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3-D Microemulsion® Bio-Barrier Rapidly Treats Cis-DCE and Vinyl Chloride Contamination and Maintains Reductive Dechlorination Over a 1,200-Day Period


icon-pdf 3-D Microemulsion® Bio-Barrier Rapidly Treats Cis-DCE and Vinyl Chloride Contamination and Maintains Reductive Dechlorination Over a 1,200-Day Period Download the PDF

CASE SUMMARY

Cis-1,2-dichloroethene (cis-DCE) and vinyl chloride (VC) were migrating off-site at this commercial facility. A pilot test of enhanced anaerobic bioremediation was performed to determine if a bio-barrier using 3-D Microemulsion, a form of HRC Advanced®, could effectively reduce the cis-DCE and VC contamination before it moved off-site. The remediation design included the subsurface injection of 3-D Microemulsion upgradient of contaminated well MW-9.

TECHNOLOGY DESCRIPTION

Reductive dechlorination is a process used to degrade certain contaminants in groundwater (e.g., cis-DCE and VC) to ethene. 3-D Microemulsion is a highly effective agent to facilitate this process. 3-D Microemulsion is composed of free lactic acid, controlled-release lactic acid (polylactate), and certain fatty acid components esterified to a carbon backbone molecule of glycerin. When injected into contaminated soil and groundwater, 3DMe produces a sequential, staged release of its electron donor components. The immediately available free lactic acid is fermented rapidly while the controlled-release lactic acid is metabolized at a more gradual rate. The fatty acids are converted to hydrogen over a mid- to long-range timeline giving 3DMe an exceptionally long electron donor release profile. This staged fermentation provides an immediate, mid-term, and very long-term controlled release supply of hydrogen (electron donor) to fuel the reductive dechlorination process.

REMEDIATION APPROACH

The objective at the site was to demonstrate the ability of 3-D Microemulsion to prevent the off-site migration of cis-DCE and VC by contaminant reduction. The reduction was to be achieved by the introduction of 3DMe into the subsurface through 8 injection points spaced 5 feet apart (Figure 1).

contaminants-of-concern 3-D Microemulsion® Bio-Barrier Rapidly Treats Cis-DCE and Vinyl Chloride Contamination and Maintains Reductive Dechlorination Over a 1,200-Day Periodfig-1-injection-points 3-D Microemulsion® Bio-Barrier Rapidly Treats Cis-DCE and Vinyl Chloride Contamination and Maintains Reductive Dechlorination Over a 1,200-Day Period

project-details3 3-D Microemulsion® Bio-Barrier Rapidly Treats Cis-DCE and Vinyl Chloride Contamination and Maintains Reductive Dechlorination Over a 1,200-Day Period

RESULTS

Within 60 days of the application of 3-D Microemulsion, concentrations of the target contaminants were significantly reduced (Table 1 and Figure 2). Over the 1,200-day monitoring period, cis-DCE was reduced by a magnitude of 3 from 4,300 to 3 micrograms per liter (μg/L). VC was reduced by 2 orders of magnitude from 7,300 to 24 μg/L, interrupted briefly by an anomalous spike likely to be laboratory error. As a result of this process, ethene concentrations increased by 102 percent, from 3,100 to 6,500 μg/L, after 130 days (a clear indication of complete dechlorination). Elevated levels of ethene were maintained for more than 300 days until ethene monitoring ended at Day 350 (Figure 2).

table-1-results 3-D Microemulsion® Bio-Barrier Rapidly Treats Cis-DCE and Vinyl Chloride Contamination and Maintains Reductive Dechlorination Over a 1,200-Day Period
table-2-results 3-D Microemulsion® Bio-Barrier Rapidly Treats Cis-DCE and Vinyl Chloride Contamination and Maintains Reductive Dechlorination Over a 1,200-Day Period

CONCLUSION

Overall, the results of this pilot test clearly show that when using 3-D Microemulsion, chlorinated ethene degradation via enhanced reductive dechlorination can be achieved both rapidly (60 days after injection) and successfully maintained over the long term.