Progress and challenges in recycling coal gasification wastewater using coal water slurry

This review comprehensively summarizes recent advances in utilizing coal gasification wastewater (CGW) for resource recovery and non-hazardous treatment via coal water slurry (CWS) technology. CGW is characterized by persistent organic pollutants and toxic components, with its environmental risks amplified by the presence of diverse harmful elements and trace heavy metals. On the other hand, CGW is rich in organic substances and possesses high calorific value indicate its significant potential for resource utilization. Given the dual concerns of energy needs and ecological impact, the key aim of CGW treatment is pollutant reduction and wastewater reuse toward achieving zero discharge. Among the various treatment technologies for CGW, the integrated approach combining CWS with gasification is considered the most effective method for achieving both objectives. Initially, this review paper analyzes the sources, composition, and characteristics of CGW. Then the co-slurry mechanism of coal wastewater slurry (CWWS) involving CGW, dispersants, and coal powder, along with the challenges in the formation process, and the application of advanced characterization tools and methods are discussed Subsequently, the gasification principles, carbon conversion efficiency, product characteristics, and pollutant migration and release behaviors of CWWS are systematically reviewed. Finally, the review concludes with a discussion of the current limitations of CWWS gasification for both academic research and industrial application, followed by future perspectives. • Resource recovery and non-hazardous disposal are the objectives for CWWS prepared by CGW. • The CGW characteristics with environmental risk and energy potential are summarized. • The theories, existing problems, and potential solutions of CGW-based slurry preparation are identified. • Gasification principle, products distribution, and harmful components flow of CWWS are focused. • The advantages and challenges for CWWS prepared by CGW are proposed and outlooked.