Carbamazepine removal from low-strength municipal wastewater using a combined UASB-MBR treatment system

Abstract

An Upflow Anaerobic Sludge Blanket reactor combined with a two-stage membrane bioreactor were operated for 193 days in order to evaluate the biological removal of carbamazepine -CBZ from low-strength municipal wastewater. The system worked in three different organic loads stages (0.7 ± 0.1 kg COD·m⁻³·d⁻¹, 0.4 ± 0.1 kg COD·m⁻³·d⁻¹ and 0.1 ± 0.0 kg COD·m⁻³·d⁻¹) to assess the impact of the influent OLR on operational parameters such as anaerobic and aerobic sludge retention time -SRT, acidity, volatile fatty acids -VFA, biomass activity or biogas production. The highest carbamazepine removals were achieved during the anaerobic stage (UASB reactor), reaching averages of 48.9%, 48.0% and 38.2% operating at high, medium and low OLR, respectively. The aerobic treatment (MBR) served as post-treatment, improving the removals, and the global UASB-MBR system reached averages of 70.0%, 59.6% and 49.8% when the influent was at medium and low OLR, respectively. The results demonstrate the potential of combined biological systems on the removal of recalcitrant pharmaceuticals.