Valorization of suspended solids from wine effluents through hydrothermal liquefaction: a sustainable solution for residual sludge management

The growing concern over the environmental impacts of the wine industry has driven the search for sustainable technologies to manage its waste, particularly the residual sludge generated during effluent treatment. This sludge, rich in organic matter, represents a significant source of pollution if not properly treated. However, their energy content allows them to turn this environmental liability into an asset through innovative valorization. Hydrothermal liquefaction (HTL) emerges as a promising technology in this context. This process allows the direct conversion of residual sludge into high-energy-value liquid biofuels. Unlike other treatment methods, HTL can process wet biomass without needing prior drying, making it particularly suitable for managing sludge from wine effluents. Thus, this research aims to evaluate the conversion of residual sludge derived from wine effluent treatment into biofuels through a hydrothermal liquefaction simulation, integrating this process into a sustainable biorefinery for levulinic acid and bioethanol production. The methodology considers the determination of the composition and treatment of the wine effluent to define a case study. The biorefinery processes, as well as the HTL, are designed and simulated in Aspen Plus V.14, and also they are evaluated technically and economically. As a result, levulinic acid, sustainable aviation fuel, bioethanol, propylene glycol, and electrical energy are produced. In addition, the biorefinery reduces the effluent's Chemical Oxygen Demand (COD) by 99%. In conclusion, valorizing suspended solids from wine effluents through HTL is technically and economically feasible.