Synthetic hospital wastewater treatment by coupling submerged membrane bioreactor and electrochemical advanced oxidation process: Kinetic study and toxicity assessment

In this work, the combination of membrane bioreactor (MBR) and electro-oxidation (EC)) process was studied for the treatment of a synthetic hospital wastewater fortified with four pharmaceutical pollutants namely carbamazepine (CBZ), ibuprofen (IBU), estradiol (E-E) at a concentration of 10 mu g L-1 venlafaxine (VEN) at 0.2 mu g L-1. Two treatment configurations were studied: EC) process as pre-treatment and post-treatment. Wastewater treatment with MBR alone shows high removal percentages of IBU and E-E (similar to 90%). Unlikely for CBZ and VEN, a low elimination percentage (similar to 10%) was observed. The hydraulic and the solid retention times (HRT and SRT) were 18 h and 140 d respectively, while the biomass concentration in the MBR was 16.5 g L-1. To enhance pharmaceuticals elimination, an ED pretreatment was conducted during 40 min at 2 A. This configuration allowed a 92% removal for VEN, which was far greater than both treatments alone, with lower than 30% and 50% for MBR and E0, respectively. The MBR-EO coupling (EC) as post-treatment) allows high removal percentages (similar to 97%) of the four pharmaceutical pollutants after 40 min of treatment at a current intensity of 0.5 A with Nb/BDO as electrodes. This configuration appears to be very effective compared to the first configuration (EO-MBR) where ED process is used as a pre-treatment. Toxicity assessment showed that the treated effluent of this configuration is not toxic to Daphnia magna except at 100% v/v. The MBR-EO coupling appears to be a promising treatment for contaminated hospital effluents. (C) 2017 Elsevier Ltd. All rights reserved.