Atteia O, Jousse F, Cohen G, Höhener P
Bordeaux INP - EA 4592 - ENSEGID, Institut Carnot/ISIFOR, 1 Allée F. Daguin, 33607 Pessac, France.
Bordeaux INP - EA 4592 - ENSEGID, Institut Carnot/ISIFOR, 1 Allée F. Daguin, 33607 Pessac, France.
J Contam Hydrol. 2017 Jul;202:23-32. doi: 10.1016/j.jconhyd.2017.04.006. Epub 2017 Apr 21.
This study compared four treatment techniques for the removal of a toluene/n-decane as NAPL (Non Aqueous Phase Liquid) phase mixture in identical 1 cubic meter tanks filled with different kind of sand. These four treatment techniques were: oxidation with persulfate, surfactant washing with Tween80®, sparging with air followed by ozone, and thermal treatment at 80°C. The sources were made with three lenses of 26×26×6.5cm, one having a hydraulic conductivity similar to the whole tank and the two others a value 10 times smaller. The four techniques were studied after conditioning the tanks with tap water during approximately 80days. The persulfate treatment tests showed average removal of the contaminants but significant flux decrease if density effects are considered. Surfactant flushing did not show a highly significant increase of the flux of toluene but allowed an increased removal rate that could lead to an almost complete removal with longer treatment time. Sparging removed a significant amount but suggests that air was passing through localized gas channels and that the removal was stagnating after removing half of the contamination. Thermal treatment reached 100% removal after the target temperature of 80°C was kept during more than 10d. The experiments emphasized the generation of a high-spatial heterogeneity in NAPL content. For all the treatments the overall removal was similar for both n-decane and toluene, suggesting that toluene was removed rapidly and n-decane more slowly in some zones, while no removal existed in other zones. The oxidation and surfactant results were also analyzed for the relation between contaminant fluxes at the outlet and mass removal. For the first time, this approach clearly allowed the differentiation of the treatments. As a conclusion, experiments showed that the most important differences between the tested treatment techniques were not the global mass removal rates but the time required to reach 99% decrease in the contaminant fluxes, which were different for each technique.
本研究在装满不同种类沙子的相同1立方米水箱中，比较了四种去除作为非水相液体（NAPL）相混合物的甲苯/正癸烷的处理技术。这四种处理技术分别是：过硫酸盐氧化、用吐温80®进行表面活性剂冲洗、空气鼓泡后接臭氧处理以及80°C热处理。污染源由三个26×26×6.5厘米的透镜制成，其中一个的水力传导率与整个水箱相似，另外两个的值小10倍。在用自来水对水箱进行约80天的预处理后，对这四种技术进行了研究。过硫酸盐处理试验表明，污染物有平均去除率，但如果考虑密度效应，通量会显著下降。表面活性剂冲洗并未使甲苯通量有显著增加，但提高了去除率，经过更长时间处理可能导致几乎完全去除。鼓泡去除了大量污染物，但表明空气通过局部气体通道，去除一半污染物后去除效果停滞。在80°C的目标温度保持超过10天后，热处理达到了100%的去除率。实验强调了NAPL含量中高空间异质性的产生。对于所有处理，正癸烷和甲苯的总体去除情况相似，这表明在某些区域甲苯去除迅速而正癸烷较慢，而在其他区域则没有去除。还分析了氧化和表面活性剂处理结果中出口处污染物通量与质量去除之间的关系。首次通过这种方法清楚地区分了不同处理。总之，实验表明，测试的处理技术之间最重要的差异不是总体质量去除率而是污染物通量降低99%所需的时间，每种技术所需时间不同。
