Disproportionate PFAS mass loading from landfill leachate: implications for biosolids management policy

Land application of biosolids has long been an accepted and important part of circular nutrient management, returning carbon, nitrogen, and phosphorus from wastewater treatment plants (WWTPs) to agricultural soils. However, recent and growing concerns over per- and polyfluoroalkyl substances (PFAS) have placed biosolids programs under increasing regulatory pressure, resulting in outright bans in several jurisdictions. Landfill leachate (LL) co-treatment at WWTPs is common, but most WWTPs perform poor PFAS treatment, allowing most influent PFAS to end in the treated effluent and biosolids. This short communication analyses the current state of knowledge in regard to PFAS mass loadings between LL an WWTPs, and follows by surveying current biosolids PFAS regulations, bans, and monitoring requirements across major global jurisdictions and argues that prevailing regulatory responses are potentially misdirected. While public and regulatory attention has focused on the end product, biosolids, addressing and intercepting concentrated upstream PFAS sources such as industrial wastewaters and LL remains largely unmanaged prior to co-treatment at WWTPs. LL frequently contains PFAS concentrations orders of magnitude higher than municipal wastewater influent and, where co-treated, can contribute to a disproportionately large (∼11.7%) PFAS mass loading, while representing a relatively small fraction of total influent flow (0.05-1.3%). In the absence of upstream controls, increasingly restrictive biosolids standards risk dismantling effective nutrient recycling programs without delivering meaningful reductions in environmental PFAS loading. Source control, targeted monitoring, and pretreatment of LL offers a more balanced and effective policy pathway.