Enhanced Nitrogen Removal Of The Tail Water From Municipal Wastewater Treatment Plant By Plant Carbon Source-sulfur Denitrification

At present,the most restrictive factor for the tail water of urban sewage treatment plants in my country to be used for the water supply of urban inland rivers and lakes is the high TN content,of which NO₃^--N accounts for 80%.Therefore,there is an urgent need for sewage treatment plant tail water.Perform deep denitrification.Wastewater treatment plant tail water has the characteristics of low carbon to nitrogen ratio and high ratio of NO₃^--N.When removing nitrogen,additional carbon sources or other electron donors are required.Therefore,the development of low-cost carbon sources or electron donors has become a research hotspot in this field.And puzzles.In response to this problem,this study is based on the principle of plant carbon source-sulfur denitrification.First,the composition,carbon release and denitrification potential of the low-cost plant carbon sources of reed stalk,rice stalk,walnut husk and corn cob were compared.Comprehensively screen the optimal carbon source to be used in the plant carbon source-sulfur denitrification filter column,and study the impact of plant carbon source-sulfur filling method,hydraulic retention time（HRT）and other key operating parameters on the enhanced denitrification of tail water,revealing the plant Carbon source-changes in the microbial community of sulfur denitrification and denitrification.The main conclusions are as follows:（1）Corncob has the highest total cellulose and hemicellulose content（73.8g/100g）among the four plant carbon sources of reed stalk,rice stalk,walnut husk,and corncob,and the corncob is not easy to be deformed and has a rough surface.The static carbon release experiment showed that the average COD concentration in the extract of the four plants after stabilization（3d-15d）was rice stalk（8.40±4.27 mg/L）>corn cob（4.26±1.87 mg/L）>reed stalk（3.32±1.32 mg/L）>Walnut shell（2.46±1.44 mg/L）.In the stable stage（15-25d）of the plant carbon source sulfur polyculture denitrification potential experiment,the average removal rate of TN is in the order of corncob（25±9%）>rice stalk（24±11%）>reed stalk（23±8%）)>Walnut shell（21±8%）,the p H changes before and after the carbon-sulfur polyculture denitrification test were rice stalks>corn cobs>reed stalks>walnut shells.Comprehensive consideration,corn cob is the most suitable plant as a plant carbon source-sulfur denitrification material.The results of high-throughput sequencing and q PCR showed that the microbial community on the surface of the lower corncob with sulfur filling at the upper end of the corncob and lower end was the most abundant,and the diversity of the microbial community was more abundant when the HRT was 2h than when the HRT was 4h,and its dominant phyla was deformed Bacteria（36.15%）,Bacteroides（14.39%）,Chloroflexus（10.34%）and Acidobacteria（8.74%）.With the direction of the water flow of the denitrification filter column,the total proportion of Proteobacteria and Bacteroides on the corncob packing also gradually decreased,from 67.61%near the inlet to 45.84%near the water outlet.