Removal of micropollutants from urban wastewater using a UASB reactor coupled to a MBR at different organic loading rates

This study examines the removal of micropollutants (MPs) in a hybrid process that combines anaerobic and aerobic redox conditions under different Organic Loading Rates (OLRs). A laboratory-scale pilot-plant composed of an Upflow Anaerobic Sludge Blanket reactor (UASB) combined with a membrane bioreactor (MBR) was operated. Six MPs were analyzed: the hormones estrone, 17-α-ethinyl estradiol and 17-β-estradiol, the plasticizer bisphenol A and the pharmaceuticals carbamazepine and diclofenac. In order to study its influence on removal efficiencies, the system was operated at three different OLRs: high (0.67 ± 0.15 kg COD/m3 d), medium (0.37 ± 0.06 kg COD/m3 d) and low (0.11 ± 0.02 kg COD/m3 d). The results demonstrated the synergistic effects due to the double biological treatment, with removal rates above 90% for the hormones and the plasticizer. Pharmaceuticals were the most resistant compounds, being only partially removed in the liquid phase. Removal rates of the MPs were higher at high OLR of the influent.