Isolation And Identification Of Anaerobic Denitrifying Bacteria And Study On Nitrogen Removal From Aquaculture Wastewater

Aquatic productivity is usually based on the quantity and quality of nitrogen,which plays an important role in aquaculture system.As a serious threat to the aquaculture organisms,accumulated ammonia and nitrite in the aquaculture water,While nitrate control is usually not concerned.Although the toxicity of nitrates to aquaculture is much lower than that of ammonia and nitrite at the same concentration,the high concentration of nitrate also affects the growth of the culture object,and its effect can not be ignored.This article mainly studies the isolation and identification of denitrifying bacteria and the aim to the study of growth and metabolic properties for the application of biological denitrification.Denitrifying bacteria is useful for micro-organisms in situ or ectopic repair because of its concentration on more simple and economical.Biological denitrification is the nitrate nitrogen(nitrite nitrogen)into gaseous product removal,is considered one of the most cost-effective biological nitrogen removal method.This paper focuses on the biological denitrification of denitrifying bacteria isolated from aquaculture wastewater,the research is carried out that separation and identification of denitrifying bacteria,the characteristics of the growth and metabolism of the strain and its denitrification performance and other aspects,etc.The main results obtained are as follows:(1)Isolation and Identification of Anaerobic Denitrifying Bacteria and Removal capability of nitrateTwo strains of anaerobic denitrification were screened from the biofilm on the biofilter in the water treatment unit of Dalian.The Strain of DN10 and DN20 were initially identified as belonging to the genus Vibrio and Halomonas.Two strains of anaerobic denitrifying bacteria have better ability to remove nitrate nitrogen,and there is almost no accumulation of NO2--N in the process of removal,which has the value of further research and utilization.(2)The Growth and Metabolic Characteristics and Biological Denitrification of the Strain DN20The denitrification conditions for strain DN20 included temperature,salinity,pH,NO3--N concentrations and C / N(molar ratio)in the culture medium were tested.After optimizating,the growth ability of the strain was significantly improved,and the denitrification rate was also greatly enhanced,and concentrated that strain DN20 is a moderate halophilic denitrifying bacterium.On the basis of the experiment of optimal metabolic conditions,the growth and metabolism of strain DN20 were observed experimentally.The results showed that the removal rates of NO3--N and NO2--N respectively reached 82.9% and 72.8%.In the above culture process,the removal efficiency of nitrate nitrogen was significant,although the removal rate of nitrite nitrogen was also higher,but not completely removed,indicating that the strain DN20 under the best conditions of culture,can be denitrified-nitrification at the same time.The strain DN20 was observed for ammonia and nitrite nitrogen removal capacity,the strain also had better ability to remove ammonia nitrogen and nitrite nitrogen.Therefore,the biological denitrificating ability of strain DN20 had a good reference and value for simulated and actual aquaculture wastewater,the treatment has a certain application prospects in the aquaculture wastewater.