Food Waste Valorization Through Pyrolysis to Biochars

Sustainable waste management necessitates that industries shift from the current linear model into a more closed loop operation, where wastes become raw materials for the production of new products (i.e. circular economy). Biomass and associated waste materials can be converted into value-added products through the use of thermochemical and biological processes. The pyrolysis process is a convenient thermochemical method, whereby biomass is efficiently converted into useful products. This work aims to produce a value-added product called biochar, which is intended for use as a soil enhancer and can be further processed into even higher value-added products. The first phase of the work involved simulations of the pyrolysis process using Aspen and drying experiments of selected food items (i.e. tomatoes, carrots, potatoes, and cucumbers) prior to the pyrolysis process. The drying stage was followed by elemental analysis and proximate analysis of the dried food samples and their blends, which consisted of individual food items, binary mixtures, and a ternary blend of the three selected food samples. The major step in this study is the thermogravimetric analysis in which food waste decomposition into biochar and gaseous products was studied and analyzed in terms of yield and kinetics, and pyrolysis behaviour throughout the process. Finally, the viability of the study was assessed using technoeconomic and life cycle analyses for selected scenarios involving the production of value-added products from food waste using pyrolysis. The results of the simulations are promising and indicated a good potential of the process in producing desired product yield and characteristics. Moreover, the drying curves are also presented and discussed along with the results of the TGA which are also analyzed and discussed. Finally, the process economics and LCA resulted in estimates that led to the selection of the best routes for the production of value-added products from blended and pure food waste streams.