某Cr(Ⅵ)污染场地修复的PRB反应材料及结构设计研究

渗透反应格栅(permeable reactive barrier,PRB)在国外被广泛应用于场地尺度的地下水污染修复,因其无须外源动力、不占地面空间、运行成本低等优势在国内受到广泛关注。不同场地水文地质条件、污染物类型、污染羽分布具有差异性,前期场地调查、反应材料的筛选、反应墙尺寸结构的设计对于PRB的有效运行至关重要。本文以PRB修复河南某Cr(Ⅵ)污染场地为例,详细阐述场地调查、材料筛选、材料反应参数确定、PRB结构优化等方面的研究过程及成果,可为后续PRB修复技术的应用提供参考。研究结果表明:PRB修复技术适用于该场地,铸铁与活性炭混合材料为最佳修复材料;反应门长40 m(反应材料厚2 m,上下游分别为2 m厚砾石层),东西两侧隔水墙长为60 m的U型漏斗-门系统型PRB,可有效捕获并修复污染羽,工程成本远低于连续反应墙式PRB,为该场地修复最优PRB结构类型。

Reactive materials and structural design of PRB for remediation of a Cr(Ⅵ) contaminated sit

Permeable reactive barrier (PRB) is widely used overseas in large scale groundwater remediation. It has attracted much interest in China because of the advantages of using no external power, occupying little surface space, and low operating cost. Since hydrogeological conditions, pollutant types, and distribution of pollution plume vary in different sites, early site investigation, reactive material selection, and reaction wall structural design are highly significant for the effective operation of PRB. This paper, taking the example of PRB application in remediation of a Cr(Ⅵ) contaminated site in Henan Province, describes in detail the research process and the results of site investigation, material screening, reaction parameter determination, and PRB structural optimization in preparation for PRB application. It shows that the PRB remediation technology is applicable to this site, and material containing cast iron and activated carbon is the best remediation material. The U-shaped funnel-gate PRB has a 40 m long reaction gate and two 60 m long water barriers. It can effectively capture and rehabilitate the contaminated plume at a much less engineering cost than continuous reaction wall PRB. So the U-shaped funnel-gate PRB is thought to be the optimal PRB structure for this site.