Analysis and Characteristics of Hydrochar and Liquid Products Produced via Hydrothermal Liquefaction of Poultry Wastes

Abstract

Hydrothermal liquefaction (HTL) of poultry waste is a potential method for converting high-moisture organic wastes into energy-dense solid and liquid products. In this study, the conversion of poultry waste into biocrude and hydrochar via HTL was explored. The fuel properties and chemical structure of biocrude and hydrochars were examined using standard fuel analytical and spectroscopic techniques. The products were produced from poultry waste via HTL at temperatures ranging from 200 to 350 °C, in 50 °C increments, with a reaction time of 30 minutes. The findings revealed a clear relationship between temperature and product distribution. Specifically, the yield of hydrochar decreased from 24.78 wt% at 200 °C to 23.05 wt% at 300 °C, and the liquid yield increased from 12.14 wt% to 21.15 wt%, indicating that higher temperatures promote better depolymerization and solubilization. Elemental analysis revealed a higher carbon content of 67.26% and a lower oxygen content of 18.96%. This led to an increase in the higher heating value of 31.10 MJ kg⁻¹. The liquid products had an acidic pH level of 5.5, which indicated the presence of organic acids. However, elemental analysis revealed a significant nitrogen content of 5.13% in biocrude. As a result, bio-oil produced from HTL of poultry waste should be upgraded through hydrotreatment (hydrodeoxygenation and hydrodenitrogenation) with H₂ or a catalyst to minimize oxygen and nitrogen before utilization as a transportation and heating fuel. Therefore, conducting HTL at higher temperatures significantly increases liquid yield and energy density while minimizing solid waste. These findings highlight the significant potential for using poultry waste in HTL to produce sustainable bioenergy and valuable liquid intermediates.