Review on the Adsorption Removal of Contaminants from Wastewater Using Biochar Derived from Agricultural Waste

Valorisation of agricultural wastes can improve the economic efficiency of crop production while reducing environmental pressures. Owing to its simplicity, high efficiency, low cost, and scalability, the use of biochar as an adsorbent for contaminant removal has been widely studied. Producing biochar from agricultural wastes and applying it to remove contaminants from aqueous and solid matrices, including wastewater and soils, follows the principles of the circular economy and supports environmental remediation and agricultural development. This review summarises adsorption mechanisms, biochar production routes from agricultural wastes, and applications in wastewater treatment. It also evaluates economic performance and environmental impacts, and identifies current challenges and future research directions.