Polybrominated diphenyl ether (PBDE) removal from wastewater: a perspective on advancing microbial technologies

Contaminants of emerging concern (CEC) continue to plague wastewater treatment facilities in their battle to recover water resources and circumvent environmental contamination. Of particular challenge are legacy pollutants - pollutants that are no longer in use but continue to enter wastewater treatment facilities due to their historic uses. Among these pollutants are polybrominated diphenyl ethers (PBDEs), a flame retardant used in many consumer products. PBDEs have been detected in waterways worldwide and were documented to impact juvenile Chinook salmon in the waterways of Puget Sound in Washington State, USA. This has both economic impacts in the region where salmon is a major commercial export, and societal implications where native tribes have deep cultural heritage connections with salmon. PBDEs are primarily removed from wastewater by sorption to wastewater sludge. However, this process can result in long-term impacts when PBDEs re-emerge in landfill leachates after sorptive material disposal. In this perspective, we explore what is currently understood about engineered solutions for the removal of PBDEs from wastewater, and we present an approach for the permanent destruction of PBDEs, which combines anaerobic bioprocesses for initial debromination, followed by aerobic treatments for the final degradation of the PBDEs. Through this perspective, we hope to inspire global research efforts to develop sustainable biological treatment solutions for CEC destruction during wastewater treatment.