The AnMBR system was continuously fed with the brewery wastewater for 90 days, from days 147 to 238, excluding the BGB324 from days 213 to 216 when the system was shut down due to a recirculation pump failure. The maximum permeate COD was approximately 255 mg/L, which occurred on day 153 when the AnMBR was operated at a high MLSS concentration of 12.5 g/L with a high feed COD concentration of 19.1 g/L (Fig. 2). High permeate COD concentrations around 250 mg/L were also observed between days 179 and 186, which was likely caused by two batches of wastewater fed during this period. These batches had low TSS and COD concentrations but may have contained chemicals from cleaning detergents, which are toxic to biomass. A significant decrease in the MLSS concentration was observed after processing these two batches of wastewater. However, in spite of the fluctuation in the wastewater characteristics, the COD concentration in the membrane permeate remained relatively constant through the brewery wastewater treatment stages (Fig. 2). The average effluent concentration from 67 measurements over the brewery wastewater treatment period was 171.0 mg/L, with 250.0 mg/L determined as the 90th percentile. The effluent COD concentration for the brewery wastewater treatment was higher than that (100 mg/L) observed in the treatment of the synthetic wastewater at 10 gCOD/L/d. The BOD analysis showed that the BOD5 of the membrane permeate was in the range of 30–39 mg/L (Fig. 3) for the brewery wastewater treatment, while the COD concentration in the membrane permeate fluctuated between 148 and 290 mg/L.