Polybrominated diphenyl ethers in an advanced wastewater treatment plant. Part 1: Concentrations, patterns, and influence of treatment processes

Abstract

Concentrations and patterns of the mono- through deca-substituted polybrominated diphenyl ether (PBDE) flame retardants were determined in all major unit operations and processes within a tertiary-level wastewater treatment plant (WWTP) having post-filtration ultraviolet light disinfection. The results show that PBDEs do not appear to be degraded substantially or otherwise removed by wastewater treatment processes such as anaerobic, anoxic, and aerobic biological treatment, anaerobic digestion, dissolved air flotation, or sand–anthracite filtration. An overall removal efficiency of 93% was observed for PBDEs in the WWTP due to sorption onto wastewater sludges, well below that predicted by equilibrium partitioning models. High levels observed in the resulting WWTP biosolids (~2.4 mg·kg–1 dry weight) may contaminate a wider environment through their use as a soil amendment. Lower concentrations of PBDEs contained within high volumes of aqueous WWTP effluent (~26 ng·L–1) may result in a large PBDE flux into receiving waters, posing a potential threat to drinking water supplies and fisheries resources. Key words: polybrominated diphenyl ethers (PBDEs), flame retardants, municipal wastewater treatment, domestic sewage, mass balance, congener patterns.