KB-1® Bioaugmentation for Source Area Treatment and Downgradient Plume Biobarrier Application

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Courtesy of SIREM

Problem
A trichloroethene (TCE) release at the site in the early 1980’s led to concentrations of TCE and cis-1,2-dichloroethene (cDCE) as high as 592 and 90 milligrams per liter (mg/L), respectively, in the source area, where dense non-aqueous phase liquid (DNAPL) was suspected to be present. The downgradient plume had concentrations of TCE, cDCE, and
vinyl chloride (VC) as high as 2, 34, and 5 mg/L, respectively. The contaminated zones were up to 130 feet below ground surface. The site also contained manufactured gas plant waste, which included Fe, As, and Mn, and mobilization (i.e., increased concentrations) of these metals was a concern.

Solution
Bench–scale testing demonstrated that a combination of EHCTM electron donor and bioaugmentation with the KB-1® culture resulted in the greatest removal of chlorinated volatile organic compounds (CVOCs). Field pilot testing included biostimulation with EHCTM and bioaugmentation with the KB-1® culture to create a biobarrier (28 feet x 21 feet x 40
feet) in the river bank area and to create a biologically active zone (20 feet x 15 feet x 56 feet) within the source area.

Results
TCE was rapidly reduced in the source area with increases initially in cDCE and VC. VC degradation was subsequently confirmed by increases in ethene concentrations up to 11 mg/L in the source area. TCE concentrations decreased in the plume biobarrier after one month, followed by decreases in cDCE and VC and the production of ethene (2 mg/L). CVOC mass reduction of greater than 99% was achieved in the plume biobarrier in 7 months. Within 7 months of bioaugmentation, Dehalococcoides (Dhc) concentrations increased from near non-detect levels (103 Dhc per liter) to 109 Dhc per liter within the plume biobarrier and source area. Data from the pilot test confirmed: reductions in concentrations
of dissolved Fe, As, and Mn in the treatment areas and that the risk of metals mobilization and undesirable downgradient impacts is minimal.

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