Biochar is a stable carbon-rich material that is produced by the thermochemical conversion of waste biomass in an oxygen-limited environment. Due to its low production cost, significant surface area, accessibility, thermal stability, high porosity, and the presence of multiple functional groups on its surface, biochar has been used as a promising adsorbent for the treatment of wastewater contaminated by a variety of pollutants. Biochar can be obtained from various sources, including biowaste. Biowaste feedstock refers to organic materials derived from living organisms that can be used as a source of raw material for biochar production. These feedstocks include a diverse range of organic materials derived from biological sources, such as agricultural residues, food waste, livestock manure, and organic municipal solid waste. This chapter provides a concise overview of the use of biochar produced from biowaste for the treatment of wastewater contaminated by dyes. The biochars, which were mostly produced by pyrolysis and hydrothermal carbonization at temperatures between 200°C and 900°C, demonstrated excellent adsorption capacities for the pollutants and correlated well with the Langmuir and Freundlich isotherm models and pseudo-second-order kinetics. The biochars can be further activated and modified to increase their surface area and, subsequently, their adsorption capability. The sorption mechanisms involve both physical and chemical processes. Prospective studies were outlined that will ensure practical applications of biowaste-based biochar. © 2025 Elsevier Inc. All rights reserved.
