Degradation of emerging contaminants by acclimated activated sludge

The emerging organic micro-pollutants (EMOPs) cannot be effectively removed by conventional wastewater treatment processes. In this paper, the most commonly detected EMOPs in the effluent of wastewater treatment plants, including trimethoprim, sulfamethoxazole, carbamazepine, diclofenac, triclosan and methyl 3,5-dichloro-4-hydroxybenzoate, were selected to acclimate activated sludge, to enhance the biodegradation of EMOPs. The results showed that the acclimated activated sludge can significantly enhance the removal of trimethoprim, sulfamethoxazole, diclofenac, triclosan and methyl 3,5-dichloro-4-hydroxybenzoate, but slightly improve the degradation of carbamazepine. The distribution of six EMOPs between water and sludge phases demonstrated that biodegradation made a major contribution to their removal. The maximal degradation rate constants were determined to be 0.9028 (sulfamethoxazole), 0.5374 (trimethoprim), 0.4123 (triclosan), 0.3544 (diclofenac), 0.2534 (methyl 3,5-dichloro-4-hydroxybenzoate) and 0.0224 (carbamazepine). Degradation intermediate products were detected in water phase at the end of the acclimation process through the comparison of high-performance liquid chromatography figures before and after the acclimation process, suggesting that degradation products of EMOPs might be in the effluents. In summary, the acclimation of activated sludge could be an option for removing EMOPs, and more attention should be paid to the degradation products of EMOPs in the effluent.