Effect of carbon dioxide on thermal treatment of food waste as a sustainable disposal method

Abstract

Herein, carbon dioxide (CO2) was applied to thermal treatment of real food waste to develop an environmentally benign way to dispose food waste. The food waste used in this study was collected from a food waste treatment plant. The application of CO2 to the thermal treatment of food waste affected the amount of non-condensable gases and condensable compounds produced from the thermal process, while it did not affect the amount of solid residue. When CO2 was supplied during the thermal treatment of food waste, less condensable compounds but more non-condensable gases such as H2, CO, and CH4 were generated during the thermal treatment of food waste at a range of temperatures from 400 to 700 °C. In addition to the change in product distribution, the generation of cyclic compounds was inhibited by applying CO2 to the thermal treatment. For example, approximately 30% less ring-structured compounds (e.g., benzene derivatives) were produced from the thermal treatment at 700 °C in CO2 condition than from the thermal treatment in inert condition. This was likely because CO2 inhibits gas phase free radical addition and/or dehydrogenation of linear compounds. This study suggests that the application of CO2 to thermally treating food waste would help develop a more environmentally friendly food waste treatment method.