Deep insight on mechanism and contribution of arsenic removal and heavy metals remediation by mechanical activation phosphogypsum

• Published in: Environmental pollution (1987) 2023-11, Vol.336, p.122258-122258, Article 122258
• Main Authors: Ma, Mengyu, Xu, Xiangqun, Ha, Zhihao, Su, Qingmuke, Lv, Chenyang, Li, Jia, Du, Dongyun, Chi, Ruan
• Format: Article
• Language: English
• Subjects: Arsenic (As); Heavy metals; Phosphogypsum; Soil remediation
• ISSN: 0269-7491; 1873-6424
• DOI: 10.1016/j.envpol.2023.122258

Arsenic-containing wastewater and arsenic-contaminated soil can cause serious environmental pollution. In this study, phosphogypsum with partial mechanical activation of calcium oxide was used to prepare a new phosphogypsum-based passivate (Ca-mPG), and its remediation performance on arsenic-contaminated soil was evaluated in terms of both effectiveness and microbial response. The results showed that the optimum conditions for the preparation of the passivate were optimized in terms of single factor and response surface with a ball milling speed of 200 r/min, a material ratio of 6:4 and a ball milling time of 4 h. Under these conditions, the adsorption capacity was 37.75 mg/g. The leaching concentration of arsenic (As) in the contaminated soil after Ca-mPG modification decreased from 25.75 μg/L to 5.88 μg/L, which was lower than the Chinese national standard (GB/T 5085.3–2007); Ca-mPG also showed excellent passivation effect on other heavy Metals (copper, nickel, cadmium, zinc). In addition, As-resistant bacteria and passivators work together to promote the stabilization effect of contaminants during the remediation of As-contaminated soil. The mechanisms of Cu, As(III)/As(V), Zn, Cd, and Ni removal were related to ion exchange, electrostatic adsorption of substances on heavy metals, calcium binding to other substances to produce precipitation; and microbially induced stabilization of HMs, oxidized. Overall, this study demonstrates an eco-friendly "waste-soil remediation" strategy to solve problems associated with solid waste reuse and remediation of HM-contaminated soils. [Display omitted] •A novel phosphogypsum-based passivator was developed.•Ca-mPG absorbed As(V) in solution and passivated Cu, As, Zn, Cd, and Ni in soil.•Mechanisms for HMs removal include precipitation, adsorption and microbial passivation.