Biodiversity and quantification of functional bacteria in completely autotrophic nitrogen-removal over nitrite (CANON) process.

The research was conducted to investigate the microbial diversity and population with the different concentration of NH(4)(+)-N in a biofilm reactor filled with volcanic filter for completely autotrophic nitrogen-removal over nitrite (CANON) process. The reactor had an excellent performance with the decreasing of NH(4)(+)-N concentration from 400 to 200 mg L(-1) while NH(4)(+)-N removal loading reduced at the NH(4)(+)-N concentration of 100 mg L(-1). Biodiversity analysis indicated that Nitrosomonas related aerobic ammonia oxidizing bacteria (AOB) and Planctomycetales-like anaerobic ammonia oxidizing (anammox) bacteria were dominant functional bacteria. Despite the different influent NH(4)(+)-N concentration, anammox bacteria had a low and stable biodiversity, which was not the same to AOB. With the concentration reduction of influent NH(4)(+)-N, the estimates of total bacteria population ranged between 2.29×10(11) and 1.44×10(12) copies mg(-1) total DNA, and the quantity of AOB decreased while anammox bacteria kept stable. The population of Nitrospira increased and little Nitrobacter was detected during the experiment.