| In recent years,with the country to vigorously focus on ecological environmental protection and ecological environment,the water environment governance and water ecological control efforts are constantly strengthen the indicators of water quality monitoring of sewage treatment is more strict.Along with the rapid development of economy and society,the improvement of people's living standards,consumption and emissions of fish,meat and other protein increased,the nitrogen content in the wastewater of life increased,lead to changes in sewage water quality index,carbon nitrogen ratio decreased,the growth effect of traditional sewage treatment technology and water treatment microorganism breeding.In the plan of "13th Five-Year",the national standard of ammonia nitrogen and total nitrogen is included in the national control standard.The state is not qualified to discharge,strict punishment is strictly prevented,and the emission of nitrogen containing substances in domestic sewage is also clearly defined.In order to solve the problem of wastewater containing nitrogen,the biological nitrogen removal with the advantages of products with high efficiency and clean,no two pollution has become the focus of concern.This study is based on the theory of heterotrophic nitrification and denitrification,which is one of the new technologies in biological denitrification.And facing the technical bottleneck that is easy to appear in the high and cold period winter,causes the growth of microorganism to slow down or even stagnate,and the related microbial denitrification performance is difficult to get normal effect.All of the above problems are carried out by this research.A high efficiency denitrification bacteria with low temperature resistance was isolated and purified from the medium test fillers in Songhua River,and compared with the macro morphological characteristics and gene level respectively.The results of 16 Sr DNA gene sequencing were analyzed by homologous comparison,and a new strain of Pseudomonas sp.was harvested and named Pseudomonas mohnii.M-8,and the physical and chemical properties of the strain were verified by physiological and biochemical experiments.In the study,the microorganism selection growth and directional culture were carried out by using the traditional strain separation and purification method,combined with 2? low temperature and nitrification medium,and the strains with high efficiency of denitrification under the low temperature condition were screened.The morphology,length,width,shape and gloss of the bacteria were observed by scanning electron microscopy.The 16 Sr DNA gene was sequenced and the multiple sequence alignment was performed by Blast software and MEGA software to establish a Neighbor-Joining phylogenetic tree.From Gram stain,flagellum dyeing,sports observation,ability identification of extracellular polysaccharide,identification of catalase,identification ofgelatinase,identification of amylase,identification of methyl red test,identification of anaerobic growth test,salt tolerance test,temperature test and heavy metal test.Understand the physiological and biochemical characteristics of strains from multiple perspectives.In the experiment of abiotic factors,a single variable method was controled.Under the condition of p H=7,C/N ratio,and sodium citrate as the sole carbon source,the best value of biological growth could be reached,and the maximum amount reached about 5times of the initial inoculation amount.At the same time,the removal efficiency of ammonia nitrogen was the highest under the aerobic condition of p H=8 and C/N ratio of10 and sodium citrate as the sole carbon source,which were 75%,91%,82% and 91%respectively.When ammonia nitrogen was used as the sole nitrogen source,the ammonia nitrogen could be removed efficiently by nitrogen removal,and no nitrite and nitrate accumulation was found during the process.The removal rate of nitrite and nitrate nitrogen was 84% and 99.7% in the denitrification characteristics of the only nitrogen source culture medium with nitrite and nitrate as the only nitrogen source culture medium.In order to solve the competitive viability and denitrification efficiency of the strain in the actual sewage water body,two parallel membrane bioreactors were set up,and the polyurethane foam was used as the biological carrier in the early stage to carry out the directional culture of the biofilm,so that the purified single strain was shortened in the actual sewage treatment period.Enhance its competitiveness in the microbial environment.The removal rate of ammonia nitrogen and COD was low at the initial stage of reactor assembly,and the removal rate of ammonia nitrogen and COD increased obviously after increasing the influent C/N.A membrane bioreactor was set up to test the application of sewage in real life.The treatment effect of the strain on ammonia nitrogen and COD in the actual sewage was investigated,and the key factors regulating the reaction were set up,and the water quality of the effluent was compared.So as to provide some reference for the practical application of the future strains. |
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