Green Remediation — DNAPL
Bond Optics Project Highlights
Contaminant: cVOC (Chlorinated Volatile Organic Compound)
Location: Bond Optics, Lebanon, New Hampshire
Industry: Custom optics for aerospace
Problem Situation: TCE (trichloroethylene) contamination; more than 100,000 ug/L
BioStryke™ Solution: BioStryke™ ERDENHANCED™
Results: Single application remediation, no rebound
The objective of the ERD program was to decrease TCE concentrations in the source area to less than 1,000 μg/L, so the site could segue to monitored natural attenuation (MNA) for managing the dissolved-phase plume. To reach this goal, consultant of record proposed using BIOSTRYKE’s proprietary formulation BioStryke™ ERDENHANCED™ to create an anaerobic treatment zone in the source area and expedite residual TCE source mass destruction. BioStryke™ ERDENHANCED™ stimulates native microflora to scavenge the terminal electron acceptors (TEAs), such as oxygen, nitrate, oxidized iron/manganese, and sulfate which can limit cVOC dechlorination.
ERDENHANCED™ also provides organic carbon to serve as an electron donor source that microflora could ferment, ultimately yielding volatile fatty acids and molecular hydrogen to further drive dechlorination. This green technology is performed in-situ without excavation and disposal, or long-term use of power-consuming and carbon dioxide-emitting motors.
Because the remediation program was focused on source control, the greater than 99.99 percent decrease in TCE concentrations in the source area indicated that the program was successfully dechlorinating source mass as it became desorbed from the soil and more bioavailable for dechlorination, as demonstrated by the significant increase in cis-1,2-DCE, which is the preferred daughter product of TCE dechlorination.
TCE concentrations started decreasing in 2005 and were documented at less than 10 μg/L in May 2010, a value 2 orders of magnitude less than the targeted goal of 1,000 μg/L. As the source mass was removed, the molar percentage of parent compounds went from 99.6 percent of the total cVOCs at the start to less than 0.3 percent 8-1/2 years later.
Similarly, the cis-1,2-DCE concentrations began to decrease in 2006 after the residual TCE mass was destroyed and concentrations plummeted. As shown in the above figure, cis-1,2-DCE concentrations in the source area decreased from a peak of 154,000 μg/L in 2006 to 960 μg/L in May 2010, a decrease of over 99 percent in 3-1/2 years. The detection of increased methane and ethene confirm that BioStryke™ ERDENHANCED™ expedited the destruction of cVOCs, resulting in ethene generation.
Green Remediation of a DNAPL
In conclusion, BioStryke™ ERDENHANCED™ is a sustainable, green technology that is performed in-situ with no power requirements after the injection event is complete. By eliminating the need for excavation and offsite disposal of impacted soil, or long-term operation of a pump-and-treat or other active remedial system, the project can minimize its carbon footprint while reducing overall remediation costs. Total costs for the project, including the injection program, BioStryke™ ERDENHANCED™ , and remedial design and implementation, was less than $75,000; demonstrating, BioStryke™ ERDENHANCED™ is a cost-effective remedial strategy for destroying cVOC source mass.