Study On The Removal Efficiency Of Nitrate By Aerobic Denitrifying Bacteria(Alishewanella Sp.Y7)and Its Self-Aggregation Characteristics

With the rapid development of modern industry and social economy,the excessive amounts of nitrogen in the wastewater caused environment pollution problem increasingly prominent.Biological denitrification technology is the most economical and effective method,however,the traditional biological denitrification technology is high energy consumption,processing,such as complicated structure,covers an area of a big problem.Aerobic denitrification,as a kind of new biological nitrogen removal technology,because its can be a simultaneous nitrification and denitrification in the same structure and has high efficiency,low energy consumption,and the advantages of the structure is simple and is widely used,however,aerobic denitrification technology in the actual application will produce by biomass loss and it is difficult to efficiently to sustain denitrification effect.This study from the laboratory long running new reactor sludge and screened strain has good denitrification efficiency and higher since the aerobic denitrification strains capable of gathering,a preliminary analysis on the physiological and biochemical indexes and molecular biology identification,on the basis of the influence factors of the denitrification efficiency,the strain of Extracellular polymers(EPSs),composition and content of fluorescent components are studied,which provides the practical application of aerobic denitrifying bacteria.This study from the laboratory in the activated sludge,under the condition of C/N=6 new isolated from a strain of both aerobic denitrification characteristics and the characteristics of bacteria,preliminary determined for alternative and destroy bacteria(named Alishewanella sp.Y7(strain Y7)).Strains for carbon source for sodium citrate,p H 7,5% inoculated quantity,initial nitrate of 50 mg/L,the condition of fluid amount to 20 ml,nitrate nitrogen and total nitrogen removal rate is best,95.34% and 90.16%,respectively.EPSs contains a certain amount of inorganic nitrogen and nitrate nitrogen are generally stay loose bound extracellular polymers(LB-EPSs);And nitrate nitrogen are mainly distributed in tightly bound extracellular polymers(TB-EPSs).EPSs in strain cells from aggregate indeed play a vital role in the process.Produce EPSs to strain Y7 growth in the process of study,and discusses the impact of EPSs on strains from the ability to gather the results showed that the strain of EPSs Y7 main ingredients for protein and polysaccharide,and protein content than polysaccharide content,in the whole training period,polysaccharide and protein has the highest ratio of 0.35.Further since the aggregation ability before and after the strain EPSs extract determination found that before the EPSs extraction Y7 strains since the biggest aggregation index was 56.94%,while the EPSs to automatically gather the contribution rate of 45.5%.Enrichment culture and denitrification process EPSs different components that strains from different flocculating ability.In the process of enrichment culture strains of the main components of the EPSs for protein and polysaccharide,and protein from 511.80 mg/g DCW decreased to 44.42 mg/g DCW,polysaccharide content is 176.81 mg/g DCW from down to 5.29 mg/g DCW;In the denitrification process of 40 h h,8 h and 32 polysaccharide were 104.34,20.13 and 19.32 mg/g DCW,and protein content were 39.43,0 and 2.96 mg/g DCW.Three-dimensional fluorescence spectroscopy(3D-EEM)results show that the EPSs contains tryptophan and tyrosine protein class protein substances,but did not detect the humic acid.According to the regional analysis results show that the extension of incubation time as,EPSs IV area material percentage decreased obviously,fluorescent component in zone I and III material percentage reduced first increases,and II material percentage increased significantly.