GCB Bioenergy. 2024;16:e13175. | 1 of 37 https://doi.org/10.1111/gcbb.13175 wileyonlinelibrary.com/journal/gcbb Received: 28 March 2024 | Revised: 6 June 2024 | Accepted: 6 June 2024 DOI: 10.1111/gcbb.13175 REVIEW Biochar produced from waste-based feedstocks: Mechanisms, affecting factors, economy, utilization, challenges, and prospects Shams Forruque Ahmed 1 | Fatema Mehejabin 2 | Ashfaque Ahmed Chowdhury 3,4 | Fares Almomani 5 | Nadeem A. Khan 6 | Irfan Anjum Badruddin 7 | Sarfaraz Kamangar 7 1 Department of Mathematics & Physics, North South University, Dhaka, Bangladesh 2 Science and Math Program, Asian University for Women, Chattogram, Bangladesh 3 School of Engineering and Technology, Central Queensland University, Gladstone, Queensland, Australia 4 Fuel and Energy Research Group, Centre for Hydrogen and Renewable Energy (CHRE), Central Queensland University, Gladstone, Queensland, Australia 5 Department of Chemical Engineering, Qatar University, Doha, Qatar 6 Interdisciplinary Research Center for Membranes and Water Security (IRC-MWS), King Fahd University of Petroleum and Minerals, Dhahran, Saudi Arabia 7 Mechanical Engineering Department, College of Engineering, King Khalid University, Abha, Saudi Arabia This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. © 2024 The Author(s). GCB Bioenergy Published by John Wiley & Sons Ltd. Abbreviations: BC, biochar; BCF, biochar-clay composite filter; BET, Brunauer–Emmett–Teller; BJH, Barret–Joyner–Halender; CaCl 2 , calcium chloride; CO 2 , carbon dioxide; Cr, chromium; FAAS, flame atomic absorption spectrophotometer; FeCl 3 , ferric chloride; GHG, greenhouse gas; HHV, high heating value; KOH, potassium hydroxide; MgCl 2 , magnesium chloride; MSP, minimum selling price; NO x , nitrogen oxide; NPV, net present value; OM, organic matter; PAH, polycyclic aromatic hydrocarbon; PCM, phase change material; POP, persistent organic pollutants; SDG, sustainable development goals; SEM, scanning electron microscopy; SFG, Surface functional group; TG, thermogravimetric; TGA, thermogravimetric analysis; TTIP, titanium isopropoxide; TWCB, torrefied woodchip briquettes; WCB, woodchips briquettes; XRD, X-ray powder diffraction. Correspondence Shams Forruque Ahmed, Department of Mathematics & Physics, North South University, Dhaka 1229, Bangladesh. Email: shams.forruque@northsouth. edu; shams.f.ahmed@gmail.com Abstract Biochar possesses unique characteristics, including a substantial surface area, a high carbon content, sufficient capacity for cation exchange, and a robust struc- ture. However, biochar contains hazardous pollutants like volatile organic com- pounds that harm soil properties and functionality. Although several studies on biochar production from various feedstocks have been undertaken in recent years, several issues about feedstock preparation, economic feasibility, influenc- ing factors, and the proper utilization of biochar production processes need to be addressed. This paper thus addresses these issues by providing potential so- lutions identified through a comprehensive review. Slow pyrolysis of lignocel- lulosic biomass and Acacia nilotica yields biochar from 20 to 52 wt% at various temperatures and residence times. Biochar yield varies from 29 to 48.3 wt% when waste tires and corn stalks are rapidly pyrolyzed at higher temperatures and for shorter periods. Torrefaction of algal biomass at moderate temperatures with