Hydrogen Production by Supercritical Water Gasification of Wastewater from Food Waste Treatment Processes

Korean food wastes have high moisture content (more than 85 wt%) and their major treatment processes such as drying or biological fermentations generate concentrated organic wastewater (CODs of about 100,000 mgO2/L). For obtaining both wastewater treatment and hydrogen production from renewable resources, supercritical water gasification (SCWG) of the organic wastewater was carried out in this work. The effect of catalyst, reaction temperature, and reactor residence time on COD destruction and composition of gas products was examined. As a result, a SCWG of the wastewater over NiY/activated charcoal at 700 C, 28 MPa yielded 99 % COD destruction and hydrogen-rich gas production (45 vol% H2). A liquid-phase thermal pretreatment to destroy solid particles from the wastewater was proposed for more effective operation of the SCWG system.