Experimental and model enhancement of food waste hydrothermal liquefaction with combined effects of biochemical composition and reaction conditions

Excessive food waste presents an opportunity to simultaneously alleviate waste and produce renewable resources. The present work uses hydrothermal liquefaction (HTL) with elevated temperatures (280–380 °C) and times (10–60 min) to convert categorized food residues collected from a university campus dining hall into biocrude oil. Analysis of distinct feedstocks presented different biochemical compositions (protein, carbohydrate, and lipid) and yielded between 2 and 79% biocrude oil for the respective optimized HTL temperatures and times. Reaction pathways and elemental distributions (C,H,N) elucidated HTL product qualities based on feedstocks and optimized reaction conditions. Both descriptive HTL process energy recoveries and consumption ratios are included. An improved predictive model was able to accurately determine biocrude oil yield (R²_adj 98.3%) of different food wastes under different reaction conditions, as well as predict previously published data (R² 94.3%). Combined experimental and analytical results were used to assess the sustainability and robustness of the HTL process.