Hack Norman, Reinwand Christian, Abbt-Braun Gudrun, Horn Harald, Frimmel Fritz H
Karlsruhe Institute of Technology (KIT), Engler-Bunte-Institute, Chair of Water Chemistry and Water Technology, Engler-Bunte-Ring 9, 76131 Karlsruhe, Germany.
Karlsruhe Institute of Technology (KIT), Engler-Bunte-Institute, Chair of Water Chemistry and Water Technology, Engler-Bunte-Ring 9, 76131 Karlsruhe, Germany.
J Contam Hydrol. 2015 Dec;183:40-54. doi: 10.1016/j.jconhyd.2015.10.005. Epub 2015 Oct 23.
Mass transfer and biological transformation phenomena in the capillary fringe were studied using phenol, salicylic acid, benzenesulfonic acid, and the iodinated X-ray contrast agent iomeprol as model organic compounds and the microorganism strain Pseudomonas fluorescens. Three experimental approaches were used: Batch experiments (uniform water saturation and transport by diffusion), in static columns (with a gradient of water saturation and advective transport in the capillaries) and in a flow-through cell (with a gradient of water saturation and transport by horizontal and vertical flow: 2-dimension flow-through microcosm). The reactors employed for the experiments were filled with quartz sand of defined particle size distribution (dp=200...600 μm, porosity ε=0.42). Batch experiments showed that phenol and salicylic acid have a high, whereas benzenesulfonic acid and iomeprol have a quite low potential for biodegradation under aerobic conditions and in a matrix nearly close to water saturation. Batch experiments under anoxic conditions with nitrate as electron acceptor revealed that the biodegradation of the model compounds was lower than under aerobic conditions. Nevertheless, the experiments showed that the moisture content was also responsible for an optimized transport in the liquid phase of a porous medium. Biodegradation in the capillary fringe was found to be influenced by both the moisture content and availability of the dissolved substrate, as seen in static column experiments. The gas-liquid mass transfer of oxygen also played an important role for the biological activity. In static column experiments under aerobic conditions, the highest biodegradation was found in the capillary fringe (e.g. βt/β0 (phenol)=0 after t=6 d) relative to the zone below the water table and unsaturated zone. The highest biodegradation occurred in the flow-through cell experiment where the height of the capillary fringe was largest.
使用苯酚、水杨酸、苯磺酸以及碘化X射线造影剂碘普罗胺作为模型有机化合物，以荧光假单胞菌作为微生物菌株，研究了毛细边缘中的传质和生物转化现象。采用了三种实验方法：间歇实验（均匀水饱和度和扩散传输）、在静态柱中（具有水饱和度梯度和毛细管中的平流传输）以及在流通池中（具有水饱和度梯度和水平与垂直流传输：二维流通微观模型）。用于实验的反应器填充有粒径分布确定的石英砂（dp = 200...600μm，孔隙率ε = 0.42）。间歇实验表明，在有氧条件下且基质接近水饱和度时，苯酚和水杨酸具有较高的生物降解潜力，而苯磺酸和碘普罗胺的生物降解潜力相当低。以硝酸盐作为电子受体的缺氧条件下的间歇实验表明，模型化合物的生物降解低于有氧条件。然而，实验表明，水分含量也有利于多孔介质液相中的优化传输。如静态柱实验所示，毛细边缘中的生物降解受到水分含量和溶解底物可用性的影响。氧气的气液传质对生物活性也起着重要作用。在有氧条件下的静态柱实验中，相对于潜水面以下区域和不饱和区域，在毛细边缘发现了最高的生物降解（例如，t = 6 d后，βt/β0（苯酚）= 0）。在毛细边缘高度最大的流通池实验中发生了最高的生物降解。
