Abstract
A bench-scale oxygen-based membrane biofilm reactor (O2-MBfR) was used to treat greywater for organics and nitrogen removal. Highly dynamic multifunctional biofilm formed on fiber surfaces of the O2-MBfR. With an organics loading up to 4.26 g COD/m2-day, the MBfR successfully achieved simultaneous organics and nitrogen reduction, with average removal ratios of 95% for total chemical oxygen demand (TCOD), 98% for linear alkylbenzene sulfonates (LAS), and 99% for inorganic nitrogen (InON). Increasing feed loading rates led to the gradually decrease of dissolved oxygen (DO) concentration from 1.67 to 0.37 mg/L in the reactor, inducing the formation of complex biofilm containing distinct aerobic, aerobic-anoxic, and aerobic-anoxic-anaerobic layers; these all contributed to the simultaneous removal of both organics and nitrogen in MBfR. Mechanisms of organics and nitrogen removal included nitrification and aerobic denitrification in aerobic biofilm, partial nitrification in the aerobic-anoxic biofilm, and partial nitrification and anaerobic denitrification in the aerobic-anoxic-anaerobic biofilm due to the co-existence of multifarious functional microorganisms in the O2-MBfR. This study lays the foundation of process optimization and cost-cutting for the practical application of O2-MBfR for greywater treatment.