Hydrothermal liquefaction of municipal solid wastes for high quality bio-crude production using glycerol as co-solvent

This study is focused on the valorization of heterogeneous municipal solid waste collected from the landfill using hydrothermal liquefaction process using glycerol as a co-solvent. The effects of temperature (300–350 °C) and residence time (15–45 min) on the yields and quality of the product fractions were investigated at 8 wt% solid loading. The yield of bio-crude significantly increased from 15.2 wt% with water as the solvent, to 58 wt% with water-glycerol (1:1 v/v) as the solvent possessing an energy content of 35.6 MJ/kg at 350 °C, 30 min. The quality of the bio-crude obtained using glycerol was comparable to that using tetralin as a hydrogen donor co-solvent. Phenolic compounds and cyclooxygenates were the major compounds in the bio-crude, and aliphatic hydrocarbons increased with residence time. Maximum energy recovery of 95% was achieved in the products with an energy consumption ratio of 0.43 for the bio-crude signifying the energetic feasibility of the process.