The effect of salinity on ammonia-oxidizing bacterial community in the Conventional Sequencing Batch Reactor (CSBR) and Intermittently Aerated Membrane Bioreactor (IAMBR)

The effect of salinity on the community compositions and abundance of ammonia-oxidizing bacteria (AOB) were investigated in the conventional sequencing batch reactor (CSBR) and intermittently aerated membrane bioreactor (IAMBR). The salinity loadings were set at 0, 5 and 10 g/L (referring to NaCl) respectively. The removal of total organic carbon (TOC) and conversion of ammonia-nitrogen (NH4+- N) were stable in the IAMBR, while significant decreases were observed in the CSBR under high salinity. Denaturing gradient gel electrophoresis (DGGE) analysis revealed that the dominant AOB species were Nitrosospira-like and Nitrosomonas-like species in the two reactors. The cluster analysis showed significant changes of the AOB populations with the increase of salinity in the CSBR. The results of Real-time PCR also showed higher AOB content in the IAMBR than that in the CSBR. These can interpret the better performance of the IAMBR than CSBR under increased salinity stress.