Anaerobic membrane bioreactor for high-strength wastewater treatment: batch and continuous operation comparison
The anaerobic membrane bioreactor (AnMBR) is a recent development in high-rate anaerobic bioreactors. This study assessed the treatment of high-strength wastewater by an AnMBR using batch and continuous feeding operation. The results showed that the AnMBR could establish a biomass concentration of 6–8 g/L in approximately 20 days due to retention of micro-organisms by the membrane, resulting in 86% chemical oxygen demand (COD) removal efficiency in the treatment of high-strength brewery wastewater. Batch operation was proven to be effective for an organic loading rate (OLR) up to 2 gCOD/L/day and was beneficial to the membrane filtration. However, the treatment capacity of the AnMBR with batch feeding was limited by the high instantaneous OLR during the feeding period. Compared to batch operation, continuous feeding can achieve improved stability and better effluent quality, but prolonged continuous permeation may make the membrane more susceptible to fouling. Although a critical flux of 22 L/m2/h was determined for the membrane filtration in the AnMBR tested, a decrease in the membrane permeability was still observed in the long-term filtration at a flux of approximately 10 L/m2/h.