| Biological denitrification is the most commonly used and most economical and effective method in sewage denitrification at present,but the traditional biological denitrification process has many problems,such as long process flow,large area,high cost and complicated engineering process.The experimental group found that the biological sponge iron reactor had a strong removal effect on COD and nitrogen in the previous study.Therefore,on the basis of previous studies,this paper will further explore the mechanism of simultaneous nitrification and denitrification in biological sponge iron reactor under the synergistic action of iron and microorganisms.This paper to simulate domestic wastewater as the research object,using the parallel experiments,NH4+-N concentration in waste water by gradient increase,compared the ordinary active sludge,a single sponge iron and biological denitrification performance of sponge iron reactor,the reactor was studied in the process of denitrification of nitrogen changes and related enzyme activity,further reveals the biological denitrification mechanism of sponge iron reactor;The denitrification performance of biological sponge iron reactor under different dissolved oxygen and temperature was investigated.On the basis of previous experiments,the strengthening effect of organic carrier and compound bacteria on biological sponge iron reactor was further explored,which laid a foundation for the popularization and application of this method.The conclusions are as follows:（1）when simulating domestic sewage,it was found that biological sponge iron reactor had stronger denitrification effect than ordinary activated sludge and pure sponge iron reactor.（2）the intervention of sponge iron has little effect on the nitrification related enzyme activity in the ordinary activated sludge reactor,but it can promote the denitrification related enzyme activity.（3）the biological sponge iron reactor in the DO concentration of 2-4 mg/L,for the removal rate of COD,TN,NH4+-N,reach the highest,82.88%,91.37%and 96.1%,respectively,when the temperature is 25℃,the TN the removal rate of COD,NH4+-N,reach the highest,88.13%,95.51%and 97.44%,respectively,therefore,sponge iron bioreactors denitrification and determine the best conditions for the DO concentration for 2-4 mg/L,the temperature is 25℃.（4）the intervention of organic carrier can improve the denitrification performance of the ordinary activated sludge and biological sponge iron reactor,and at the same time,accelerate the nitrification process of the ordinary activated sludge reactor,promote the denitrification reaction,and further improve the denitrification efficiency of the reactor;（5）the internal and external DO distribution of organic carrier is not uniform due to its porous structure,which has a certain impact on the activity of AMO and NOR in the ordinary activated sludge reactor,but has little impact on the activity of NAR and NIR.The organic carrier has little effect on AMO and NOR in biological sponge iron reactor.It promotes the activity of NAR,promotes the further transformation of NO3--N,and improves the denitrification performance of the reactor.（6）the intervention of complex bacteria could improve the denitrification efficiency of biological sponge iron reactor,and the TN removal rate increased by 3.4%,which had little impact on the removal of NH4+-N and COD. |
