Assessment of bioelectrochemical materials and aeration in constructed wetlands for reducing contaminants of emerging concern from reverse osmosis brine

Reverse osmosis (RO) can be used to produce clean water from wastewater effluents but it generates pollutant-rich brines, including nutrients and Contaminants of Emerging Concern (CECs). We evaluated laboratory-scale constructed wetlands (CWs) built with coke and biochar substrates (and sand as control) under non-aerated and aerated conditions for their efficiency in removing nutrients and CECs from RO brines. We assessed the treatment of brine produced by aged and new RO membranes, covering different pollutant loads. Brine from the newly installed RO membrane contained CEC concentrations up to 40 times higher than the aged-membrane brine. Nutrient removals were similar in all CWs (>60% for nitrogen and phosphorous). Biochar CWs exhibited >90% removal for 12 out of 13 CECs, even under high-pollution input conditions, where coke and sand showed average removals of 73%. Aeration increased the removal of certain CECs (ca. 30%) only in coke-built CWs under the high-pollution input conditions. Adsorption of CECs on biochar was low (