Fouling behaviour of industrial waste-based ceramic membrane in anaerobic membrane bioreactor treating low strength wastewater

This work describes the fouling of industrial waste sugarcane bagasse ash ceramic membrane (pore size ~ 8.6 µm; water permeability 27.2 × 103 L/m2 h bar) in wastewater treatment in anaerobic membrane bioreactor (AnMBR). AnMBR system was operated in sequential batch reactor (SBR) mode at 18 h hydraulic retention time for 31 days. For influent concentration of 171 ± 12 mg COD/L, average chemical oxygen demand (COD) removal was high (~ 94%). Biomass activity of anaerobic sludge improved from 0.15 (day 1) to 0.35 mg CODremoved/mg MLVSS.d (day 31). Operating flux was maintained at 17.8 ± 1.4 L/m2 h and the transmembrane pressure reached up to 170 mbar on day 31, increasing at a rate of 15.7 mbar/d. Specific bound extracellular polymeric substance (EPS) concentration was much higher in surface deposits (356 mg EPS/g MLVSS) than in the reactor sludge suspension (32.3 ± 14.4 mg EPS/g MLVSS). Though SBR is a good alternative configuration to reduce membrane exposure to sludge and hence control the fouling rate, formation of cake layer (due to deposition of sludge fines on membrane surface) still cannot be prevented. Calculation of total filtration resistance (Rt) showed the resistance of the caked surface deposits, Rc (2.19 × 1012 m−1) to be dominant at 83% of Rt. Of the two fouling control strategies tested viz. filtration-relaxation (4 min–1 min) and permeate backflushing (up to 3 times operating flux), backflushing was more effective. These findings indicate the potential of these alternative membranes in wastewater treatment application; at the same time, further investigations are required to minimize membrane fouling.