Remediation of Soil Contaminated by Heavy Metals Using Biochar: Strategies and Future Prospects

With the rapid development of industry and human society, massive heavy metals have been released into varied environments, the long-term accumulation of heavy metals is difficult to be removed and toxic to the ecological environment subtly. Global heavy metal pollution is serious, so it is necessary to study and develop economically feasible, green and effective remediation strategies to solve these pollution problems. In soil contaminated by heavy metals, especially in farmland, a vast number of heavy metals will directly or indirectly accumulate the food chain, and then lead to a severe threat to food production and security. Heavy metal pollution in soil threatens health and ecological sustainable development of all kinds of life, including human beings. Biochar, as a current and environmentally friendly material, has been widely used for remediation of water and soil polluted by heavy metals, carbon sequestration and other aspects, exhibiting the great application potential. The adsorption effect of biochar depends largely on its raw material source, preparation method and conditions, so the biochar obtained by traditional preparation method needs to be improved due to its limited adsorption capacity. Increasing scholars have focused on modification biochar in the past decade, and the combined application technology of biochar has also achieved huge progresses. Based on this, this review summarizes the current research progress of biochar in remediation of heavy metal pollution, the production, properties, repair mechanism, and modified methods. Simultaneously, the applications of biochar combined with microbial technology are introduced in detail, and we also propose the future research and development direction of biochar used for remediation of soil contaminated by heavy metals.