Department of Civil and Environmental Engineering and the Andlinger Center for Energy and the Environment, Princeton University, Princeton, NJ 08544, United States; Department of Civil, Architectural, and Environmental Engineering, University of Colorado Boulder, Boulder, CO 80309, United States.
Department of Civil, Architectural, and Environmental Engineering, University of Colorado Boulder, Boulder, CO 80309, United States; China National Offshore Oil Corporation Research Institute Ltd., Beijing 100028, China.
Sci Total Environ. 2020 Jul 1;724:138169. doi: 10.1016/j.scitotenv.2020.138169. Epub 2020 Mar 23.
Bioelectrochemical systems (BESs) have demonstrated great promise in augmented biodegradation of petroleum hydrocarbons in water-saturated soils. However, bioremediation of unsaturated soil in vadose zone has been a challenge due to poor mass transfer and low conductivity. This study proposed a moisture retention layer (2 cm thickness) around the BES anodes to enhance soil remediation under unsaturated conditions. The active soil BESs (closed circuit) includes two reactors with anodic moisture-retaining layers of soil-polyacrylamide hydrogel (SHB) and graphite granule-polyacrylamide hydrogel (GHB) mixtures, and another reactor filled with only soil (SB) without moisture-retaining layer. An open circuit SB was served as a control to simulate natural attenuation. This study demonstrated for the first time that moisture retention layers around the BES anodes could significantly extend and enhance hydrocarbon degradation in vadose zone soil. Results showed that SHB reactor could maintain 43-100% longer duration for electricity generation than other reactors. Correspondingly, SHB showed the best removal (average 21-37%) of total petroleum hydrocarbon (TPH) in spatial distribution, which was ~91% and ~164% higher than other BESs and control, respectively. This study demonstrated that by using low-cost and environmentally friendly hydrogel, BESs could become a viable remediation method for vadose zone soil.
生物电化学系统 (BES) 在增强水饱和土壤中石油烃的生物降解方面表现出巨大的潜力。然而，由于传质和电导率较差，包气带非饱和土壤的生物修复一直是一个挑战。本研究提出在 BES 阳极周围设置保水层（2cm 厚），以增强非饱和条件下的土壤修复。活性土壤 BES（闭路）包括两个带有土壤-聚丙烯酰胺水凝胶（SHB）和石墨颗粒-聚丙烯酰胺水凝胶（GHB）混合物的阳极保水层的反应器，以及另一个仅填充土壤（SB）而没有保水层的反应器。开路 SB 作为对照模拟自然衰减。本研究首次证明，BES 阳极周围的保水层可以显著延长和增强包气带土壤中的烃类降解。结果表明，SHB 反应器的发电持续时间比其他反应器长 43-100%。相应地，SHB 在空间分布上表现出最佳的总石油烃 (TPH) 去除（平均 21-37%），分别比其他 BES 和对照高出约 91%和 164%。本研究表明，通过使用低成本和环保的水凝胶，BES 可以成为包气带土壤修复的可行方法。
