Utilization of biochar for the removal of nitrogen and phosphorus

In recent years, excessive amounts of nitrogen (N) and phosphorus (P) in the environment have seriously affected the environment and human health. Due to its high removal efficiency, high flexibility and good economic and environmental benefits, biochar (BC) is a stable carbon-rich product formed by thermal decomposition of biomass such as agricultural and forestry wastes under anoxic conditions. The fine pore structure of the original material has strong adsorption capacity, low solubility, stable physical and chemical properties, rich pore structure, and large specific surface area. BC can be made from any organic material, common raw materials are rice husk, straw, animal manure, sewage sludge and some other agricultural wastes. It has received widespread attention as an adsorbent that efficiently adsorbs and removes N and P. It can not only be used to control environmental pollution, but also has a good application prospect in soil improvement and engineering treatment. If it is widely used in engineering, its expected effect will be beneficial to the overall environment. At present, the number of review articles in this area is relatively small. In order for scholars to understand the research progress in this area more conveniently and quickly, through a lot of literature review and summary, this article summarizes the research status of BC on N and P adsorption, and elaborates. The influence factors and adsorption mechanism of N and P were introduced, the application of N and P adsorbed by BC as fertilizer in soil was introduced, the application of BC in engineering treatment was introduced, and the economic and environmental benefits of BC were analyzed. After summarizing the current findings, we explore the future development of BC's adsorption of N and P and issues that need to be considered in the future development process. It is expected that this systematic review will help other interested researchers to participate in further exploration of this research area. (C) 2020 Elsevier Ltd. All rights reserved.