Of Dioxins In The Waste Incineration Process, Low Temperature Heat Treatment And Uv Photolysis Test Research

Municipal solid waste (MSW) Incineration technology has been a rising technology in China gradually. Controlling technologies of dioxins in MSW incinerator have been pop topics in environmental pollution research all over the world. This study gives synthesis mechanism of precursors, low temperature thermal-treatment of fly ash produced from MSW incinerator, and Ultra-violet photolysis of dioxins in flue gas produced from heating PCP, which are the foundation of controlling technologies of dioxins from MSW incineration for the future.Model studies were performed to determine the content and homologue profile of dioxins which produced from PCP as precursor of PCDD/Fs. The effects have been discussed. The pathways of dioxins formation were found.The photochemical decomposition of PCDD/Fs was investigated in flue gas produced from PCP. Photodegradation experiments were performed in the gaseous phase by direct irradiation with medium pressure mercury lamps. The dechloration, degradation and synthesis of the dioxins occurred under different conditions. A maximum degradation rate was about 99.5%, and maximun reduction rate of I-TEQ was about 88%. The addition of O₃ catalyzed photolysis of dioxins. O3 produced OH radical which has powerful oxidable ability. Dioxins were attacked by OH radical initially and then occurred electrophilic addition reaction. As a result, dioxins were decomposed by photocatalytic degradation. The photolysis rate of dioxins in solutions were higher than those in fule gas.The thermal treatment of fly ash from waste incinerator in low temperature showed that under oxygen deficient conditions a dechlorination/hydrogenation reaction was observed. The degradation rates were from 42% to 100%. The optimum condition was in nitrogen atmosphere, 400℃, and two hours.Some suggestions were proposed for the farther research of controlling technologies of dioxins in the end of this paper.