Alternative Treatment Technologies

Phytoremediation refers to the use of plants and plant systems to remove, transfer, destroy or stabilize contaminants in soils, sediments and water contaminated with metals and/or organic chemicals. The roots of plants support microbial communities that may be capable of breaking down the contaminant of concern, or the plant may take up and transform or evaporate the contaminant through its leaves thereby removing it from the soil or groundwater. The specific mechanisms by which phytoremediation occurs will be dependant upon the contaminant, plant and site characteristics.

Although the numerous attempts to use phytoremediation have occurred, its effectiveness has not been conclusively demonstrated. A demonstration study to remove TCE from a shallow contaminated groundwater was undertaken at former air force base. Cottonwood trees were planted over one acre and the effectiveness of the system was monitored by examining TCE concentrations in the groundwater, in the soil surrounding the root zone and in tree tissues. By the end of the fifth growing season, biodegradation of the TCE could be observed locally beneath and immediately down gradient of the trees. The study is continuing and additional information about the study can be found in PhytoremediationRprt.htm. It should be noted that in most SVE applications, the soil is not saturated and the effectiveness of phytoremediation under those circumstances is uncertain.

The figure below shows a photo of a hybrid poplar field used for phytoremediation of TCE at the Edward Sears Property at the former Carswell Air Force Base in Fort Worth, Texas.