Municipal solid waste incineration (MSWI) has become a mainstream waste management strategy globally, yet the hazardous fly ash (FA) it generates—accounting for 3–15% of waste mass—poses critical environmental challenges due to its high concentrations of potentially toxic heavy metal elements (HMs), dioxins, and soluble chlorides. Paradoxically, FA's richness in Ca, Si, Al, and Fe endows it with latent mineral resource value, positioning this material at the nexus of environmental risk and circular economy opportunity.

Currently, three principal technological pathways have emerged for FA treatment. Cement-based stabilization/solidification (S/S) using ordinary Portland cement or alternative binders immobilizes HMs through physical encapsulation and chemical incorporation, though field evidence reveals substantial re-leaching risks after years of landfill aging. Chemical stabilization with phosphate or sulfur-donor chelating agents achieves >90% immobilization efficiency for Pb and Cd, yet faces challenges of pH-dependent stability and high reagent costs. Alkali-activated materials enable FA to serve as either precursor or encapsulated waste, forming dense geopolymeric networks that chemically bind HMs while producing low-carbon binder materials. Thermal treatments such as vitrification and sintering effectively destroy organics and recover metals, but energy intensity limits scalability. Despite these advances, critical gaps still exist. FA's extreme compositional heterogeneity—with Zn concentrations varying by over 3000-fold across sources—undermines any single treatment approach. Long-term stability under realistic landfill conditions, including carbonation, freeze-thaw cycling, and organic acid exposure, remains poorly understood and inadequately assessed by short-term compliance tests. Molecular-scale immobilization mechanisms require further elucidation to enable predictive modeling. Economic viability constrains adoption of advanced technologies in many regions.

Against this background, we would like to organize a Special Issue to bring together cutting-edge research that addresses the fundamental mechanisms, technological innovations, and practical applications of MSWI fly ash treatment and valorization. By bridging fundamental mechanisms with practical applications, this issue aims to accelerate the transition from hazardous waste disposal toward sustainable, resource-efficient solutions that maximize environmental and economic benefits.

Topics covered include, but are not limited to:

• Advanced stabilization/solidification technologies
• Chemical stabilization reagents
• Thermal treatment and resource recovery
• Fundamental mechanisms of HMs immobilization
• Long-term performance and environmental risk assessment
• Recycling and valorization into construction materials
• Life cycle assessment and economic analysis
• Regional management strategies and case studies

Guest Editors

Dr. Yibing Zuo

Spanish National Research Council (CSIC)/Huazhong University of Science and Technology

Prof. Baomin Wang

Dalian University of Technology

Prof. Zuhua Zhang

Tongji University

Submissions and Publication

1. Acceptable paper types: Original Research Report/Communication/Review/Progress Report.
2. Please prepare your manuscript using the Manuscript Template (note that the Graphical Abstract, Author Contribution Statement, Declaration of Competing Interest, and Author Biography are required), and see the full Submission Guidelines for further details.
3. Please submit your manuscript via the ScholarOne Manuscripts system before February 28, 2027, and please select “Treatment and Valorization of MSWI Fly Ash: From Mechanisms to Applications”.
4. Once a themed issue paper is accepted, it will be quickly released online on the SciOpen platform, without waiting for other papers of this issue.

Open Access Sponsorship

As a fully open-access journal, MRSE will provide maximum exposure for published articles, making the research available to all to read and share. In addition, MRSE will waive the Article Processing Charge (APC) for the invited contribution.

Contact

Dr. Yibing Zuo, yibing.zuo@ietcc.csic.es

Prof. Baomin Wang, wangbm@dlut.edu.cn

Prof. Zuhua Zhang, zhangzuhua@tongji.edu.cn

Editorial Office of Materials Reports: Solidwaste and Ecomaterials, mrse@mater-rep.com