Study On The Aerobic Denitrification Bacteria Using For Removing Nirtogen Oxides In Flue Gas And The Suspension Bioreactor In Start-up Phase

The flue gas usually contains 3 %-8 % of oxygen, and aerobic denitrification bacteria can remove nitrogen oxides through denitrification from flue gas under aerobic condition.In this study, through the enrichment, screening and purification, two highly efficient aerobic denitrifying strains were screened out, one was from activated sludge and the other from the sand by the sea, and the two strains were named as HFHV(Halomonas variabilis)and HFAAT(Agrobacterium tumefaciens), respectively. The strain HFAAT, the colony of which was smaller and round, and the growth temperature was at 20-40 oC and the suitable growth p H value was 6.0-9.0. The strain HFHV, the colony of which was round and its edge was uniform, and the growth temperature was at 20-50 oC and the suitable growth p H value was 5.5-8.5. Both of them were Gram negative. The strain HFAAT was determined as Agrobacterium tumefaciens through utilizing BLAST to compare the 16 Sr DNA sequences in the Gen Bank nucleic acid database, combining with the physiological and biochemical test results. And there was no report on the aerobic denitrification performance of the strain. HFHV was identified as Halomonas variabilis based on the analysis of its gene sequence which showed highest similarity(99 %) to Halomonas variabilis.Comparing the aerobic denitrification performance of the two strains, the comprehensive performance of HFHV was the better. Thus HFHV was inoculated to the laboratory developed suspension bioreactor, and a start-up phase experiment was conducted and the effects of various parameters on the performance of aerobic denitrification were investigated. The results showed that the strain HFHV had good biochemical activity when the p H was in the range of 7-9, and the optimal inoculation amount was 10 %, the optimal C/N ratio was 9 and the optimal air flow rate was 1 L/min in the suspension bioreactor. When the initial nitrate concentration was 250 mg/L, the degradation rate was 94.32 %, and the removal amount was 985 mg. When the initial nitrate concentration was 4000 mg/L, the maximum removal amount can reached6666.68 mg at 60 h. Aerobic denitrifying bacteria had high degradation efficiency and tolerance to nitrate in suspended bioreactor, which can be further used in the study ofaerobic denitrification treatment of nitrogen oxides.