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. A novel integrated UV-biofilter system using UV reactor as the pretreatment process was setup to trea high concentration of volatile volatile organic compounds (VOCs). Another control biofilter with the the UV pretreatment was also established to compare the performance of the two systems. Chloro benzene The selected systems could eliminate chlorobenzene completely (100% removal efficiency.) The selected systems were operated in parallel under differen inlet chlorobenzene concentrations (500, 1000, 1600, mg · m -3) ) at the inle concentration of 500 mg · m -3, only 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 perfor mance 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.