EOS Remediation
Overview | Features | Specifications | FAQs
EOS Remediation’s products are specifically developed and designed for cost-effective, in situ treatment of groundwater. Products include: EOS®, a powerful organic substrate for Enhanced Anaerobic Bioremediation, EOS® AquaBupH™, a new patent-pending technology that addresses the same range of contaminants as EOS®, with the added benefit of incorporating a colloidal buffer into the premier EOS® Technology for immediate and long-term pH adjustment, EOx™ a calcium-based product for Enhanced Aerobic Bioremediation designed to effectively function in both groundwater and saturated soils.
All EOS Remediation information reprinted with permission from EOS Remediation
Innovea Technologies represents EOS Remediation in their product offering. Contact us to learn more about the products and how they can serve your remediation needs.
Enhanced Anerobic Bioremediation
EOS Remediation, a leader in Enhanced Anaerobic Bioremediation technologies, leveraged its research and experience to develop market-leading products and appropriate supplements to maximize effectiveness. Combining these elements allows EOS customers to rest assured that they are buying products that deliver optimum results.
• EOS®, our core technology, is a significant advancement in the treatment of groundwater contaminated with chlorinated solvents, energetic materials, oxidized heavy metals, and radionuclides. The proven EOS® Technology substantially reduces the cost to restore contaminated aquifers. This innovative and effective product is a water-miscible concentrate that is easy to handle in the field. EOS® includes rapidly biodegradable substrates to “jump start” bacterial growth, slow-release biodegradable substrates to support long-term respiration, and a suite of nutrients for enhancing the growth of halorespiring and other indigenous bacteria. It is active in the aquifer for longer than three years and is non-toxic to the environment. This product can be distributed across a large aquifer volume and is effective in promoting reduction of chlorinated solvents, perchlorate, energetics, acid rock drainage, oxidized metals and other recalcitrant chemicals.
• EOS® Vitamin B12 Supplement offers added value by providing an optimal diet for the halorespiring bacteria in the form of a proprietary Vitamin B12 Supplement. Competing products do not include amino acids, trace minerals, B vitamins and the additional B12 supplement found in EOS® 598B42.
• EOS® AquaBupH™ is an ideal product for in situ bioremediation of contaminated sites having an acidic pH. By incorporating buffering materials into the proven EOS® patented technology, this revolutionary new patent-pending product addresses the same range of contaminants as EOS®, with the added benefit of immediate and long-term pH adjustment. Additionally, the buffering materials in EOS® AquaBupH™, when diluted with water, are designed for effective distribution across contaminant plumes.
Enhanced Aerobic Bioremediation
• EOx™ is an oxygen releasing compound to complement our scientifically-proven family of anaerobic bioremediation products. EOx™, a calcium-based product, is designed to be effective in both groundwater and saturated soils. The controlled release of oxygen from EOx™ accelerates biodegradation by indigenous aerobic microorganisms, resulting in a higher level of sustained bioactivity and increased contaminant removal. When hydrated, EOx™ slowly releases oxygen over an extended period of time to degrade a wide range of organic contaminants (e.g., gasoline, fuel oils, MTBE; creosote; PAHs; PCP; vinyl chloride).
• EOS®, our flagship product, is an emulsified oil substrate with lactate, nutrients and vitamins that is used to remediate contaminated groundwater by dynamically stimulating anaerobic biodegradation and biotransformation. This product is
· A water-miscible concentrate
· Easy to handle in the field
· Active for longer than three years in an aquifer
· Non-toxic to the environment
· Able to be distributed over a larger volume of the aquifer (relative to other in situ treatments)
· Effective in reducing chlorinated solvents, perchlorate, explosives (such as RDX, HMX and TNT), acid rock drainage, oxidized metals and other recalcitrant chemicals
These factors make EOS a superior in situ remediation alternative compared to other in situ techniques and products currently available.
The use of emulsified oils, EOS®, for groundwater bioremediation is a significant advancement in the treatment of groundwater contaminated with chlorinated solvents, energetic materials, oxidized heavy metals, and radionuclides. The proven EOS® Technology substantially reduces the cost to restore contaminated aquifers. EOS Remediation is the only company licensed by Solutions-IES to apply this innovative and effective process under U.S. Patent No. RE40448 and European Union Patent No. EP 1 315 675.
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Enhanced Aerobic Bioremediation
EOS Remediation offers in situ products supporting enhanced aerobic bioremediation: EOS, EOS® 598B42 (flagship product), EOS® AquaBupH™, and VOS™. An explanation of each of these products and their specifications and uses are as follows.
EOS®
Emulsified Oil Substrate (EOS®)
• A Simple, Easy-to-Use Product with
• Slow and Rapid-Release Biodegradable Substrates and Micronutrients for
Effective Distribution in Contaminated Aquifers providing
• Superior Enhancement of Anaerobic Biodegradation with
• Greater Longevity in the Subsurface.
Contaminants that can be Treated with EOS®
• Chlorinated Solvents: PCE, TCE, TCA, CT, etc.
• Energetic Materials: Perchlorate (ClO4-), RDX, TNT, etc.
• Nitrate (NO3-)
• Oxidized Heavy Metals
• Radionuclides (TcO4-, UO2+2)
• Acid Rock Drainage
EOS® Product Formulations
EOS Remediation’s family of soybean oil emulsions / emulsified vegetable oil (EVO™) includes several product formulations. Selecting the appropriate product for your project is important. The comparison chart below provides information needed to compare and understand each product offering.
Ingredients / Composition |
EOS® 450 (% by Weight) |
EOS® 598 (% by Weight) |
EOS® 598B42 (% by Weight) |
|
Soybean Oil (food grade) |
49.9 ± 2% |
59.8 ± 2% |
59.8 ± 2% |
|
Long Chain Fatty Acids |
0.9 ± 0.2% |
0 |
0 |
|
Sodium Lactate / Lactic Acid |
4 ± 0.2% |
4 ± 0.2% |
4 ± 0.2% |
|
Food Additives / Emulsifiers / Preservatives |
10.1 ± 0.2% |
10.1 ± 0.2% |
10.1 ± 0.2% |
|
Extracts |
No |
No |
2 ± 0.2% |
|
Water |
Balance |
Balance |
Balance |
|
Percent Organic, by weight |
63 ± 2% |
72 ± 2% |
74 ± 2% |
|
EOS® Vitamin B12 Supplement |
No |
No |
Yes |
|
Ingredients / Composition |
EOS® 600 (% by Weight) |
EOS® 600XE (% by Weight) |
|
Soybean Oil (food grade) |
59.8 ± 2% |
59.8 ± 2% |
|
Sodium Lactate / Lactic Acid |
4 ± 0.2% |
4 ± 0.2% |
|
Food Additives / Emulsifiers / Preservatives |
10.1 ± 0.2% |
10.1 ± 0.2% |
|
Extracts |
No |
2 ± 0.2% |
|
Water |
Balance |
Balance |
|
Percent Organic, by weight |
72 ± 2% |
74 ± 2% |
|
EOS® Vitamin B12 Supplement |
No |
Yes |
|
Adjusted to Neutral pH prior to Shipment |
Yes |
Yes |
Note: EOS Remediation reserves the right to change Product specifications and formulations without notice and without liability for such changes.
Innovea Technologies offers project-specific recommendations for EOS Remediation products to meet your bioremediation needs. Contact us for further information and assistance.
EOS® 598B42
EOS® 598B42 is EOS Remediation’s flagship, soybean oil-based product. EOS® 598B42 with the EOS® Vitamin B12 Supplement is the preferred blend for chlorinated solvent remediation. The target market for this product is groundwater impacted with selected heavy metals or a site where the client wishes to maintain anaerobic conditions for many years. EOS® 598B42 is based on patented EOS® Process technology which grew out of more than seven years of research and testing by leading bioremediation scientists and engineers. EOS® 598B42 includes:
• Rapidly biodegradable substrates that jump start bacterial growth
• Slow-release biodegradable substrates to support long-term respiration
• A suite of nutrients for enhancing the growth of halorespiring and other indigenous bacteria
Benefit of B12 for Dehalococcoides ethenogenes
EOS® 598B42 offers added value by providing an optimal diet for the halorespiring bacteria. Several studies have shown that growth of dechlorinating microorganisms may be enhanced by providing these bacteria with amino acids and/or vitamins (Deweerd et al, Appl. Environ. Micro, 1929-1934, 1991; Holliger et al, Arch. Microbiol, 313-321, 1998; Maymo-Gatell et al, Science, 1568-1571, 1997). Consequently, microbiologists often include vitamin B12 and yeast extract to generate conditions for optimum growth (Morse et al, Draft Technical Protocol: A Treatability Test for Evaluating the Potential Applicability of the Reductive Anaerobic Biological In Situ Treatment Technology (RABITT) to Remediate Chloroethenes, ESTCP, http://www.estcp.org/documents/techdocs/Rabitt_Protocol.pdf, 1998).
In January 2005, researchers at Cornell University issued a press release on a bacterium that detoxifies PCE. The news release states that “… the academic and corporate researchers are learning more about Dehalococcoides husbandry. For example, it seems to like a cocktail of acetate, vitamin B12 and extracts of mixed microbial cultures as nutrients.”
http://www.news.cornell.edu/releases/Jan05/Strain195_genome.ws.html .
EOS® 598B42 offers added value by providing an optimal diet for the halorespiring bacteria. Competing products do not include amino acids, trace minerals, B vitamins and the additional B12 supplement found in EOS® 598B42.
Density
The density of concentrated oil emulsions is between 0.96 and 1.00 g/ml and varies as a function of oil content. The figure below shows the specific gravity of EOS® 598B42.
Specific gravity of EOS® 598B42 emulsion diluted with varying amounts of water
Viscosity
Concentrated emulsions can be highly viscous. EOS Remediation’s oil-in-water emulsions are much less viscous than NAPL oils and do not require any special handling equipment. Viscosity in the figure below is presented as the ratio of emulsion viscosity to water viscosity at 20 °C.
Ratio of emulsion kinematic viscosity to water for
EOS® 598B42 emulsion diluted with varying amounts of water
For EOS® 598B42, we typically suggest that the concentrate be diluted 19:1 to 4:1 with water prior to injection (3 to 12% final oil concentration). This ensures the injected emulsion will be between 1.3 and 2.1 times as viscous as water.
Droplet Size
For optimal oil distribution in the subsurface, the emulsion employed should have a uniform, small droplet size and surface characteristics that reduce its potential to flocculate.
EOS Remediation products are engineered to have droplet sizes significantly smaller than most pore spaces, with an effective diameter of approximately 1.0 micron. It is generally reported that pore diameters of silty and clayey sands typically vary between 20 and 100 microns. Both field and laboratory studies show EOS Remediation oil droplets can easily pass through these pores with negligible clogging (Borden et al., 2004; Coulibaly and Borden, 2004). However, using an emulsion with smaller oil droplets would be wasteful, since most bacteria are larger than 1 micron and could not access oil in the smallest pores.
The image on the left shows the emulsified oil substrate manufactured by EOS Remediation with uniformly sized droplets (size bar = 10 micron). The image on the right shows an emulsion at similar magnification that was field processed using a Silverson high shear mixer.
A second important consideration in evaluating an amendment is the transport, dispersion and retention of edible oil emulsions in a wide variety of soil types. This process can be described by colloid transport theory. When the oil droplets are significantly smaller than pore spaces (as with EOS®), oil retention is controlled by the chemical properties of the droplet and soil surfaces.
The interaction between oil droplets also plays an important role in colloidal stability. Recent work by Jain and Demond (2002) indicates that droplet capture and associated permeability loss may also be strongly related to the surface charge characteristics of the oil droplets. Depending on the type of surfactant used in preparing the emulsion and the ionic strength of the groundwater, oil droplets may repel each other or they may stick together (flocculate). If they stick together, they can coat the pore walls forming mats of droplets many layers thick.
The left photomicrograph below shows a pore with many tiny emulsion droplets, much smaller than the pore throat. However, when they clump together forming mats, they can clog very large pores (30-70 µm). The right photomicrograph shows how these mats can break off, migrate downgradient and clog other pores. As a consequence, it is very important to use emulsions that do not clump together.
The Secret of Good Oil Distribution “Emulsions should NOT Flocculate”
The surfactants used in EOS® 598B42 have been tested and chosen so sorption to silts and clay soils in the aquifer sediment is relatively low. Our oil droplets are engineered to have a slight negative surface charge. This negative charge allows the oil droplets to repel each other, while sorbing onto the slightly positively charged aquifer soils. Since most aqueous colloidal systems are stabilized by electrostatic repulsion, the larger the repulsive forces between particles, the less likely they are to flocculate.
Independent test results indicate that:
• Our EOS® 598B42 blend has a zeta potential (the measure of the repulsive forces between particles) of –35 mV.
• The electro-negative charge of EOS® 598B42 will allow the emulsion to remain stable in suspension (i.e. the droplets charge repels one another).
Other emulsion blenders make their emulsions, in part, with lecithin. Lecithin contains functional groups with both positive charges (ammonia groups) and negative charges (phosphate groups). As a consequence, lecithin-based emulsions adsorb very strongly to clays and more substrate is needed to treat the same volume of aquifer. EOS® 598B42 requires less product to do the same job.
EOS® AquaBupH™
EOS® AquaBupH™ is an ideal product for in situ bioremediation of contaminated sites having an acidic pH. By incorporating buffering materials into the proven EOS® patented technology, this revolutionary new patent-pending product addresses the same range of contaminants as EOS®, with the added benefit of immediate and long-term pH adjustment. Additionally, the buffering materials in EOS® AquaBupH™, when diluted with water, are designed for effective distribution across contaminant plumes.
EOS® AquaBupH™ Provides:
• An Easy-to-Use Single Product with
• All the Benefits of the Premier EOS® Technology and
• Long-term pH Adjustment for Acidic Aquifers.
A major consideration associated with any in situ acid neutralization program is maintaining the neutralizing agent in suspension. Many agents generate sludges and/or have large particle sizes that can both cause large permeability losses that effectively grout your aquifer. EOS® AquaBupH™ contains a concentrated, stable, highly reactive aqueous suspension. As with all of our products, EOS® AquaBupH™ is conveniently available in drums, totes or bulk tankers to meet the needs of your individual site. EOS® AquaBupH™ is specifically designed for the critical application of an in situ acid neutralization program. Compared to other chemicals available for aquifer conditioning, EOS® AquaBupH™ offers superior performance in usage, handling, maintenance, storage and safety.
Chemical and Physical Properties
|
Aqueous Suspension |
Typical |
Specification |
|
Soybean Oil (refined and bleached), (by wt) |
40% |
39-41% |
|
Rapidly Biodegradable Soluble Substrates, (by wt) |
4.0% |
3.5-4.5% |
|
Food Additives (Proprietary), (by wt) |
7.2% |
7.0-7.5% |
|
Alkaline Compounds (by wt) |
15% |
14-16% |
|
pH (saturated solution) |
9.0 |
8.5 – 9.5 |
|
Median Particle Size (Micron) |
2.5 |
2 – 4 |
|
Organic Carbon (by wt) |
37% |
36-38% |
|
Biodegradable Organic Substrate (by wt) |
51% |
50 – 52% |
|
Electron Equivalents per Kg AquaBupH™ |
167 |
160-175 |
|
Alkalinity Provided (eq OH- / Kg AquaBupH™) |
5 |
4.5 – 5.5 |
|
Alkalinity Provided (Kg CaCO3 equiv. / Kg AquaBupH™) |
0.25 |
0.22 – 0.28 |
EVO™
Emulsified Vegetable Oil
The use of emulsified vegetable oils (EVO™) for groundwater bioremediation is a significant advancement in the treatment of groundwater contaminated with chlorinated solvents, energetic materials, nitrates, oxidized heavy metals, and radionuclides. The proven EOS® Technology substantially reduces the cost to restore contaminated aquifers.
EOS Remediation uses sustainable green chemistry in its family of groundwater bioremediation products. The addition of emulsified vegetable oils provides food for the microorganisms and stimulates biodegradation activity. The EOS® Technology has successfully turned land once deemed unusable into productive and safe real estate. The company annually completes more than 200 projects worldwide. Since first developed by Dr. Borden in 1999, millions of pounds have been successfully applied at sites throughout the world.
EVO™ Product Specification:
Ingredients / Composition |
EVO™ (% by Weight) |
|
Soybean Oil (food grade) |
45 ± 5% |
|
Fast Release Substrate |
4 ± 0.5% |
|
Food Additives / Emulsifiers / Preservatives |
5 ± 2.5% |
|
Water |
Balance |
Note: EOS Remediation reserves the right to change Product specifications and formulations without notice and without liability for such changes.
VOS™
Thixotropic Gel for Vadose Zone Remediation
The use of a “Thixotropic Gel for Vadose Zone Remediation”, VOS™, is a significant advancement in the treatment of unsaturated soils. The unique thixotropic nature provides the ability of this gel to form a stable oil/water suspension that will remain in place after injection. The substrate will maintain high saturation levels, sequester the contaminants, provide food for microorganisms and stimulate biodegradation activity. Initial results suggest that the VOS™ Technology can cost-effectively turn land once deemed unusable into productive and safe real estate.
Enhanced Aerobic Bioremediation
EOx™ is a scientifically-proven technology for stimulating aerobic bioremediation. The controlled release of oxygen from EOx™ accelerates biodegradation by indigenous aerobic microorganisms. This results in a higher level of sustained bioactivity and increases contaminant removal. When hydrated, EOx™ slowly releases oxygen over an extended period of time to degrade a wide range of organic contaminants (e.g., gasoline, fuel oils, MTBE, creosote, PAHs, PCP, vinyl chloride).
EOx™ Benefits:
• Controlled release of oxygen.
• Long-term source of oxygen (9+ months).
EOx™ Provides:
• Over 16% oxygen by weight.
• More oxygen per $ than other commercially available “advanced” oxygen-releasing compounds.
EOx™ Applications:
• Direct application of EOx™ powder or water slurry in excavations.
• EOx™ and water slurry injection for source treatment or permeable reactive barriers (PRBs).
EOx™ is economical. EOx™, priced at US$4.25 per pound, offers capital cost savings over other commercially available “advanced” oxygen-releasing compounds. By stimulating the bacteria that biodegrade hydrocarbons, your site is restored and ready for redevelopment in less time and with lower corresponding cost than if you used other technologies. Using EOx™ helps nature take the lead.
Specifications
|
Product Properties |
EOx™ Standard Specification |
|
Composition |
CaO2, CaO, Ca(OH)2 |
|
Calcium Peroxide, % by weight |
Min.75 |
|
Available Oxygen, %% by weight |
Min.16.6 |
|
Particle Size Distribution |
Through 200 mesh Min.99 Through 325 mesh Min.50 |
|
Bulk Density, g/L |
500-650 |
|
Moisture, % |
Max. 2.0 |
|
pH Approx. |
10.5 – 12 |
|
Appearance |
White or yellowish powder |
|
Packaging |
Fiber Drum, 110 lbs net contents |
FAQs
Frequently Asked Questions about EOS Remediation products. For more information, Contact us at Innovea Technologies. We have experience with all EOS Remediation products, uses, and considerations.
How does EOS® work?
EOS is engineered for effective distribution in the subsurface. Unlike some competitive products, EOS’ small droplets have a slight negative charge to prevent them from coalescing, simultaneously enhancing sorption onto slightly positively charged aquifer materials. The EOS emulsion is designed to transport through the pore spaces and adhere to the sediment, providing a carbon source that will last for years.
Very simply, anaerobic bacteria required for reductive dechlorination need a food source. EOS provides both quickly available carbon (lactate) and slow-release carbon (soybean oil) with nutrients required for biotic stimulation. In the presence of the available food and nutrients, the anaerobic bacteria “breathe” the chlorinated solvents resulting in harmless waste products and energy for growth.
More specifically, the biotic processes that remediate dissolved halogenated solvents involve a series of oxidation/reduction reactions. Oxidation is the removal of an electron from a compound; reduction is the addition of an electron. EOS, like many additives used for the enhanced reductive dechlorination of hydrophobic chlorinated organic carbons, provides a source of electrons that ultimately benefit halorespiring bacteria. These bacteria require anaerobic conditions to metabolize dissolved chlorinated solvents, which are electron acceptors. Thus, EOS is oxidized, while the chlorinated solvents are sequentially reduced.
The reductive dechlorination process requires the addition of a degradable organic compound, such as EOS, into the aquifer to overcome the continuous electron acceptor supply, such as oxygen, nitrates and sulfates that are naturally present. Electron acceptors can enter the contaminated aquifer from upgradient regions or be delivered into the contaminated aquifer through recharge or gaseous oxygen diffusion from the vadose zone. The degradation process initially makes use of the available dissolved oxygen, followed by the nitrates and then the sulfates. Dechlorination of halogenated organic compounds works best under sulfate-reducing and methanogenic conditions.
The electron donor EOS continues to biotically degrade through a fermentation process, which produces molecular hydrogen. Fermenting bacteria work especially well in anaerobic environments. The bacteria gain energy, which is necessary for life, by splitting the organic compounds in EOS and generating chemically oxidized and reduced compounds.
Finally dechlorinating bacteria, such as Dehalococcoides, derive energy by using the molecular hydrogen as an electron donor and the chlorinated organic compounds as electron acceptors. The microbes substitute the chlorine atoms on the halogenated solvent with the molecular hydrogen in the dehalorespiration process. This results in the sequential chemical reduction of the chlorinated organic compounds eventually yielding harmless byproducts such as ethene and ethane.
Will EOS float on the water table?
Unlike field-prepared emulsions and straight soybean oil and its derivatives, EOS will not float on the water table. EOS is engineered to prevent agglomeration or flocculation of the small oil droplets, allowing the emulsion to spread the designed distance in the subsurface while sorbing to soil surfaces.
Will emulsified oils mobilize contaminants?
EOS adheres to the aquifer sediments very quickly, so contaminants are not mobilized.
Will EOS clog the aquifer?
EOS is engineered to have droplet sizes significantly smaller than most pore spaces. The slight negative charges on the droplets repel the droplets from each other, while sorbing them onto the slightly positively charged aquifer soils.
The Secret of Good Oil Distribution – “Emulsions should NOT Flocculate”
Does emulsification cause the soybean oil to biodegrade too rapidly?
EOS will remain effective in the aquifer for at least three to five years. Emulsification absolutely increases biodegradation rates, which helps explain why EOS is such an effective product. Without emulsification, soybean oil would degrade so slowly that it would not effectively stimulate biodegradation processes.
Do contaminants sorb to oil preventing biodegradation?
EOS treatment results in a small temporary increase in sorption of the contaminants into the oil phase, a clearly beneficial effect. Biodegradation does not occur in the oil, but can retard migration of the contaminant, especially DNAPL. Years of laboratory and field research have proven that, over time, contaminants are eventually released back to aqueous phase as biodegradation proceeds. The contaminants are then more susceptible to degradation in the newly enhanced environment.
How long will EOS last?
Extensive laboratory and field studies have shown that EOS will support anaerobic biodegradation for three to five years depending on the amount of substrate injected and site conditions. In a laboratory column study, Long and Borden (2005) showed that a single injection of emulsified soybean oil can support complete reductive de-chlorination of 10,000 µg/L to PCE to ethene for up to seven years. Field tests of the emulsified oil technology by the Air Force Center for Environmental Excellence (AFCEE) have shown that emulsified edible oils have lasted over three and one-half years at Dover Air Force Base (AFB), over three years at Edwards AFB, and over two and one-half years at Altus AFB. A recent biobarrier project supported by the Environmental Security Technology Certification Program (www.estcp.org/projects/cleanup/200221o.cfm) demonstrated that a single EOS injection lasted over one and one-half years while reducing influent perchlorate concentrations to below detection (over 99.9% reduction) with concurrent reduction of 1,1,1-TCA to non-toxic end-products (Zawtocki et al., 2004). Monitoring is continuing to evaluate the effective life of this barrier.
Based on bench scale and field studies, proper application of EOS should last at least three to five years in the aquifer. As part of the engineering design criteria, you control the life expectancy of the remediation. Your EOS Remediation representative can assist you with designing sufficient substrate life for your project.
Can I use EOS for source control?
Absolutely. For source control applications, EOS is usually injected on a grid spacing or in a series of closely spaced barriers. Depending on the proximity of property boundaries, a recirculation system may be considered.
How do I determine my well spacing?
Field tests have shown that EOS can be distributed large distances in the subsurface from just a few injection points. However, drilling costs are only one part of the total project cost. Using a larger well spacing can increase the total cost by increasing the time (i.e. labor cost) for injection.
The adjacent graph illustrates the effect of drilling costs and injection well-flow rates on the least cost well spacing. When injection rates and drilling costs are low, it is actually less expensive to use closely spaced wells. However, as drilling costs and/or feasible injection rates increase, larger well spacings become more cost effective. For large projects, it is useful to generate cost estimates for several different well spacings to find the least cost alternative. A site-specific analysis should consider the available water supply, access restrictions, continuous versus intermittent injection, labor and drilling costs, etc.
How do you inject EOS?
EOS, a low-viscosity fluid, requires no specialized material handling or pumping equipment. It is designed to migrate out into the aquifer away from the injection point at ambient temperature and low pressure. The ability to emplace the material into the aquifer at a considerable distance from the injection point is a major benefit of EOS.
EOS is delivered to a site in 55-gallon drums, totes or in bulk as a concentrate and must be diluted with a ratio of at least four parts of water to one part of EOS before injection. Based on your specific design, either a “water chase” or an initial dilution ratio of 10:1 can be used for injection purposes. Both methods are equally effective and each has its advantages. The key consideration is to provide the correct amount of EOS throughout the treatment zone.
A benefit of using EOS at your site is employing your choice of injection methods. Our experience has shown that where direct push technology can be used, installation of micro wells (¾ to 1-inch PVC wells) can be very cost effective option. However, micro wells are neither better nor worse than conventionally installed wells. If multiple technologies are appropriate, cost factors normally determine the conveyance choice.
There are a variety of injection techniques, including injecting multiple wells simultaneously, to reduce injection costs. EOS can be diluted in a holding tank and then injected or can be injected using a Dosatron. The Dosatron eliminates tank mixing and reduces injection labor costs. Your EOS Remediation representative can help recommend suitable injection methods.
Do we need to chase EOS with water?
EOS is designed to be easily emplaced throughout the aquifer treatment zone. We have found that using chase water reduces labor costs. Increasing the dilution rate of the concentrate has the same effect as water chase. Instead of diluting the concentrate 4:1 with water and using a water chase, you could simply increase the dilution with no follow-up water chase. By using chase water, the system can be automated to deliver potable water into the subsurface. A low-pressure feed of potable water does not require onsite supervision; an injected dilute emulsion, however, should be monitored. Either method meets the design requirement.
Can EOS be used in a recirculation system?
There are numerous sites where recirculation has been used during the injection of EOS Recirculation during injection offers the advantages of providing an on-site water supply and increasing groundwater flow gradients to draw EOS through the aquifer.
Have regulators accepted EOS?
Yes. EOS is a natural, food-grade substrate that stimulates biodegradation.
Have regulators disallowed the use of any EOS products?
No.
How do you prevent migration of EOS outside (downgradient) of the intended remediation area?
We have found that EOS does not migrate a significant distance away from the injection point. Once the injection process stops, the driving force ceases. EOS, by design, sorbs to the aquifer materials and does not continue to migrate with groundwater. Downgradient monitoring using visual indicators combined with low injection pressures can be used to evaluate how far EOS has moved through the aquifer. Recirculation is another way to provide hydraulic control during injection or to move EOS in a particular direction or distance in the subsurface.
What groundwater parameters should we monitor after injection?
Your monitoring program may be specified for your site by the regulatory agency with site jurisdiction. At a minimum, your monitoring program should incorporate the contaminants of concern and reduction-oxidation (REDOX) potential. Field parameters of pH, conductivity and dissolved oxygen are also recommended. Apparent turbidity, observed as a faint white tint, can sometimes be used as a visual indicator of EOS presence.
A more detailed monitoring program could include additional metals such as iron, manganese, arsenic, total organic carbon, light hydrocarbon gases (methane, ethane, ethene) and possibly volatile fatty acids. Increasingly complex sites could also monitor for phospholipids fatty acids and Dehalococcoides.
How do you measure the presence of EOS in the aquifer?
The most obvious method is to visually examine a sample of groundwater. If EOS is present, the sample will have a light whitish cast to milky appearance. If the concentration of EOS is low and not discernible visually, then laboratory tests measuring total organic carbon or volatile fatty acids can be used.
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