Superfund Innovative Technology Evaluation (SITE)
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A study was performed to investigate the feasibility of applying the DUOX chemical oxidation technology to chlorinated solvent-contaminated media at the Roosevelt Mills site in Vernon, Connecticut. The Roosevelt Mills site is a former woolen mill that included dry-cleaning operations. The plant also housed metal-plating operations.
The primary contaminants of concern are chlorinated organic solvents:
- Tetrachloroethene (PCE)
- Vinyl chloride
The DUOX technology, developed by researchers at the Environmental Research Institute at the University of Connecticut, is said to provide a cost-effective, in situ oxidation process to neutralize chlorinated organic chemicals. The technology uses a combination of two types of oxidants to destroy unsaturated chlorinated solvents. The oxidants belong to the persulfate and permanganate families of inorganic compounds.
Sodium persulfate is used to satisfy the soil oxidant demand (SOD) and minimize the quantity of potassium permanganate needed to mineralize target compounds. This facilitates the transport of permanganate through the aquifer, allowing for more uniform distribution of permanganate and the use of a much smaller quantity. In turn, this alleviates problems caused by excess permanganate (that is, precipitated manganese dioxide that can result in reduced aquifer permeability).
The study was performed under the auspices of EPA’s Superfund Innovative Technology Evaluation (SITE) Program. The SITE study consisted of:
- A site characterization outside and inside the Roosevelt Mills building to identify chlorinated source material and characterize the extent of the dissolved phase plume
- A laboratory treatability study to evaluate the effectiveness of the DUOX technology on the impacted media at the site
Results from the study are as follows:
- A chlorinated solvent source area was located underneath the Roosevelt Mills building in a portion (the upper 3 feet) of the foundation fill material. It appears that pure-phase tetrachloroethene exists as distinct globules within the coarse-grained fluidized zone.
- Ground water results, both from inside and outside the building, indicate the presence of a dissolved chlorinated solvent plume emanating from the vicinity of the source area identified in the building.
- The near-surface fill material (the source area matrix for the PCE) exhibits a very low soil oxidant demand.
- Permanganate alone and in combination with persulfate is effective in reducing the levels of chlorinated solvents in the site ground water, as shown in spiked soil samples simulating a free-phase globular distribution.
- Persulfate alone, as tested, was ineffective in reducing the levels of chlorinated solvents in any of the experiments. However, due to low SOD, there is no need to use persulfate for the chlorinated solvent source area.