Research On The Effect Of FeOM On The Degradation Characteristics Of Aniline And The Interaction Of Iron And Bacteria In The Biological Sponge Iron System

Water pollution is one of the most important factors that cause the shortage of water resources in our country,and the discharge of refractory organic wastewater that is not up to standard is an important reason for water pollution.In recent years,with the national "water pollution control action plan" introduced,the government has put forward more stringent requirements for the control of water pollution.Aniline is an essential chemical raw material,and it is also a toxic substance that seriously polluted environment and threatened human health.In the study of biological treatment of aniline wastewater,the research of highly effective aniline degradation bacteria is one of the most widely concerned issueconcern,however,the study of iron bacteria used in this field has not been reported.In addition,in the Fe⁰-Bioferric process,the research of interaction and mutually reinforcing characteristics between zero valent iron and high strain has not been reported.In this paper,a new strain of ZL-1,which has the function of iron oxidation,was isolated through the process of the domestication,enrichment,isolation,purification and screening of bacteria.Based on the strain of morphology observation,physiological and biochemical experiments and 16 S r DNA molecular identification,the strain is Klebsiella oxytoca strain.Then the growth curve and aniline degradation characteristics of the strain ZL-1 were studied.The results showed that:?1?the growth curve of ZL-1 strain was consistent with Logistic model,and it could be capable of using aniline as the sole carbon and nitrogen source;?2?the final product of degradation of aniline by ZL-1 strain was ammonia nitrogen,and no nitrous nitrogen and nitrite were found;?3?in the 500 mg/L aniline solution,the optimum growth conditions were p H7.0,temperature 25?,salinity 0.5%,and the DO is the higher,the better the removal effect of aniline;?4?the aniline resistance of the strain ZL-1 was 1500 mg/L.When the reactor was running for 24 hours,the aniline of 1500 mg/L began to degrade rapidly;?5?when carbon source,nitrogen source and phosphorous source were added to the reactor,the addition of carbon source did not promote the degradation of aniline;in the external nitrogen source,sodium nitrate can promote the degradation of aniline.When the molar ratio of C: N= 3:1,the degradation rate of aniline can increased by 7.9% in 20 h.In addition,when C: P =1: 1,the removal rate of aniline in 20 h reached 98.2%,and too high and low phosphate salt would inhibit the degradation of aniline.In the treatment of simulated aniline wastewater with sponge iron system composed of sponge iron?Fe⁰?and ZL-1 strain,it was found that the removal rate of aniline was nearly 20% higher than that of ZL-1 strain alone in 24 hours.ZL-1 strain is an iron oxidizing bacteria,Fe²⁺ is one of the basic elements of its life activities,and iron oxidase activity reflects its ability to utilize Fe²⁺.In addition to the use of Fe²⁺,iron oxidizing bacteria also promoted the dissolution of Fe²⁺,and compared the effects of 3 strains with different Fe²⁺ oxidation capacity on the dissolution of Fe²⁺.The amount of iron dissolved in the ZL-1 bacterial liquid reactor was more than 60mg/L in the reactor without adding bacteria in 24 hours.There were more than 35 mg/L of the reactor with PF-1 strain?zero iron oxidase activity?and 86 mg/L more than the reactor with the MH-1 strain?the best oxidase activity?.On the basis of this,the corrosion behavior of sponge iron under the action of each strain was studied,the results showed that:The bio-corrosion of sponge iron is related to the physiological characteristics of the strain,regardless of whether it is an iron oxidizing bacteria.PF-1 strain is a Bacillus licheniformis,which has no iron oxidase activity,but can ferment glucose to produce acid and secrete a large amount of mucus,the presence of mucus causes the formation of biofilm on sponge iron,the formation of biofilm promotes the formation of oxygen concentration or other concentrated polarized batteries,which accelerates the corrosion rate of sponge iron;The strain ZL-1 is a facultative anaerobic Klebsiella oxytoca strain which can ferment glucose to produce acid under anaerobic conditions.The sponge iron is a kind of porous material,which can provide the aerobic,facultative and anaerobic microenvironment for microorganisms at the same time.This microenvironment can promote the fermentation of ZL-1 strain to accelerate the dissolution of sponge iron;The MH-1 strain is an obligate aerobic Pseudomonas putida,which does not secrete mucus and ferment acid.Its life activities need to consume a lot of oxygen,which reduces the rate of oxygen corrosion.In the activity of iron oxidase of PF-1 strain < iron oxidase activity of ZL-1 strain < iron oxidase activity of MH-1 strain,the average corrosion rate of sponge iron under the action of PF-1 strain> average corrosion rate under the action of ZL-1strain> average corrosion rate under the action of MH-1 strain was obtained by 80 days of corrosion study.Based on the study of the biological corrosion mechanism of ZL-1 strain,the effect of external conditions on the dissolution of sponge iron under the action of ZL-1 strain was studied.The results showed that:Under the normal growth condition of ZL-1 strain,the lower the p H value of the solution,the larger the DO,the more the sponge iron dosage and the smaller the sponge ironcan promote the sponge iron dissolution under the action of ZL-1 strain.However,the dissolution rate of sponge iron under the action of ZL-1 strain increased with the increase of the dosage of bacteria,which increased first and then decreased,and the dissolution rate of iron was the highest when the dosage of bacteria was 20%.In the biological sponge iron system composed of sponge iron?Fe⁰?and ZL-1 bacteria,the dissolution of iron can not only meet the growth needs of ZL-1 strain,but also promote the production of Fenton-like action in the system.H₂O₂,which can form Fenton-like action,is produced from the life activities of ZL-1 strain and produced by sponge iron reduction in the acidic environment.In addition,the generation of H₂O₂ is greatly affected by the environment,the lower the p H value,the smaller the sponge iron particle size,the more H₂O₂ generation,the sponge iron dosage and the amount of mud residue,H₂O₂ production with the increase of its dosage,the trend of increasing and decreasing was,the dosage of sponge iron was 90g/L,the amount of sludge was 2.5g/L,and the amount of H₂O₂ was the most.In addition,the production of OH is also affected by the environment.The influence of p H value,sponge iron particle size,sponge iron dosage and sludge dosage is similar to that of H₂O₂.