Study On Hydrothermal Degradation Law Of Dioxins In Municipal Waste Incineration Fly Ash

With the rapid development of China's economy,the amount of municipal waste discharge has increased rapidly,and the incineration has become more and more important in the three innocuous treatment methods due to its significant advantages such as volume reduction,reduction,and energy recovery.However,the fly ash produced by the municipal waste incineration process contains toxic components such as dioxins and heavy metals,and is classified as hazardous waste by the state.Currently,it has not been economically and reliably disposed.Since dioxin is mainly concentrated on the carbonaceous material in the fly ash,the fly ash can be obtained by flotation to obtain a carbon concentrate rich in high concentration of dioxins.This paper studies the hydrothermal degradation of dioxincontaining carbon concentrate in municipal solid waste incineration fly ash.The main research contents and conclusions of this paper are as follows:(1)The fly ash sample is pretreated by ammonium leaching to remove salts and calcium hydroxide to create better flotation conditions.After flotation,the total dioxin content in the fly ash residue decreased from 44181.11 pg/g to 19615.00 pg/g,a decrease of 55.60%.The flotation process can greatly reduce the amount of carbon and PCDD / PCDFs in municipal waste incineration fly ash;(2)Further research on the influencing factors of hydrothermal degradation of dioxins revealed that the degradation rate of dioxins increased with increasing temperature;under anaerobic conditions,the degradation rate increased with the increase of pH value of the reaction system;under aerobic conditions,The degradation rate decreases with the increase of the pH value of the reaction system;the oxygenation under hydrothermal conditions can greatly improve the degradation rate of dioxins;(3)Further research on the degradation of dioxins in carbon concentrate by hydrothermal method,the results show that the best conditions for the degradation of dioxin in carbon concentrate are neutral aerobic environment,reaction saturation temperature 220 oC,heating 6 h,the total I-TEQ removal rate was 46.41%.Therefore,the hydrothermal method is beneficial to the degradation of dioxin in the fly ash.The introduction of oxygen significantly reduces the reaction temperature of the fly ash,which not only improves the degradation rate,but also reduces the requirements of the reaction equipment,and has certain industrial application prospects.