Screening Of Low C/N Iron Oxidation Denitrifying Bacteria And Denitrification Characteristics Of Water Source Reservoirs

Reservoir as the main water source in People's Daily life,to a certain extent,has been damaged to varying degrees,serious has been unable to be used,and the main reason for these is nitrogen pollution.Sediments from the Li Jiahe and heihe reservoir screening out under the condition of low C/N efficiently and ferrous oxide of nitrogen nitrate reduction,the mixed bacteria,and the population structure of the mixed bacteria and denitrification performance appraisal and analysis,at the same time explore under different environmental conditions of the mixed bacteria denitrification characteristics and the response surface method optimization was used to construct the best denitrification efficiency model,the mixed bacteria of metabolites were analyzed,and the mixed bacteria denitrification technology with the mixed bacteria immobilized microorganisms technology unifies,explore immobilized system influence on nitrogen removal efficiency of the mixed bacteria.The main conclusions are as follows:(1)Ferric oxide nitrate that can effectively denitrify the mixed flora Z3-2,Z3-12and Z3-18 were successfully screened from the reservoir sediments under low C/N conditions.Illumina Mi Seq PE300 high-throughput DNA sequencing was used to analyze the structure and composition of the mixed flora.The results showed that the structure composition of the 3 groups of mixed bacteria was similar,among which Zoogloea belonging to ferrous oxidizing bacteria accounted for the largest proportion(74.28%,71.27%and 69.25%,respectively),followed by Fe(III)reducing bacteria Geothrix.Based on three groups of ferrous oxide nitrate reductive nitrogen mixture characteristic research shows that three groups of mixture are efficient denitrification efficiency and reaction after 78 h,the mixed bacteria Z3-2?Z3-12 and Z3-18 nitrate nitrogen removal rate of 99.82%,99.80%and 99.85%respectively,total nitrogen removal rate of 89.91%,89.99%and 90.95%respectively,and the whole process of denitrification were no accumulation of nitrite nitrogen and ammonia nitrogen.(2)To investigate the denitrification characteristics of the mixed flora reduced by ferrous oxide nitrate at different temperatures,pH,C/N and Fe²⁺concentrations.The experimental results showed that the mixed bacteria group reduced by ferrous oxide nitrate had a better effect on the removal of ferrous oxide and nitrogen when the temperature was 25?40?,pH 6.5?8.0,C/N 1.8 and Fe²⁺concentration was 30mg/L.Response surface methodology(RSM)was used to determine the optimal conditions for denitrification of mixed bacterial communities reduced by ferrous nitrate.The results showed that under the initial pH value of 6.65,temperature of 32.10?,C/N of 2.34 and Fe²⁺concentration of 16.47 mg/L,the total nitrogen removal rate of the mixed flora reached the maximum of 95.26%.(3)For ferrous oxide nitrate reductive metabolites mixture,scanning electron microscopy(sem),EDS analysis results show that the metabolites are mainly contain substances in C,N,O,P,Ca,Fe and other elements,including top C content accounted for 35.34%,followed by O 24.11%,19.11%Fe element,P 15.81%,Ca and N accounted for 4.32%and 2.2%,respectively.After XRD observation and analysis,it is concluded that the metabolites of the mixed flora are mainly ferrous phosphate octahydrate(Fe₃(PO₄)₂(H₂O)₈)and some amorphous iron oxides.(4)Microbial immobilization technology was combined with denitrification technology of mixed bacteria reduced by ferrous oxide nitrate.Scanning electron microscope results showed that the mixed bacteria could be well fixed on the surface or interior of 13 kinds of immobilized carrier materials.Under the same volume condition,the microbial quantity on the carrier was much higher than that under the free condition.The denitrification performance of the immobilized system,its repeatability and environmental factors showed that the denitrification performance of the immobilized bacteria group was improved after the immobilized bacteria group was fixed,and the immobilized carrier had a buffer-protective effect on the mixed bacteria group reduced by ferrous oxide nitrate under low temperature,weak acid conditions and various adverse conditions.