Liang Dehua, Wang Fei, Xue Shengrong, Yan Jiawei, Xu Yang, Lv Guojun, Yan Jianhua
State Key Laboratory of Clean Energy Utilization (Zhejiang University), Hangzhou, 310027, China.
State Key Laboratory of Clean Energy Utilization (Zhejiang University), Hangzhou, 310027, China.
J Environ Manage. 2025 Apr;380:125020. doi: 10.1016/j.jenvman.2025.125020. Epub 2025 Mar 18.
Washing is a widely used pretreatment method for the resource utilization of municipal solid waste incineration fly ash (MSWI FA). However, the high concentrations of heavy metals and chlorides in alkaline washing pretreatment waste liquids can adversely affect the environment and human health, necessitating proper disposal. Therefore, in this study, the heavy metal removal and ultrasonic-assisted two-stage dechlorination process from MSWI FA alkaline washing waste liquids using Friedel's salt were developed. When the end-point pH was 9 and Friedel's salt dosage was 4 g/L, the removal rate of key heavy metals from MSWI FA alkaline washing waste liquids exceeded 95 %. A series of characterization showed that Friedel's salt can effectively remove heavy metals from waste liquids through isomorphic substitution, ion exchange, surface adsorption and precipitation formation. Experimental results demonstrated that when the molar ratio of Ca: Al: Cl was adjusted to 2.5:1.2:1 in the first stage and 7:3:1 in the second stage, combined with an ultrasonic power of 600 W, the ultrasound-assisted two-stage dechlorination method achieved a chloride removal efficiency exceeding 93.8 % from the alkaline washing solution of MSWI FA. And, 272.6 g of Friedel's salt was obtained while treating 1 L of waste liquids. This study revealed that ultrasonic-enhanced dechlorination occurs through mechanisms that promote the dissolution and dispersion of CaO while inhibiting the formation of CaAl(OH). In addition, the combination of alkaline washing pretreatment and waste liquids reuse, an integrated idea was provided, which was helpful for the comprehensive utilization of MSWI FA.
水洗是城市生活垃圾焚烧飞灰（MSWI FA）资源利用中一种广泛使用的预处理方法。然而，碱性水洗预处理废液中高浓度的重金属和氯化物会对环境和人体健康产生不利影响，因此需要进行妥善处置。因此，本研究开发了利用弗里德尔盐从MSWI FA碱性水洗废液中去除重金属及超声辅助两段脱氯工艺。当终点pH值为9且弗里德尔盐用量为4 g/L时，MSWI FA碱性水洗废液中关键重金属的去除率超过95%。一系列表征表明，弗里德尔盐可通过同晶替代、离子交换、表面吸附和沉淀形成等方式有效去除废液中的重金属。实验结果表明，当第一阶段Ca:Al:Cl的摩尔比调整为2.5:1.2:1，第二阶段调整为7:3:1，并结合600 W的超声功率时，超声辅助两段脱氯法对MSWI FA碱性洗涤液的脱氯效率超过93.8%。并且，处理1 L废液可获得272.6 g弗里德尔盐。本研究表明，超声强化脱氯是通过促进CaO的溶解和分散同时抑制CaAl(OH)的形成的机制发生的。此外，提供了碱性水洗预处理与废液回用相结合的一体化思路，有助于MSWI FA的综合利用。
