Wastewater remediation using municipal solid waste-derived hydrochar

Abstract

Industrialisation and population growth increase solid waste generation and the release of toxic pollutants into the environment. Therefore, novel approaches are necessary for both wastewater remediation and solid waste management. Current bio-waste adsorbents, such as bio-based activated carbon are expensive because of the high temperatures required for adequate preparation and activation. A promising alternative that can be chemically activated without high temperature is hydrochar, produced via hydrothermal liquefaction of the organic fraction of municipal solid waste. The comparative advantage of hydrochar over other bio-waste adsorbents is the high concentration of oxygen containing surface functional groups (COO-, -OH, -CO- and -C=O) that act as adsorption sites for heavy metals and phenolic components. This study explored the use of hydrochar as a bio-adsorbent in removing alkali and alkaline earth metals and phenolic components from a simulated wastewater stream of the hydrothermal liquefaction process. The simulated wastewater consisted of the five most abundant metals and four most abundant phenolics in the hydrothermal liquefaction aqueous product. These results were compared to adsorption using the real hydrothermal liquefaction aqueous product. Furthermore, the possibility of recovering adsorbed components and regenerating the hydrochar for multiple adsorption cycles was also investigated. ...