Biotransformation of trace organic compounds by activated sludge from a biological nutrient removal treatment system

The removal of trace organic compounds (TOrCs) and their biotransformation rates, kb (L gSS−1 h−1) was investigated across different redox zones in a biological nutrient removal (BNR) system using an OECD batch test. Biodegradation kinetics of fourteen TOrCs with initial concentration of 1-36 μg L−1 in activated sludge were monitored over the course of 24 h. Degradation kinetic behavior for the TOrCs fell into four groupings: Group 1 (atenolol) was biotransformed (0.018-0.22 L gSS−1 h−1) under anaerobic, anoxic, and aerobic conditions. Group 2 (meprobamate and trimethoprim) biotransformed (0.01-0.21 L gSS−1 h−1) under anoxic and aerobic conditions, Group 3 (DEET, gemfibrozil and triclosan) only biotransformed (0.034-0.26 L gSS−1 h−1) under aerobic conditions, and Group 4 (carbamazepine, primidone, sucralose and TCEP) exhibited little to no biotransformation (<0.001 L gSS−1 h−1) under any redox conditions. BNR treatment did not provide a barrier against Group 4 compounds.