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JCCES Projects
The major issues currently addressed by the JCCES Program include contamination of soils by heavy metals, petroleum by-products, and chlorinated solvents, such as trichloroethene/perchloroethene (TCE/PCE). Heavy metal contamination at DOE sites includes several target metals. Two of the most significant contaminants are lead and mercury, both of which are toxic. Lead is a common soil contaminant throughout DOE and results from a variety of sources, including small arms ranges used by security personnel for training. The mercury contamination found at DOE sites resulted from improper storage and disposal practices that allowed the metal to seep into the soil. Currently, technologies for the remediation of heavy metal contaminated soils (e.g., soil washing technologies) are expensive and are feasible for relatively small areas contaminated with high concentration of metals. As a result, there is a need within the DOE complex to identify technologies that address widespread, low to moderate levels of soil contamination and that can be implemented at reduced cost. Petroleum contaminated soils (PCS) are found at many DOE sites where petroleum by-products were spilled, placed in unlined lagoons or otherwise mismanaged. Petroleum products consist of a combination of carbon-based compounds that can pollute local soil and can migrate into nearby water supplies. Other factors complicating the remediation of these areas can include the pH of the soils and the age of the contaminated material. Chlorinated solvents are used typically as degreasers for cleaning metals. Although TCE/PCE normally volatilize in air, these chemicals have contaminated soils at numerous DOE sites (as well as industrial sites worldwide) due to improper storage and disposal practices. TCE/PCE that has leached into the soil cannot volatilize; therefore, it remains a long-term pollutant in soil. Under the JCCES, scientists are investigating two methods for the remediation of contaminated soils: bioremediation and phytoremediation. Bioremediation is the process of stimulating the natural decomposition of carbon-based contaminants by providing optimum conditions for the natural microorganisms that break down these contaminants. Phytoremediation involves the use of plants to extract contaminants from soil rather than break them down. Phytoremediation projects under the JCCES have focused on the extraction of non-organic contaminants like heavy metals.
Remediation of Organic Contaminants—Petroleum Contaminants and Chlorinated Solvents Currently, DOE faces a daunting task in the remediation of petroleum-contaminated soils and chlorinated solvents throughout its complex. DOE landfills are estimated to contain over 3 million cubic meters of buried waste. This waste exists in a variety of forms, including carbon-based (i.e., organic) pollutants, such as petroleum hydrocarbons and chlorinated ethenes (e.g., TCE/PCE). It is reported that DOE sites contain 200 million cubic meters of contaminated soil. Given that currently available remediation technologies are inadequate or unacceptable due to excessive costs, increased risks, long remediation schedules or the production of secondary waste streams, the mission to identify and evaluate innovative remediation technologies is critical. Poland faces similar problems of contaminated soils as a result of the refining of crude oil. Disposal practices for process wastes generated by crude oil refinement have created conditions that are unacceptable under today's environmental standards. The use of unlined lagoons for process waste disposal was the industry norm for many years in Poland and in the United States. As late as the 1980's, the United States was using unlined process waste lagoons, while in Poland the practice still exists. Polish oil refineries can be used as "test beds" for developing technologies (e.g. bioremediation) that can be used at DOE sites with similar contamination problems. Bioremediation is a process in which the conditions for microbial growth and the associated breakdown of organic contaminants are optimized by supplying adequate amounts of electron acceptors, water, and nutrients to the contaminated material. Because biodegradation rates for these organic substances are highest under aerobic conditions, maintaining high oxygen levels in the system is critical. "Biopiling," the method being used in these projects, is an ex situ process where oxygen and other amendments are forced through the contaminated material either by vacuum extraction or by injection to stimulate the microbial growth thereby breaking down the organic contaminants. Remediation of Inorganic Contamination - Heavy Metal Contaminated Soils Decades of metal mining and refining (i.e., smelting) within the Upper Silesian region of Poland have resulted in extensive heavy metal contamination of soil. This contamination is found in moderate to high concentrations (500-5,000 mg/kg of soil) of lead and tends to be concentrated in the top 30 cm of the soil. This lead pollution has many characteristics in common with contamination found within the DOE complex where the contamination exists in the top layers of the soil and has been spread over a relatively wide area. Under the auspices of the JCCES, OST initiated a phytoremediation project to demonstrate and refine the process by which plants can remove heavy metals from the soil. This project combines the DOE need for an effective and efficient technology to remediate moderate levels of heavy metal contamination with IETU's experience and qualifications in this area. The goal of this project is to adapt and further refine phytoremediation for deployment at DOE sites. Considerable research has been reported on the laboratory-scale application of phytoremediation; however, little information is available concerning the cost, performance, and advantages of full-scale applications. An objective of this project is the optimization of field-scale application of phytoremediation and the documentation of those results. Different species of plants, which have the ability to uptake and sequester heavy metals, are being evaluated. In addition, the effects of the ethylene diamine tetracetic acid (EDTA) to increase the availability of these metals to plants and the use of a chlorophyll fluorometer to optimize the phytoremediation process also have been investigated. The target metal for this project is lead. As the project has progressed, a high priority has been placed on the reduction of cost associated with this developed technology. Field studies have shown that up to 70% of the project cost can be attributed to soil amendments like EDTA; therefore, it is imperative that soil amendments be applied in an economical manner.
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