Sustainable reuse of modified incineration sewage sludge ash (M-ISSA) for stabilization of highly As-contaminated soil

• Published in: Journal of cleaner production 2024-09, Vol.472, p.143477, Article 143477
• Main Authors: Gao, Shengya, Wang, Qiming, Hui, Yin, Ma, Zihan, Li, Jiang-shan, Poon, Chi Sun
• Format: Article
• Language: English
• Subjects: adsorption; Arsenic; coprecipitation; hematite; human health; Incinerated sewage sludge ash; iron; Modification; polluted soils; sludge ash; Stabilization; toxicity; X-ray diffraction; X-ray photoelectron spectroscopy
• ISSN: 0959-6526
• DOI: 10.1016/j.jclepro.2024.143477

Arsenic (As) is an environmental hazardous contaminant, seriously threatening human health. Chemical activation can effectively enhance As adsorption performance of incinerated sewage sludge ash (ISSA). Through modification, the iron (mainly present as hematite) in the ISSA was rearranged to KFeO2. Based on the results of the present study, addition of modified ISSA (M-ISSA) in contaminated soil had a positive effect on As immobilization. A set of laboratory batch experiments including toxicity characteristic leaching procedure (TCLP), synthetic precipitation leaching procedure (SPLP), and sequential extraction procedure (SEP) were carried out to investigate effects of M-ISSA dosages and curing time on immobilization of As contaminated soil (100, 500, 1000 mg As/kg soil). Results indicated that a higher addition amount of M-ISSA enhanced the effectiveness of stabilization and significantly reduced the As leachability after a stabilization period of 28 d. Particularly, in 1000 mg As/kg soil, M-ISSA reduced the labile As concentration in the TCLP test from 21.45 to 0.73 mg/L and in the SPLP test from 27.75 mg/L to 7.83 mg/L. M-ISSA transformed As in soil to more stable forms that were bounded to amorphous iron hydrous oxides. The number of stable fractions saw a sharp rise from 31% to 60%, when the M-ISSA addition was 5%. Different characterizations were conducted including X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and scanning electron microscope (SEM), in order to demonstrate the stabilization behavior and mechanism of As and M-ISSA. The main stabilization mechanism was associated with adsorption and coprecipitation processes. Overall, this study proposed a novel recycling method for ISSA that could be chemically modified into a reliable and efficient additive for the immobilization of As contaminated soil. [Display omitted]