Site pollution by manufacturing and processing facilities has always been an important subject, and rapidly advancing technologies have been a great asset in dealing with this pollution. Dr. Jeff Gillow has been on the forefront of developing new in situ bio-remediation technologies for ARCADIS, a company strongly focused on cleaning up groundwater contamination.
The in situ bio-remediation of soils is the cleaning up of contaminants within the soil without removing the soil itself. As opposed to traditional means of remediation, in which the soil is excavated and carried to a remote site for treatment, ARCADIS’ in situ method treats the soils and groundwater without disturbing the site. This method of treating a contaminant plume is preferable as it dramatically lowers the cost of treatment whereas traditional excavation is expensive to perform and imposes a dramatic environmental cost.
In bio-remediation, as Gillow explained, injection and extraction wells are drilled into the contaminant plume. Organic carbon is then injected into the groundwater and naturally follows the same path as the contaminant itself, where the contaminant undergoes a aqueous phase transformation into a non-toxic, stable form of the chemical. This process, according to Gillow, works the best for hexavalent Chromium, which is a common contaminant at many manufacturing facilities. Nearly all of the chemical is then transformed into a stable form, essentially removing it from the groundwater ecosystem.
Applying this technology to other metals, such as uranium, can be difficult. Uranium does not react with the organic carbon in the same way as Chromium, but interacts with the other minerals and metals in the soils in such a way that it is difficult to predict how it will behave with in situ bio-remediation. Remediation of uranium has been studied for the past 30 years, explained Gillow, but nothing has been applied toward actually dealing with the contaminant. To gain a better understanding of what is going on, Gillow has started using X-Ray analysis to study the chemistry on a much finer scale. “If we want to look at Chromium [or uranium], we go to X-Ray microprobe analysis… with that, we get resolution to 10 microns. We can get information on what minerals we’re creating in these [aqueous phase] transformations.”
Gillow concluded his talk by stating that a better understanding of the immobilized forms of unique metals would lead to the application of in situ bio-remediation to a wider range of metal contaminants.