22 Jun Surprise Daughters!
Surprise Daughters!
A surprising event adds an extra dimension to what we assume for our day, month, or life. Some unexpected events are fun, like a surprise party; others are life-changing, like the birth of twins. When it comes to chlorinated solvent remediation, the surprise arrival of the twin daughters cis-1,2-dichloroethylene (DCE) and vinyl chloride (VC) adds an extra dimension that can be scope-altering.
The interesting question regarding daughter products is – “who’s surprised?” Some remedies are almost guaranteed to produce the nightmare of persistent daughter products.
Biodegradation, enhanced or not, is a stepwise process. As reactions proceed from the parent compound to the non-toxic endpoint, intermediate reaction products are lost to the environment. A critical substrate such as hydrogen (H₂) may also be exhausted. A crucial vitamin like B-12 can be depleted. A key microbe absent. These are just some of the deficiencies that lead to unwanted daughter products.
Daughter products are commonly detected in PCE, TCE contaminated groundwater before treatment. So, you may seek to avoid daughters by using ZVI-based remedies that degrade through β-elimination and, in theory, should not produce daughters, yet you still see significant daughter generation.
At RPI, we approach chlorinated solvent remediation differently. Our CAT 100 manages daughter generation through a marriage of bio, metallic iron, and adsorption. This combination is unique because metallic iron is bound to the carbon throughout the micropores. The manufacturing process and the resulting BOS 100® are patented and not comparable to anything else on the market. The whole that arises in CAT 100 is a technology beyond the sum of its parts. See Figure 1 as an example.
Figure 1. CAT 100 Manages the Chlorinated Ethene Daughter. CAT 100’s synergistic degradation mechanisms have been shown to generate significantly fewer daughter products and to degrade parent and daughter products completely to ethylene in an expedited time frame compared to traditional enhanced reductive dechlorination (ERD) approaches. Within the source area at a site in KY, total chlorinated ethylene (TCE+DCE+VC) concentrations in the source area have been reduced by >99.9% in less than three years. The initial TCE concentration was 47,800 ppb and is currently non-detect. DCE and VC concentrations peaked approximately six months post-application and have since declined to 6.9 ppb and 5.6 ppb, respectively.
Featured Case Studies:
Fiscally Conscious Phased DNAPL Remediation — Legacy Liability to Managed Closure
CAT 100 and BOS 100® Application at Northern European Active Industrial Site
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