Microbiology community changes during the start-up and operation of a photosynthetic bacteria-membrane bioreactor for wastewater treatment

Abstract

A pilot-scale photosynthetic bacteria-membrane bioreactor was applied to treat wastewater and culture photosynthetic bacteria (PSB) cells, and microbial communities at different stages were analyzed to reveal the underlying roles of efficient long-time operation of this reactor. After 40days start-up, the reactor was successfully operated for 180days. The results showed that the PSB-membrane bioreactor operated stably, with high COD and NH3-N removal efficiency of 95%. The PSB biomass could maintain a high cell concentration with a 10% harvest each day. Analysis of the microbial community showed that bacterial communities changed dramatically at different stages. The dominant bacteria were Ectothiorhodospira in the beginning to Caenispirillum and Pannonibacter during the stable operation. The Shannon index from 1.876 dropped to 1.477 after 6months. The diversity of PSB community decreased during the process. It revealed that the microbial community on the membrane was more diverse than that inside the bioreactor.