Frequently Asked Questions

How is emulsified vegetable oil (EVO) applied as an electron donor? Newman Zone® EVO products have a viscosity similar to water when diluted to a concentration of 1% to 5% oil by volume.  Any injection method that effectively distributes water in the subsurface will also distribute diluted Newman Zone®.  Newman Zone® is a vegetable oil-in-water emulsion with oil droplets that range from 0.15 microns to 0.6 microns.  The small droplet size makes the emulsion kinetically stable (no oil/water separation) and allows oil droplets to move through soils without blocking soil pore throats.  As oil droplets are retained on soil surfaces, the vegetable oil slowly ferments to produce molecular hydrogen and volatile fatty acids such as acetic acid. Will the injection of Newman Zone® EVO products mobilize contaminants? Although we have seen increases of dissolved phase contaminants has great as an order magnitude within an injection zone, we have never seen migration of oil and contaminants out of the injection area (Newman and Pelle, 2006).  Contaminant displacement during injection or recirculation of large volumes of dilute emulsion should be considered in the site specific injection plan.  In general we have observed the initial spike in dissolved contaminant concentrations from NAPL or solvents adsorbed to soils to stimulate reductive dechlorination in the source area. Will the injection of Newman Zone® EVO products result in contaminant removal by partitioning? Although it is possible to see an initial drop in dissolved organic contaminants due to portioning into the vegetable oil phase we rarely observe this as a major removal mechanism where significant contaminant concentrations are present.  When contaminant free water such as potable water is used to deliver large volumes of Newman Zone® EVO we often see a sudden drop of contaminants as a result of both dilution and oil/water partitioning.  But dissolved concentrations usually rapidly return to their baseline levels soon after injection.  As an example, removal of chlorinated solvents by partitioning and dilution usually results in the sudden removal of all contaminants from the dissolved phase.  In contrast, reductive dechlorination produced from EVO injection continues for weeks, months or even years as reflected by a generally decreasing concentration of the parent compounds and a sequential increase in the concentration of series of daughter products which are, in turn, degraded to inert substances (cf. CE-TCE-DCE-VC-ethene). Will Newman Zone® EVO products float on the water table or migrate upward through the aquifer? As long as the stabilizing surfactants are present the sub-micron droplets in Newman Zone® produce an EVO suspension that when diluted has the same density as water and a uniform stable droplet size.  Unlike field emulsions where large droplets can coalesce into ever larger droplets until they float and eventually separate into free phase oil (creaming) Newman Zone® will remain stable until it comes under microbial attack.  We have never observed oil water separation in wells or upward migration in the subsurface.  Oil droplets are initially retained by adsorption onto soil particles, and once microbes degrade the stability of the emulsion, oil films or larger droplets appear to be strongly retained in the soils with no further migration. How do we measure the presence of EVO in soils in the subsurface? Even when diluted to low concentrations, Newman Zone® products have a milky white appearance and are easily visible in ground water (see turbidity information).  An easy way to make rough qualitative measurements of oil content in the field is by measuring turbidity (serial dilutions may be required).  Other total organic matter lab methods such as total organic carbon (TOC) or chemical oxygen demand (COD) can also be used.  After oil droplets have been retained in the subsurface soils, indirect methods that measure reduced conditions in the subsurface such as oxidation reduction potential ORP or fermentation products such as volatile fatty acid (VFAs) or TOC can be used to confirm that oils is still present and active. RNAS has US Patent Number 6,806,078 and international patents that cover the production and use of EVO.  Does that mean that we can’t use field emulsions or use a competitor’s EVO product? RNAS is not aware of any enforceable third party intellectual property that would limit the general use of vegetable oil emulsions for bioremediation.  The use of innocuous oils for remediation dates back to the 1970s and the use of vegetable oil emulsions for bioremediation was first discussed in the early 1990s.  Although improvement patents (see EVO patents) have issued on the basic concept of using oil-in-water emulsions for bioremediation there are no US or international patents that would prevent the use of Newman Zone® or our competitors emulsion products for bioremediation.  The RNAS patents describe our unique process of emulsification and pasteurization that produces a better quality EVO product.  We encourage our customers to compare our prices and product quality to that of our competitors so they know they are getting a good value.

Is Newman Zone® EVO a microemulsion? The term microemulsion was established by chemists in the 1940s and 1950s to describe a unique class of emulsions with unusual properties including (1) they are thermodynamically stable and form from oil, water, and surfactant spontaneously without shear mixing (2) they are optically transparent and consist of oil droplets or micelles that are well under 0.1 microns in size, often as small as 0.01 microns (3) there are no discernible separate oil and water phases – the micelles are so small the suspension appears to be a single phase, more like a solution than a suspension of oil droplets in water(link to microemulsion paper).  Newman Zone® EVO products have none of these properties.  Our products contain very small oil droplets but all of them are larger than 0.15 microns.  Newman Zone® oil-in-water emulsions are opaque and milky white even at relatively low concentrations.  Manufacture of Newman Zone® requires a tremendous amount of high shear mixing force as described in US patent 6,806,078. Does the injection of Newman Zone® EVO products reduce permeability in the saturated soils? By using oil-in-water emulsions with oil droplets between 0.15 microns and 0.6 microns, droplet capture by straining is reduced and blockage of soil pores is largely eliminated.  This keeps the initial emulsion injection from reducing soil permeability.  However, the desired growth of biomass in the biologically active zones associated with EVO injection may result in some reduction of permeability. How long will Newman Zone® EVO products remain active after injection? Electron donor longevity depends on a number of factors including water temperature, pH, and the presence of competing electron acceptors such as sulfate.  The first injection of Newman Zone® at a relatively high concentration of 5% oil by volume showed peak activity three years after injection with some reduction in activity in years four and five (Newman, et al., 2005).  Water temperature was 27 degrees Celsius so the longevity could have been much longer in colder water.  At low doses at sites with fast ground water flow or high levels of sulfate we have seen longevity of as little as one or two years, for sites with minimal ground water flux, cold water and a relatively low concentration of competing electron acceptors a longevity of greater than five years may be possible. How do you inject Newman Zone® EVO products? Newman Zone® can be applied with any method that will inject or recirculate water.  Direct push points, temporary injection wells or active recirculation systems have all been used to effectively distribute EVO in the subsurface.  Oil retention can be much higher in fine grained soils than sandy soils which can limit the length of the flow path.  As a general rule of thumb if you can move the EVO from the point of injection to the point of delivery within few days to a couple of weeks it will be possible to transport emulsion ten to fifty meters in fractured rock or sandy soils.  The initial strong retention of oil on silt and clay particle surfaces and limited injection velocities normally limits practical flow paths such soils to a few meters. Is injection of chase water needed with Newman Zone® EVO products? Good EVO distribution in the subsurface is best achieved by injecting large volumes of diluted emulsion whenever practical.  We prefer to inject emulsion at the desired concentration as a continuous injection and limit the clean water chase to flushing EVO from the injection equipment, and well screens and sand-packs.  This keeps biofouling and equipment cleanup to a minimum.  Injection of concentrated emulsion followed by a water chase can be used to distribute emulsion in the subsurface but we feel it is more likely to result in preferential flow paths and uneven distribution.  RNAS provides rental injection systems to make dilution and continuous injection of dilute emulsion into multiple well points easy (RNAS Rental Equipment). Is the injection of Newman Zone® EVO products broadly accepted by regulatory authorities? All ingredients in Newman Zone® products are food grade and nontoxic.  Newman Zone® is produced with food processing equipment using food industry best practices for sanitation and cleanliness.  Unlike competitors products, our emulsion is pasteurized and packed in clean food grade packaging to eliminate product spoilage or microbial product contamination even in our pH neutral products.  Newman Zone® has been injected in dozens of states in the US as well as used in many international projects without any significant regulatory concerns.  Newman Zone® products and those of our competitors who manufacture in the US use soybean oil for their EVO products.  In the US 80% or more of the soybeans are genetically modified (GMO).  Unless you pay roughly twice the market price for an “identity preserved” (IP) non-GMO soybean oil, you should assume that any emulsion made in the US is likely to have some GMO crop content.  Some of our clients in Europe have expressed concerns about GMO content.  For this reason we now offer non-GMO soybean oil or rapeseed oil Newman Zone® products manufactured in Europe.