Belastningen på Vetlanda avloppsreningsverk från IFA-deponins lakvatten vid Flishults avfallsanläggning : En belastningsanalys av nuläge samt beräknad PFAS-reduktion med pilottestade reningstekniker

Sammanfattning

Leachate from municipal solid waste landfills contains a complex mixture of contaminants that can negatively affect both receiving wastewater treatment plants and downstream water bodies. Each landfill is unique and the composition of the deposited waste varies, giving rise to varying contaminant profiles in the leachate. Leachate must therefore be analysed and evaluated in order to assess the pollution risk and the load it imposes on receiving treatment plants and water bodies. This study quantified the pollutant load on Vetlanda wastewater treatment plant (WWTP) from the leachate of the non-hazardous waste landfill (IFA) at Flishults waste management facility, including metals, total nitrogen, biochemical oxygen demand, total organic carbon and PFAS. Further, the study examined how pilot-tested PFAS treatment technologies affected the pollutant load, and whether a hypothetical direct discharge of the leachate to the receiving water body Emån would result in exceedances of applicable environmental quality standards. The load analysis was based on monitoring data and flow measurements from Njudung Energis monitoring programme for the period 2020–2025, with PFAS data covering the period 2022–2025. Treatment efficiency was calculated from the results of pilot trials conducted by ECT2 and Swedish Hydro Solutions AB. Although IFA leachate accounted for only 2–3 % of the total incoming water volume to the WWTP during the study period, it contributed up to 17 % of the nickel load and 34–55 % of the PFAS load. The increasing share of nickel was not attributable to rising concentrations in the leachate, but rather to a decline in contributions from other sources. Metal concentrations in the leachate have decreased substantially since the late 1990s and currently fall below applicable permit limit values, whereas PFAS concentrations show no equivalent downward trend. Both pilot-tested treatment technologies demonstrated a significant reduction of the PFAS load to the WWTP. In the hypothetical direct discharge scenario, calculated concentrations of PFOS and PFAS 11 in Emån remained below applicable environmental quality standards after dilution. Overall, the study demonstrates that the IFA leachate, despite its limited volume, contributes a significant share of the pollutant to the WWTP and that the pilot-tested treatment technologies have the potential to substantially reduce the PFAS load ahead of upcoming discharge requirements.