Enhanced in-situ bioremediation (EISB) is a cost-effective groundwater remediation technology for chlorinated solvents such as tetrachloroethene (PCE) and trichloroethene (TCE). Laboratory and field data have shown that the Dehalococcoides group of microorganisms is solely responsible for the complete dechlorination of PCE and TCE to ethene.

Why is this important? First, not all sites contain Dehalococcoides. This means that cis-1,2-dichloroethene (cis-1,2-DCE) can accumulate during EISB. Second, not all strains of Dehalococcoides have the gene called vinyl chloride reductase. This means that if you have the wrong strain of Dehalococcoides that vinyl chloride will accumulate. The introduction (bioaugmentation) of competent Dehalococcoides organisms at sites where they are absent or where inadequate strains exist rectifies these potential deficiencies, and spells the difference between a successful versus an unsuccessful EISB remedy.

Despite a growing body of scientific evidence supporting bioaugmentation there is still debate as to whether bioaugmentation is a beneficial practice. Practitioners often question: “Why do you need bioaugmentation if the bugs are everywhere?” – an incorrect assumption refuted by numerous peer-reviewed publications, and argue that bioaugmentation is expensive. The fact that the cost of bioaugmentation is so small, and its value is so great, is a very compelling reason to consider bioaugmentation. This is particularly true for sites where Dehalococcoides are absent, or the wrong strains are present, and even at sites where Dehalococcoides are present but so poorly distributed, that it will take extended time periods to grow them to effective cell densities.

An axiom that strongly applies to the value of bioaugmentation is “time is money”. What is the cost of waiting? If results are not observed after months or even years of adding electron donors; clients, regulators, and even the public may request additional monitoring, increased frequency or amounts of added electron donor, or other costly activities. Bioaugmentation reduces future costs and concern, and provides peace of mind to all stakeholders.

Bioaugmentation also captures the value of electron donors, and associated application costs. Why spend tens or even hundreds of thousands of dollars over months or years waiting for a result, when that value can be captured sooner? Early bioaugmentation improves the efficiency of electron donor use, reducing the total amount needed. Delaying bioaugmentation allows competing microbial populations to grow to higher cell densities wasting electron donor on undesirable reactions (e.g., methanogenesis, metals reduction).

Bioaugmentation is an inconsequential one-time cost compared to the overall life cycle cost of EISB remedies. It adds value by capturing the worth of electron donors, improving donor efficiency, decreasing the management of degradation intermediates, and reducing or eliminating future costly management decisions. With all these benefits, one has to ask, “Can you afford not to bioaugment?”

The most feasible option to benefit from bioaugmentation’s cost savings is application KB-1™ Dechlorinator. KB-1™ has been used at more than 35 sites in 14 states, and in Europe to establish or improve complete dechlorination of chlorinated ethenes for EISB of source areas and plumes in porous media and fractured rock environments.

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