Study On Process Performance Of Autotrophic Biological Nitrogen Removal And Synergistic Phosphorus Removal In Tail Water Of Sewage Treatment Plant

In order to improve the effluent quality of urban sewage treatment plants and control the eutrophication of water bodies,the combined process of Biological Aerated Filter（BAF）and sulfur/pyrrhotite autotrophic denitrification filter（sulphur/pyrrhotite autotrophic denitrification filter）was used for advanced treatment of nitrogen and phosphorus in secondary effluent.The start-up characteristics of the reactor were studied,and the effects of different influent nitrogen concentration and temperatures on the system were investigated.Combined with the microbial characteristics in the high-throughput sequencing research system,the conversion process of nitrogen and phosphorus was analyzed,and the impact load resistance of the combined process was also investigated.The practicality of the technology was further investigated by treating the actual secondary effluent.The main research results are as follows:（1）When the influent TN of the reactor is less than 25mg/L:the aerated biological filter can completely convert NH₄⁺-N to NO₃^--N,and the removal rate of NH₄⁺-N is over 95%;at the same time,in the sulfur autotrophic denitrification filter,The NO₃^--N concentration in the effluent is about 0.04 mg/L,the denitrification efficiency is high,and the maximum NO₃^--N removal load is 0.098kg/（m3?d）.When the initial PO₄^3-concentration was 0.5 mg/L,the removal rates of TP by the aerated biological filter and the sulfur autotrophic denitrification filter were 23%and 92%,respectively.The process also showed good N and P removal effect in the actual sewage treatment stage.（2）Compared with the elemental sulfur autotrophic denitrification denitrification,the composite sulfur matrix denitrification denitrification can effectively reduce the amount of SO₄^2-.Under the same NO₃^--N removal amount,the average amount of SO₄^2-is reduced by 36%.At the same time,the composite sulfur matrix can stably maintain the p H in the reactor between 6.27-7.13,which is suitable for the growth of Thiobacillus denitrificans without the need for additional alkalinity.（3）The combined process has good resistance to nitrogen shock load,and the maximum NO3--N amount that can be removed by the reactor is 35mg/L.The temperature has a great influence on the denitrification and phosphorus removal of the reactor.When the temperature drops from 30℃to 10℃,the removal rate of NH₄⁺-N in Biological Aerated Filter decreases from 94.57%to 57%,and the removal rate of NO₃^--N in sulfur autotrophic denitrification filter decreases from 98.71%to 49.73%.The removal rate of PO₄^3-in temperature sulfur autotrophic denitrification filter decreased from 91.26%to 57.22%.Low temperature leads to the decrease of microbial activity,which leads to the decrease of nitrification rate,denitrification rate and phosphorus removal performance of the combined process.（4）Microbiological analysis shows that Proteobacteria is the dominant phylum in BAF,accounting for 33.21%,which plays a major role in biological nitrification and pollutant degradation.At the genus level,the denitrifying microorganisms involved are mainly Nitrospira,which can oxidize nitrite to nitrate.The main denitrifying bacteria in the sulfur autotrophic denitrification filter are Thiobacillus denitrificans and Sulfurimonas,accounting for 23.6%and 7.24%respectively.Ferritrophicum and Dechloromonas are mainly related to the systematic phosphorus removal,which can oxidize Fe²⁺into Fe³⁺and promote the precipitation of PO₄^3-.This article has 50 figures,12 tables,and 108 references.