Use CENSUS qPCR or QuantArray®-Chlor to quantify Dehalococcoides and functional genes responsible for reductive dechlorination of PCE, TCE, DCE, vinyl chloride and other chlorinated compounds.

Dehalococcoides were the first bacterial group isolated and proven to be capable of complete reductive dechlorination of PCE and TCE to ethene. Since then, CENSUS qPCR and QuantArray-Chlor quantification of Dehalococcoides and reductive dehalogenase genes (TCE, BVC, and VCR) have become an indispensable component of assessment, remedy selection, and performance monitoring at chlorinated solvent sites. In fact, Lu et al. (2006) have proposed using a Dehalococcoides concentration of 1.0E+04 cells/mL as a screening criterion to identify sites where biological reductive dechlorination will proceed at “generally useful” rates.

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REASONS TO QUANTIFY DEHALOCOCCOIDES & FUNCTIONAL GENES:

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COMPLETE REDUCTIVE DECHLORINATION

Dehalococcoides is associated with complete reductive dechlorination of PCE and TCE to ethene at sites around the world. Review of the MI Databases reveals that ethene is produced at nearly 80% of sites where Dehalococcoides concentrations are at least 1.0E+04 cells/mL which is consistent with Lu et al. (2006) who proposed 1.0E+04 cells/mL as a threshold concentration for generally useful rates of reductive dechlorination

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FUNCTIONAL GENES

Quantification of the functional genes encoding TCE and vinyl chloride reductase genes (BVC and VCR) provides a critical supporting line of evidence when evaluating the potential for accumulation of daughter products versus the potential for complete reductive dechlorination to ethene.

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BROAD APPLICABILITY

In addition to reductive dechlorination of PCE and TCE to ethene, Dehalococcoides strains are capable of biodegradation of a broad range of chlorinated compounds including some chlorinated ethanes (DCA), chlorinated benzenes (HCB, PeCB, TeCB, TCB), and chlorinated phenols (PCP, TeCP, TCP, DCP).

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TRUSTED

Microbial Insights has been performing CENSUS qPCR for Dehalococcoides since 2002.

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COST EFFECTIVE

Quantification of Dehalcoccoides and functional genes has become a critical line of evidence at chlorinated solvent sites because CENSUS qPCR and QuantArray®-Chlor are inexpensive and ultimately save money by allowing site managers to make more informed decisions.

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FLEXIBLE

Analysis can be performed on almost any type of sample (water, soils, sediments, Bio-Traps®, and others).

HOW TO USE DEHALOCOCCOIDES & FUNCTIONAL GENE RESULTS:

Along with contaminant concentrations and geochemical parameters, concentrations of Dehalococcoides and functional genes are key components of remedy selection and performance monitoring at sites impacted by PCE, TCE, and other chlorinated compounds.

During Remedy Selection:

If Dehalococcoides concentrations (DHC) are less than 1.0E+04 cells/mL and concentrations of vinyl chloride reductase genes (BVC or VCR) are near or below detection limits, reductive dechlorination is unlikely to occur at a generally useful rates under existing conditions.


Biostimulation (electron donor addition): If Dehalococcoides (DHC) are detected even at low concentrations in most wells within the source area, electron donor injection may stimulate growth of these key halorespiring bacteria and promote reductive dechlorination.  Bioaugmentation would not be necessary.

Bioaugmentation (electron donor + commercial culture): If Dehalococcoides are not detected even at low concentrations in most wells within the source area, bioaugmentation may be needed.

For Performance Monitoring:

Substantial increases in the concentrations of Dehalococcoides and functional genes demonstrate the effectiveness of electron donor injection (biostimulation) or bioaugmentation.  For generally useful rates of reductive dechlorination, Dehalococcoides concentrations should increase to and remain greater than 1.0E+04 cells/mL and vinyl chloride reductase genes (BVC or VCR) should also be detected.

RESOURCES

CASE STUDIES

QuantArray-Chlor: Actionable Data for Remedy Selection

• Site managers were considering monitored natural attenuation (MNA), biostimulation, and bioaugmentation as remediation strategies at a site impacted by a complex mixture of chlorinated hydrocarbons including PCE, TCE, 1,1,2-TCA, 1,2-DCA, cis-DCE, and VC along with high concentrations of sulfate.

• QuantArray®-Chlor analysis provided actionable data for remedy selection allowing timely decisions and significant cost savings in site management.

QuantArray-Chlor: Actionable Data for Performance Monitoring

• QuantArray®-Chlor analysis allowed site managers to have a comprehensive understanding of all relevant microbial processes at the site over time which allowed timely decisions and significant cost savings in site management.

ISMs: Cost Effective Remedy Selection at a TCE Impacted Site

• The ISM study conducted at this site provided clear, actionable evidence that electron donor injection would stimulate reductive dechlorination without the need for expensive bioaugmentation. Further, this evidence was provided in a significantly more cost effective manner than a bench-scale treatability study or a pilot scale study and in a more timely manner.

CENSUS qPCR: Evaluating Biostimulation to Overcome DCE Stall

• A site impacted by PCE and TCE was experiencing an accumulation of cis-DCE (DCE stall). CENSUS qPCR quantification demonstrated that Dehalococcoides concentrations were too low for effective rates of complete reductive dechlorination.

• Avoiding the expense of bioaugmentation resulted in significant cost savings while achieving treatment goals with biostimulation alone.

FIND OUT MORE:
How Dehalococcoides Testing Can Help With These Contaminants

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