Long-term experiments with municipal wastewater were performed to assess the potential for extended biological micro pollutant removal under different redox conditions and substrate concentrations (carbon and nitrogen). A total of 31 organic micro pollutants were monitored through influent-effluent sampling of twelve municipal wastewater reactors. In accordance with the results from the sludges grown on synthetic wastewater,several compounds such as bezafibrate, atenolol and acyclovir were significantly removed in the activated sludge processes fed with municipal wastewater. Complementary removal of two compounds,diuron and diclofenac, was achieved in an oxic biofilm treatment .A few aerobically persistent micro pollutants
such as venlafaxine, diatrizoate and tramadol were removed under anaerobic conditions, but a
large number of micro pollutants persisted in all biological treatments. Collectively, these results indicate that certain improvements in biological micro pollutant removal can be achieved by combining different aerobic and anaerobic treatments, but that these improvements are restricted to a limited number of compounds.