A review of solid wastes-based stabilizers for remediating heavy metals co-contaminated soil: Applications and challenges

The remediation of heavy metals/metalloids (HMs) co-contaminated soil by solid wastes-based stabilizers (SWBS) has received major concern recently. Based on the literature reported in the latest years (2010-2023), this review systematically summarizes the different types of solid wastes (e.g., steel slag, coal fly ash, red mud, and sewage sludge, etc.) employed to stabilize HMs contaminated soil, and presents results from laboratory and field experiments. Firstly, the suitable solid wastes for soil remediation are reviewed, and the pros and cons are presented. Thereafter, the technical feasibility and economic benefit are evaluated for field application. Moreover, evaluation methods for remediation of different types of HMs-contaminated soil and the effects of SWBS on soil properties are summarized. Finally, due to the large specific surface, porous structure, and high reactivity, the SWBS can effectively stabilize HMs via adsorption, complexation, co/precipitation, ion exchange, electrostatic interaction, redox, and hydration process. Importantly, the environmental implications and longterm effectiveness associated with the utilization of solid wastes are highlighted, which are challenges for practical implementation of soil stabilization using SWBS, because the aging of soil/solid wastes has not been thoroughly investigated. Future attention should focus on modifying the SWBS and establishing an integrated long-term stability evaluation method.