How Key-hole Bioremediation Reduces Source and Down-gradient Contamination
CL-Out aerobic PCE bioremediation in a keyhole treatment reduced the mass of contamination near the source and down gradient concentrations in the plume. At a former manufacturing facility in Cincinnati, Ohio the concentration of PCE near the source was over 100,000 ug/L. Down gradient of the source the PCE concentrations were less than 10% of the source concentration. Aggressive treatment in the source area reduced the source concentration and in the down gradient plume.
Source area concentrations decreased as follows after one treatment with CL-Out bioremediation:
- PCE decreased from 120,000 to 12 ug/L.
- TCE decreased from 2,000 to 12 ug/L
- Cis 1,2-DCE decreased from 9,500 to 8,100 ug/L.
- Vinyl chloride, however, increased from 1,200 to 22,000 ug/L.
The vinyl chloride increased as the aggressive cometabolic treatment stimulated incomplete reductive dechlorination by other naturally occuring organisms.
Down gradient from the source, the concentrations decreased with slight to no increase in daughter products. The down gradient plume had the following results:
- PCE decreased from 5,000 to 1,600 ug/L.
- TCE decreased from 43 ug/L to BDL.
- Cis 1,2-DCE decreased from 140 to 23 ug/L.
- Vinyl chloride was not detected before or after treatment.
Keyhole treatment was a cost effective approach to reducing the mass of contamination in a ground water plume by focusing aggressive treatment on the source area. Concentrations in the rest of the plume decreased as the microbes and treated water dispersed through the plume.
Aerobic PCE Bioremediation By Cometabolism
CL-Out is a consortium selected for aerobic PCE bioremediation. CL-Out cometabolizes PCE by growing on a simple sugar and producing a metabolic enzyme to degrade PCE. The microbes produce a dioxygenase enzyme that breaks the carbon bond in PCE. This reaction eliminates the biproducts of reductive dechlorination. Also, the synergistic effect of the CL-Out consortium cometabolizes the full suite of chloroethenes and chloroethanes.
