This study explores the influence of wastewater feedstock composition on hydrothermal
liquefaction (HTL) biocrude oil properties and physico-chemical characteristics. Spirulina algae,
swine manure, and digested sludge were converted under HTL conditions (300°C, 10-12 MPa,
and 30 min reaction time). Biocrude yields ranged from 9.4% (digested sludge) to 32.6%
(Spirulina). Although similar higher heating values (32.0-34.7 MJ/kg) were estimated for all
product oils, more detailed characterization revealed significant differences in biocrude
chemistry. Feedstock composition influenced the compounds identified as well as the biocrude
functional group chemistry. Molecular weights tracked with obdurate carbohydrate content and
followed the order of Spirulina < swine manure < digested sludge. A similar trend was observed
in boiling point distributions and the long branched aliphatic contents. These findings show the
importance of HTL feedstock composition and highlight the need for better understanding of
biocrude chemistries when considering biocrude oil uses and upgrading requirements.