Applying mechanochemical (MC) method to treat waste containing dioxins is our research area. Two fly ash samples are collected from baghouse filters cleaning the effluent of a rotary kiln pyrolysis＋ fluidized bed post-combustor and of a simple fixed bed medical waste incinerator (MWI). Dioxins and other organics in fly ash are removed, octa-chlorinated dibenzo-p-dioxin and -furan (OCDD/OCDF) are used to dope the fly ash before their MC treatment in a laboratory developed planetary ball mill. In the case of fly ash from a simple fixed bed MWI, the contents of OCDD and OCDF are decreased by 64.7% and 63.6% respectively and the degree of chlorination decreases from 6.86 to 5.53. The treated fly ash is characterized by a more homogeneous distribution, a significant decrease in overall particle size as well as great enlargement in surface area and significant reduction of the original CaCO₃ content. The experimental results show that the MC degradation of dioxins is significant, and certain compounds (CaCO₃ et al.) in fly ash may act as dechlorinating reductant (e.g. CaO) in the process. The experiment may be practically helpful for removal of dioxin-like POPs in medical waste incineration fly ash.

Key words: fly ash, dioxin, mechanochemical treatment, ball milling, degradation efficiency