Occurrence and removal of legacy plasticizers and flame retardants through a drinking water treatment plant

Abstract

The occurrence of thirty-four flame retardants and plasticizers throughout treatment steps in a drinking water treatment plant (DWTP) was analyzed to assess removal efficiencies of filtration, ultraviolet (UV) treatment, and chlorination. Legacy compounds and replacements were included to compare their presence and persistence. Twenty-four-hour composite sampling, offset to account for retention time, was performed at a direct filtration DWTP in Montreal, Canada over a three-day period. Polybrominated diphenyl ethers (PBDEs), considered legacy flame retardants, were infrequently detected or at concentrations <1 ng/L. When overall removal efficiencies could be calculated, the removal of ∑7PBDEs was 49 and 94 % for days 2 and 3, respectively. No removal could be calculated on day 1 as PBDEs were only detected in finished drinking water. Higher brominated PBDEs BDE-183 and BDE-154 were only detected in raw water. Organophosphate esters (OPEs), considered replacement flame retardants, were frequently detected in all water samples. The total average concentration of ∑15OPes was 501 ng/L in raw water and 162 ng/L in drinking water, with an average removal efficiency of 67 %. OPEs were mainly removed during filtration, with TCIPP, TDCIPP, and TPHP showing statistically significant removal of 76, 84, and 95 %, respectively. The total average concentration of ∑8plasticizers was 2938 ng/L in raw water and 116 ng/L in drinking water. All plasticizers, except for metabolite MEHP, had significant removal from filtration, and the overall removal of plasticizers ranged from 20 % for DEP to 99 % for DEHP. Drinking water treatment decreases the concentration of these contaminants in drinking water but was less effective in removing flame retardants than plasticizers, as indicated by their higher number of PBDEs detected and higher concentrations of OPEs measured. To our knowledge, it is the first report of the removal of PBDEs, OPE metabolites and plasticizer replacements (DEHA, DIDA, DINCH, DINP) during drinking water treatment.