Removal of alcohol ethoxylates, alkyl ethoxylate sulfates, and linear alkylbenzene sulfonates in wastewater treatment

An environmental monitoring study was conducted to assess the removal of alkyl ethoxylate sulfates (AESs), alcohol ethoxylates (AEs), and linear alkylbenzene sulfonates (LASs) during wastewater treatment. Samples were obtained from six trickling filter and four activated sludge treatment plants located in the midwestern United States. The average removal rates for AESs, AEs, and LASs in activated sludge treatment were 98, 97, and >99%, respectively. Lower and more variable removal rates were observed at trickling filter treatment plants with average values of 83, 90, and 82% for AESs, AEs, and LASs, respectively. Using average influent concentrations and removal rates, the predicted exposure concentrations for these surfactants in U.S. receiving waters immediately below treatment plant outfalls were less than their corresponding biological predicted no-effect concentrations in greater than 98% of the locations under low-flow conditions.