Hydrothermal treatment of MSWI fly ash was performed in this paper with a purpose to reduce its dioxin content. First a hydrothermal reactor was set up with a mixture of ferric sulphate and ferrous sulphate serviced as the reactant, then the effects caused by reaction conditions such as reaction temperature, pre-treatment by water-washing and reactant dosage were checked; the results showed that as a promising technology, hydrothermal treatment exhibited considerable high The chlorine contents of the raw MSW (Raw MSW), the product after the hydrothermal treatment
before the washing process (Unwashed Product) and the product after the hydrothermal treatment
followed by the washing process (Washed Product) are presented in Figure 5, where the total chlorine
content in the raw MSW is taken as 100%. The unwashed product exhibited low organic chlorine
content because it was converted into inorganic chlorine during the hydrothermal process. After the
washing process, the inorganic chlorine content was significantly reduced from 87% to 3%. This result
confirmed that the washing process effectively removes inorganic chlorine in the product as explained
in the previous work [1