Heterotrophic nitrifiers and aerobic denitrifiers technology of simultaneous nitrification and the analysis of microbial diversity

To analyze the differences among microbial communities of heterotrophic nitrifiers and aerobic denitrifiers technology, 6 heterotrophic nitrifiers were screened from the bio-ceramic reactor. The results obtained showed that the removal rate of COD reached over 45%, and that of TN and NH₄⁺-N reached over 60%. After domesticating the activated sludge to enrich aerobic denitrifiers, 5 aerobic denitrifiers were isolated from it. The removal rates of TN were 90.4%, 91.2%, 94.6%, 95.6% and 97% by strains of f1, f2, f3, f5 and f7, respectively. The process of removing ammoniac nitrogen was done by setting the heterotrophic nitrifying bacteria and aerobic denitrifiers on the sequencing batch reactor. The PCR-DGGE profiles showed that the shift of microbial diversity corresponded to the effect of nitrate removal. Between 2 d and the 15 d, the diversity was 47.62%; it was 72% between 15 d and 30 d, which was the highest; the lowest one was just 42.86% between 2 d and 30 d, and at this time, the heterotrophic nitrobacteria wgy5 and wgy21, the aerobic denitrifiers d5 and Pseudomonas sp. were dominant bacteria in SBR.