Influence of Hydrothermal Carbonization Products on the Anaerobic Digestion of Sewage Sludge

Numerous studies have been conducted to address the challenges associated with the disposal of sewage sludge through anaerobic digestion (AD). Various methods aimed at enhancing the performance of AD process fed with sewage sludge have been explored, with a specific focus on increasing biogas production. Presently, predominant approaches involve the utilization of different processes bio-products as enhancers for methane production. In this study, the selected approach involves the sequential integration of Hydrothermal Carbonization (HTC) process with AD, where the products of the former serve as inoculum for the latter. HTC converts biomass into hydrochar by means of carbonization reactions. This process is particularly interesting because it can process wet biomass without a previous drying process. Three main products result from HTC: a gas, a liquid, and a solid phase, the latter known, as hydrochar. Hydrochar is supposed to be a good accelerator of methane production.