Study On Ectoine Assist Synchronous Heterotrophic Aerobic Nitrification And Denitrification Of Denitrifying Bacteria

Ammonia nitrogen is one of the main pollutants in water.China has put ammonia nitrogen and other nitrogen compounds included in the total pollutant emission control system.Purification of ammonia nitrogen in water has become a hot issue.Currently,the current physical and chemical denitrification and biological denitrification are the two main methods to remove nitrogen in wastewater.Biological method with high efficiency,no secondary pollution and other advantages.Among them,Simultaneous Heterotrophic Nitrification and Aerobic Denitrification(SND)has attracted more and more attention because of its rapid growth rate,high denitrogenation efficiency and high adaptability.Although many SND denitrification has been applied to the treatment of ammonia nitrogen wastewater,most of it is aimed at laboratory artificial wastewater,and less research on the actual wastewater treatment.Because of the current salt concentration of wastewater discharged by many industries are too high,such as Aquaculture wastewater,seafood processing wastewater.These wastewater is not conducive to the growth of many SND denitrification strains,reducing the efficiency of denitrification and denitrification of strains in high-salt wastewater.Halophilic bacteria in long-term high-osmotic pressure environment,in order to maintain their own good growth state will self-regulation synthesis of a small organic solute molecules to maintain the osmotic pressure balance inside and outside the cell,the material is called osmotic pressure compensation solute.Ectoine(1,4,,6-tetrahydro-2-methyl-4-pyrimidinecarboxylic acid,1,4,5,6-tetrahydro-2-methyl-4-pyrimidinecarboxylic acid,Halobacterium is produced in response to hypertonic environment,it can maintain osmotic pressure balance inside and outside of microbial cells under hyperosmotic conditions,and at the same time can stabilize the structure of proteins in cells;in heat shock or cold shock can be used as cell stress Protectants;Properties that maintain the viability of biological macromolecules in cells under extreme conditions.Therefore,the combination of Ectoine and SND denitrification strains to treat the sewage and wastewater of high salt,high concentration ammonia nitrogen and so on has an important theoretical and practical significance.In this paper,a denitrifying strain A06 SND was isolated from a sediment of a salt pond in Dalian.The strain A06 was identified by 16S rDNA.The strain was identified as Acinetobacter genus and named as Acinetobacter sp.A06.The characteristics of the strain Acinetobacter sp.A06 for denitrification were investigated.The optimal carbon source for the strain was sodium citrate,the optimum C/N was 7.5,the optimum pH was 8,the optimum NaCl concentration was 0,30 mL.The SND denitrification process of strain Acinetobacter sp.A06 under the optimal conditions was investigated.The denitrification rate reached 98.84%after 120 h,and no nitrite and nitrite were produced during denitrification.In this paper,the effects of different osmotic pressure compensation solutes on the denitrification of strain A06 were further investigated under extreme conditions.Different osmotic pressure compensation solutes can assist denitrification of strain Acinetobacter sp.A06.Among them,Ectoine assists the denitrification to the best effect.Increasing the concentration of Ectoine can improve the denitrification rate of Acinetobacter sp.A06,but the concentration of Ectoine is 250-300 mg/L,the denitrification rate of Strain A06 also tended to be stable.When different concentrations of Ectoine were applied to denitrification of Strain A06,the highest denitrification rate was observed when the concentration of Ectoine was 250 mg/L.The effect of Ectoine on Acinetobacter sp.A06 was aided by denitrification at high NaCl concentration,high ammonia concentration and extreme pH.When the concentration of ammonia,ammonia nitrogen and pH were 30 g/L and 1000 mg/L,respectively,the denitrification rate was the best.In this paper,we also investigated the assimilation of Ectoine-secreting strain on denitrification of Acinetobacter sp.A06 under high ammonia nitrogen and high salt conditions,respectively.The strain Halomonas sp.B01 at high ammonia nitrogen concentration,under high salt conditions Denitrification can promote the production of Ecotine during denitrification.Finally,the treatment of landfill leachate by the strain Halomonas sp.B01 and the strain Acinetobacter sp.A06 was carried out.After seven days of treatment,the removal rate of ammonia nitrogen in the landfill leachate was 98.81%and the residual amount was 27 mg/L,Landfill pollution discharge standards "(GB16889-2008)ammonia nitrogen concentration limits compared to less than its minimum allowable limit.