Submerged membrane bioreactor in treatment of simulated restaurant wastewater

Submerged membrane bioreactors (MBRs) were employed as a subsequent process following the electrocoagulation and electroflotation of restaurant wastewater, which is characterized as high content of oil, grease, suspended solid and detergent. The performance of two parallel MBRs was tested with simulated restaurant wastewater of respectively low and high initial concentrations of oil and detergent. The organic matter removal, sludge production and sludge properties, as well as membrane filtration performances were investigated. The overall COD removal efficiencies were 98.3% and 99.1%, respectively, when the initial influent contained 5 and 100 mg/L oil. The biological treatment was found to be the dominant contributor for COD removals in the MBRs. The presence of detergent showed a positive effect on fouling mitigation due to the modification of the membrane surface and the formation of relatively loose sludge cake. (C) 2012 Published by Elsevier B.V.