Laboratory experiments and simulations of MTBE transport in layered heterogeneous porous media

摘要

Methyl tert-butyl ether (MTBE) has been considered as a typical volatile organic compound (VOC) in the subsurface environment, which can result in a significant risk to subsurface ecosystems and human health. As the awareness on groundwater quality is increasing, it is of great importance to identify the effect of heterogeneity on VOCs transport through subsurface porous media. Thus, experiments on transport through homogeneous and layered heterogeneous porous media were carried out. In this study, NaCl and MTBE were used as a nonreactive tracer and a VOC, respectively. The results of tracer tests in homogeneous sand columns indicate that the test values fit well with simulated values. The breakthrough curves of homogeneous porous media show that the flow velocity of MTBE is slower than that of the NaCl, which means MTBE has been seriously retarded during transport process. In addition, MTBE transport is greatly dependent on the heterogeneity of the porous media with higher retention in the layered heterogeneous media compared to homogeneous media, which refers to non-Fickian transfer. The results imply that the layered heterogeneity could weaken the contamination intensity, thereby retarding the contaminant transport and prolonging the contaminants contact time in the heterogeneous porous media.