Applications of In-Situ Chemical

Oxidation/Reduction

Jay Romano

Manager

Redox-Tech NE

Environmental Business Council of New England

Energy Environment Economy

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Redox Tech, LLC

Fundamentals of In-Situ Remediation

“Providing Innovative In Situ Soil and

Groundwater Treatment”

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Redox Tech, LLC

• Business founded in 1995.

• Headquarters in Cary, NC. Other offices in GA, SC, IL, MA, and CA.

• New England Office opened in 2005.

• In situ treatment with biological and chemical manipulation, both reduction and oxidation – over 800 projects completed.

• In situ Soil Blending.

In Situ Remediation is a TOOL!

Site Characterization for In Situ

Treatment Designs

• Horizontal and Vertical Delineation;

• MNA Field Measurements (Ph, ORP, and DO);

• Alkalinity, Dissolved Iron, Sulfate, etc…

• Site Geology;

• Total Oxidant Demand (TOD);

• Utility Locations; and

• Nearby Receptors.

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In Situ Remediation – The Design Delivery and Chemistry are Key

• Requires fundamental understanding of geochemistry and microbiology.

• Requires confidence in the consultants work.

• Requires delivery that mimics the target contaminant distribution.

• Without both proper data, delivery and formulation, remediation likely to fail.

• May require Pilot Study.

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Total Oxidant Demand (TOD)

• Water-phase contaminant is not only material that will be oxidized

• Sorbed phase contaminant

• Free-phase contaminants

• Naturally-occurring organic material (NOM)

• Reduced soil and water minerals

• Can be estimated with site data

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Total Oxidant Demand

Total Oxidant Demand can vary between <0.1 to 155 g/Kg

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Treatment Classes

• Chemical Oxidation

• Chemical Reduction

• Aerobic Bioremediation

• Anaerobic Bioremediation

• Metals Stabilization

• Thermal (steam)

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Chemical Oxidants

• Permanganate – widely used for chlorinated

alkenes, PCE, TCE, DCE, VC

• Peroxide (Fenton’s) – relatively inexpensive, but

can be difficult to inject

• Persulfate – replacing many peroxide applications

because of safety and gas generation

• Ozone – still occasionally used for gas stations

Base Activated Sodium Persulfate

• Competes with permanganate, Fenton’s chemistry, ozone and peroxide;

• Oxidizes a broader range of organic contaminants than permanganate ;

• Oxidizes more compounds than Fenton’s chemistry and does not have gas generation;

• Slower reaction time than other oxidants which can translate to less rebound; and

• Much safer to handle than other oxidants.

Sodium Persulfate Injection

Enfield, CT

• Gasoline Release in the 1980s;

• Remediation activities included product recovery,

SVE, pump and treat and soil excavation;

• Following 20+ years of remediation, groundwater

concentration were still elevated under the

roadway and nearby properties; and

• Redox Tech NE was invited to bid on a Fenton’s

Reagent design and proposed activated sodium

persulfate as an alternative.

Injection Design

• 17,000 square foot treatment area;

• Average TVOC approximately 18,000 ppb;

• 5 to 7 foot thickness;

• 44 injection points (2 rounds);

• 54,000 lbs of sodium persulfate;

• 450 gallons per point;

• 2 target depth intervals; and

• Completed in 11 days;

Groundwater Treatment Results

• Average TVOC approximately 4,000 ppb (78%);

• Elevated sulfate still present in groundwater

(>1,000 mg/L); and

• 22 out of 36 target monitoring wells below

groundwater standards (GW Protection and

Residential).

Redox Tech’s Oxygen BioChem (OBC)

• A slow-release oxygen generating formula designed to provide short-term chemical oxidation (1-2 months) and long term anaerobic oxidation via sulfate reduction (1-2 years)

• Patented combination of sodium persulfate and food grade calcium peroxide

• Can be added to excavations or injected into groundwater

• One of the preferred products in New Hampshire

• Predecessor to Klozur CR

Oxygen BioChem vs. Competitors

Oxygen BioChem (OBC) Competitors

Greater oxygen – as much as

46 wt %

Typically 10 to 20 wt %

Both chemox and biorem. Mostly bioremediation

Greater solubility –40 wt %

for the persulfate portion

Typically less than 5%

soluble

Better value - $3.25 per

pound

Typically $4 to $10 per pound

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Enhanced

Anaerobic Bioremediation

• Aquifers are sometimes limited by carbon (or food) source for bacteria

• In some instances, the proper bacteria (e.g. dehalogenators) are not present

• Overstimulation can result in domination by methanogens

• Examples: Redox Tech’s ABC, FMC’s EHC and Regenesis’ HRC

• Data should support the use of these products

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Anaerobic BioChem (ABC)

• Sodium Lactate

• Ethyl Lactate – green solvent

• Fatty Acids – all dissolved

• Dipotassium Phosphate for micronutrients

and pH buffering

• Can bioaugment with RTB-1 (DHC)

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ABC® Advantages

• Long lasting (2+ years) but water soluble so large

volume of chase water not required

• Lower injection pressures

• Does not require hydrolysis of oils to release fatty

acids

• No emulsion breaking potential

• No soap formation from bringing pH up to high

• Demonstrated buffering

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Anaerobic BioChem (ABC+)

• Mixture of ABC® plus zero valent iron (ZVI)

• Combination of chemical reduction (ZVI)

and anaerobic bioremediation

• Less likely to form VC

• Licensed with Adventus & Waterloo to add

ZVI to carbon amendment

• Injected over 1,500,000 pounds ABC+

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ZVI REACTION

• β-elimination pathway minimizes daughter products

• very low concentration of chlorinated intermediates

• intermediates degrade

• Surface reaction at ZVI

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Combined Bio and Chemical Reduction

Redox Potential Comparison

-800

-600

-400

-200

0

200

400

0 5 10 15 20 25 30

Treatment Time (days)

Redox

Pote

ntial (m

V)

Control ABC® ABC+®

ABC+ Injection

Wrentham, MA

• 5,000 square foot area and a 15 foot thickness

• Dense material with gravel, which required pre-clearing

top 5 feet with auger

• 5,400 lbs of ABC+

• 18 injection points with 5 depth intervals

• November 2009: PCE = 1,300 ppb and TCE = 93,000 ppb

• May 2010: PCE = ND < 50 ppb and TCE = ND < 50 ppb

• Dissolved gases detected and cis-1,2-DCE (3,300 ppb) and

VC (910 ppb) spiked in May 2010. Cis-1,2-DEC and VC

reduced in November 2010 to 670 ppb and 430 ppb.

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Technical Advantages of Sulfate

• Exists naturally in most groundwater

• High solubility in comparison to other electron

acceptors

• Easily applied as an aqueous solution

• Proper application of sulfate enhanced

biodegradation will result in no adverse health effects

• Results are surprisingly rapid

Sulfate Reduction Case Study

Site Background

Former gasoline service station with two confirmed releases in 1992 and 2001

Historical remedial efforts with limited success included groundwater pump and treat and monitored natural attenuation

Geology consists of fine to medium sand with groundwater present about 10 feet bgs

Pilot study was not intended to be a “full scale” site remediation

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Jackson, Michigan October 3, 2007

0

50

100

1st

Qtr

3rd

Qtr

East

West

North

• Baseline Conditions

Sulfate is depleted in

core

Sulfate background is >

50 ppm

Max. BTEX is >10,000

ppb

Sulfate

BTEX

Sulfate Depleted

In core of plume

BTEX Plume

GW Flow

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Jackson, Michigan January 16, 2007

• 3 months after initial

application

• Sulfate still elevated in

core of plume

• BTEX >5,000 ppb is

shrinking

Sulfate

BTEX

Sulfate Increasing

BTEX Shrinking

Metals Treatment

1. Lead treatment with phosphate buffer.

2. Arsenic/lead treatment with phosphate, calcium

buffer and hydrogen peroxide.

3. Hexavalent chromium treatment with ferrous

chloride and hydrated lime.

4. Bench Scale Study

5. Majority of project are to assist dig and haul.

Heated Water/Steam & Recovery

• Site in Lawrence, MA;

• Estimated 500 gallons of No. 6 Oil;

• Injected heated water into subsurface to create steam;

• Project was completed in 8 days;

• Approximately 700 gallons of product was recovered in 6 weeks;

• No measurable product; and

• Heated water can be used as an activator.

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Delivery Capabilities

• Proprietary injection tools that are integrated with

Geoprobe.

• Permanent injection points (PVC riser and screen).

• Injection of gasses, liquids and solids in largely

varying geological environments - pressures from

10 to 2000 psi (Hydraulic Fracturing).

• Excavations/Trenches.

• In Situ Soil Blending for shallow soil (<25’ bgs.).

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Why Injection Isn’t for Amateurs

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Pump and Treat Gone Bad

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Hydraulic Fracturing

• Injection of water, solution or slurry at

pressure that exceeds the lithostatic pressure

and cohesive strength of the formation.

• Results in short-term enhancement of soil

permeability.

• Increases radius-of-influence and injection

rate.

Hydraulic Fracturing Concept

UNFRACTURED SOIL

FRACTURED

TO GEOPROBE RODS

ZONES

BEFORE FRACTURE(Diffusion Controlled)

AFTER FRACTURE(Connection & Diffusion Controlled)

DETAIL "A"VAPOR MOVEMENT IN SOIL MICROSTRUCTURE

SEE DETAIL "A"

GROUT HEAD - ATTACHES

GEOPROBE RODS

SEAL AROUND GEOPROBE RODS

WITH BENTONITE AS RODS

GEOPROBE RIG

ARE PUSHED.

GROUND SURFACE

PUMP

" NYLOBRADE FLEXIBLE PVC HOSE

Pressure – Time History

Fracture

Maintenance

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ABC+ Injection Equipment

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In Situ Soil Blending

• Efficient and uniform delivery of remediation amendments

• Production rates comparable to dig, haul and backfill

• No long term liability associated with disposal

• Costs that can be 2 to 10 times less expensive than dig and haul, depending upon the extent of contamination

• No RCRA TSD permits are required

• Can treat a wide range of compounds, such as chlorinated solvents, pesticides, PAHs, etc

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In Situ Soil Blending – The Beginning

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In Situ Soil Blending - Improved

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Improvements in Blender

• Weight reduced by ~50% which reduces transportation costs by factor of two ($5-6 per mile now)

• Horsepower approximately doubled

• Independent acting dual motors in custom designed mixing head

• Torque load sensing on both sides of head so rotation speed automatically adjusts – prevents “deadheading”

• Base is common excavator so parts readily available

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In Situ Soil Blending

Cambridge, MA

Dichloroethane (DCA) Contamination

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Post In Situ Soil Blending

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USEPA Site

Rhode Island

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Treatment Area

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Blending Activity – Day 1

• Top Photo – A view of the

excavation prior to blending

activity

• Bottom Photo – A view of the

application of the first 1K

pounds of KMnO4

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Blending Activity – Day 1 (Continued)

• Top Photo – A view of the

initial mixing with an

excavator.

• Bottom Photo – A view of the

soil blending thoroughly mixing

the KMnO4 with the

contaminated soil.

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Day 1 – Area Completed

• 2,000 pounds of KMnO4

blended with ~ 300 cy of

contaminated soil (Area shaded

in purple).

• KMnO4 not observed in down

gradient monitoring wells.

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Day 5 – Area Completed

• 7,000 pounds of KMnO4

blended with ~ 1,500 cy of

contaminated soil (Area shaded

in purple).

• Approximately 8,500 gallons of

water was used to blend the

KMnO4 with the soil.

• KMnO4 observed in 3 down

gradient monitoring wells ( ).

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Day 7 – Soil Blending Completed

• 10,000 pounds of KMnO4

blended with ~ 2,100 cy of

contaminated soil (Area shaded

in purple).

• Approximately 10,500 gallons

of water was used to blend the

KMnO4 with the soil.

• KMnO4 observed in 4 down

gradient monitoring wells ( ).

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Day 12 – Post Blending Monitoring

• KMnO4 observed in 7 monitoring

wells ( ).

In Situ Remediation Issues

• Underestimated contaminant mass;

• Unknown underground structures;

• Poorly marked utilities;

• Daylighting;

• Back Pressure;

• Surface grade;

• Aboveground obstructions; and

• Poorly identified geology

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The End

• In Situ Remediation is 1 of many tools;

• Injection is not the only application technique;

• Know your site;

• Work with your In-Situ contractor;

• Understand the function of the chemical; and

• For more information: www.redox-tech.com