| Nitrogen pollution is an important class of pollutants,Nitrogen pollution is an important pollutant,which not only has a negative effect on the aquatic ecosystem,but also threatens human health.Denitrification by nitrifying bacteria and denitrifying bacteria is currently the most widely used biological denitrification technology,and the prerequisite for denitrifying bacteria to achieve efficient denitrification is to have sufficient carbon sources.Nitrogen removal is achieved by nitrifying bacteria and denitrifying bacteria.The previous study of the research group found that aerobic denitrifying bacteria with iron oxidation ability existed in the biological sponge iron system.The denitrification reaction of this kind of bacteria under aerobic conditions was conducive to the realization of synchronous nitrification and denitrification process in the reactor,but it required relatively high carbon and nitrogen.In practical projects,glucose or acetic acid is often added to achieve efficient nitrogen removal,which consumes limited resources and increases the operating cost of the sewage plant.Based on the organic carbon source in wastewater as the research object,the system of biological sponge iron is constructed,to explore the influencing factors of system denitrification and how to reasonable and efficient use of wastewater in the organic carbon source to improve the effect of biological denitrification of sponge iron system,try to solve the problem of high efficient nitrogen.At the same time,the carbon source utilization strategy is optimized by changing the water inlet mode and water distribution flow ratio of the biological sponge iron system.The denitrification capacity of the process under the carbon source utilization strategy is simulated and analyzed by using the dynamic model,which provides theoretical support for making up for the lack of research on denitrification of the biological sponge iron system and realizing the integrity of the system in the wastewater treatment and application process.The results show that:?1?The experiment on the factors affecting the denitrification of the batch biological sponge iron system was conducted.The results showed that when the filling ratio of polyurethane foam carrier was 20%,the cycle of run was 12 h,and the average influent water C/N was higher than 8.8,the biological sponge iron reactor had better denitrification performance.?2?The carbon source utilization method of batch biological sponge iron system was studied by changing the way of influent.The results showed that the different ways of influent had no significant difference on the removal effect of COD and NH+ 4-N in the batch biological sponge iron system,and reflected that the low content of COD also provided favorable conditions for the large-scale reproduction of autotrophic bacteria,which was conducive to the nitrification of aerobic section;the way of influent has a significant effect on the denitrification efficiency of the system.The reasonable distribution of carbon source makes the nitrification reaction complete,and the production of more nitrification fluid provides a large amount of alkalinity for the denitrification process,which is conducive to the denitrification process.After the addition of carbon source in the process of denitrification under the method of rational utilization of carbon source,the average TN removal efficiency increased by 16.5% and 19.4% respectively.?3?A baffled biological sponge iron reactor was constructed successfully.By comparing the denitrification effect of single point water influent and multi-point water influent,it was found that there was no difference in the removal effect of COD and NH+ 4-N between single point water influent and multi-point water influent,and the water outlet met the national level a standard,while the TN removal effect of multi-point water influent was 7% higher than that of single point water influent,indicating that the multi-point water influent added organic carbon source for denitrification in the process of the amount of electron donor shortage problem.It is more beneficial to denitrification in baffled biological sponge iron reactor.?4?The treatment effect and operation law of the reactor under different parameters such as hydraulic retention time?HRT?and carbon-nitrogen ratio?C/N?were studied.The results show that the removal rate of COD and NH+ 4-N in the reactor does not fluctuate significantly when the HRT is adjusted by adjusting the influent flow of the reactor,and the system has a strong ability to resist the impact of organic load.The average removal rate of TN with HRT of 12 h is 10.1% higher than that of 8h.The longer the HRT,the longer the effective removal time of denitrification,and the better the removal effect.The improvement of C/N has no significant adverse effect on the removal of COD,and the change of C/N has a significant effect on the removal of NH+ 4-N and TN.The improvement of C/N can optimize the removal of TN.?5?Exploring the carbon source utilization method of the baffled biological sponge iron system,it is found that simultaneous nitrification and denitrification?SND?can occur in the baffled biological sponge iron system.When each cell simultaneously enters into the water and the ratio of inflow flow is 1#:2#:3#=3:2:1,the TN removal rate is the highest,with an average removal rate of 65.9%.According to the denitrification dynamics theory,the denitrification rate equation is R=-1.18×10-3X and the total nitrogen degradation constant is 1.18×10-3h-1. |
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