Bioremediation of pesticides adventus

Bioremediation of Pesticides

Introduction

This document summarizes Adventus experience treating organochlorine pesticides (OCPs) in soil and groundwater using DARAMEND® and EHC™ bioremediation amendments. Adventus has offered DARAMEND for ex situ treatment of recalcitrant compounds in soil for more than 10 years. DARAMEND has also shown to be effective for in situ applications. As OCPs bind strongly to the soil, the impacts are often limited to the upper couple of feet and regular agricultural equipment could be used for in situ application of the DARAMEND amendments. Variations of these materials have also been found effective for in situ treatment of OCPs in groundwater. EHC and DARAMEND are also effective for treatment of a number of other inorganic and organic compounds and could hence be used for mixed impacts. In addition, formulations of these compounds are available for simultaneous immobilization of heavy metals such as arsenic, chromium and lead.

DARAMEND for OCPs in Soil

DARAMEND is an advanced biological treatment technology for soil, sediment and solid wastes contaminated with recalcitrant organic compounds. DARAMEND has been successfully applied to more than 2,000,000 tons of soil, sediment, and other materials contaminated with persistent compounds including polynuclear aromatic hydrocarbons (PAHs), PCP, phthalates, chlorinated herbicides and pesticides, organic explosive compounds and wood preservatives at a variety of industrial and Department of Defense (DOD) sites in the United States, Canada, and Europe. Given our excellent record of performance, Adventus is willing to guarantee the remedial performance of our technology.

The key components of DARAMEND bioremediation technology are (i) amendment of the material to be remediated with DARAMEND organic amendments, and (ii) regulation of oxygen availability and moisture content by mechanical tillage and irrigation, respectively. The treatment schedule and the exact formula of the DARAMEND amendments vary depending on the compound to be treated. For OCPs, an approach with cycled anaerobic and aerobic conditions have been found to be the most effective and the DARAMEND amendments are comprised of organic material, and reduced iron and/or reduced zinc. The organic fraction is derived from natural plant fibers rich in cellulose and hemicellulose, and therefore serves as a carbon source for microbiological consumption. DARAMEND also provides major, minor and micro nutrients required for rapid microbial growth. DARAMEND bioremediation enhances and promotes natural bioremediation rates by adjusting conditions in a soil matrix to stimulate biodegradation of target compounds. No microbial inoculation is conducted. The amendments will be manufactured regionally (Illinois or Iowa) using a proprietary process.

Ex Situ Applications

Traditionally, DARAMEND has been applied to excavated soil in on-site biotreatment cells. Adventus recently completed the full-scale remediation of a pesticide impacted superfund site in Montgomery, Alabama. At this site Toxaphene, DDT, DDD, and DDE were remediated in a land treatment cell over an average of 8 treatment cycles. The results from this project as well as a few other pesticide projects recently completed using DARAMEND bioremediation are highlighted in Table 1 and Appendix A.

Figure 1: Placement of soil into treatment cell.

Adventus Group Brasil - www.AdventusGroup.com.br - Av. Paulista, nº 37 - 4º andarCEP 01311-902 Phone: (55 11) 2246 2759 / Fax: (55 11) 2246 2799

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Table 1: Influence of DARAMEND bioremediation on OCPs in soils at sites in the USA and Canada.

Site Compound Concentration (mg/kg) Treatment Period Initial Final

Uniroyal Chemical, Ontario, Canada

2,4-D 97 3.8 9 months 2,4,5-T 8.1 1.3

DDT 53.5 4.7 CIBA-Giegy, Ontario, Canada

Metolachlor 72 <1 10 months Atrazine 15 <1.5 W.R. Grace, South Carolina, USA

Toxaphene 239 5.1 4 months DDT 89 16.5

THAN Superfund Site, Alabama, USA

Toxaphene 189 11

10 months DDT 84 9 DDD 180 52 DDE 25 6

ATOFINA Chemicals Kentucky, USA

a-HCH 7,647 446

99 days b-HCH 1,200 373 Lindane 567 14 d-HCH 747 57 HCB 10.9 1.3

In Situ Treatment of OCPs in Soil

DARAMEND bioremediation can also be effectively applied in situ as a land treatment process. Soil and amendments are blended using a rotary tiller, driven by an agricultural tractor, with an effective penetration of 2 ft. Deeper soil impacts may be treated in situ using deep soil mixing equipment or by applying the treatment in lifts. Depending on the cost of excavation and the depth of contamination this may be more cost effective than ex-situ treatment. Water content is one critical process parameter and is adjusted using agricultural irrigation equipment. The results from a couple of in situ projects are provided in Table 2.

Figure 2: Application of DARAMEND. Figure 3: Irrigation to add moisture.


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Table 2: Influence of DARAMEND bioremediation applied in situ.

Site Compound Concentration (mg/kg) Treatment Period Initial Final Agricultural Site,Florida, USA Dieldrin 45.9 15.1 2 weeks

Future Residential Development Site, CA (confidential)

DDT 2.0 0.33 3 weeks DDE 3.1 0.7

DDD 0.07 0.025

EHC for OCPs in Groundwater

EHC is a patented combination of controlled-release carbon and zero-valent iron (ZVI) particles used for stimulating reductive dechlorination of otherwise persistent organic compounds in groundwater. EHC uses the same basic chemistry as DARAMEND, but is specifically formulated for easy injection into the subsurface. EHC is provided in 50-lb bags as a dry powder and mixed with water on site into a slurry. The slurry is injected into the subsurface using a number of available technologies, including direct injection through GeoProbe rods and hydraulic/pneumatic fracturing. EHC slurry may also be applied via direct application into trenches or by using deep soil mixing equipment. Common applications include hot-spot treatment, plume treatment and plume management using a permeable reactive barrier.

Relevant Treatment Performance

EHC has been evaluated at both bench and field scale for treatment of various OCPs in groundwater (Table 3). Please note that the results refer to a single application of EHC and the treatment time refers to the elapsed time post application. More detailed information is provided for a couple of the projects in Appendix B.


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Table 3: Influence of EHC bioremediation on OCPs in groundwater/saturated soils at sites in the USA.

Site Compound

Concentration

Treatment Period Initial / Control

Final / LatestData

Pilot-Scale PRB,Pesticide Manufacturing Facility, California, USA

Dibromochloropropane [ug/L] 1.5 0.26

Still ongoing - 5 months

Ethylene dibromide [ug/L] 1.5 0.5

Nitrate-nitrogen[mg/L] 240 20

Plume Treatment using 3 Reactive Zones, Former Pesticide Manufacturing Facility, SE USA

Endrin [ug/L] 20.5 0.6 Batch study

(detects) – 4 days pp'-DDD [ug/L] 1.3 ND pp'-DDT [ug/L] 11.9 ND

Endrin Ketone [ug/L] 1.4 ND Total BHCs [ug/L] 1.1 0.51 Field data (mean

conc.) - 6 months Dieldrin [ug/L] 0.60 0.19 Endrin [ug/L] 0.58 0.36 Total BHCs+

Dieldrin+Endrin [ug/L] 2.3 1.1 Field data (mean conc.) - 10 months

Hot-Spot Treatment, Former Pesticide Manufacturing Facility, SE USA

Toxaphene [mg/kg] 127.7 8.7 Mean conc. in saturated soil – 8 months Total OCPs [mg/kg] 169.1 11.8


APPENDIX A

DARAMEND FOR OCPs CASE STUDIES

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Field Pro�le DARAMEND ®

Project Future Residential Development Site, Canada Con�dential Client Summary A future residential development was to be built on land that had concentrations of organochlorinated pesticides such as DDT and DDE that exceeded the governmental residential use guidelines. As a much less expensive and environmentally friendly solution compared to hauling and disposing of the soil, the developer contracted Adventus to provide turn-key bioremediation of the soil. To provide poof-of-concept, a two-acre pilot project was initiated. Within a period of three weeks, Adventus was able to meet the soil treatment goals using its patented DARAMEND technology. The cost of the pilot project was approximately US $40,400 per acre. Full-scale remediation of over 30 acres of land is planned for 2007, at a projected cost of US $29,900 to $32,100 per acre. The Challenge

A former agricultural site (Fig. 2 ) was being converted to residential use; however, the soil contained pesticide concentrations that exceeded the governmental guidelines for residential use. Application of pesticides over many decades to the apple trees and strawberries resulted in this contamination. A total of approximately 34 acres of land exceeded the guidelines on this 300-acre site. The impacted areas were divided into ten �elds spread across the site. A number of ponds are on site, which had been previously used for irrigation purposes. Digging and disposing of the soil would have been much more expensive to implement. A more cost-e�ective and environmentally-friendly solution was preferable.

Figure 2: Former apple orchard.

Figure 1: Breaking ground on DARAMEND soil bioreme diation.


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Field Pro�le

Lab-Scale Validation and Performance Warranty A bench-scale study was �rst performed using a soil sample to ensure the technology was going to be e�ective at the site. The study was successful, and this enabled Adventus to provide a performance warranty for the pilot work. With the exception of a mobilization fee, no payment would be required if the soils did not meet the treatment goals. Adventus is able to o�er such a strong warranty because of con�dence in the technology from past projects and experience with the site soil. Field Work DARAMEND treatment of organochlorine pesticides such as DDT, DDE, DDD, Dieldrin, Toxaphene, Chlordane, and many others requires a treatment approach where the soil is cycled between reducing conditions and aerobic conditions. The DARAMEND amendment ( Fig. 3 ), which in this case was a combination of controlled-release carbon and zero-valent iron, was spread onto the soil and incorporated using deep rotary tillers (Fig. 4 & 5 ).

Once incorporated into the soil, water is added to achieve the desired moisture content. This step initiates the reductive phase of the treatment. Native microorganisms in the soil utilize the carbon and nutrients provided by the DARAMEND to drive the oxidation reduction potential (ORP) down. Corrosion of the iron, as intended, further reduces the ORP. This combination of processes creates an environment where chlorine atoms are removed from the pesticides. After the reductive phase, the soil is tilled again to dry out the soil to a lower moisture content and introduce oxygen into the soil. This allows further breakdown of the organic pesticides and prepares the soil for further treatment cycles if necessary. In this case, only one treatment cycle was required.

Figure 3: DARAMEND 1-ton bag. Figure 4: Deep rotary tiller attached to tractor.

Figure 5: Deep rotary tiller working soil.


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Field Pro�le

The Result The results of the treatment are summarized in Table 1 for DDT, DDE, and DDD. The removal e�ciencies were 83% for DDT, 77% for DDE, and 65% for DDD. The �nal soil concentra tions met the treatment goals and the soil is suitable for residential development. If further reductions were required, additional treatment cycles would provide additional treatment. Table 1: In�uence of DARAMEND treatment on organoc hlorinated pesticide concentrations.

The Conclusion The project was completed on budget and in a period of only three weeks, at a cost of approximately US $40,400 per acre for this pilot project. Full-scale remediation of over 30 acres of land is planned for 2007, at a projected cost of US $29,900 to $32,100 per acre. These costs are far less than the costs of excavation, hauling, and disposal. In addition, the treatment method is more environmentally friendly for a number of reasons. The soil is treated on site (Fig. 6 ) as opposed to using land�ll space. The treatment method uses little energy and very few resources. Finally, contaminants are being destroyed, not just transported.

For more information, contact us by phone at 888.295.8661 or by email at info@advent us.us.

DARAMEND is a registered trademark of Adventus Inte llectual Property Inc.

DDT ( µg/g) DDE ( µg/g) DDD ( µg/g)

Composite Initial 2.0 3.1 0.065

Post DARAMEND Treatment 0.34 0.70 0.023

Removal E�ciency 83% 77% 65%

Figure 6: Treated soil.


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Project Title

Full-Scale Bioremediation of Pesticide Impacted Soil/Sediment T.H. Agriculture & Nutrition (THAN) Superfund Site Montgomery, Alabama

Summary Soil and sediment (~4,500 tons) impacted with Toxaphene, DDT, DDD and DDE were excavated from impacted areas on the site, including a surface water drainage way. Impacted soils were placed in a prepared bed on site and a cycled, anaerobic/aerobic bioremediation treatment protocol was administered. Following the application of 3 to 12 treatment cycles Toxaphene, DDT, DDE, and DDD concentrations were reduced by 95%, 89%, 71%, and 76%, respectively. The Challenge Toxaphene, DDT, and DDD exceeded remedial objectives in most areas of the site initially. Toxaphene and DDD concentrations, in particular, were highly elevated in some areas. We believe that Toxaphene and DDD concentrations in this range have previously never been successfully remediated using a biological treatment technology. The Solution Application of DARAMEND � , a proprietary organic amendment, and powdered iron through repeated and sequential application generate anoxic and oxic conditions. Amendments are incorporated to a depth of two feet using a specialized deep rotary tiller. Water is then applied to bring soil moisture content up to 90% of the soil water holding capacity (WHC). These steps are repeated for each treatment cycle. The Result The remedial goals (i.e., Toxaphene � 29 mg/kg, DDT � 94 mg/kg, DDD � 132 mg/kg, and DDE � 94 mg/kg), were reached in all areas of the treatment cell following the application of 3 to 12 treatment cycles. The number of treatment cycles required to reach the remedial goal was primarily dependent on the initial concentrations. Analytical results indicate that mean Toxaphene, DDT, DDD, and DDE concentrations were reduced from 189 mg/kg, 81 mg/kg, 180 mg/kg, and 25 mg/kg to 10 mg/kg, 9 mg/kg, 52 mg/kg, and 6 mg/kg, respectively. This corresponds to removal and destruction e�ciencies (RDE) of 95%, 89%, 71%, and 76%. In some sampling zones initial pesticide concentrations were much higher than the mean concentrations and performance in these zones was correspondingly more e�ective. For example, Toxaphene, DDT, DDD, and DDE concentrations were reduced from 720 mg/kg, 227 mg/kg, 590 mg/kg, and 65 mg/kg to 10.5 mg/kg, 15 mg/kg, 87 mg/kg, and 8.6 mg/kg, respectively, in heavily impacted regions of the site. This corresponds to RDE’s of 99%, 94%, 85%, and 87%


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Field Pro�le

The Cost The treatment cost per ton varied according to the initial concentration and ranged between $29/ton and $63/ton. The average unit cost for the treatment of approximately 4,500 tons of soils was approximately $55/ton. The Timeline As indicated above, variable contaminant concentrations resulted in variable treatment time requirements. Remedial goals were reached after three treatment cycles (6 weeks) in less heavily impacted regions on the Site, while the most heavily impacted areas required 12 treatment cycles (24 weeks). On average, the remedial goals were achieved following the application of approximately 8 treatment cycles (16 weeks).

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Figure 1. In�uence of DARAMEND Bioremediation on Toxaphene , DDT, DDE, and DDD

concentrations in soil during the full-scale treatment of impacted soils at the THAN superfund site in Montgomery, Alabama.

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Adventus Americas Inc. 2871 W. Forest Road - Suite 2

Freeport, IL 61032 USA Ph. 815/235-3503 Fx: 815/235-3506

Email: [email protected]

Adventus Americas (Canada) 21345 Fewster Drive

Mississauga, Ontario, Canada Ph: 905/273-5374 Fx: 905/273-4367

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Adventus Group Brasil - Av. Paulista, nº 37 - 4º andarCEP 01311-902 Phone: (55 11) 2246 2759 / Fax: (55 11) 2246 2799

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Project Title

Con�dential Chemical Facility, Ontario, CA

Summary Adventus’ DARAMEND technology was selected for use at a pil ot-scale demonstration for the treatment of 350 tons of soil impacted by phenoxy-acid herbicides (2,4-D, and 2,4,5-T), and other chlorinated pesticides (DDT, DDD, and DDE).

The Solution The treatment process involved the application of DARAMEND to a 60 cm thick layer of soil within a treatment cell. Due to the volatile and highly toxic nature of the phenoxy-acid herbicides the treatment cell was covered with a polyethylene clad greenhouse. Negative pressure was maintained within the greenhouse by continuously drawing air from the greenhouse and discharging it through a granular activated carbon �lter. Soil undergoing treatment was subjected to several treatment cycles and was irrigated to 90% of the soil water holding content at the start of each treatment cycle.

The Result The application of DARAMEND served to reductively de-chlorinate, and subsequently mineralize the chlorinated herbicides and pesticides. The concentrations of the target contaminants, 2,4-D, 245-T, and DDT, were reduced by over 96%, 84%, and 91% respectively (Figure 1).

Figure 1: E�ect of DARAMEND treatment on the concentr ations of 2,4-D, 2,4,5-T, DDT, DDD, and DDE during a pilot-scale demonstration at a Chemical facili ty in Ontario.

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Field Pro�le

The Cost The estimated treatment cost for the full-scale application of DARAMEND bioremediation at this site, which would have involved the treatment of 35,000 tons of similarly contaminated material, was approximately US$127.00/ton. The cost associated with this project is slightly elevated when compared with most similarly sized projects due to the extremely toxic and semi-volatile nature of the contaminants, and consequently, the environ-mental, health and safety procedures required.

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Project Former Agricultural Site, Florida, USA Con�dential Client Summary In November 2004, Adventus conducted a 2,600-ton in situ pilot-scale technology validation project using Adventus’ patented DARAMEND technology to remove organochlorine pesticides from impacted soils at a former agricultural site in Florida. The treatment area consisted of two treatment plots identi�ed as North and South, each containing a 1-foot layer of soil with elevated concentrations of dieldrin. The remedial goal was met in a 2-3 week period and subsequent �eld monitoring showed that soil dieldrin concentrations decreased by 67% in that period at a total project cost of approximately $12.50/yd3. The Challenge

Results from the site characterization sampling indicated an average initial soil dieldrin concentration of 45.9 µg/kg in the treatment plots. The remedial objective was to treat the dieldrin to below 15 µg/kg.

The Solution Two sequential Daramend treatments consisting of sequential anoxic and oxic conditions were applied. These conditions were generated through the application of DARAMEND amendments (0.5 % by weight), which were applied to the soil surface and incorporated to a depth of 1 foot with a tractor-driven deep rotary tiller or disc (Figure 1). After amendment incorporation, water was applied to bring the soil moisture content up to 90% of the soil water-holding capacity (Figure 2). These steps were repeated for the second treatment cycle. Each cycle consisted of an eight day anoxic phase, followed by a two day oxic phase. Figure 1: In-place application of DARAMEND Figure 2: Irrigation to meet optimal soil moisture

amendment. content for bacterial degradation.


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Field Pro�le

The Result The soil dieldrin decreased from an average of 45.9 µg/kg to 15.1 µg/kg in two treatment cycles, which comprises a removal rate of 67% (Figure 3). A third treatment cycle was able to reduce the concentration by 85 to 90%. Figure 3: Rapid, Cost-E�cient and

E�ective DARAMEND Bioremediation of dieldrin-impacted soil.

The Time Line and Cost The remedial objective was reached within a 2-3 week period at a total project cost of approximately $12.50/yd3.

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APPENDIX B

EHC FOR OCPs CASE STUDIES

Field Pro�le EHC™

Project EHC TM Treatment of Groundwater Plume Containing Chlorinated Solvents, Con�dential Client - SE USA The Challenge Groundwater at a former manufacturing facility was impacted by chlorinated solvents, primarily carbon tetrachloride (CT) and trichloroethylene (TCE), as well as organochlorinated pesticides (OCPs). Adventus employed its EHC™ in situ integrated biological and chemical reduction (ISCR) technology yielding safe, rapid and e�ective in situ treatment. After only 3 months of EHC application, the CT concentration decreased from 260 ppb to 7.8 ppb (97% removal) without the accumulation of catabolic intermediates. Treatment improved further at the 6-month sampling, showing a removal to 0.8 ppb (99.7% removal). All six of six monitoring wells met the groundwater clean up criteria for volatile organic compounds (VOCs). The Solution EHC™ is a patented combination of controlled-release carbon and zero valent iron (ZVI) particles used for stimulating reductive dechlorination of otherwise persistent organic compounds in groundwater. The volume requiring treatment was 110 ft (34 m) wide by approximately 190 ft (58 m) long, from 15 to 40 ft (4.6 to 12 m) below ground surface (bgs). The approach was to create three, 10 ft (3 m) wide reactive zones: one at the upgradient edge, and two in the middle of the treatment area. The theory behind this approach is that the volatile fatty acids, hydrogen, and ferrous iron released from EHC would migrate downgradient to treat the plume. Further, contact between contaminants and the ZVI that is incorporated in the EHC product would be chemically treated. A total of 45,000 lbs (20,455 kg) of EHC were applied at the site. Within the reactive zones, the application rate was 0.5% by dry soil mass; however, the overall application rate for the total area treated was 0.08%. The injections were completed in June of 2005 using direct injection (Figure 1 ). The �rst round of monitoring well sampling occurred in September of 2005.

Figure 1: Application of EHC slurry using direct injection.


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Field Pro�le

Figure 2: In�uence of EHC treatment on chloroethene and chlo romethane concentrations (MW #2).

The Result Excellent treatment results were attained, as shown in Table 1 where the pre-treatment and 3-month post-treatment results are presented for all wells in the treatment area. The full range of analyzed chloroethenes and chloromethanes are shown in Figure 2 for the most highly contaminated well. All constituents at this well were reduced by signi�cant amounts, with CT being reduced by 99.7%. Figure 3 shows the contoured �eld data for carbon tetrachloride one year prior to injection, and three and six months following the injections. All values were less than 1 ppb at the six-month sampling, and all VOC treatment goals were met. Figure 4 shows the degradation of OCPs over time due to EHC application. Table 1: In�uence of 3 months of EHC treatment on TCE and CT conc entrations in groundwater

from all wells in treatment area. All values in ppb.

MW #1 MW #2 MW #3 MW #4 MW #5 MW #6 TCE Pre-treatment <1.0 2.5 1.5 44 <1.0 1.0 TCE Post-treatment <1.0 1.1 <1.0 1.3 <1.0 <1.0 CT Pre-treatment <1.0 260 <1.0 3.7 0.34 (est.) 4.2 CT Post-treatment <1.0 7.8 <1.0 <1.0 <1.0 <1.0

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Figure 4. In�uence of EHC treatment on OCPs in groundwater.

The Timeline and Cost The EHC injection was completed in twenty days. Three months following EHC additions the concentration of chlorinated solvents decreased by as much as 97%, and as much as 99.7% after 6 months. The concentrations of all VOCs were below the site clean up criteria for all sample locations. The EHC product cost was US$0.17/ft3 (US$6/m3).


Field Pro�le EHC™

Project Former Pesticide Manufacturing Con�dential Client Southeast USA Summary A pilot study was conducted to determine the applicability of deep in situ DARAMEND® bioremediation* for treatment of soil containing volat ile organic compounds (VOCs) and organochlorine pesticides (OCPs). A total of 43,590 lbs of DARAMEND® was injected into four injection points. The i njections were conducted using hydraulic fracturing. Sampling conducted 7 months after the injections showed a decrease in Toxaphene and total OCP with over 90%. Bench-Scale Treatability Study Adventus conducted bench-scale tests to determine the applicability of deep in situ DARAMEND® bioremediation for treatment of soil containing VOCs and OCPs. A pilot-scale demonstration project is currently proceeding on site.* The bench-scale work evaluated several DARAMEND® treatm ent scenarios, using a number of DARAMEND®

products, and compared straight anoxic conditions to a cycled aerobic/anoxic protocol. The testing was performed in sealed columns to simulate in situ conditions and prevent contact with the atmosphere. The most e�ective treatment consisted of the addition of DARAMEND® product D2002/6390Fe20, which contains slow-release organic carbon, nutrients, and micro-scale zero-valent iron. This treatment reduced the total OCPs from 46.9 mg/g to 1.1 mg/g after 117 days of treatment, representing greater than 97% reduction in total OCPs. During this same period, the VOCs, primarily xylene and ethylbenzene, were reduced by over 99%. Pilot Study Field Injection Given the success of this treatment technology at bench-scale, a pilot-scale demonstration project was initiated in October of 2003. The goal of the project was to reduce source zone soil concentrations of OCPs and VOCs through the deep in-situ injection of DARAMEND® into the source area . A series of four applications of 1% DARAMEND® by weight with respect to the mass of soil in the tre atment area was implemented. The applications were planned for intervals of between 14 and 21 days. Soil in the treatment zone was a highly weathered limestone at depths of 31’ to 37’. The injection method consisted of driving rods to these depths using a Geoprobe rig, followed by hydraulic fracturing and injection of DARAMEND®. Four locations were chosen for injection, with two to three depths per location. At each location a total of approximately 2,800 pounds of DARAMEND® was injected (i.e . 1,400 pounds per injection at locations with 2 depths and 930 pounds per injection at locations with 3 depths). The DARAMEND® product was delivered to the site in 25 kg bags for ease of handling and the material was handled with negligible dust creation. DARAMEND® was placed in a hopper, and mixed in-line with a guar s olution for delivery to the subsurface treatment area. To enhance groundwater movement through the DARAMEND® fractures, sand was introduced, at ratios of 1:2 and 1:1 sand to DARAMEND® by mass. The product was su ccessfully injected in each of these scenarios.


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Field Pro�le

Sampling of the treatment area to determine the aerial and vertical extend of the DARAMEND® injections was performed using Geoprobe sampling equipment. The DARAMEND® layers were easily visible in the cores, whether the fracture was a hairline fracture near the tip of the fracture, or whether it was a few inches in thickness closer to the injection location (Figure 1). Results

Soil concentrations of Toxaphene and total OCPs were measured in June of 2004. Given the fact that OCPs bind strongly to the soil, the concentrations vary widely from one location to the next. For samples that were taken from as close to the same location and depth as possible, and for samples that showed a decrease in concentration between November 2003 and June 2004, the results are tabulated in Table 1. Four out of twelve samples showed an increase between these sampling dates, however the median concentrations of those increases were 9 µg/g and 12 µg/g for Toxaphene and total OCPs respectively. These data show that the soil concentrations of Toxaphene and total OCPs decreased signi�cantly between the dates shown. The decrease in the average concentration of both Toxaphene and total OCPs was 93%.

Table 1. In�uence of in-situ DARAMEND on average Toxaphene an d total OCP concentrations

between November 2003 and June 2004 for selected samples.

Toxaphene (µg/g) Total OCPs (µg/g) Average Nov 2003 Value 127.7 169.1

Average June 2004 Value 8.7 11.8

Decrease in Average Concentration 93.2% 93.0%

*Prior to establishment of EHC™, this product was r eferred to as Deep In situ DARAMEND®.

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Figure 1: DARAMEND® layer injected between clay and weathered limestone.


Bioremediation of pesticides adventus

Engineering

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