Fate of dioxins in a municipal solid waste incinerator with state-of-the-art air pollution control devices in China

Abstract

The variation of municipal solid waste (MSW) components and the improvement of incinerators have an obvious effect on dioxin emissions. However, there is a knowledge gap on dioxin distribution characteristics following China's implementation of MSW classification. To reveal the fate of dioxins under ultra-low emission standards in leading cities in China, a systematic investigation was carried out in a typical modern MSW incinerator in Shenzhen, China. The dioxin mass balance was built using improved models, which included expanded samples, e.g., the leachate, the raw gas and raw ash from boiler, and the chemicals and residuals from air pollution control devices (APCDs). The results indicated a positive dioxin balance of 0.88 μg I-TEQ/t MSW according to the conventional method containing fly ash, bottom ash, and stack gas. In the new model revealing dioxin characteristics after APCDs, a higher value of 0.89 μg I-TEQ/t MSW was found due to the leachate, slaked lime, and activated carbon-containing dioxins. The distribution of dioxins in output samples of fly ash, bottom ash, stack gas, and leachate were 149.0 %, 41.8 %, 1.6 %, and 0.6 % of MSW, respectively. For incineration itself, the balance was 0.85 μg I-TEQ/t MSW, which indicated the possible release owing to the "memory effect" for the other two methods. This study provided new insight for the accurate estimation of dioxin emissions and a typical case report of MSW incineration with ultra-low dioxin emissions.

Keywords: Leachate; Mass balance; Positive balance; Ultra-low emission.