
As regulatory frameworks evolve, including USEPA’s draft human health risk assessment for PFOS and PFOA in biosolids, facilities must adopt integrated strategies such as source control, pre-treatment, and residuals management. Practical strategies may include isolating PFAS-rich industrial inputs, implementing advanced separation processes, or stabilizing biosolids by using chemical methods or thermal treatment for PFAS destruction, to limit downstream impacts.
What is the Path Forward for PFAS Management in WWTPs?
Bench-scale and pilot testing play a vital role in selecting and optimizing these technologies for WWTPs and other remediation systems. Langan’s Treatability Facility at the New Jersey Institute of Technology supports clients by testing advanced and innovative treatment methods to evaluate PFAS removal efficiency and develop full-scale implementation strategies. These targeted studies help reduce uncertainty, minimize risk, and identify sustainable, regulatory-compliant solutions.
Langan’s PFAS experts work with clients to translate research into practical remediation strategies—bridging the gap between bench-scale results and field-scale success. By combining robust data analysis, targeted testing, and integrated planning, project teams can achieve efficient, science-based management of PFAS in wastewater and biosolids systems.
Amita Oka, PhD, is an environmental scientist with over 15 years of experience, specializing in remedial technology evaluation, engineering design, and full-scale implementation of physical, chemical, and bioremediation alternatives. Her work also focuses on in-situ treatment, treatability testing, and pilot testing of PFAS-impacted media. Located in Langan’s Princeton office, Dr. Oka is actively involved in the Langan Treatability Facility at New Jersey Institute of Technology.
Charbel Abou-khalil, PhD, is an environmental engineer in Langan’s Princeton office, specializing in PFAS remediation, wastewater treatment, and site characterization. His 10 years of experience include contaminated site investigation and remediation, soil and groundwater sampling, vapor intrusion investigation, and remedial investigation, design, implementation, and monitoring.
1 Central to the work performed by Dr. Charbel Abou-khalil at the University of Notre Dame (Doudrick Lab) and a continued resource in his work as a practitioner.