Sewage sludge (SS), a hazardous solid waste with a high water and pollutant content, should be disposed of correctly. Hydrothermal liquefaction (HTL) shows tremendous potential to treat organic matter with substantial water content like SS. In this paper, we examined the impact of key factors on the characteristics and yield of bio-oil during HTL of SS. We clarified the impacts of each component on the yield through model compounds based on that and constructed a component additivity model for forecasting the bio-oil yield from biomass with complex component composition. In the reactions of the model compounds, cellulose showed synergistic interaction with protein and alkali lignin in the bio-oil yield but lipids showed antagonistic effects with protein and alkaline lignin. The co-HTL results of these binary mixtures improved our model and further clarified the reaction mechanism of HTL of SS.
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