Study On Photolysis Of Hydrogen Sulfide From Malodorous Gas Using Electrodeless UV Lamp

With the development of economy and society, on one hand more and more odor sources appear in the community, on the other hand, the pursuit of high quality of life is growing among people, odor pollution has caused widespread concern. With low odor threshold and is harmful to health when at higher concentration, hydrogen sulfide gas is one of the most important part of the malodorous substances, furthermore, the source of hydrogen sulfide have a broad distribution. Photolysis and oxide process with UV lamp is regarded as a promising technology to control gaseous pollutants. As a new type of UV source, there are many advantages of High Frequency Electrodeless Lamp (HFEL) when compared with traditional UV lamp, such as high efficient, high radiation intensity and long length of life. In this study, we investigated the efficiency of removal of H₂S with self-design HFEL, and then explored the removal efficiency of methanethiol in the malodorous gases with HFEL .The main results as follows:(1)In the study of characteristics of HFEL, we found that HFEL could produce a large mass of ozone, with air humidity 65% and gas flow 300L/min, the zone yield of bubble and column HFEL were 1.25g/h, 0.33g/h. The results showed that reduced gas flow or increased air humidity, the yield of ozone would decline to varying degrees.(2) Comparison between three different technique were investigated, The results showed that: when the residence time was 5.8s, and the initial concentration of hydrogen sulfide was 3.1²4.6mg/m³, the average removal efficiency of hydrogen sulfide by UV light photolysis and oxidation, UV photolysis alone and O³ oxidation alone were 96.6%, 31.5%, 13.3%. The removal efficiency of UV/O₃ was about 38.7～65.0% higher than the sum of effect by using each of them alone. So the study proves that there are synergistic effects between UV radiation and O³.(3) Off-gas came out of the reactor with ozone concentration from 50 to 70 ppm and H₂S concentration from 1.6 to 15.8 mg/m³, after passed through the Fe₂O₃ Catalytic system, the residual H₂S gas and ozone were completely removed.(4) In the study of small pilot experiments we found that the malodorous gas from removal water of sludge, with H₂S concentration from 0.8 to 8.2 mg/m³ and methanethiol concentration from 0.1 to 2.5mg/m³.?The mixed odors after passed through the small pilot plant, with flow rate 500L/min (residence time 2.5s), the removal efficiency of H₂S was 70⁹0% which was about 10% less than dealt with the single H₂S gas, and the removal efficiency of methanethiol was more than 90%.The HFEL deodorizing device have good removal efficiency not only to hydrogen sulfide but also to methanethiol, which will promote the popularization and application of UV deodorization technology.