Enhanced nitrogen and phosphorus removal from urban wastewater in a membrane sequencing batch reactor system

Membrane sequencing batch reactor (SMBR) is a membrane separation process coupled to a sequencing batch reactor (SBR). In this study, a SMBR system was operated in an anaerobic-alternating oxic/anoxic (O/A) mode [A-(O/A)ⁿ-SMBR]. Different alternating O/A time settings were studied and high performance on nutrient removal was achieved in the system. When the alternating O/A time was set at 30730min,15/15min,10/10min and 5/5min, the removal efficiencies of COD,NH₃-N,TN and TP was kept at 92.97-94.82%, 91.9-97.8%, 86.57-90.13% and 88.68%~94.86%, respectively. And the denitrifying P-uptake ratio and the specific nitrifying rate was 32.18%,41.75%,53.63%,50.06% and 4.11,4.23,4.35 and 4.36 mgNH₃-N/gVSS.h, correspondingly. The alternating O/A operation mode allowed the multi-nitrification/denitrification (phosphorus removal) occurred in series in the A-(O/A)ⁿ-SMBR system. As a result, performance of nutrient removal and the ability of denitrifying phosphorus removal were enhanced.