Anaerobic dynamic membrane bioreactor treating sulfamethoxazole wastewater: advantages of dynamic membrane and its fouling mechanism.

ABSTRACT

Discharge of improperly treated sulfamethoxazole (SMX) wastewater seriously threats environmental security and public health. Anaerobic dynamic membrane bioreactors (AnDMBRs) technology would be cost-effective for SMX wastewater treatment, considering its low cost and satisfactory treatment efficiency. The performance of AnDMBR, though demonstrated to be excellent in treating many types of wastewaters, was for the first time investigated for treating SMX wastewater. Particular efforts were devoted to elucidating the advantages of dynamic membrane (DM) and the governing mechanism responsible for DM fouling with the presence of SMX. The threshold SMX concentration for AnDMBR was found to be 90 mg/L and the AnDMBR exhibited excellent removal efficiency of COD (90.91 %) and SMX (88.95 %) as well as satisfactory acute toxicity reduction rate (88.84 %). It was noteworthy that the DM made indispensable contributions to the removal of COD (14.26 %) and SMX (22.20 %) as well as the acute reduction of toxicity (25.81 %). The presence of SMX significantly accelerated DM fouling mainly by increasing its specific resistance, which was attributed to the increased content of small particles, high-valence metal ions and EPS content (mainly hydrophobic proteins), resulting in a denser DM structure with lower porosity. Besides, the biofouling-related bacteria (Firmicutes) was found to be enriched in the DM with the presence of SMX.