TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Method: The method further comprises: recovering carbon from the aqueous phase; providing the aqueous phase to a digester to generate biogas; steam methane reforming of the biogas to convert the methane fraction to hydrogen and carbon dioxide; steam gasification of the biogas to convert the methane fraction to syngas; processing the syngas to produce a liquid hydrocarbon; adding a catalyst to the first hydrothermal treatment; producing the aqueous suspension of the biomass before the first hydrothermal treatment; converting the organic phase to a fuel; and feeding some of the fuel back into the first hydrothermal treatment as at least a portion of the first organic solvent. The step of recovering carbon from the aqueous phase includes producing carbon dioxide. The carbon dioxide is used to cultivate algae. The carbon dioxide is fed into the first hydrothermal treatment. The step of producing the aqueous suspension of the biomass includes cultivating algae and dewatering the algae. The first temperature is no more than 200 degrees C. The first multi-phasic mixture further includes a solid phase, the separation step further comprises separating the solid phase from the organic and aqueous phases, and the method further comprises a second hydrothermal treatment comprising treating the solid phase under a second hydrothermal condition comprising a second treatment temperature above the first treatment temperature and a pressure of 200-3000 psi to produce a second multi-phasic mixture of an organic phase and an aqueous phase, and separating the organic phase from the aqueous phase of the second multi-phasic mixture. The second hydrothermal treatment further includes treating the solids together with a second solvent. The method further comprises recovering carbon from the aqueous phase separated from the second multi-phasic mixture. The second hydrothermal treatment comprises a second subcritical hydrothermal treatment. The carbon recovered from either aqueous phase is fed into the second hydrothermal treatment as carbon dioxide. The first hydrothermal treatment is accomplished in a continuous steady-state reactor. Preferred Components: The first organic solvent comprises a hydrocarbon. The aqueous suspension of the biomass is present at 5-30 wt.%. The volume ratio of water to the first organic solvent used in the subcritical treating step is 1:1-10:1. The biomass has a carbon and nitrogen ratio (C:N) of less than 10. The organic phase has C:N of greater than 40 after the separation step.