Screening Of Predominant Denitrifiaction Bacteria And The Application In Sediment Remediation By Using The Immobilized Technology

The high throughput DNA sequencing technology was adopted to investigate the microbial community of the river sediment. The dominant denitrification bacteria were screened from the sediment, the optimal cultivation included the medium and growth conditions. The enriched denitrification microorganisms were also analyzed using The high throughput DNA sequencing technology.After the immobilization of the denitrification enrichments, the nitrogen removal efficiency and the mechanism of the immobilized granule were studied in the lab.(1)The microbial community structure of the sediment collected from Shedu River, Yixing City was analyzed using the high throughput DNA sequencing technology. The results showed:the three genera(Betaproteobacteria、 Gammaproteobacteria、Deltaproteobacteria)of one phyla(Proteobacteria)and two pphyla(Firmicutes、Chloroflexi)are dominant groups in the sediment, which was similar to the community structures observed in the other freshewater lakes. However, only 22.45% sequences achieved were at genus level,and The heterotrophic nitrification and aerobic denitrification bacteria accounted for 1.67% in the sediment, while the total denitrification bacteria account for 6.17% in the sediment.(2)The predominant denitrification bacteria were screened from the raw sediment by enrich panning. Pseudomonas、Alcaligenes、Proteiniclasticum、Achromobacter、 Methylobacillus were dominant microflora,which accounted for 94.43% of the total bacteria. Among the analyzed bacteria, the genera (Pseudomonas) belonging to Gammaproteobacteria,accounted for 50% and functioned as,the most primary advantage denitrification bacteria.The corresponding culture conditions were:carbon source CaCO3+Na3C6H5O7,carbon concentration 3g/L,temperature 30℃,pH=8,trace elements 0.4ml/L,inoculation amount 5%.The removals of the TN、NH4+-N were 84.4%、84.8%, respectively.(3)To make it easier to form ball, reduce the gel beads swelling and improce its resistance to fragility, the granule immobilization technology of nitrogen removal bacteria was examinated..The optimized scheme was:0.6% attapulgite,0.5% CaCO3,3.5% SiO2,8% PVA,0.25-1% Na-alginate,0.05-0.1% Na-alginate(g)/microbe liquid(ml).The beads crosslinked after 4～5 hours’ cooling with saturated H3BO3、 CaCl2 solutions, were found to be the best immobilized ones.(4) The nitrogen removals were compared among detached engineeringbacteria amendment, beads addition without microorganism, and the amendment of engineering bacteria added activated beads. The removal of N after adding beads without microorganism was 10%,due to the adsorption of the beads. The removals of NH4+-N, TN after adding detached engineeringbacteria were 50.5%,49.3% respectively. The removals of NH4+-N, TN after adding activated beads went up to 68.13%、67.8%.The denitrification effect of detached engineeringbacteria was more apparent.However, the activated beads showed a more continuous denitification activity..The optimum dosage of the activated beads was 1.77-2.12kg/m2.This study can provide an alternative for in situ bioremediation for endogenouspollution of river.