Ying Fang,Qianwen Liu,Yang Song,Hui Cai,Ying Yang,Zhaoguang Yang,Haipu Li
Dissolved Fe(II) widely exists in high-arsenic (high-As) groundwater, whose concentration (12–518 µM) is positively correlated with that of As(III). In order to realize the environmental-friendly and highly efficient in-situ simultaneous oxidation and adsorption of As(III) under anoxic conditions, peroxymonosulfate (PMS) was directly dosed into Fe(II)-rich high-As groundwater. Compared with hydrogen peroxide (88.2%) and peroxydisulfate (66.6%), the involvement of PMS gave the best As(III) removal efficiency of 98.8% after 1 min treatment, owing to the dual aspects of the best oxidation of As(III) and the best adsorption of As(V). During As(III) oxidation process, more SO 4 • − and 1 O 2 generated and unactivated PMS in Fe(II)-PMS process were responsible for the most efficient oxidation. During the enhanced As(V) adsorption process, the presence of PMS changed the structure of the in-situ formed Fe(III) colloid to provide more adsorption sites. Besides, the higher PMS concentration caused better As(III) oxidation, As(III) immobilization, and As(V) adsorption efficiencies. A wide range of Fe(II) (125–500 µM) coupled with PMS (244 µM) could immobilize more than 90% of As(III) ( C 0 = 1000 µg/L), and As(III) ranging from 0.2 mg/L to 2.0 mg/L also could be removed over 90% in Fe(II)-PMS process. The coexistence of HCO 3 – , Cl − , and humic acid slightly affected As(III) immobilization. Furthermore, after treatment, residual Fe ions concentration, residual total arsenic concentration, sulfate ions concentration, and pH value met the drinking water standard. This study could provide a very promising and attractive technology for a fast and efficient in-situ purification of Fe(II)-rich high-As groundwater.
Sun Xiaolei,Li Qiao,Shen Jinyou,Han Weiqing,Li Jiansheng,Sun Xiuyun
In this study, we report the co-treatment of municipal solid waste incineration fly ash and high arsenic-containing wastewater. The appropriate liquid-solid ratio for co-treatment and the feasibility of co-treatment with 5000 mg/L arsenic in wastewater were investigated, as well as the risk of heavy metals leaching from the co-treated products in the actual leachate. Further, a new index for assessing the risk of heavy metals releasing into the environment was proposed. The results demonstrated that the optimal liquid-solid ratio was 10 mL/ 20 g, considering that it allowed the maximum co-treatment amount of wastewater and would not affect the subsequent disposal of co-treated products in landfills. In the presence of 5000 mg/L arsenic in wastewater, the chemical speciation distribution and leaching toxicity of As, Cr, Cu, and Pb in the co-treated products would not change significantly. The leaching results of co-treated products in actual leachate indicated that the co-treated products can favor the stabilization of As, Cr, and Pb in leachate. The migration and transformation index value of Cu suggested the risk of Cu releasing in a leachate scenario. Through co-treatment, wastewater can be completely absorbed into the fly ash without the need for further treatment, featuring significant economic and environmental benefits. Graphical Abstract
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