Isolation And Nitrogen Removal Characteristic Of The Aerobic Denitrification Bacteria

Nitrogen is the nutrient substance of organism,when the nitrogen concentration in water exceeds the standard,it will cause the eutrophication of water body and make the water quality serious pollution.Traditional biological nitrogen remo val conducts in aerobic nitrification tank and anaerobic denitrification tank.In thi s paper,the strains of aerobic denitrifying bacteria are isolated from activated slu dge systems.Then to study the strain on aerobic denitrification performance and heterotrophic nitrification performance.The strain AD-2 is applied to intermittent aeration device,and the influences of process parameters,which affect refinery wastewater treatment by the strain AD-2.Efficient aerobic denitrifying bacteria AD-2 and AD-4 are isolated from the activated sludge of water sewage treatment system.According to sequence analys is of the 16 Sr DNA and construct phylogenetic tree,strain AD-2 is identified as Pseudomonas stutzeri;strain AD-4 is identified as Paracoccus sp.The influences of the factors,which affect the strains’ performance of aerob ic denitrification,are discussed by single factor variable method.The results sho w that suitable process parameters of strain AD-2 are pH between 6 and 9;sodi um citrate,sodium succinate or glucose as carbon source;C/N ratio of 7;inocul ation quantity of 5%;incubation time of 16h;nitrate concentration of 0¹000mg/L.Suitable process parameters of strain AD-4 are pH between 7 and 8;sodium succinate or sucrose as carbon source;C/N ratio of 7;inoculation quantity of 5%;incubation time of 32h;nitrate concentration of 0⁵00mg/L.Most aerobic denitrifying bacteria have the capability of heterotrophic nitrific ation.The study found that the strain AD-2 and AD-4 both have the capability of heterotrophic nitrification.It is discussed that the factors of the strains’ performance of heterotrophic n itrification.The results show that strain AD-2 and AD-4 in C/N=12 heterotrophicnitrification medium for 48 h,total nitrogen removal rates are 89.8% and 92.2%,ammonia nitrogen removal rates are 92.0% and 95.1%.The strain AD-2 and AD-4 have the the capability of heterotrophic nitrification-aerobic denitrification.Under aerobic condition,the strain AD-2 is applied to intermittent aeration a pparatus for processing refinery wastewater containing nitrogen,which can achiev e simultaneous nitrification and denitrification.Under suitable aeration intensity,t he strain AD-2 is added to the reactor by the proportion of 10%,COD/N of 12,ammonia concentration 50¹00mg/L,HRT 32 h,then TN removal rate can reach about 80%,NH₄⁺-N removal rate can reach 90%.