SBIR: Phase II: Removal of Contaminants from Soil Using an Enhanced Phytoextraction Process

这个小型企业创新研究的第二阶段项目描述了一种新的方法的发展，通过结合植物修复和土壤的电动修复过程，从土壤中原位去除污染物。植物修复是一种低成本、低维护的土壤修复技术，可用于重金属、放射性核素和有机污染物污染土壤的修复。然而，它的应用仅限于表面污染，因为清理深度严格取决于植物根系的长度。就污染物输送而言，它也是一种被动技术。污染物在土壤中的移动完全是由缓慢的植物根系吸力引起的，因此污染物去除的效率取决于植物根系在土壤地下的延伸。第一阶段开发的新型联合电动力植物修复技术利用电场在土壤中引起的电动力效应，实现根际污染物的有效运输，并增强植物根系中的金属积累。第一阶段的研究结果表明，与传统的植物修复工艺相比，采用电动植物修复工艺可以使芥菜植物的铅浓度提高两个数量级。第二阶段将侧重于优化和扩大控制在外加电场条件下植物对污染物的提取的工艺参数。现场试验结果将对该过程进行技术和经济评价，并就联合电动植物修复对具有不同化学和水文地质特征的污染场地的适用性提出建议。所开发的电动植物修复工艺将在重金属、放射性核素和/或有机污染物污染的土壤原位清理中具有广泛的应用。与传统的植物修复工艺相比，所提出的工艺可以应用于污染物位于比植物超积累体根区更深的土壤。这将极大地扩展植物修复在深污染场的应用。

This Small Business Innovation Research Phase II project describes the development of a new method for in situ removal of contaminants from soil by combining the processes of phytoremediation and electrokinetic remediation of soil. Phytoremediation is an attractive approach for cleanup of soil because it is a low cost and low maintenance technology, which can be applied in treatment of soils contaminated by heavy metals, radionuclides and organic contaminants. However, its application is limited to surface contamination only because the cleanup depth is strictly determined by the length of the plant roots. It is also a passive technology in terms of contaminant transport. The movement of contaminants in the soil is induced exclusively by a slow plant root suction, thus the efficiency of the contaminant removal depends on the extension of the plant roots in the soil subsurface. The new combined electrokinetic phytoremediation technology developed in Phase I utilizes the electrokinetic effects induced in soil by the application of an electric field to achieve an efficient transport of contaminants in the rhizosphere and to enhance metal accumulation in the plant roots. The Phase I results demonstrated that using the electrokinetic phytoremediation process up to two orders of magnitude higher lead concentration could be achieved in Brassica juncea mustard plants compared to the conventional phytoremediation process. Phase II will focus on the optimization and scaling-up of the process parameters governing the enhancement of contaminant extraction by the plants in conditions of the applied electric field. The field test results will yield technical and economical evaluation of the process and recommendations about applicability of the combined electrokinetic phytoremediation to contaminated sites with varying chemical and hydrogeological characteristics. The developed electrokinetic phytoremediation process will have large applications for in situ cleanup ofsoils contaminated by heavy metals, radionuclides, and/or organic contaminants. Compared to conventional phytoremediation processes, the proposed process can be applied to soils where contaminants are located deeper than the root zone of plant hyperaccumulators. This will significantly extend the application of phytoremediation to the sites with deep contaminant plumes.