Biochar (BC), a high-carbon substance produced by thermally treating biomass, has emerged as a desirable, sustainable adsorbent for environmental clean-up, particularly for wastewater treatment. This review is an exhaustive survey of the literature, covering recent progress in biochar preparation, characterization and performance compared with traditional adsorbents such as activated carbon.
The structural and physicochemical properties of biochars, including pH, surface area, porosity and functional groups, which influence their capacity to adsorb pollutants, are given special attention. The discussion includes a sustainability evaluation via life cycle assessment (LCA) and carbon footprint analysis to demonstrate the potential for biochar systems to be carbon-negative and environmentally beneficial when produced from waste biomass.
Additionally, the study focuses on how BC can be recycled and regenerated across various treatment cycles, thereby increasing its lifespan. Cost–benefit analysis is used to assess the economic scalability of BC filters, especially in rural communities. Lastly, the possibility of incorporating BC into decentralized wastewater treatment units in off-grid, resource-constrained communities is described.
In general, this research highlights the triple role of BC in pollution removal, climate change mitigation and sustainable sanitation, making it a promising tool for the circular economy and rural environmental governance.
