Wang Huan, Zhu Fenfen, Chen Renhua, Qiu Yuqun, Zhao Bing
School of Chemistry and Life Resources, Renmin University of China, No. 59 Zhongguancun Street, Beijing 100872, China.
School of Chemistry and Life Resources, Renmin University of China, No. 59 Zhongguancun Street, Beijing 100872, China.
Waste Manag. 2025 Feb 1;193:419-429. doi: 10.1016/j.wasman.2024.12.028. Epub 2024 Dec 25.
The high chlorine content in municipal solid waste incineration (MSWI) fly ash is a key factor restricting its treatment and disposal. In this study, a new treatment method was proposed to enhance the deep dechlorination of fly ash by coupling supercritical CO (SC) treatment with water washing. Simultaneously the alkaline compounds in fly ash can fix CO and achieve CO credits. The results showed that supercritical CO significantly improved the removal of chlorine. The treatment of "double water washing + SC + washing again" reduced the chlorine content in fly ash to 0.83 %, while "SC + double water washing + SC + washing again" reduced the chlorine content to 0.88 %, and the removal rate of chlorine was as high as 96.8 % and 96.5 %, respectively. In addition, supercritical CO promoted the decomposition of insoluble chloride (Friedel's salt) and the removal rate of insoluble chloride salts can reach 89.1 %. On the other hand, after supercritical CO treatment, fly ash can quickly and efficiently absorb CO, and the amount of CO absorbed after two supercritical CO treatments was 64 g/kg. Lastly, supercritical CO could significantly stabilize heavy metals in fly ash and reduce the concentrations of Pb and Cr in the washing solution.
城市固体废弃物焚烧（MSWI）飞灰中高氯含量是限制其处理与处置的关键因素。本研究提出一种新的处理方法，通过将超临界CO（SC）处理与水洗相结合来强化飞灰的深度脱氯。同时，飞灰中的碱性化合物可以固定CO并实现CO减排。结果表明，超临界CO显著提高了氯的去除率。“两次水洗 + SC + 再次水洗”的处理方式将飞灰中的氯含量降低至0.83%，而“SC + 两次水洗 + SC + 再次水洗”则将氯含量降低至0.88%，氯的去除率分别高达96.8%和96.5%。此外，超临界CO促进了不溶性氯化物（Friedel盐）的分解，不溶性氯化物盐的去除率可达89.1%。另一方面，经过超临界CO处理后，飞灰能够快速有效地吸收CO，两次超临界CO处理后吸收的CO量为64 g/kg。最后，超临界CO能够显著稳定飞灰中的重金属，并降低洗涤液中Pb和Cr的浓度。
