Comparison between a sequencing batch membrane bioreactor and a conventional membrane bioreactor

An operation of a membrane bioreactor in sequencing batch mode named a sequencing batch membrane bioreactor (SBMBR) was investigated for enhancing nitrogen and phosphorus removal. Its performance was compared with a conventional membrane bioreactor (CMBR) at various influent COD/TN ratios of 3.4–28.2. The operational parameters were optimized to increase the treatment efficiency. COD removal averaged at 94.9 and 97.7%, respectively, for SBMBR and CMBR during the 8 months experimental period. The SBMBR system demonstrated good performance on nitrogen and phosphorus removal at different COD/TN ratios. When COD/TN was 6.3 and the total nitrogen (TN) load was 0.22 kg/(m 3 days), the TN and ammonium nitrogen removals of the SBMBR were maintained over 65 and 90%, respectively. Total phosphorus (TP) removal of the SBMBR was approximately 90% during most of the experimental time. In comparison, the CMBR did not perform so well. Its effluent TN concentration was close to that in the influent at COD/TN = 6.3 and TP removal was not stable. The specific nitrification rate test showed that pH value affected the activity of nitrifiers but no irreversible harm was induced. Furthermore, the sequencing batch mode operation of MBR retarded membrane fouling according to the monitoring of trans-membrane pressure (TMP).