PFAS (Per- and Polyfluoroalkyl Substances) are everywhere around us in society; in products, the atmosphere, waste, wastewater, surface water, drinking water, groundwater, soil, plants, animals and in our bodies. The use and spread of PFAS is a global societal challenge and even the most remote places on earth are no longer unaffected by PFAS substances. One of the reasons why PFAS has been attractive in many products and industrial applications is the substances' extreme chemical and thermal stability. However, the same properties create challenges in the environment as the persistence of PFAS implies that even low emissions over time can be accumulated in different environments with a high risk of negative health and environmental effects. Today there are thousands of known and unknown PFAS with widely varying properties and toxicity, which makes both risk assessments and management of this growing environmental problem difficult.
A national mass balance for PFAS shows that emissions from products and atmospheric deposition are the major sources of PFAS to Sweden. The PFAS-amounts that are spread to the environment via wastewater and sewage sludge can be considered a minor part. However, due to the persistence of PFAS substances, measures to minimize the addition via these pathways may be relevant in order to reduce the total environmental load.
Considering the toxicity and persistence of PFAS, their use has been heavily regulated in recent times and the levels that are considered acceptable in the environment have been lowered. Many PFAS have already been banned in Sweden or the EU and assessment grounds or action limits have been defined for various PFAS in e.g. surface water bodies, groundwater and drinking water to initiate measures to reduce the spread of the substances. Already announced and upcoming stricter regulations will further increase the need for measures to minimize human exposure to PFAS and their dispersal in the environment. Regardless of which measures that are implemented, PFAS will remain in the environment for a long time, even if a global ban of the chemicals is implemented. A long-term management of PFAS is thus necessary with a gradual removal from the cycle. The focus of mitigation actions should primarily be on heavily contaminated land and landfill leachate.The review of existing data at Swedish sewage treatment plants and receiving recipients shows that today's treatment processes do not remove PFAS even of some PFAS are removed and end up in the sludge. At some sewage treatment plants, however, an effective separation of certain PFAS is observed, which should be investigated further. PFOS levels in many of the investigated inland surface waters receiving effluent from treatment plants and PFAS from other sources/pathways exceed existing limits. In many cases, however, analysis limitations prevent an assessment.
Ongoing activities around various treatment and destruction techniques for PFAS show that there are currently no techniques that achieve a far-reaching PFAS removal from municipal wastewater without significant resource consumption and related costs. For a continued use of sludge as a fertilizer, upstream mitigation is needed, with e.g. disconnection or treatment of PFAS-contaminated leachate. However, several ongoing projects indicate that a certain part of PFAS in wastewater can be removed as a side-effect of advanced treatment for pharmaceutical removal.The report also provides guidance to stakeholders on how the PFAS problem can be tackled. In addition, the report shows a great need to improve and spread knowledge about PFAS with, above all, measurement data and knowledge about treatment techniques and PFAS in sludge in order to be able to meet the PFAS challenge.