Frequently Asked Questions About Bioremediation of Contaminated Soils, Sediments and Groundwater  

Health and Safety

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.

General Technology

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 Information

1. 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.

O-Sox Information

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, dioxane, 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.

A-Sox Information

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?

For more information about remediation of soil, sediment and groundwater contamination, please contact Adventus Group.