Isolation And Identification Of Sulfur Oxidizing Bacteria And Their Study On Sulfur Removal By Oxidation

With the rapid development of chemical industry,printing and dyeing,paper making,metallurgy and other industrial production,a large number of thiosulfate wastewater has been produced,which has brought a great threat to the living environment of human beings.Thiosulfate is poisonous and will lead to the death of aquatic organisms.Many microorganisms that live in water can also use thiosulfate ions as energy,as they consume oxygen in the thiosulfate oxidation-process,leading to an increase in the biochemical oxygen requirement.In addition,these microorganisms produce sulfuric acid in the process of thiosulfate oxide,which lowers the p H value of water,which may affect the microbial community in water and change the entire aquatic ecosystem.For thiosulfate wastewater,the physical and chemical methods used at present have high energy consumption and high comprehensive treatment cost,while the biological methods are also developing rapidly because of their low treatment cost and low secondary pollution.This paper set up the screening of aerobic and anaerobic conditions,2 strains isolated facultative anaerobic oxidation sulfur bacteria,aerobic and anaerobic conditions of p H and microbial inoculation quantity and the concentration of sodium thiosulfate,different factors on the strain F1、F5 in addition to study the influence of sulfur,sulfur conversion of different reaction condition is analyzed,and the strain F1 sulphur removal rate,response surface optimization.This experiment under aerobic and anaerobic conditions,from daqing dawn lake lake sediment source of bacteria and campus,enrichment and separation of two strains screened facultative anaerobic sulfur oxidizing bacteria F1、F5,through a microscope to observe the morphological,physiological and biochemical identification and and 16 srDNA in molecular biology,strain F1、F5 respectively citric acid bacillus(Citrobacter freundii),Mr Charest’s bacteria(Serratia surfactantfaciens).Strains F1 and F5 were gram-positive bacteria with rodshaped shape and no flagella.The effects of different factors on the sulfur removal of Citrobacillus F1 and the sulfur conversion of different reactions are different under aerobic and micro-oxygen conditions.Under aerobic conditions,with the increase of p H,concentration of sodium thiosulfate,light duration and dissolved oxygen,the thiosulfate removal of strain F1 firstly increased and then decreased.With the increase of inoculation amount,the thiosulfate removal of strain F1 increased firstly and then remained basically unchanged.When yeast was used as carbon source,the removal rate of thiosulfate reached the maximum.With the increase of p H,inoculation amount and concentration of sodium thiosulfate,the thiosulfate removal rate of strain F1 increased firstly and then decreased under microoxygen condition.The thiosulfate removal rate of C.citrate F1 under aerobic condition was higher than that under micro oxygen condition.The thiosulfate removal rate under aerobic condition was 62%,and the thiosulfate removal rate under micro oxygen was 51%.Under aerobic conditions,the main products of thiosulphate in citrate bacillus F1 are sulfate,and a small part of thiosulphate and sulfides.Under micro-oxygen conditions,the main products of thiosulphate in citrate bacillus F1 are sulfate,and a small part of thiosulphate and sulfides.The formation of products under aerobic and micro-oxygen conditions is opposite.The response surface optimization results showed that the desulfurization efficiency of C.citrate F1 reached the maximum of 62.11% when the p H was 7,the inoculation amount of bacteria liquid was 9 m L,and the concentration of sodium thiosulfate was 1.2 g/L.When the p H value of high and low,with microbial quantity increase,the F1 on the removal rate of thiosulfate are increased before they are decreasing,p H and microbial quantity of the interaction relationship between was not significant,in the same way,the interaction relationship between the p H and concentration of sodium thiosulfate was not significant,microbial inoculation quantity and the interactive relationship between the concentration of sodium thiosulfate is not significant.The effects of different factors on the sulfur removal of serratia F5 and the sulfur conversion of different reactions were different under aerobic and micro-oxygen conditions.Under aerobic conditions,with the increase of p H,sodium thiosulfate concentration and dissolved oxygen,the thiosulfate removal of strain F5 firstly increased and then decreased.With the increase of inoculation amount,the removal of thiosulfate in strain F5 increased firstly and then remained unchanged.With the increase of light duration,the thiosulfate removal rate of strain F5 decreased gradually.When the carbon source used was glucose,the removal rate of the strain F5 reached the maximum.With the increase of p H,inoculation amount and concentration of sodium thiosulfate,the thiosulfate removal rate of strain F5 increased firstly and then decreased under microoxygen condition.The thiosulphate removal rate of Serrella F5 under aerobic condition was higher than that under micro-oxygen condition,the thiosulphate removal rate was up to 55% under aerobic condition,and the thiosulphate removal rate was up to 45% under micro-oxygen condition.Under aerobic conditions,the main product of thiosulphate of serratia F5 is sulfate,and the other small part is tetrasulfate.Under micro-oxygen conditions,the main product of thiosulphate of serratia F5 is tetrasulfate,and the other small part is sulfate.