Hydrothermal carbonization of digestate and leachate in a lab-scale batch reactor

The use of biomass as a feedstock for renewable energy and biomaterials production is gaining increasing attention due to economic and environmental issues. Among all substrates, the organic fraction of municipal solid waste represents a valuable resource for anaerobic digestion facility. This process generates biogas, digestate and leachate. The last two streams are by-products, with potential harmful environmental impact and significant disposal costs. Thus, a proper handling of these biowastes is needed. In the present study, a bench-scale hydrothermal carbonization reactor was operated with two mixtures of digestate and water or leachate varying the residence time and the reaction temperature. The results indicated that aforementioned operating parameters affect the composition and the yield of the obtained hydrochar and that the substitution of water with leachate is technically feasible.