Hydrogen Release Compound (HRC®)

Product

HRC® is a controlled release, electron donor material, that when hydrated is specifically designed to produce a controlled release of lactic acid. The newly available lactic acid is critical for the production of hydrogen to fuel anaerobic biodegradation processes in soil and groundwater.

Purpose

To make available time release lactic acid for fermentation by subsurface microbes that in turn generates hydrogen. Hydrogen is the key ingredient in the anaerobic contaminant degrading process known as reductive dechlorination. Reductive dechlorination is the mechanism by which chlorinated compounds are biodegraded into less harmful constituents such as ethene and ethane.

Functionality

HRC® is typically applied using direct-injection techniques. This process enables the viscous HRC® material to be pressure injected into the zone of contamination and moved out into the aquifer media. Once in the subsurface, HRC® can reside within the soil matrix fueling reductive dechlorination and promoting reducing aquifer conditions for periods of up to 24 months or longer through the controlled release of lactic acid and subsequent hydrogen production.

HRC® is supplied as a viscous liquid for direct injection into contaminated groundwater and saturated soils. This specially formulated product produces a controlled release of lactic acid upon contact with water (Figure 1). This newly available source of lactic acid is then metabolized by microbes to produce hydrogen which is then used in a naturally occurring process known as anaerobic reductive dechlorination (Figure 2). The reductive dechlorination process results in the step-by-step biological degradation of chlorinated contaminants. HRC® can be used to degrade a range of chlorinated compounds including: degreasing agents (PCE, TCE, TCA and their breakdown products), carbon tetrachloride, chloroform, methylene chloride, certain pesticides/herbicides, perchlorate, nitrate, nitroaromatic explosives and dyes, chlorofluorocarbons, certain metals and radionuclides.

More on Reductive Dechlorination

As discussed, reductive dechlorination is a term used to describe the mechanism by which chlorinated hydrocarbons are biologically degraded under anaerobic conditions. In this natural process, anaerobic microbes substitute hydrogen (H) for chlorine (Cl) on chlorinated contaminant molecules, thus dechlorinating the compound. Being a natural process, reductive dechlorination usually proceeds at very slow, unsustainable rates. HRC® increases the rate of dechlorination up to several orders of magnitude, rapidly taking the contaminant through a step-wise dechlorination process that ultimately results in the production of non-toxic compounds such as ethene and ethane. Under the influence of HRC®, this process may continue.

The Reductive Dechlorination Process

The Reductive Dechlorination Process

Product Specifications

  • A viscous, honey-like material rated at 20,000 centipoise
  • Composition: Glycerol Tripolylactate
  • Non-hazardous, food grade product
  • Packaged and delivered in 30 lb. PVC buckets
  • Expected shelf-life of material = 3 years

Field Applications

  • Direct-injection (most common) for source area and permeable reactive barrier applications
  • Re-circulation wells
  • Straight HRC® application in excavations
  • Straight HRC® application in ex-situ soil mixing
  • Hydraulic fracturing of tight soil media
  • Fractured bedrock injection using straddle packers
  • Direct application into wells via gravity feed

Benefits of Use

  • Controlled release of lactic acid to promote reducing conditions and produce hydrogen in 8 to 10 nM range which is optimal for anaerobic reductive dechlorination
  • Long-term source of lactic acid/hydrogen to the subsurface (up to 24 months or longer)
  • Single product application (for majority of sites)
  • Clean, low-cost, non-disruptive application
  • Not limited by presence of surface structures
  • No Operations and Maintenance
  • Faster and often lower cost than drawn out monitored natural attenuation (MNA)
  • Complimentary product application design and site analysis from Regenesis

Application Considerations

  • Existing aerobic or anaerobic conditions
  • Contaminant type and mass
  • Subsurface geology (distribution)
  • Depth to groundwater
  • Groundwater flow rates
  • Viscosity/Pumping (heating of material sometimes required for ease of application)
  • Free product (if present call Regenesis tech services to discuss options)

Product Categories


Quick Links

Additional Information:

HRC® an Amber Colored, Viscous Material

Technical Diagram: HRC/HRC-X Molecular Structure and the Reductive Dechlorination Process

Click to Enlarge

Bird's Eye View of Direct Push Injection of HRC® at Chlorinated Solvents Site

HRC® Material Pre-Application

Convenient and Practical Direct Push Injection of HRC® on a busy, Operating Street