REMOVAL OF ALCOHOL ETHOXYLATES, ALKYL ETHOXYLATE SULFATES, AND LINEARALKYLBENZENE SULFONATES IN WASTE-WATER TREATMENT

An environmental monitoring study was conducted to assess the removal of alkyl ethoxylate sulfates (AESs), alcohol ethoxylates (AEs), and li near alkylbenzene sulfonates (LASs) during wastewater treatment. Sampl es were obtained from six trickling filter and four activated sludge t reatment plants located in the midwestern United States. The average r emoval rates for AESs, AEs, and LASs in activated sludge treatment wer e 98, 97, and >99%, respectively. Lower and more variable removal rate s were observed at trickling filter treatment plants with average valu es of 83, 90, and 82% for AESs, AEs, and LASs, respectively. Using ave rage influent concentrations and removal rates, the predicted exposure concentrations for these surfactants in U.S. receiving waters immedia tely 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.