Ahn Dayoung, Choi Jae-Kyeong, Kim Heonki
a Department of Environmental Sciences and Biotechnology , Hallym University , Korea.
J Environ Sci Health A Tox Hazard Subst Environ Eng. 2017 Jun 7;52(7):590-597. doi: 10.1080/10934529.2017.1293992. Epub 2017 Mar 10.
This study examines the effect of controlled groundwater flow paths induced by hydraulic barriers on the removal of NAPL constituent. An aqueous solution of thickener [0.05% (w/v) sodium carboxymethyl cellulose, SCMC] was continuously injected into a horizontally set two-dimensional physical model (sand-packed), forming aqueous plume(s) of high viscosity. The water flux at the down gradient of the model was measured using a flux tracer (n-octanol) and passive flux meter (PFM, packs of granular activated carbon). A non-reactive tracer (pentafluorobenzoic acid, PFBA) was used to identify the plume of high viscosity (hydraulic barrier) and ambient groundwater. When the barrier of high viscosity was formed, the plume was separated from the background water with little mixing, which was confirmed by the concentration profile of PFBA; whereas, the measured flux of ambient groundwater showed a distinctive distribution, due to the hydraulic barrier. When two barriers were set, the ambient water flux was enhanced in the middle, and the removal rate of PCE from the non-aqueous phase liquid (NAPL), measured by PFM, was found to improve by 26% during three hours of water flushing. When an aqueous solution of surfactant [0.37% (w/v), sodium dodecyl sulfate, SDS] was applied instead of water into the domain with two barriers set around the NAPL-contaminated spot, the removal of PCE from the NAPL increased by 101% for a three-hour time period. Based on the observations made in this study, hydraulic barriers formed by continuous injection of thickener solution change the flow direction of groundwater, and may increase the flux of groundwater (or aqueous solution of remediation agent) through a NAPL-contaminated region, improving the removal of NAPL.
本研究考察了水力屏障诱导的可控地下水流路径对疏水性有机污染物组分去除的影响。将增稠剂水溶液[0.05%（w/v）羧甲基纤维素钠，SCMC]连续注入水平设置的二维物理模型（填砂）中，形成高粘度的水相羽流。使用通量示踪剂（正辛醇）和被动通量计（PFM，颗粒活性炭包）测量模型下游的水通量。使用非反应性示踪剂（五氟苯甲酸，PFBA）来识别高粘度羽流（水力屏障）和周围的地下水。当形成高粘度屏障时，羽流与背景水分离，混合很少，这通过PFBA的浓度剖面得到证实；然而，由于水力屏障，测得的周围地下水通量呈现出独特的分布。当设置两个屏障时，中间的周围水通量增加，通过PFM测量发现，在三小时的水冲洗过程中，非水相液体（NAPL）中PCE的去除率提高了26%。当将表面活性剂水溶液[0.37%（w/v），十二烷基硫酸钠，SDS]代替水应用于在受NAPL污染点周围设置了两个屏障的区域时，在三小时内，NAPL中PCE的去除率提高了101%。基于本研究的观察结果，通过连续注入增稠剂溶液形成的水力屏障改变了地下水的流动方向，并可能增加地下水（或修复剂水溶液）通过NAPL污染区域的通量，从而提高NAPL的去除率。
