Valorization of Horse Manure Waste through Hydrothermal Liquefaction: A Thermochemical Approach to Renewable Biocrude

The valorization of agricultural residues, such as horse manure mixed with bedding material, into renewable biofuels remains constrained by the limitations of conventional conversion methods. Hydrothermal liquefaction (HTL), a thermochemical process particularly well-suited for wet lignocellulosic biomass, offers a promising alternative but remains underexplored for equine waste mixtures. This study investigates the influence of reaction temperature on the yield of biocrude from a 1:9 horse manure-to-bedding mixture. Experiments were conducted at temperatures of 275°C, 300°C, 325°C, and 350°C, using a 10% solid content and a residence time of 40 minutes. The results indicate a strong positive correlation between temperature and biocrude yield, increasing from 7.3 wt% at 275°C to a maximum of 15.3 wt% at 350°C. Concurrently, solid residue declined from 38.0 wt% to 9.0 wt%, indicating enhanced conversion efficiency. These findings emphasize the critical role of thermal conditions in optimizing HTL processes and confirm the viability of converting equine agricultural waste into energy-dense biocrude. The study provides valuable insights for the design and development of sustainable biorefineries targeting high-moisture agricultural residues.