Enhanced treatment of composite industrial wastewater using anaerobic-anoxic-oxic membrane bioreactor: performance, membrane fouling and microbial community

Abstract

BACKGROUND: A laboratory-scale anaerobic-anoxic-oxic membrane bioreactor (AAO-MBR) system was used to remove organic compounds and nitrogen in the composite industrial wastewater collected from an industrial park. RESULTS: The recommended conditions for both chemical oxygen demand (COD) and nitrogen removal were as follows: hydraulic retention time of 73.6 h, sludge retention time of 35 days and mixed liquor return ratio of 300%. Under this condition, COD and total nitrogen removal efficiencies were 89.4% and 77.7%, respectively. After treatment, most organic compounds were removed, but there were still a few refractory organic compounds in the final effluent, such as 2-hydroxydesmethylimipramine, 1-dichloromethyl-3-methyl-benzene and N-phenyl-2,3-dichloromaleimide. Compared to carbohydrates, proteins in the extracellular polymetric substances accumulated more easily on the membrane surface, resulting in the membrane fouling. Ternary analysis at the family level indicated that the bacteria Desulfuromonadaceae, Rikenellaceae, and Spirochaetaceae were dominant in the anaerobic sludge, and played an important role in hydrolysis and fermentation. The abundance distributions of Nitromonadaceae, Caldilineaceae and Xanthomonadales were above 50% in the anoxic sludge, and these bacteria played an important role in denitrification. CONCLUSION: The results can provide valuable information for optimizing the operation of the AAO-MBR system for the treatment of composite industrial wastewater. © 2019 Society of Chemical Industry.