Electrooxidation pretreatment prevents membrane fouling and improve treatment efficiency of a membrane bioreactor treating reject water and condensate generated during sludge dewatering

Abstract

This study explored electrooxidation pretreatment of reject water and condensate generated using sludge dewatering with goal of improving its treatment using a membrane bioreactor (MBR) and also prevent membrane fouling. Initially the important parameters for electrooxidation process were optimized. The results showed that a total current of 4.03 A/L, current density of 60 mA/cm2, pH 7, and 1500 mg/L of Cl- ion concentration were best in terms of solubilization and removal of fouling-causing substances from wastewater. The colour removal from the wastewater could be as high as 92.4% (7 colour unit (CU) of treated effluent) under optimum operating condition. For biological treatment, a four-tank biological system consisting of consequently placed anoxic and aerobic compartments with final tank containing a MBR was used. When compared with untreated wastewater, the MBR treating EO pretreated wastewater showed significant improvement in terms of membrane fouling measured as transmembrane pressure (TMP). Further improvement in the nitrogen and TOC removal could be achieved by extending the EO treatment duration and subsequent HRT of MBR treatment. The findings from the study clearly demonstrates the potential for integrating a combined electrooxidation and MBR treatment in the conventional wastewater treatment plant for reducing its influent pollutant load.