Study On The Operation Condition Control Of The Elemental-sulfur-autotrophic Denitrification Process

At present,the nitrate pollution in the water environment is serious,"cutting source"is an effective way to control nitrate pollution.When dealing with low C/N ratio of wastewaters,compared to heterotrophic denitrification,autotrophic denitrification has the advantages of no need to add organic matter and less residual sludge.Where elemental sulfur autotrophic denitrification due to the efficient,economically viable,in recent years,attracted widespread attention.Aiming at the problem of low nitrogen removal rate in the traditional sulfur autotrophic reactors,this paper added fillers in the upflow reactors to intercept microorganisms,and used small particle size sulfur particles and sodium bicarbonate to improve the mass transfer efficiency in the system,so as to improve the rate of denitrification.Through the study of influencing factors,the operating conditions are optimized.Finally,the ability of the reactor to treat the actual low C/N ratio of industrial wastewater was investigated.The main results are as follows:1.Nylon and Filtered Sponge Fillers can be used in the elemental sulfur autotrophic denitrification process.After the operation of 70d,the similar high rates of denitrification?1.3-1.4kg/?m³·d??was obtained under the volume load of 1.5 and 1.89kg/?m³·d?.Methylophilales-unclassified and sulfurimonas from Proteobactria were the dominant microbial strains,with the relative abundance of 54-57%and 22.6-24.6%,respectively.2.NH₄⁺-N and DO are not the main influencing factors in this reactor.S/N?molar?ratio in continuous reactor should be more than 5.5.the optimum molar ratio Inorganic C/N was1.52.When the reactor has a denitrification rate of about 2 kg/?m³·d?,the rising velocity can be 0.35 m/h.3.With an influent concentration of NO₃^--N is 150mg/L,a HRT is 2.4h,inorganic C/N is 0.76.When the temperature was slowly reduced from 35±1°C to 20±0.5°C,the denitrification rate of the reactor was not adversely affected,and it was about 1.4-1.5kg/?m³·d?.Indicating that the elemental sulfur biofilm reactor is more adaptable to the temperature drop,and has the ability to run efficiently at room temperature.4.The actual photovoltaic wastewater?COD/TN:1,pH:6-9,NO₃^--N:150-200mg/L?was treated with this reactor at room temperature?19-27°C?.When the inorganic C/N is 1.9-3.57,a HRT is 3h.The effluent concentration of NO₃^--N is less than 20mg/L,and the rate of denitrification is 1.41-1.53kg/?m³·d?,and the running effect is good,which has the ability to deal with such low C/N industrial waste water.