Phytoremediation is an exciting and innovative technology using plants and the microbes associated with their growth, as a means to remediate contaminated soils, groundwater or surface water. Compared to other conventional technologies, the use of plants to remediate contaminated environments is cost effective and ecologically sound. This technology is in its advanced development stage, ready for full-scale implementation. All Phase Environmental Inc. has assembled some of the finest scientists and professionals in the nation to offer our customers phytoremediation services. The personnel used for our phytoremediation projects include environmental engineers, biologists, landscape architects, geologists and botanists.
Historically, remediation of soil and groundwater focused on microbes or physical treatment techniques (air stripping, adsorption, heat, etc.) to perform the cleanup work. However, there are multitudes of plants and microbes associated with their growth that have the ability to do this work for us. Turning contaminated sites into nurseries or wetlands will not only clean them up, it will aesthetically enhance them.
Our phytoremediation processes are passive, requiring only initial planting and periodic testing and observation. Because there is no air stripping or water discharge, the need for air pollution discharge permits or NPDES permits are eliminated. The use of landfill space for contaminated soil will no longer be necessary. Phytoremediation can also generate useful biomass with commercial value.
Our process of planting and growing plants will be more cost effective than constructing and maintaining mechanical systems. Savings are realized when no air or water disposal permits are required. There will be no filter or activated carbon changes required. Finally, depending upon the contaminant, there may be no hazardous waste disposal costs and no future liability issues.
There are six (6) processes that constitute phytoremediation. Several of these may work together at the same time or they may work individually. The processes are as follows:
- Natural Attenuation:
The plants take up and assimilate contaminants
The plants volatilize the contaminants into the atmosphere.
Using enzymes, the plants degrade the contaminants within plant tissues.
In the rhizosphere of some plants, released plant exudates and enzymes that stimulate biochemical activity enhance the biodegradation of environmental contaminants.
Plants may absorb and precipitate large quantities of toxic metals in soils, reducing their bioavailibility and preventing their entry into groundwater and food chains.
Some native plants may have an affinity to encroach on contaminant plumes rich in nitrogen, where they then begin phytoremediation using one or more of the principals described above.
Of special interest to DOD applications will be the ability to use our technology to remediate soil and groundwater contaminated with perchlorate. Research data has confirmed that wetland and woody plants are capable of decontaminating water contaminated with perchlorate. The primary phytoprocesses identified as important in the removal of perchlorate from contaminated water included: (1) uptake and phytodegradation in the tree branches and leaves, and (2) rhizodegradation.
The phytodegradation process was evident as perchlorate was taken up into the green plants and not simply accumulated, but was slowly transformed. The rhizodegradation occurred as exudates, secreted by plant roots, supply nutrients sustaining the growth of a rich and diverse consortium of perchlorate degrading bacteria. In the presence of isolated and identified root-colonizing bacteria, perchlorate was rapidly degraded to chloride in the rhizosphere with minimum uptake into the tree leaves and branches.