Anaerobic digestion enhanced by biochar additives for effective treatment of industrial wastewater containing refractory organic matters: a comprehensive review

With industrialization accelerating and carbon emissions rising in recent years, the treatment of industrial wastewater containing refractory organic compounds must align with goals of energy conservation and emission reduction under the principle of carbon neutrality. Integrating anaerobic digestion (AD) with biochar (BC) presents a promising biological approach to mitigating the inhibitory effects of pollutants in wastewater treatment. By simultaneously utilizing waste biomass resources, the integration of these two sustainable biotechnologies within the biochar-anaerobic digestion (BC-AD) process not only enhances bioenergy recovery but also contributes substantially to the reduction of carbon emissions. This study addresses key challenges in the anaerobic treatment of industrial wastewater and introduces BC in terms of its functional applications, modification techniques, performance benefits, and prospects for achieving carbon neutrality. Experimental findings demonstrate that BC contributes significantly to maintaining neutral pH by regulating hydraulic retention time (HRT) and organic loading rate (OLR). The study presents a novel framework for the BC-AD process in treating industrial wastewater, emphasizing its potential to suppress refractory organics and eliminate toxic inorganics. By examining practical applications and identifying the challenges associated with large-scale implementation, this study improves the development and deployment of this integrated biotechnology. The primary objective is to encourage further investigation and industrial adoption of the BC-AD approach for low-carbon and environmentally sustainable wastewater treatment. Special emphasis is placed on the modification and application of BC to improve pollutant degradation and bioenergy recovery within AD systems, thereby underscoring its promise as an innovative solution aligned with carbon neutrality goals. © Higher Education Press 2025.