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MicroZVI-Colloidal Zero Valent Iron

Benefits:

  • Superior, wide-area distribution into groundwater
  • Easy application
  • Long-lasting, powerful In Situ Chemical Reduction (ISCR)

MicroZVI can be used to:

  • Target source areas, including Dense Non Aqueous Phase Liquids (DNAPL)
  • Remediate chlorinated solvents, hexavalent chromium, pesticides and more (see our range of Treatable Contaminants Guide)
  • Enhance biological degradation through ISCR

What is MicroZVI?

MicroZVI consists of highly dispersible colloidal ZVI (cZVI) particles (<5 μm) suspended in glycerol and proprietary dispersants. This combination results in unsurpassed distribution, reactivity and longevity compared to other ZVI products (see diagram 1 below). As a result, treatment is more efficient, saving time and cost onsite.

It destroys contamination through:

  • ISCR-enhanced anaerobic biological degradation: creating a strongly reducing and hydrogen rich environment for reductive dechlorination
  • Direct abiotic chemical reaction

MicroZVI can be used in conjunction with 3-D Microemulsion to provide the necessary iron to activate abiotic chemical reduction (including the β-elimination pathway) of chlorinated organic groundwater contaminants like perchloroethene (PCE), trichloroethene (TCE), dichloroethene (DCE), and vinyl chloride (VC). The end products of these biogeochemical reductions are ethene and ethane. MicroZVI can also be co-injected with Bio-Dechlor Inoculum Plus® (BDI+), see the Biological Degradation section below.

REGENESIS-ZVI-particle-size-matters

Diagram 1: The effects of Particle Size © REGENESIS

Target Contaminants:

Chlorinated Solvents, Hexavalent Chromium, Pesticides and more

MicroZVI is especially effective at promoting rapid biological degradation of:

  • Chlorinated Solvents:
    • Chlorinated Ethanes
    • Chlorinated Ethenes
  • Haloalkanes
  • Pesticides and Herbicides
  • Energetics
  • Hexavalent Chromium (Chrome VI)

For a complete listing of treatable contaminants please visit our Range of Treatable Contaminants Page.

Typical Soil and Groundwater Remediation Application Methods:

Application/Injection:

  • Permanent injection wells
  • Direct-push injection points

MicroZVI is diluted with water on-site and easily applied into the subsurface using low pressure injections. MicroZVI is compatible with and can be co-applied with products like 3-D Microemulsion (3DMe) and Bio-Dechlor Inoculum Plus® (BDI+).

About In Situ Chemical Reduction (ISCR)

ZVI products, such as MicroZVI and CRS, are used in soil and groundwater remediation as an in situ chemical reduction (ISCR) reagents. Chemical reduction is the process of adding or donating electrons to contaminants (while chemical oxidation is the process of removing or accepting electrons from contaminants). The ZVI acts as a reducing agent to provide electrons directly to the contaminant for degradation or to support processes that require electrons to degrade contaminants.

Abiotic Degradation

Zero-valent iron can provide an abiotic degradation pathway involving the direct reaction of ZVI with groundwater contaminants. The abiotic, “beta-elimination pathway” for chlorinated ethenes is shown in the bottom of Figure 1. The abiotic pathway involves short-lived dichloroacetylene and chloroacetylene intermediates, bypasses the formation cDCE and VC, and ultimately results in ethene and ethane.

Figure 1

Figure 1: ISCR or beta-elimination (double-line arrows). Beta-elimination avoids the formation of cDCE and VC.

Biological Degradation

Biological degradation involves the destruction of contaminants by anaerobic bacteria that are supported by the molecular hydrogen that is produced by the fermentation of organic hydrogen donors or by the reaction of ZVI with water. The biological degradation pathway for perchloroethene (PCE) and trichloroethene (TCE) is provided in Figure 2. This pathway, called reductive dechlorination (or hydrogenolysis), involves the sequential replacement of a chlorine atom with a hydrogen atom and is always accompanied by the formation cis-1,2-dichloroethene (cDCE) and vinyl chloride (VC). Many common anaerobic bacteria can transform PCE to TCE and then to cDCE, but only Dehalococcoides ethenogenes (DHC) can transform cDCE and VC to ethene.

Figure 2

Figure 2: Reductive dechlorination sequentially replaces chlorine atoms with hydrogen atoms. The intermediates cDCE and VC are more toxic than parent compounds PCE and TCE.

 

Supplementing dechlorinating bacteria with zero-valent iron and organic hydrogen donors can enable more rapid and complete biodegradation. Zero-valent iron quickly deoxygenates groundwater and provides an electrochemically reducing environment that is highly fertile for the microbes involved in anaerobic bioremediation. In many situations this favorable environment can be sustained for several years.

ISCR-Enhanced Bioremediation

ISCR-enhanced bioremediation is a term describing the remediation approach that combines zero-valent iron (ZVI), an organic hydrogen donor, and contaminant-degrading microbes (native or bioaugmented) in order to degrade contaminants in soil and groundwater. This approach is most commonly used for chlorinated contaminants, e.g. chlorinated ethenes. ISCR-enhanced bioremediation is particularly effective because it stimulates anaerobic biological degradation by rapidly creating a reducing environment favorable to reductive dichlorination. Furthermore, ISCR-enhanced bioremediation may limit the formation of undesirable daughter products such as cDCE and VC by degrading parent compounds via direct chemical reduction.

ISCR-enhanced bioremediation can be used to treat contaminants such as chlorinated solvents, haloalkanes, and chlorinated pesticides. Contaminants that are resistant to abiotic degradation (e.g. 1,2-dichloroethane or dichloromethane) and compounds that can inhibit bioremediation (e.g. 1,1,1-trichloroethane or chloroform) may be effectively treated by ISCR-enhanced bioremediation. ISCR-enhanced bioremediation can be used for source zones, plumes, and barrier applications.

Want to learn more about zero-valent iron products?

 



Next Steps

  • Do you have a project and need a remediation solution now? Visit our Request a Design page.
  • Have you got questions or want to explore ideas? Contact Us to get in touch with a local representative.

FAQs about MicroZVI

MicroZVI is a liquid iron-based reagent for the enhanced biogeochemical in situ chemical reduction (ISCR) of a wide range of contaminants. It consists of highly dispersible colloidal ZVI (cZVI) particles (<5 μm) suspended in glycerol and proprietary dispersants. MicroZVI is injected into contaminated groundwater to treat chlorinated hydrocarbons, pesticides, haloalkanes, energetics and other toxic volatile organic compounds (CVOCs).

MicroZVI destroys contamination through:

  • ISCR-enhanced anaerobic biological degradation: creating a strongly reducing and hydrogen rich environment for reductive dechlorination.
  • Direct abiotic chemical reaction.

MicroZVI is right for your project if you are treating source areas with halogenated hydrocarbon contaminants, hexavalent chromium, pesticides or other CVOCs, and your treatment would benefit from multiple pathways, both abiotic and biotic, for contaminant degradation in groundwater.