Nitrogen source effects on the denitrifying anaerobic methane oxidation culture and anaerobic ammonium oxidation bacteria enrichment process

The co-culture system of denitrifying anaerobic methane oxidation (DAMO) and anaerobic ammonium oxidation (Anammox) has a potential application in wastewater treatment plant. This study explored the effects of permutation and combination of nitrate, nitrite, and ammonium on the culture enrichment from freshwater sediments. The co-existence of NO 3 − , NO 2 − , and NH 4 + shortened the enrichment time from 75 to 30 days and achieved a total nitrogen removal rate of 106.5 mg/L/day on day 132. Even though ammonium addition led to Anammox bacteria increase and a higher nitrogen removal rate, DAMO bacteria still dominated in different reactors with the highest proportion of 64.7% and the maximum abundance was 3.07 ± 0.25 × 10 8 copies/L (increased by five orders of magnitude) in the nitrite reactor. DAMO bacteria showed greater diversity in the nitrate reactor, and one was similar to M. oxyfera ; DAMO bacteria in the nitrite reactor were relatively unified and similar to M. sinica . Interestingly, no DAMO archaea were found in the nitrate reactor. This study will improve the understanding of the impact of nitrogen source on DAMO and Anammox co-culture enrichment.