Dissertation > Environmental science, safety science > Processing and comprehensive utilization of waste > General issues > Wastewater treatment and utilization

Isolation and Identification of Water Denitrification Complex Microorganisms and Research on Pathway of Denitrification

Author HuangShi
Tutor WangZhanWu; ZhaoBaoHua
School Hebei Normal
Course Microbiology
Keywords ammonia nitrogen nitrite nitrogen nitrate nitrogen bacillus complex strains nitrogen transfer pathway
CLC X703
Type Master's thesis
Year 2012
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With the rapid development of industry and agriculture, water pollution has become one of the important factors which restrict social and economic sustainable development in China. Ammonia nitrogen is the main factors of water pollution. It’s a broad prospect to purify water body with denitrification microbial. But in recent research works, most pay more attention on the purifying of cover water and less on the furifying of sediment, more on the use of single microorganism strains, less on composite bacteria and spore bacteria. Those are the reasons of the-purifying effecocy lower and unstable. In this study, polluted water sediment is as the material to isolate composite strain, which will posses the function of removing the ammonia nitrogen, nitrite nitrogen and nitrate nitrogen in the same time. Then the nitrogen transfer pathway of the excellent composite strain also have been studied.311Bacillus strains, including103nitrite bacterium strains,112nitrifying bacterium strains and96denitrifying bacterium stains were isolated from the water sediment. One excellent composite strain, Y907+X802+F512was obtained via nitrogenous substances removing experiments in natural water under laboritaery and open water area conditions. The three bacteria have strong function of removing ammonia nitrogen, nitrite nitrogen and nitrate nitrogen. After inoculation48h, the remove rate of ammonia, nitrite and nitrate nitrogen were54.0%,59.3%and75.3%respectively, under laboratory conditions. After7days, the removal rate of ammonia nitrogen, nitrite nitrogen and nitrate nitrogen were59.7%,93.3%and92.7%respectively, in natural water conditions. The results indicated that the composite strains have obvious nitrogenous removing functionsClassification and safety identification of the strains were carried out. Y907and X802are aerobic bacteria, F512is facultative aerobic bacteria. Y907, X802and F152were identified as Bacillus megaterium Paenibacillus lactis. Brevibacillus reuszeri respectively via phenotype observed, physiological and biochemical identification and16s rDNA sequencing analysis. The three bacteria were safety to mice and freshwater fish. The effects of different environmental conditions on the removal nitrogen have been studied.. The result suggested that Y907, X802. F512have a wide range of adaptability in different environment. Three strains could use almost any carbon source, sodium carbonate, acetic acid, tartaric acid sodium potassium sodium, glucose, sucrose and so on. Relativly. the optimal carbon sources are glucose for Y907and F512, sucrose for S802. The optimal C/N for Y907is5, for X802and F512are10. The optimal incubation temperature and pH are the same,25℃and pH7.Sediment purification test was carried out in Baiyang wet land for30days. The results indicated that the combination strain could obviously degradate organic matter, remove out total nitrogen, total phosphorus, total potassium, soluble phosphorus, potassium, ammonia in sediment. The relative remove rate of ammonia was the highese, up to132%.Nitrogen transfer pathway of the three bacteria were studied. The results indicated that the denitrification pathway of the three bacteria was basically the same, which included that A) Ammonia nitrogen was transformed to bacteria protein or other cell compositions; B) The three of nitride:ammonia nitrogen, nitrite nitrogen and nitrate nitrogen transformed into each other. C) Denitrification generate nitrogen or nitrogen oxides released into the air

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