Three-stage pretreatment of food waste to improve fuel characteristics and incineration performance with recovery of process by-products.

[Display omitted] • A three-stage pre-treatment method for food waste (FW) adapted to incineration was proposed, and resources were recovered along with energy. • The freshwater in FW was recovered by a freeze-drying process and its availability was detected and proven. • The negative effect of the presence of lipids on the fuel properties evolution of torrefaction products was investigated. • The fuel properties and combustion performance of coal-like torrefaction products from FW were well evaluated. As of 2020, the annual generation of municipal solid waste (MSW) in China has surged to 235.12 Mt, and food waste (FW) accounts for more than 60 %. The most common treatment method is incineration, which accounts for 62.13 %. This research proposes a three-stage pretreatment method for FW that is suitable for incineration while recovering by-products and energy from the pretreatment process. The first stage is dehydration; as compared to hot air drying (HAD) processes, freeze drying (FD) exhibits a higher dehydration and oil preservation rate, allowing for the preservation of organic matter content and the recovery of freshwater resources from FW. The second stage is oil recovery; the FW extracted oil (FWEO) can be used to produce biodiesel, and this stage also helps to improve the effectiveness of the subsequent torrefaction process. The third stage improves the energy and fuel characteristics of the organic residue of FW and enhances the combustion performance by optimizing the torrefaction temperature. The solid fuel obtained at a torrefaction temperature of 350 °C shows the best combustion performance, with a solid yield of 35.76 %, a torrefaction temperature of 300 °C might be chosen to further improve the solid yield. [ABSTRACT FROM AUTHOR]