Production of biochar from biowaste and its application in wastewater treatment

Efficient management of solid wastes such as food wastes, agricultural wastes, and sewage sludge is a global priority. One of the solutions to address solid waste management is to convert wastes to useful and environment-friendly materials such as biochar. Biochar is generated from natural organic feedstocks by thermal treatment in an oxygen-limited environment. Biochar has gained significant considerations for the removal of pollutants from wastewater due to its unique characteristics such as surface area, surface charge, and porosity. In this chapter, the application of pyrolysis, hydrothermal carbonization (HTC), and gasification methods to produce biochar is discussed. Among the different methods, pyrolysis is the most widely employed to produce biochar. Furthermore, research suggests that the temperature and feedstock composition have significant impacts on biochar properties. In addition, pretreatment methods such as oxidation, alkali, hydrothermal, ultrasonic, and microwave and posttreatment methods such as activation have been used to improve the characteristics of biochar. Finally, the removal of heavy metals, nutrients, and organic pollutants, including emerging micropollutants, from wastewater by biochar-based methods is elaborated.