Frequently Asked Questions About Bioremediation of Contaminated Soils, Sediments and Groundwater
1. Are there any special health and safety concerns associated with application, handling or disposal of your products?
Adventus products are all natural and completely innocuous, which facilitates the safe handling of environmentally attuned materials that are easy to apply. There are no bulky or hazardous material disposal issues. Safety is an integral part of Adventus’ philosophy and work day. We believe that safety is best achieved using a proactive approach which begins with training. All of our approved remediation contractors are required to receive and maintain certain fundamental training courses, which includes HAZWOPER and OSHA training, plus annual refresher courses.
1. What is the core scientific basis behind your technology innovations?
The patented combination of controlled-release organic carbon plus ZVI uniquely yields In Situ Chemical Reduction (ISCR™) conditions inherent to very low redox (Eh) conditions (e.g.-550 mV). This gives EHC® and DARAMEND® powerful technical advantages over other materials that provide only carbon (i.e. emulsified oils, molasses or lactate-based substrates), or only ZVI.
2. Is pH buffering important?
Yes. The engineered pH buffering capacity of our products is another key differentiator. Different Adventus products are designed to release alkalinity, acidity, or to maintain a neutral pH. In contrast, the addition of conventional organic substrates only (e.g., emulsified oils, molasses or lactate-based materials) to promote COI biodegradation can lead to aquifer acidification. Result? More costs, uncertainty, delays, and client dissatisfaction.
3. Does your technology facilitate Natural Attenuation processes?
Yes. EHC® and DARAMEND® enhance the natural reductive dechlorination and other biological processes that occur under hypoxic conditions. Other technologies may offer short term COI reduction via sorption reactions, et cetera, but many are known to alter the environmental conditions such that natural attenuation mechanisms are adversely influenced.
4. Do you produce dead-end intermediates?
No. Terminal COI destruction occurs via the unique combination of physiochemical (i.e., ZVI reactions) and microbiological removal mechanisms. As such, COIs are rapidly and completely removed without the accumulation of potentially problematic catabolites, such as cis-DCE from TCE; DNT from TNT; chloroform (CF) from carbon tetrachloride (CT).
5. Is there product longevity in the field? What about rebound?
Depending on their site-specific formulations, EHC® and DARAMEND® products will remain present and active in the environmental for 12 months (fast release formulations) to >60 months (slow release formulations), hence COI rebound phenomena are not observed. Rebound is quite common when using readily biodegradable, liquid substrates.
6. Are specialty microorganisms or inoculants required?
ISCR is the combined effect of chemical and biological oxygen scavenging which facilitates rapid oxygen consumption and establishment of reduced Eh. Generation of significantly lowered reducing conditions usually eliminates any requirement for specialty microorganisms or inoculants. However, in some cases, the addition of Dehalococcoides inocula such as KB-1™ in combination with the EHC® ISCR amendments, may assist in decreasing microbial acclimatization time, and KB-1 plus EHC has proven to be useful in accelerating site remediation. However, our experience suggests that the same end points will ultimately be realized without inoculum addition.
7. Is field performance predictable?
Yes. EHC® and DARAMEND® employ uniquely integrated chemical and microbiological degradation processes which allow treatment to proceed at an accurately predictable rate.
8. How wide is the applicability of your products to the various organic and inorganic contaminants that potentially exist?
Adventus products have been proven to be effective on a wide range of organic COIs, particularly the more recalcitrant and persistent compounds, such as highly chlorinated solvents, herbicides, pesticides and Freons. In addition, our EHC® and Daramend®, ISCR™ reagents are very effective for nitrogenous energetic compounds, perchlorate and heavy metals (such as arsenic, chromium, lead, mercury, etc.)
Standard Injection Information1. Does your groundwater remediation process result in mobilization of the COIs?
No. Using optimal volumes of EHC® slurry during injection, there is no need for extensive water flushing, which precludes potential mobilization issues
2. Can we use standard Geoprobe® rods and injection tools?
Yes. Various injection tips are commercially available for injecting slurried product into sand, gravel, silt and clay aquifers.
3. “Top-down” vs. “Bottom-up” injection?
Top-down generally preferred, although bottom-up can be equally effective, provided that the target vertical zone does not exceed 3 m in thickness.
4. Which pump to use?
Conventional pumps capable of 250 psi or greater, such as the GS2000 which comes with the Geoprobe® are usually adequate.
5. What is the concentration of the slurry that must be injected?
20 to 30% solids.
6. What is the expected injection flow rate?
It depends on the site. Typically, around 5 gpm can be achieved in medium to fine sand environment.
1. What are the main differences between O-Sox and comparable market alternatives?
EHC-O O-Sox contain a well-buffered source of controlled release oxygen plus inorganic nutrients (mainly nitrogen) that can accelerate the biodegradation of various organic compounds and enhance certain natural attenuation processes. In addition, the O-Sox technology is a superbly well designed stainless steel canister and sleeve system which greatly simplifies installation, removal and replacement.
2. Do I need microbial inoculants?
In most cases, the naturally occurring (indigenous) microorganisms are well adapted to the organic constituents of interest and inoculants are not required.
3. What contaminants are amenable to O-Sox treatment?
The rate and extent of removal of all organic compounds that are biodegraded under aerobic conditions are usually enhanced via the addition of oxygen and inorganic nutrients. Petroleum-based aromatic (e.g., benzene, toluene, xylene, phenol) and aliphatic hydrocarbon mixtures (e.g., gasoline, heating oil, Diesel fuel, jet fuel, kerosene) are primarily targets; lightly chlorinated ethenes (vinyl chloride), MTBE, pentachlorophenol, and many other compounds are also potentially amenable to O-Sox treatment.
4. How much do they cost?
O-Sox cost about 25% less than market alternatives.
5. Why should I use the O-Sox technology?
It’s a better product. And the superior design and ease of application will immediately translate into greatly reduced field time and frustration = reduced project cost.
6. Is it easy to switch over to the O-Sox technology?
Yes. EHC-O has been accepted by many state regulatory authorities and it has been employed throughout the USA and Europe. For example, see: EHC Acceptance Letter - Innovative Technologies Florida Department of Environmental Protection.
7. How long do they last?
O-Sox are typically replaced every 3 to 6 months. Various site-specific factors will influence the effective lifetime of the O-Sox cartridge; mainly i) constituent type and concentration, and ii) hydrogeological features (groundwater flow rate, Eh, pH, temperature).
8. Do I need to install new wells?
No. The O-Sox technology is designed to fit into standard 2-inch and 4-inch diameter groundwater monitoring wells. The canisters have a nominal outside diameter of 1.75 inches for the 2-inch size and 3.5-inches for the 4-inch size.
9. What is the oxygen delivery rate?
The rated delivery is at least 15 lb of oxygen per 100 lb of EHC-O, after 200 days.
10. How many O-Sox can be used per well?
All O-Sox must be placed below the groundwater table and they should be within the screened interval. The wet weight of each 2-inch and 4-inch O-Sox unit (3-ft long canister and sleeve) is about 5 and 16 lbs, respectively. We therefore recommend a maximum linkage of five 2-inch diameter systems (15 ft screened interval; 25 lbs) or three 4-inch diameter systems (9 ft screened interval; 48 lbs). Up to three sets of linked O-Sox units can be used for wells with longer screen lengths.
1. What are the main application scenarios for
A-SOX?
The A-SOX systems are most conducive to physically
challenging situations where a readily biodegradable
carbon source and reduced iron are needed to induce
in-situ chemical reductions (ISCR) of targeted compounds.
For example, A-SOX can be used in deep well settings,
PRBs that require routine amendment, and strategic
placement into “problem” well locations.
2. What contaminants are amenable to A-SOX treatment?
Chlorinated solvents, chlorinated pesticides, and
energetics are the primary targets.
3. How much do they cost?
2-inch A-SOX cost $120 and 4-inch A-SOX cost $160.
Volume discounts may apply.
4. Why should I use the A-SOX technology?
It’s simply the best product of its type on
the market, and the superior design plus ease of application
will immediately translate into greatly reduced field
time and frustration = reduced project costs.
5. Is it easy to switch over to the A-SOX technology?
Yes. EHC-A has been accepted by numerous state regulatory
authorities, and has been employed throughout the USA
and Europe.
6. How long do they last?
A-SOX have longevity of approximately 250 days, but
replacement on a longer or shorter schedule can be
optimized based on monitoring results. Various site-specific
factors will influence the effective lifetime of the
A-SOX cartridge; mainly i) constituent type and concentration,
and ii) hydro-geological features (groundwater flow
rate, Eh, pH, temperature).
7. Do I need to install new wells?
No. The A-Sox technology is designed to fit into standard
2-inch and 4-inch diameter groundwater monitoring wells.
The canisters have a nominal outside diameter of 1.75
inches for the 2-inch size and 3.5-inches for the 4-inch
size.
8. Where are they primarily used?
The EHC A-SOX can be used in existing or newly-installed
wells, either in natural or forced gradient flow systems.
For example, existing hotspot wells can be treated,
or deep, dilute, or fractured system plumes can be
treated by A-SOX placed within the capture zone of
a groundwater recirculation well or other forced gradient
system.
Q1.What is the shelf life of the product and can it be used after 10 years of storage in a warehouse?
A1. Shelf life is essentially indefinite if the product is kept dry. Although we have never used DARAMEND that has been stored for such a long time, we believe that even after a long storage period the product would perform normally. For practical purposes, we recommend a maximum 3 year storage under cool, dry conditions.
Q2. Is the technology universal or does it need adjustments for each pollutant?
A2. The DARAMEND with ZVI technology does not require adjustment for each pollutant. It is suitable for most reductively treated compounds in its standard mode of application; however, a different formulation is used when the treatment objective is for stabilization of heavy metals. The Aerobic DARAMEND and TERRAMEND technologies are suited to the treatment of petroleum hydrocarbons and wood preservatives. For a list of compounds treated by product type, see http://www.adventusgroup.com/solutions/compounds-treated.shtml
Q3. Can the technology be used for polluted soil and water with more pollutants?
A3. Yes, we have re-formulated the DARAMEND product for groundwater injection applications. This product is called EHC® and is designed to enhance and promote reducing conditions for treatment of many chlorinated organic contaminants as well as heavy metals. For compounds requiring aerobic treatment in groundwater, we have developed EHC-O®; a proprietary oxygen release compound with nutrients and buffering agents.
Q4. What soil characteristics are required to use the technology?
A4. All true soils can be treated with this technology. DARAMEND has been successfully applied to soils with a wide range of physical and chemical properties, including wide variation in soil texture (i.e., sand/silt/clay content), organic matter content, and pH.
Q5. How is water delivered / supplied if the contaminated sites are far away from a water resource?
A5. Many methods may be used, including spray irrigation systems with sprinklers and the addition of water using tanker trucks. If water is particularly scarce, it may be useful to cover the soil to limit evaporation.
Q6. How to treat pure pesticide waste when applying this technology?
A6. DARAMEND is a soil treatment technology, most appropriate for treatment of large volumes of lightly to moderately contaminated soil, sediment, or other solid materials. Concentrations of common chlorinated pesticides up to about 10,000 mg/kg can be successfully treated, subject to the remedial standard that must be achieved. In most cases DARAMEND is not well-suited to treatment of pure pesticide wastes.
Q7. Is phytoremediation required after the application of the Daramend technology? If yes, what are the conditions of applications and the final objectives and time frames?
A7. Phytoremediation is not generally required following DARAMEND treatment. We have conducted toxicity testing on soils that have been remediated with DARAMEND and found that seed germination was equivalent to that observed in soil with no history of contamination (see: Tables 3 and 4 in: http://www.epa.gov/nrmrl/lrpcd/site/reports/540r95536/540r95536a.pdf).
Q8. What is the percentage of detoxification in nature for organic pesticides especially for DDT and DDE?
A8. The degree of treatment depends on the starting concentrations and treatment goals. In general, overall removal rates up to about 95% can be achieved for most soil/contaminant combinations. Depending on concentrations and goals, removal rates much higher than 95% are more difficult and may not be economically achievable.
Q9. Can Daramend be used for a whole broad spectrum of all kind of pesticides? What if contaminated by fertilizers or herbicides?
A9. The pesticides we have the most confidence/experience in treating are listed here - http://www.adventusgroup.com/solutions/compounds-treated.shtml. However, we are certainly able to treat more compounds than this. Please inquire regarding specific compounds of interest. Fertilizers and many herbicides are easier to treat than the more recalcitrant organochlorine pesticides (OCPs) that DARAMEND treats so effectively.
Q10. Is your technology efficient for the treatment of DDT?
A10. Yes; performance data from another site where soils contained DDT is available at: http://www.adventusgroup.com/projects/daramend/th_agri_nutrition_site.shtml .
Q11. Is the technology only applicable on flat arable land? Is it also applicable on slopes?
A11. One of the keys to application of the technology is achieving very good soil mixing. If the soil can be adequately mixed and properly moistened on a slope without soil erosion, then the treatment can be applied at that site. Alternative designs have entailed physical transport of soils to temporary treatment facilities / pads. Multiple pads can be established, as needed.
Q12. Till what depth will the technology work? If only the topsoil is treated, what do you do with the soil, for example contaminated soil at 2m below ground level?
A12. Deeper soil can be treated either in-situ, with deep soil mixing equipment, or excavated and treated ex-situ, in batches.
Q13. What are the minimum and maximum contamination levels that can be treated?
A13. In general, all forms of bioremediation are most appropriate for treatment of lightly to moderately contaminated soils. Concentrations of common chlorinated pesticides and herbicides up to about 10,000 mg/kg can be successfully treated, subject to the remedial standard that must be achieved. If you provide some sample site data via the online template at http://www.adventusgroup.com/dara_site_eval.shtml we can confirm (non) treatability.
Q14. Is it necessary to know the type of contamination before treatment? i.e. organochlorines, carbamates and others ? If yes, does your technology require testing in advance for that?
A14. Yes, we need to know the type and concentration of contaminant present in order to ensure that the proper DARAMEND treatment approach is employed.
Q15. Are there contaminants that may be present at a site that could pose a threat to the success of the technology? E.g. certain herbicides, high levels of heavy metals or other factors/contaminants?
A15. Highly acid or alkaline soils will need to have the pH adjusted prior to treatment. High arsenic and cyanide levels may also prove problematic.
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