Enrichment of denitrifying anaerobic methane oxidation microbes in a hollow fiber membrane bioreactor

The process of denitrifying anaerobic methane oxidation (DAMO) can be catalyzed by DAMO bacteria called Methylomirabilis oxyfera with or without the involvement of DAMO archaea. Enrichment of DAMO microbes often takes a long time (7~18 months) to show a faint denitrification function in reported DAMO process. This study aimed to fast enrich DAMO microbes in a hollow fiber membrane bioreactor (HFMB) as the special structure of hollow fiber can increase the mass transfer of methane. It is found that HFMB shows DAMO activity in a shorter period of time (<3 months) and the denitrification rate reaches 50 mg·L-1·d-1 NO3--N. The next-generation DNA sequencing on the microbes in HFMB shows that Anaerolineaceae, Azospira, CL500-3 are dominant with 3908%, 1368% and 1154% of the total microbes, respectively. Meanwhile, Methylomirabilis (DAMO bacteria) and Methanosarcina (DAMO archaea) are only 002% and 013%, respectively. It is speculated therefore that the DAMO process in HFMB may have been catalyzed by other microbes that are different from the known DAMO microbes.