Hydrothermal carbonization as an all-inclusive process for food-waste conversion

Abstract

Food waste is highly energetic biomass but its recycling and disposal process is costly and time-intensive, and the wet, inhomogeneous waste is unwelcome in biomass plants. Searching for an alternative processing pathway, we studied the feasibility of a decentralized, small-scale hydrothermal carbonization plant. Restaurant food waste was converted at 200 °C for 6 h into high-quality hydrochar that has fuel qualities similar to those of lignite and which could be used for co-combustion. We successfully treated the liquid phase with ultraviolet radiation to minimize the total organic carbon and chemical oxygen demand in order to facilitate conventional disposal. Such a plant would pay for itself and begin to generate profit within eight years. We see hydrothermal carbonization in the catering industry as a sustainable and convenient solution for food-waste conversion.