Utilization of liquid by-products from hydrothermal carbonization for the production of value-added products: a combined process using purple phototrophic bacteria and anaerobic digestion

Nowadays great attention has been paid to HTC for the production of biocoal since it is a process that operates with high moisture lignocellulosic biomass and other organic residues. However, one major challenge associated with HTC is the high amount of liquid by-products generated, which is often underused. In addition, the higher chemical oxygen demand (COD) levels of L-HTC makes it harmful to the environment and challenging to handle. Thus, cost-effective strategies are required for better utilization of L-HTC. In that regard, an innovative integrated process is proposed for the valorization of the liquid by-products from HTC utilizing a combined process with purple phototrophic bacteria and anaerobic digestion for the production of energy carries, specifically hydrogen (H2) and biomethane (CH4). The proposed activity can improve the overall feasibility of HTC process and allows to produce multiple energy carriers in an integrated approach while improving the resource efficiency.