Performance of a Submerged Anaerobic Membrane Bioreactor (SAnMBR) for Food Wastewater Treatment: Treatment Efficiency and Membrane Fouling

This study investigated the response of an AnMBR to various organic load rates by evaluating COD removal efficiency, biogas production and membrane fouling behaviour. The reactor was equipped with a submerged hollow fibre UF membrane and operated in continuous mode. Performances at three HRTs (5, 2 and 1 day) were investigated. Wide fluctuation of feed characteristics was observed, though it did not cause significant variation in performance. Average MLSS was 2.0-2.6 mg/L, SRT was constant at 50 days and average OLRs were 0.44, 1.43 and 3.14 Kg m–3 d–1 in Phase I, II and III. The reactor was able to achieve total COD removal efficiencies of 88 – 95% with effluent COD concentrations of 96, 170 and 373 mg/L in the three Phases. Daily biogas production went up from 0.36 L/day in Phase I to 2.7±0.6 L/day in Phase III showing a positive correlation with the increase of OLR. The membrane had a maximum flux rate of 6.4 LM–2 H–1 and showed no significant sign of fouling until towards the end of Phase III. High level of EPS (97-105 mg/gVSS) supposedly aggravated membrane fouling due to development of cake sludge. The study clearly supports the applicability of submerged AnMBR in treating meat processing wastewater.