地学前缘 ›› 2021, Vol. 28 ›› Issue (5): 208-214.DOI: 10.13745/j.esf.sf.2021.2.17

• 地下水污染修复 • 上一篇    下一篇

地下水曝气-砂滤处理产生的废弃石英砂中铁砷含量与形态分布

张耀强1(), 胡冰冰1, 谢世伟2, 袁松虎1,*()   

  1. 1.中国地质大学(武汉) 生物地质与环境地质国家重点实验室, 湖北 武汉 430074
    2.武汉科技大学 城市建设学院, 湖北 武汉 430065
  • 收稿日期:2020-05-12 修回日期:2020-09-18 出版日期:2021-09-25 发布日期:2021-10-29
  • 通讯作者: 袁松虎
  • 作者简介:张耀强(1996—),男,硕士研究生,主要从事地下水污染修复技术研究。E-mail: 383103273@qq.com
  • 基金资助:
    国家自然科学基金创新群体项目(41521001);湖北省自然科学基金创新群体项目(2018CFA028)

Content and speciation distributions of Fe and As in disposed quartz sand from groundwater treatment by sequential aeration and sand filtration

ZHANG Yaoqiang1(), HU Bingbing1, XIE Shiwei2, YUAN Songhu1,*()   

  1. 1. State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences (Wuhan), Wuhan 430074, China
    2. School of Urban Construction, Wuhan University of Science and Technology, Wuhan 430065, China
  • Received:2020-05-12 Revised:2020-09-18 Online:2021-09-25 Published:2021-10-29
  • Contact: YUAN Songhu

摘要:

高铁高砷地下水严重威胁饮水质量,曝气-砂滤法因处理效果好且成本低在农村地区得到广泛应用。砂滤过程石英砂表面富集铁和砷后需定期更换,然而废弃石英砂堆置具有砷释放风险。本文以江汉平原某水厂砂滤池废弃石英砂为研究对象,采用激光剥蚀-等离子体质谱(LA-ICP-MS)、拉曼光谱(Raman)、X射线衍射(XRD)和分步化学提取等手段,研究了砂样中的Fe和As含量及形态分布。结果表明,砂粒表面形成了一层厚度为20100 μm的高铁砷薄层,薄层内部Fe和As含量显著高于两侧,Fe和As分布高度相关(R2=0.985)。砂样表面铁矿物以无定型/弱结晶型为主,同时检出赤铁矿和臭葱石等矿物。砂样中Fe和As总含量分别为20.1 mg/g和53.4 μg/g。砂样表面铁主要以易溶解态、碳酸盐结合态和易还原态为主,As主要吸附在铁矿物上。研究区降雨充沛,当废弃石英砂遭遇雨水冲刷或淹没时,可能导致铁砷薄层中As解吸或随Fe矿物还原溶解而释放。

关键词: 废弃石英砂, 高砷地下水, 砷释放, 砂滤, 饮用水处理

Abstract:

Drinking water security is threatened by elevated iron (Fe) and arsenic (As) concentrations in groundwater. Sequential aeration and sand filtration has been widely used for the high-performance, low-cost groundwater treatment in rural areas. During filtration, Fe, As-enriched quartz sand needs periodic replacement. The disposed sand frequently piles up on land, risking As release. In this research, the content and speciation distributions of Fe and As in disposed quartz sand collected from a drinking water treatment plant in the Jianghan plain, were investigated by LA-ICP-MS, Raman spectroscopy, X-ray diffraction and sequential chemical extraction. The results show that the sand surface was coated with a 20-100 μm thick Fe, As-rich layer, with Fe and As significantly concentrated in the central layer than on the outer layers; the As and Fe spatial distributions in the coating were highly correlated (R2> 0.985). The Fe phases were mainly amorphous and weakly crystalline, and the presence of hematite and scorodite was detected. The total contents of Fe and As in the quartz were 20.1 mg/g and 53.4 μg/g, respectively. The highly dissolvable Fe (oxy)hydroxides and carbonate-bound, reducible Fe species predominated in the coatings, whereas As was mainly adsorbed on the surface of Fe phases. Due to the abundant rainfall in the study area, As release from the disposed quartz sand could occur as a consequence of rain washing or anaerobic Fe bio-reduction.

Key words: disposed quartz sand, high-arsenic groundwater, arsenic release, sand filtration, drinking water treatment

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