March 2004 Meeting Abstract

CAP18™ is a formulation of food-grade, long-chain (C18) fatty acids, refined from natural vegetable oils, for environmental remediation solutions. CAP18™ can be used for cost-effective, rapid treatment of chlorinated solvents, perchlorate, nitrate, and explosives, found as contaminants in soil and ground water. CAP18™ remediation is accomplished in-place without high capital costs, disruptive site activities, or complex engineered delivery systems.

CAP18™ stimulates microbes living in the soil and aquifer to naturally degrade contaminants under anaerobic (oxygen-free) conditions. The long-chain fatty acids are consumed via a process known as beta-oxidation, which establishes optimal anaerobic conditions for contaminant degradation, and produces hydrogen over a sustained period of time (many months to years). The hydrogen is utilized by microbes to biologically destroy contaminants by stripping chlorine or nitrogen atoms from the molecule. Unlike many other bioremediation substrates, CAP18™ inhibits microbial reduction of acetate to methane, thereby providing more substrate for hydrogen generation, and reducing microbial reduction of carbon dioxide with hydrogen.

Advantages of CAP18™

CAP18™ benefits from three important advantages over engineered or active remediation systems:

(1) Low capital cost. CAP18™ can be applied with standard direct-push techniques or via standard monitoring wells. No permanent equipment is required.

(2) Low maintenance cost. After CAP18™ injection, the only continuing costs are routine sampling common to all remediation systems. In some cases, more than one application may be necessary.

(3) Minimal site disruption. CAP18™ is emplaced rapidly (typically in hours or days) with mobile equipment. No equipment is left onsite to be maintained, occupy valuable space, or disrupt site operations.

In addition, CAP18™ offers many advantages over other natural attenuation enhancements:

(4) CAP18™ is a liquid with a viscosity similar to vegetable oil, and can be injected via monitoring wells or temporary points using standard grout pumps or diaphragm pumps.

(5) CAP18™ dissolves slowly and provides a long-term hydrogen source that lasts for months. Unlike more soluble or less viscous amendments, frequent re-injection or recirculation systems are not necessary.

(6) CAP18™ is a metabolically diverse substrate composed of C18 fatty acids, which produces a wide range of compounds for microbial hydrogen production ideal for diverse aquifer conditions.

(7) CAP18™ is a concentrated hydrogen source, providing fuel to establish optimal groundwater conditions and overcome competitive demand.

(8) Normalized to the cost of hydrogen produced, CAP18™ is the same cost or often less expensive than other soluble or insoluble substrates.

(9) CAP18™ contains natural compounds that inhibit microbial reduction of acetate to methane. Compared to other substrates, CAP18™ yields efficient hydrogen utilization for contaminant destruction rather than for methane production.

How CAP18™ Works

CAP18™ dissolves slowly to release C18 fatty acids. The C18 fatty acids stimulate microbial hydrogen production. Other microbes then use the hydrogen produced to reduce the contaminants.

The Limitations of CAP18™

All bioremediation products share certain limitations, such as application to dense non-aqueous phase liquids (DNAPLs), distribution in impermeable aquifer matrices, adequate site characterization, etc. If water is used in the injection process, ensure the water is unchlorinated or dechlorinated to reduce disinfectant properties. One limitation of CAP18™ is application to aquifers containing very hard water. Hard water is characterized by high concentrations of calcium, which bonds with long-chain fatty acids and removes them from solution (similar to soap scum from soaps), reducing hydrogen production efficiency. This additional demand must be considered in calculations of CAP18™ requirements.

How to Apply CAP18™

CAP18™ project design is based first upon an accurate site characterization. Once the site is characterized, widely published protocols are useful for determining if a site is appropriate for stimulating natural biodegradation in general. Contaminant mass and distribution, and background hydrogen and contaminant demand are important design criteria that should be evaluated specifically prior to CAP18™ application:

CAP18™ can be applied in many designs: across treatment areas with a grid pattern of injection points (Cascade design), as a barrier through which groundwater moves (Curtain design), or directly into excavated areas. CAP18™ has a viscosity similar to vegetable oil. It can often be injected via standard monitoring wells, or via temporary well points installed by direct-push techniques. Although general design options are provided, application methods are very flexible with CAP18™.

CAP18™ is not an extremely thick liquid and thus does not require pre-heating, specialized high-pressure pumps, or subassemblies for injection. Injection can be readily accomplished through direct-push equipment. In addition, the viscosity of CAP18™ is sufficiently low that injection can be accomplished through existing or newly installed, permanent or temporary well points.

Groundwater Analytes Recommended for Project Design and Evaluation

Free software is available from us to help you estimate the amount of CAP18™ required for a site. Important factors include evaluation of the volume of the treatment area and basic hydrological and soil parameters. The concentrations of all contaminants that undergo anaerobic degradation should be measured in both soil and ground water. Analytes recommended in order to estimate the natural background demand include dissolved oxygen, nitrate, total iron, manganese (available for reduction), sulfate, and calcium (or hardness) concentrations.

Where to Order and to Get Help With CAP18™

CAP18™ is distributed by DBI Remediation Products, LLC. For technical and general support on CAP18™ applications, including royalty-free graphics (Microsoft PowerPoint slides), free software to help you estimate CAP18™ requirements, and general application support, or to place an order, contact: Matt Dingens, DBI Remediation Products, LLC, 115 Franklin Turnpike, #367, Mahwah, NJ 07430, Telephone/Fax (201) 327-8077; e-mail mdingens@dbiproducts.com

Please join your colleagues at the March 2004 BAPG Meeting

Stephanie Reynolds-Smith

BAPG Executive Vice-President