Phytoextraction: an assessment of biogeochemical and economic viability

Abstract:

Phytoextraction describes the use of plants to remove metals and other contaminants from soils. This low-costtechnology has potential for the in situ remediation of large areas of contaminated land. Despite more than 10 yearsof intensive research on the subject, very few commercial phytoextraction operations have been realised. Here, weinvestigate the viability of phytoextraction as an effective land-treatment technology. A Decision Support System(DSS) was developed to predict the effect of phytoextraction on soil metal concentration and distribution, as well asthe economic feasibility of the process in comparison to either inaction or the best alternative technology. Changesin soil metal concentration are mechanistically predicted on the basis of plant water use, metal concentration insoil solution, soil density, plant root distribution and our so-called root-absorption factor. The root-absorptionfactor is a ‘lumped parameter’ describing the xylem/soil solution metal concentration quotient. Phytoextractionis considered to be a viable option if it can satisfy environmental regulations and simultaneously be shown to bethe most cost-effective technology, either alone, or in combination with other remediation technologies. To date,commercial phytoextraction has been constrained by the expectation that site remediation should be achieved ina time comparable to other clean-up technologies. However, if phytoextraction could be combined with a profitmaking operation such as forestry, then this time constraint, which has often been considered to be the Achillesheel of phytoextraction, may be less important.

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