A novel integrated UV-biofilter system using UV reactor as the pretreatment process was setup to trea high concentration of gaseous volatile organic compounds (VOCs). Another control biofilter withou the UV pretreatme...A novel integrated UV-biofilter system using UV reactor as the pretreatment process was setup to trea high concentration of gaseous volatile organic compounds (VOCs). Another control biofilter withou the UV pretreatment was also established to compare the performance of the two systems. Chloro benzene was selected as a model compound. The two systems were operated in parallel under differen inlet chlorobenzene concentrations (500, 1000, 1600, mg·m?3). The experimental results indicate tha the integrated system could eliminate chlorobenzene completely (100% removal efficiency) at the inle concentration of 500 mg·m?3, whereas only 60% removal efficiency was achieved for the control biofi ter. Also the elimination capacity for the organic carbon of the integrated system was much higher tha that of the control biofilter. On the basis of intermediates analysis by Ion Chromatography and Ga Chromatography-Mass Spectrometry, the UV pretreatment has been proven to be able to enhance th performance of the following biofilter by transferring the recalcitrant target to some more biodegrad able and soluble organic products (such as formic acid and chlorophenol). Furthermore, the produce ozone, a harmful by-product from UV photo-degradation, could be easily eliminated by the followin biofiltration process.展开更多
Rotating drum biofilters (RDBs) could effectively remove volatile organic compounds (VOCs) from waste gas streams. A mathematical model was developed on the basis of mass transport and mass balance equations in an RDB...Rotating drum biofilters (RDBs) could effectively remove volatile organic compounds (VOCs) from waste gas streams. A mathematical model was developed on the basis of mass transport and mass balance equations in an RDB,the two-film theory,and the Monod kinetics. This model took account of mass transfer and biodegradation of VOC in the gas-water-biofilm three-phase system in the biofilter,and could simulate variations of VOC removal efficiency with a changing specific surface area and porosity of the media due to the increasing of biofilm thickness in the biofilter. Toluene was used as a model VOC. This model was further simplified by introducing a coefficient of the gas velocity and ne-glecting the water phase due to the complexity of operating conditions. The equations for the biofilm phase,gas phase,and biofilm accumulation in this model were solved using collocation method,ana-lytic method,and the Runge-Kutta method separately. A computer program was written down as MATLAB to solve this model. Results of numerical solutions showed that toluene removal efficiency in the RDB increased and reached the maximum values of 97% on day 4 after the startup,and then de-creased and remained at 90% after 5 more days of operation. Toluene concentration was high at the outermost layer where more than 70% toluene was removed,and was low at the innermost layer where less than 10% toluene was removed. The dynamic removal efficiencies from this model correlated reasonably well with experimental results for toluene removal in a multi-layered RDB.展开更多
基金the National Natural Science Foundation of China (Grant No. 50708049)
文摘A novel integrated UV-biofilter system using UV reactor as the pretreatment process was setup to trea high concentration of gaseous volatile organic compounds (VOCs). Another control biofilter withou the UV pretreatment was also established to compare the performance of the two systems. Chloro benzene was selected as a model compound. The two systems were operated in parallel under differen inlet chlorobenzene concentrations (500, 1000, 1600, mg·m?3). The experimental results indicate tha the integrated system could eliminate chlorobenzene completely (100% removal efficiency) at the inle concentration of 500 mg·m?3, whereas only 60% removal efficiency was achieved for the control biofi ter. Also the elimination capacity for the organic carbon of the integrated system was much higher tha that of the control biofilter. On the basis of intermediates analysis by Ion Chromatography and Ga Chromatography-Mass Spectrometry, the UV pretreatment has been proven to be able to enhance th performance of the following biofilter by transferring the recalcitrant target to some more biodegrad able and soluble organic products (such as formic acid and chlorophenol). Furthermore, the produce ozone, a harmful by-product from UV photo-degradation, could be easily eliminated by the followin biofiltration process.
基金Supported by the Program for New Century Excellent Talents in University from the Ministry of Education of China (Grant No. NCET–05–0701)the China Postdoctoral Science Foundation (Grant No. 2005037206)the Scientific Research Foundation for the Returned Overseas Chinese Scholars from the Ministry of Education of China,and the Science Foundation and Postdoctoral Science Foundation of Hunan Univer- sity
文摘Rotating drum biofilters (RDBs) could effectively remove volatile organic compounds (VOCs) from waste gas streams. A mathematical model was developed on the basis of mass transport and mass balance equations in an RDB,the two-film theory,and the Monod kinetics. This model took account of mass transfer and biodegradation of VOC in the gas-water-biofilm three-phase system in the biofilter,and could simulate variations of VOC removal efficiency with a changing specific surface area and porosity of the media due to the increasing of biofilm thickness in the biofilter. Toluene was used as a model VOC. This model was further simplified by introducing a coefficient of the gas velocity and ne-glecting the water phase due to the complexity of operating conditions. The equations for the biofilm phase,gas phase,and biofilm accumulation in this model were solved using collocation method,ana-lytic method,and the Runge-Kutta method separately. A computer program was written down as MATLAB to solve this model. Results of numerical solutions showed that toluene removal efficiency in the RDB increased and reached the maximum values of 97% on day 4 after the startup,and then de-creased and remained at 90% after 5 more days of operation. Toluene concentration was high at the outermost layer where more than 70% toluene was removed,and was low at the innermost layer where less than 10% toluene was removed. The dynamic removal efficiencies from this model correlated reasonably well with experimental results for toluene removal in a multi-layered RDB.
