Co-Hydrothermal Carbonization of Polystyrene and Brewery Waste: Evaluation of Fuel Properties and the Effect of Blending Ratio and Temperature on Hydrochar Properties

This study investigates the co-hydrothermal carbonization (Co-HTC) of polystyrene (PS) and brewery waste (BW) to produce high-quality hydrochar with enhanced fuel properties. Experiments were carried out with different PS-to-BW ratios and reaction temperatures to assess their impact on hydrochar yield, physicochemical properties, and combustion performance. The results showed that higher PS content notably enhanced both the hydrochar yield and higher heating value (HHV), demonstrating increased energy recovery potential. FTIR analysis revealed a gradual reduction in peak intensities with increasing temperature, indicating enhanced decomposition and structural transformation of functional groups. Examination of combustion properties demonstrated improved ignition and firing behavior, evidenced by reduced combustion durations and elevated combustion indices. Van Krevelen analysis showed that the co-hydrochars migrated toward the coal compositional region, supporting their potential as a sustainable alternative to conventional solid fuels. These findings underscore Co-HTC as a promising waste-to-energy strategy for the concurrent valorization of plastic and biomass waste streams.