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Enhancing the Microbial Removal of Organic Micropollutants in Wastewater Treatment Processes

The discharge of trace levels of organic micropollutants (OMPs) to water bodies from wastewater treatment plants has raised concerns over the adverse effects on the health of aquatic and terrestrial organisms. Operational costs of current OMP removal technologies (e.g. reverse osmosis and UV treatment) are prohibitive expensive for many water treatment facilities. Previous studies have demonstrated that oxidative stress can induce the synthesis of oxidoreductases, which can catalyze OMP hydroxylation and further biodegradation. We present the results of an experimental study to promote OMP removal from farm and municipal wastewater by inducing enzyme production using dynamic oxygen control. Microbial consortia from dairy farm runoff sludge was cultivated in fed-batch reactors (FBR) given synthetic wastewater containing acetate as carbon source and a mixture of ten OMPs (trimethoprim, sulfamethoxazole, tylosin, carbamazepine, ibuprofen, naproxen, triclosan, sucralose, atrazine and nonylphenol) at a concentration of 0.1 mg/L. Removal of OMPs was caused by a combination of biotic and abiotic factors. Triclosan, atrazine and trimethoprim were largely removed by non-biological processes. Cyclic perturbation of dissolved oxygen concentration enhanced the biodegradation of ibuprofen, sulfamethoxazole, tylosin, nonylphenol and naproxen. These results indicate that cyclic DO perturbation in biological treatment processes can enhance OMP removal, however the specific mechanism behind this behavior is yet to be elucidated.