Ecoremediation is a concept created by plant ecologists and microbiologists at the Cal Poly, San Luis Obispo, Environmental Biotechnology Institute (EBI), which combines the concepts of ecosystem restoration and phytoremediation (cleanup of contaminants using plants). An important part of phytoremediation is also bioremediation (cleanup of contaminants using microorganisms).

The term ecoremediation is a combination of the words ecosystem (or ecological system) and remediation. The ecoremediation concept was born of an effort to improve upon the existing concepts of phytoremediation.

Phytoremediation utilizes native plants and trees to slow down the flow of groundwater by uptakeof the water through the roots of the plants. Contaminants in slower-moving groundwater spend more time in the rhizosphere (root zone), where they can be consumed by bacteria. This technique has been used for a number of years to treat many kinds of compounds. (An exhaustive bibliography can be found at the EPA's Technology Innovation Office website, http://www.clu-in.org/products/phytobib/biba-b.html). More recently, phytoremediation has been used in treating organic compounds such as those found in petroleum.

Phytoremediation of petroleum involves a number of interrelated processes. The phreatophytes (plants whose roots tap the water table) typically used in phytoremediation can consume large quantities of water, as much as 50 to 300 gallons per day for a single plant. Undoubtedly, one important process of phytoremediation is therefore the "sink" phreatophytes create for compounds in the groundwater. However, plants also extract and give off many biologically beneficial nutrients from their roots, and perhaps the most important contributions to treatment are the biochemical root interactions with petroleum-degrading bacteria and fungi that allows them to thrive.

Although phytoremediation has been used for a number of years, the thought behind such systems has typically been to utilize one or two (often non-native) species of phreatophytic trees in rows or regular patterns in a high density. Such designs are often successful as treatment systems, but require ongoing maintenance in the form of watering and nutrients, because they are not naturally stable over the long term. A form of this type of phytoremediation using native poplars and willows is being employed at the O13 site, in the southeastern section of the oil field.

Phytoremediation at O13

 

The basic premise behind ecoremediation is that a by creating a diverse but native system of plants in a particular ecosystem, a stability is created unlike the more traditional forms of phytoremediation. It is understood that diverse ecosystems are much more capable of withstanding changes in the environment, such as drought or disease, than systems comprised of one or two species. Most importantly for remediation, EBI scientists expect that the increase in plant diversity will lead to a stronger population of petroleum-degrading microorganisms in the rhizosphere (root zone), and ultimately to a treatment system that improves upon the existing effectiveness of phytoremediation. Of course, the restoration of a stable ecosystem and habitat is a great ecological benefit in and of itself.

Design Plan of C8 Ecoremediation Site

 

Conceptual View of Restored Ecoremediation Site

 

C8 Ecoremediation Site - 2001

C8 Ecoremediation Site - 2005

Each year, EBI scientists publish reports on the progress and results of studies performed at the Guadalupe Restoration Project. Click here to view the most current reports. Information from prior years may be requested by contacting the Guadalupe Field Office.

For more information about Cal Poly's Environmental Biotechnology Institute, please visit their website at www.ebi.calpoly.edu/about/ecoremediation.pdf.

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