Industrialization has resulted in the discharge of a certain amount of lead (Pb) from industrial sources causing damage risk to water quality and human health. Adsorption is an effective technique to remove Pb, and biochar has been widely studied owing to its advantages of low cost and high adsorption capacity. This review summarizes the influence of raw materials and modification methods on the adsorption capability of biochar. The adsorption isotherms and kinetics of biochar were summarized, and the main Pb removal mechanisms were studied systematically. In addition, the challenges and future perspectives were discussed comprehensively. It is expected that the review could provide insightful fundamentals for the experimental research and practical applications of biochar.

The amount of food waste is increasing with the development of society and the increase in population; the rough treatment of food waste could result in a serious environmental crisis and waste of resources. Hydrothermal treatment is a promising scheme to achieve the harmless treatment and utilization of food waste. Although there are many studies on the hydrothermal treatment of food waste, there is still a lack of systematic summary and comprehensive analysis of the relevant literature. In this review, we provide an in-depth analysis of the specific impact mechanisms of hydrothermal conditions on the gaseous, solid, and liquid products. Meanwhile, the hydrothermal conversion mechanisms of food waste components are systematically sorted out. The review also discusses the potential application areas for the derived products from the hydrothermal treatment of food waste. Finally, the main challenges and future research directions are proposed to improve the development of the hydrothermal treatment of food waste.