A Denitrification Process In Which Plant Leaf Leachate Is An Electron Donor

Due to the acceleration of urbanization and the accumulation of nitrogen and phosphorus in water bodies,the pollution of water bodies is serious.When the nitrogen content in water bodies exceeds a certain amount,it will damage the balance of nature and even endanger human health,therefore,the removal of nitrogen and phosphorus is the key to wastewater treatment,and the removal of nitrate nitrogen is an important part of wastewater treatment,but the removal efficiency of nitrogen oxide is affected by many factors,including p H,dissolved oxygen,temperature,electronic donor,etc,the electronic donor is one of the most important factors affecting Denitrification.Many scholars have explored the nitrogen removal efficiency and economic benefit of simple organic matter,carbohydrate,complex organic matter as electron donors,and found that these electron donors have some deficiencies,for example,nitrogen removal effect is poor,cost is too high.Therefore,it is very important to screen and prepare electron donors with low cost and good denitrification effect as denitrification carbon sources.The traditional disposal methods of garden waste in China may not only cause great damage to the soil and lead to soil erosion by pollutants,but also produce poisonous gas and greenhouse gas easily,which endangers the common living environment of human beings and birds.There are many kinds of organic acids in garden wastes,which are valuable resources.Therefore,the resource utilization of the garden waste is the main development trend of the treatment of the garden waste.If we can “Make waste by waste”,we will realize economic and environmental benefits better and faster.In this study,we selected the leaves of Platanus orientalis and cinnamomum Camphora as the control group,and studied the effect of different electron donors and c/n ratio on the denitrification rate in a VBBR(Vertical Baffled Bioreactor),the feasibility of using garden wastes as denitrifying electron donors was analyzed by fractional basic kinetics analysis,living and dead cell detection and identification analysis,and high throughput sequencing experiment,combined with the VBBR reactor,it provides the theoretical basis for the practical application of garden waste.The main conclusions of this paper are as follows:(1)When COD/N = 4,the nitrate nitrogen can be completely degraded and the organic matter utilization rate is high,so COD/N = 4 is the best C/N ratio,it can completely degrade the nitrate nitrogen of about 45mg/L,and the utilization ratio of carbon source is higher than that of glucose.(2)In the same volume of sludge,more living cells were involved in the denitrification using leaf extract as electron donor,resulting in faster degradation of nitrate nitrogen than glucose,the number of electrons provided by leaf extract of Platanus orientalis leaves was more than that of cinnamomum Camphora leaves,and the amount of nitrate in the effluent was the lowest and the nitrogen removal efficiency was the best when the leaf extract of Platanus orientalis was used as electron donor.(3)The microbial community in the sludge with leaf extract as electron donor has higher abundance and diversity.Moreover,it can make the specificity of the microbial community in the reactor better,and help to cultivate the kind of microorganism needed for denitrification.(4)The organic compounds in the leaf extract can make Proteobacteria,Rhodanobacteria,Thauera,Betaproteobacteriales,Rhodocypaceae and Burkholderiaceae dominate the microbial community in the reactor,the enrichment of these strains is beneficial to the Denitrification,thus increasing the efficiency of nitrogen removal,which is why the denitrification rate of leaf extract as an electron donor is faster than that of glucose.