Control of emerging compounds in biological treatment of wastewater by advanced pre-oxidation

The ubiquitous occurrences of pharmaceuticals in the environment have resulted to emerging adverse effects to both humans and animals. The integration of chemical and biological processes is deemed as a sound, cost-effective and environment-friendly alternative of removing emerging contaminants such as pharmaceuticals found in municipal wastewaters. This study investigates the impacts of the pre-oxidation treatment using enhanced ozonation by sonolysis (O3/US) on the performance of a membrane bioreactor (MBR) to remove selected pharmaceuticals - diclofenac (DCF), sulfamethoxazole (SMX) and carbamazepine (CBZ). The influence of chemical pre-oxidation in terms of its performance in the membrane fouling control and its biological toxicity were also investigated. The enhanced O3/US using a constant power density of 370 W/L and an ozone flow of 3.3 g/h was employed as the pre-oxidation treatment. The results indicate that the removal efficiencies of MBR with O3/US pre-oxidation were observed to be 83%, 84% and 80%, for DCF, CBZ and SMX, respectively. The transmembrane pressure (TMP) was found to be relatively lower for the MBR with pre-oxidation compared to conventional MBR (without pre-oxidation). Based on the toxicity test results, the O3/US preoxidation did not significantly lead to complete elimination of toxicity in wastewater