Waste-derived biochar for water pollution control and sustainable development

Biochar, a carbon-rich material made from the partial combustion of biomass wastes, is an emerging material of interest as it can remediate pollutants and serve as a negative carbon emission technology. In this Review, we discuss the application of biochar in municipal wastewater treatment, industrial wastewater decontamination and stormwater management in the context of sustainable development. By customizing the biomass feedstock type and pyrolysis conditions, biochar can be engineered to have distinct surface physicochemical properties to make it more efficient at targeting priority contaminants in industrial wastewater treatment via adsorption, precipitation, surface redox reactions and catalytic degradation processes. Biochar enhances flocculation, dewatering, adsorption and oxidation processes during municipal wastewater treatment, which in turn aids sludge management, odour mitigation and nutrient recovery. The addition of biochar to sustainable drainage systems decreases potential stormwater impact by improving the structure, erosion resistance, water retention capacity and hydraulic conductivity of soils as well as removing pollutants. The feasibility of scaling up engineered biochar production with versatile, application-oriented functionalities must be investigated in collaboration with multidisciplinary stakeholders to maximize the environmental, societal and economic benefits.