Reutilization of Algal Supercritical Water Gasification Waste for Microalgae Chlorella vulgaris Cultivation

Effluents obtained through a supercritical water gasification (SCWG) process at 400 and 600 °C were mixed with Bristol Medium to cultivate Chlorella vulgaris. Improvement of growth rate was observed only for the medium with the effluent at 600 °C. Low non-purgeable organic carbon implied that the inhibiting material was decomposed due to the high temperature of 600 °C. Thus, SCWG effluents might be more suitable for algae cultivation than hydrothermal liquefaction effluents. Phosphorus accumulation in C. vulgaris was improved in the SCWG mixed medium, irrespective of the treatment temperature. The media with SCWG effluents showed 2.5 times higher phosphorus accumulation in the algae, indicating the possibility of using a combination of C. vulgaris and SCWG for nutrient recycling processes.