To enhance the existing anaerobic-anoxic-oxic activated sludge processes by reducing the effective substrate, a pilot-scale plant experiment was conducted. The system included anoxic, selector, and aerobic membrane bioreactor (MBR) processes, aimed at understanding substrate reduction behavior in treating domestic wastewater containing night-soil (pH 6.8±0.5, BOD 148.6±43.7 mg/L, COD 94.6±26.4 mg/L, SS 157.3±51.2 mg/L, color 232.6±126.4 unit, T-N 39.223±13.257 mg/L). The hydraulic retention time (HRT) of the anoxic-aerobic MBR (ANOMBR) system was less than 5.7 hours. The MBR featured two plate-type membrane modules with an effective pore size of 0.4 um. The results showed residual ratios of substrate ranging from 0.03-0.08 for BOD, 0.05-0.10 for COD, 0.07-0.14 for NH4-N, and 0.28-0.38 for NO3-N. The substrate residual ratio of the upper membrane module was 10-20% lower than that of the lower membrane module in aerobic MBR. Permeate flux decreased with increasing HRT, while both transmembrane pressure (TMP) and resistance increased. TMP and resistance of the lower membrane module were relatively lower than those of the upper membrane module, which is attributed to the hydraulic shear force produced by aeration through the diffuser located at the bottom of the reactor.
