Anaerobic fluidized membrane bioreactor polishing of baffled reactor effluent during treatment of dilute wastewater

Abstract

AbstractBACKGROUNDIn this study an anaerobic fluidized bed membrane bioreactor (AFMBR) is added as a second stage to an operating anaerobic baffled bioreactor (ABR) to form a staged anaerobic baffled‐fluidized membrane bioreactor (SAB‐FMBR) operating at ambient temperature.RESULTSThe ABR first stage was operated at 3 h hydraulic retention time (HRT) and was followed by the AFMBR operated at 0.93 to 1.16 h HRT. The SAB‐AFMBR system was fed with complex synthetic wastewater with COD averaging 250 mg L−1. GAC fluidization increased the critical flux of the AFMBR due to fouling reduction associated with the cleaning action of the GAC particles on membrane surfaces. However, sustainable flux for long‐term operation of the AFMBR was lower than the critical flux determined in short‐term tests. Overall COD removal by the SAB‐FMBR system when operating at a sustainable flux (8–9 L m−2 h−1) was 96% with effluent COD of about 11 mg L−1 and suspended solids concentration near zero. The electrical energy required for system operation in the AFMBR was 0.0087 kWh m−3, much less than that of an anaerobic MBR using biogas sparging to control membrane fouling.CONCLUSIONThe AFMBR was applied successfully as a second stage polishing system for an ABR treating complex synthetic wastewater at a temperature of 25 °C. © 2014 Society of Chemical Industry