Zhong L, Truex M J, Kananizadeh N, Li Y, Lea A S, Yan X
Energy and Environment Directorate, Pacific Northwest National Laboratory, WA, USA.
Energy and Environment Directorate, Pacific Northwest National Laboratory, WA, USA.
J Contam Hydrol. 2015 Apr-May;175-176:17-25. doi: 10.1016/j.jconhyd.2015.02.001. Epub 2015 Feb 11.
In situ anaerobic biological processes are widely applied for dechlorination of chlorinated solvents in groundwater. A wide range of organic substrates have been tested and applied to support the dechlorination processes. Vegetable oils are a promising type of substrate and have been shown to induce effective dechlorination, have limited geochemical impacts, and maintain good longevity. Because they are non-aqueous phase liquids, distribution of vegetable oils in the subsurface has typically been approached by creating emulsified oil solutions for injection into the aquifer. In this study, inexpensive waste vegetable oils were suspended in a shear-thinning xanthan gum solution as an alternative approach for delivery of vegetable oil to the subsurface. The stability, oil droplet size distribution, and rheological behavior of the oil suspensions that are created in the xanthan solutions were studied in batch experiments. The injectability of the suspensions and the oil distribution in a porous medium were evaluated in column tests. Numerical modeling of oil droplet transport and distribution in porous media was conducted to help interpret the column-test data. Batch studies showed that simple mixing of vegetable oil with xanthan solution produced stable suspensions of the oil as micron-size droplets. The mixture rheology retains shear-thinning properties that facilitate improved uniformity of substrate distribution in heterogeneous aquifers. Column tests demonstrated successful injection of the vegetable oil suspension into a porous medium. This study provides evidence that vegetable oil suspensions in xanthan gum solutions have favorable injection properties and are a potential substrate for in situ anaerobic bioremediation.
原位厌氧生物过程被广泛应用于地下水中氯化溶剂的脱氯。人们已经测试并应用了多种有机底物来支持脱氯过程。植物油是一种很有前景的底物类型，已被证明能诱导有效的脱氯，具有有限的地球化学影响，并能保持良好的持久性。由于它们是非水相液体，植物油在地下的分布通常是通过制备乳化油溶液注入含水层来实现的。在本研究中，廉价的废植物油悬浮在剪切变稀的黄原胶溶液中，作为将植物油输送到地下的另一种方法。在批量实验中研究了在黄原胶溶液中形成的油悬浮液的稳定性、油滴尺寸分布和流变行为。在柱试验中评估了悬浮液的可注入性和油在多孔介质中的分布。进行了油滴在多孔介质中传输和分布的数值模拟，以帮助解释柱试验数据。批量研究表明，植物油与黄原胶溶液简单混合可产生稳定的微米级油滴悬浮液。混合物流变学保持剪切变稀特性，有助于提高底物在非均质含水层中分布的均匀性。柱试验证明植物油悬浮液成功注入多孔介质。本研究提供了证据，表明黄原胶溶液中的植物油悬浮液具有良好的注入特性，是原位厌氧生物修复的潜在底物
