Nitrogen and carbon removals from food processing wastewater by an anoxic/aerobic membrane bioreactor

An anoxic/aerobic membrane bioreactor (MBR) was applied to simultaneous removals of nitrogen and carbon from food processing wastewater in a laboratory scale experiment. By continuous runs under appropriate operational conditions, COD, NH4+N and TN removal was over 94, 91 and 74%, respectively. The anoxic reactor and aerobic MBR contributed 40-63 and 29-46% to COD removal, and 31-43 and 47-64% to NH4+N removal, respectively. Nitrification in the MBR could be enhanced by adding some carriers for growth of adhesive biomass when the system was operated at a shorter sludge retention time (SRT). The maximum volumetric COD and TN loadings as high as 3.4 kg COD m−3 day−1 and 1.26 kg N m−3 day−1 were achieved. Measurement results of sludge activity for nitrification were consistent with the effluent NH4+N concentration change.