High Standard Deodorization In Wastewater Treatment Plant By Biotrickling Filter-Vacuum Ultraviolet/Catalysis Process

At present,Discharge standard of pollutants for municipal wastewater treatment plant is implemented for the control of odors in urban sewage treatment plants.The key odorous pollutants are hydrogen sulfide and ammonia.The biotrickling filter has significant advantages in removing these odorous pollutants.However,it has low removal effiency of methyl mer captan and dimethyl sulfide which are low concentration but strong smell,that seriously restricts its deodorization effects.Although methyl mercaptan and dimethyl sulfide have been included in Emission standards for odor pollutants,they have not been included in Discharge standard of pollutants for municipal wastewater treatment plant.In order to achieve high standard deodoriz ation,it is necessary to further remove methyl mercaptan and dimethyl sulfide following Emission standards for odor pollutants on the basi s of the existing control indexs of odorous pollutants in sewage treatment plants.Given the above contents,this paper investigated the deodorization potential of the biotrickling filter firstly.Then the vacuum ultraviolet degradation process was used as following unit to further treat methyl mercaptan and dimethyl sulfide.What's more,combined with ozone-catalyzed oxidation,an efficient deodorization process of "biotrickling filter-vacuum ultraviolet/catalysis" was proposed.And then the removal efficiency of hydrogen sulfide,ammonia,methyl mercaptan and dimethyl sulfide by the efficient deodorization process was studied.Through the bench-scale experiments,the operation parameters of the biotrickling filter were optimized,and the removal efficien cy of hydrogen sulfide(30 mg/m~3),ammonia(20 mg/m~3),methyl mercaptan(1 mg/m~3)and dimethyl sulfide(2 mg/m~3)were investigated under optimized conditions.The results showed that,to treat hydrogen sulfide,ammonia,methyl mercaptan and dimethyl sulfide reach to the primary standard values by the biotrickling filter,the required empty bed residence time(EBRT)on the optimized conditions was 15,8,25 and 50 s,respectively.The optimized conditions ware that the p H of nutrient solution was 7.85?8.45,the spray density of nutrient solution was 2.83 m~3/(m2·h),and the system temperature was 25 ?.The removal efficiency of hydrogen sulfide and ammonia was higher,while the removal efficiency of methyl mercaptan and dimethyl sulfide was lower.On the basis of the optimization of the operating parameters and the improvement by using the catalytic materials,the vacuum ultraviolet/catalytic deodorization process which could effectively remove methyl mercaptan and dimethyl sulfide was formed.The results showed that when the operating conditions were controlled at the light intensity of 0.02 W/cm~3,the wavelength of 185 nm,the relative humidity of 80%?90%,the filling amount of catalytic materials of 5%,the vacuum ultraviolet/catalysis deodorization process could effectively remove methyl mercaptan and dimethyl sulfide.The process was more efficient than chemical absorption process and the biotrickling filter.Therefore,a high efficiency deodorization process named " biotrickling filter-vacuum ultraviolet/catalysis" was proposed.And the removal efficiency of hydrogen sulfide,ammonia,methyl mercaptan and dimethyl sulfide was studied.The results showed that under better conditions,when the EBRT in the biotrickling filter section and the vacuum ultraviolet/catalysis section was 7 s and 6 s respectively,the stable standard emission of hydrogen sulfide,ammonia,methyl mercaptan and dimethyl sulfide could be achieved.Among them,the biotrickling filter section was the main removal unit of hydrogen sulfide and ammonia,and the vacuum ultraviolet/catalysis section was the main removal unit of methyl mercaptan and dimethyl sulfide.Compared with the high-capacity single biotrickling filter,the EBRT of "biotrickling filter-vacuum ultraviolet/catalysis" deodorization process could be reduced by 70%,while the construction cost and the operation cost were all be greatly reduced.