Efficient anaerobic treatment of polymer-manufacturing wastewater containing polyfluoroalkyl substances

Industrial effluents often display complex characteristics and contain persistent organic compounds, some of which are toxic and difficult to remove. This study evaluated the capacity of an anaerobic reactor to treat wastewater from a polymer factory containing polyfluoroalkyl substances (PFAS), glycols, aldehydes, and phenols. The catalytic effect of metals, recovered from metallurgical effluents, on reactor performance was also assessed. Bioreactors achieved high organic matter removal linked to methanogenesis and sulfate reduction, showing good adaptation to the complex wastewater. The metal-enriched reactor showed enhanced methane production, contributing to 59% of chemical oxygen demand (COD) removal, compared to 34% in the control reactor. In contrast, sulfate reduction accounted for 40% of COD removal in the metal-enriched reactor, versus 65% in the control. The presence of metals favored the precipitation of sulfide, derived from sulfate reduction, as insoluble minerals, resulting in consistently low H₂S concentrations in the biogas from the enriched reactor. The enriched reactor produced twice as much fluoride as the control, suggesting greater C F bond cleavage and more intense defluorination of 8:2 FTS (fluorotelomer sulfonic acid), the main PFAS identified. In conclusion, anaerobic systems can effectively treat complex polymer-factory wastewater, and metal enrichment enhances PFAS degradation and overall performance. • High COD removal was achieved from highly toxic, PFAS-containing wastewater. • Methanogenesis and sulfate reduction occurred during the treatment. • Enrichment with catalytic metals enhanced defluorination of PFAS. • Efficient strategy to treat industrial wastewaters containing toxic contaminants.