Evaluation of South Korean marine waste resources for hydrochar production: Effect of process variables

This study assessed the hydrochar production potential of fish and crustacean waste from 8 marine species (Scomber japonicus, Trichiurus lepturus, Larimichthys polyactis, Trachurus trachurus, Paralichthys olivaceus Litopenaeus vannamei, Portunus trituberculatus, and Penaeus monodon) through hydrothermal carbonization (HTC) of their waste fractions. The impact of reaction temperature (200 - 240°C), fixed residence time (5 h), and water-to-biomass ratio (7) on HTC was analyzed. The results showed that hydrochar yields varied between fish (15.1 - 21.5 %) and crustaceans (36.9 - 69.3 %). The elemental composition and surface properties of the hydrochar were influenced by reaction temperature, as indicated by the pH point of zero charge. The adsorption capacity of hydrochar was tested for methylene blue (MB, 2.7 - 10.8 mg/g) and methyl orange (MO, 5.9 - 9.2 mg/g), with MO showing higher adsorption, except for Scomber japonicus, Larimichthys polyactis, and Trachurus trachurus. These findings highlight the significant potential for converting marine waste into valuable hydrochar, contributing to waste management and sustainable resource utilization.