Nowadays, due to wastewater released from underground workings, decontamination of neutral mine drainage from toxic metals and rare earth elements is a public concern. They can pollute surface waters by their high mobility and solubility in water. Among the most common technics for the removal of pollutants, the adsorption method because of effective removal of metals, easy operation, and low cost is the most successful method. Biochar, as a novel adsorbent, has been receiving much attention because of the reuse of biomass, porous structure, and abundant functional groups.