Effects Of Temperature On Denitrification Capability And Microbial Community Structure In SBBR

This research used livestock and poultry wastewater, combined with the characteristics of it, the effect of SBBR denitrification, which was developed independently by ourselves, at different temperature conditions was discussed. Meanwhile, Polymerase Chain Reaction-Denaturing Gradient Gel Electrophoresis (PCR-DGGE) molecular biology technology was applied to reveal the change of the structure of bacterium group through fingerprint diagrams recorded of16S rRNA, nxrA and nirK gene, which were especially chosed as function gene of denitrification process. DNA sequences obtained in this study were compared with others in the U.S. national center for biotechnology information (NCBI) gene pool. Then main population of sample biological membrane was identified and structure of microbial species was discussed. So a comprehensive, objective understanding about SBBR microbial community reached out to us and some denitrification processes were inferred confirmedly.The results showed as follows:(1) Operation mode of3h aeration-lh stop aeration-3h aeration-lh stop aeration could make SBBR have a high efficiency of purification for livestock and poultry waste water at34℃,29℃,24℃. CODCr concentration of effluent<120mg/L, removal rate>92%; NH4+-N concentration of effluent<15mg/L, removal rate>80%. The SBBR volume loading of CODCr and NH4+-N were respectively greater than1.1kg·m-3·d-1,0.07kg·m-3·d-1,which belonged to strengthening process category.(2) SBBR always had simultaneous nitrification and denitrification (SND), shortcut nitrification and denitrification, anaerobic ammonium oxidation (ANAMMOX) ways at34℃,29℃,24℃. When water temperature was34℃or29℃, the accumulation rate of NO2-exceeded the24℃rate in a single reaction period. So shortcut nitrification status were more than4h, and shortcut nitrification denitrifying obviously appeared.(3)16S rRNA, NxrA, Nirk genes were chosed as targets, structure change of microbes corresponding at different temperature were discussed taxonomically. Proteobacterium、 Pseudomonas sp、Nitrobacter sp.、Planctomycetales were found preliminarily in SBBR after a series of split gel band, sequencing, comparing in NCBI. ANAMMOX existed obviously in wastewater processing from a molecular biology perspective.(4) Univariate ANOVA showed that community structure of bacteriabetween the three groups at34℃,29℃,24℃were all different significantly. Temperature as an essential environmental factor during bacteria greatly influenced all kinds of microbial growth and propagation. In addition to water temperature reduction with the increased diversity,29℃or higher34℃were suitable for most bacteria except NOB, diversity of which became more abundant when temperature decreased. With comprehensive consideration,29℃for SBBR was the best operating temperature.