Synthetic wastewater was treated in a moving bed biofilm reactor(MBBR)using different operation modes

namely

continuous oxic operation mode(CMBBR)

single stage oxic sequencing batch operation mode［SBMBBR(O)］ and anaerobic/oxic sequencing batch operation mode［SBMBBR(A/O)］.The experimental results indicated that the removal of COD was similar for the three operation modes

while that of TN and TP was quite different.Compared with CMBBR

SBMBBR(O)operation mode was more favorable for the process of simultaneous nitrification and denitrification(SND)due to cyclical change of DO concentration in single period of operation and TN removal efficiency of 74% was achieved.For SBMBBR(A/O)operation mode

organic carbon in influent could be effectively utilized by poly-phosphate-accumulating organisms and denitrifiers

TN and TP could be removed simultaneously and their efficiencies were 88% and 89% respectively

which indicated that TN removal efficiency was better for SBMBBR(A/O) than SBMBBR(O).Removal of TN was accomplished by anoxic denitrification during the filling and mixing stage

SND and denitrifying phosphorus removal in aerobic stage

while removal of TP was realized through conventional phosphorus removal and denitrifying phosphorus removal processes.