Review of thermal treatments for the degradation of dioxins in municipal solid waste incineration fly ash: Proposing a suitable method for large-scale processing

Dioxin degradation is considered essential for the environmentally sound management of municipal solid waste incineration fly ash (MSWIFA). Among the many degradation techniques, thermal treatment has shown good prospects owing to its high efficiency and wide range of applications. Thermal treatment is divided into high-temperature thermal, microwave thermal, hydrothermal, and low-temperature thermal treatments. High-temperature sintering and melting not only have dioxin degradation rates higher than 95 % but also remove volatile heavy metals, although energy consumption is high. High-temperature industrial co-processing effectively solves the problem of energy consumption, but with a low fly ash (FA) mixture, and the process is limited by location. Microwave thermal treatment and hydrothermal treatment are still in the experimental stage and cannot be used for large-scale processing. The dioxin degradation rate of low-temperature thermal treatment can also be stabilized at higher than 95 %. Compared to other methods, low-temperature thermal treatment is less costly and energy consumption with no restriction on location. This review comprehensively compares the current status of the above-mentioned thermal treatment methods and their ability to dispose of MSWIFA, especially the potential for large-scale processing. Then, the respective characteristics, challenges, and application prospects of different thermal treatment methods were discussed. Finally, based on the goal of low carbon and emission reduction, three possible approaches for improvement were proposed to address the challenges of large-scale processing of low-temperature thermal treatment, namely, adding a catalyst, changing the FA fraction, or supplementing with blockers, providing a reasonable development direction for the degradation of dioxins in MSWIFA.