DENOVO

CONSTRUCTORS, INC.

WELCOME

CHEMICAL AND BIOLOGICAL TREATMENTS

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CHEMICAL AND BIOLOGICAL TREATMENTS

• Chemical oxidation

• Chemical reduction

• Biological treatment

• Many technologies can be applied “in situ” or “ex situ”.

• Certain technologies can treat soil, groundwater, or both.

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CHEMICAL OXIDATION

• In situ chemical oxidation (ISCO) – involves injecting oxidants into the subsurface to react with contaminants.

• Oxidation-reduction reactions produce harmless substances (e.g., CO2, water, inorganic chloride).

• Various oxidants are available – will depend on the type of contaminant, concentrations, and subsurface geology.

• Oxidants used, will have different oxidation potentials (relative strength).

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CHEMICAL OXIDATION – COMMON OXIDANTS

Oxidant Contaminants Treated

Peroxide, Fenton’s Reagent

TCA, PCE, TCE, DCE, VC, BTEX, chlorobenzene, phenols, 1,4-dioxane, MTBE, tert-butyl alcohol, explosives

Ozone (injected as gas - sparging)

PCE, TCE, DCE, VC, BTEX, chlorobenzene, phenols, MTBE, TBA, explosives

Ozone + peroxide TCA, PCE, TCE, DCE, VC, BTEX, chlorobenzene, phenols, 1,4-dioxane, MTBE, tert-butyl alcohol, explosives

Permanganate (potassium or sodium)

PCE, TCE, DCE, VC, BTEX, PAHs, phenols, explosives

Activated Persulfate*

PCE, TCE, DCE, VC, BTEX, chlorobenzene, phenols, 1,4-dioxane, MTBE, tert-butyl alcohol, pesticides *Activation by iron, hydrogen peroxide, heat, or high pH (lime or

NaOH)

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CHEMICAL OXIDATION – APPLICATION METHODS

• Direct push injection• Fixed well injection• In situ soil blending application• Ex situ soil blending application

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CHEMICAL REDUCTION

• In Situ Chemical Reduction (ISCR)

• Zero-valent Iron (ZVI)

• ZVI + added carbon substrate – induces anaerobic reductive dechlorination by microbes.

• Targent contaminants are mostly chlorinated solvents (PCE, TCE, DCE, VC, TCA, carbon tetrachloride).

• Also can treat some pesticides and explosives.

• Often combined with anaerobic biological treatment.

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CHEMICAL REDUCTION – APPLICATION METHODS

Injection:• Direct injection• Hydraulic/pneumatic

fracturing

Placement:• Placement into trenches or

excavations• Deep soil mixing

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BIOLOGICAL

• Aerobic and Anaerobic Remediation Methods

• Uses natural microbes in the subsurface to degrade contaminants.

• Stimulates microbes by adding oxygen, and/or nutrients.

• Biological can be combined with chemical methods (e.g., ISCO + ORC; carbon source + ZVI)

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AEROBIC BIOREMEDIATION - ORC

• Addition of oxygen and nutrients enhances aerobic bioremediation.

• Converts biodegradable contaminants into carbon dioxide and water.

• ORC can be applied as slurry or as a dry, solid powder

• Application methods – soil mixing/blending, direct injection, recirculating wells, direct placement into excavations or barrier walls.

• In situ or ex situ applications.

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ANAEROBIC BIOREMEDIATION

• Addition of carbon source (e.g., lecithin, lactic acid, molasses) and nutrients (nitrogen and phosphorus)

• Enhances anaerobic bioremediation – enhanced reductive dechlorination.

• Mainly in situ applications – comes as slurry and emulsions.• Direct injections• Soil mixing• Placement into excavations

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SPECIALTY SUPPLIERS AND PRODUCTS

• Provides chemicals and specialized products.

• Provides dosing and technical support during design.

• Some companies can provide onsite field support during application.Example Companies

PeroxyChem Regenesis

Tersus Environmental Orin

ISOTEC MECx

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PROJECT EXAMPLE –CHEMICAL REDUCTION SOIL MIXING @ AN ARMY AMMUNITION PLAN

• In situ soil mixing of 7,500 cubic yards of clay soil contaminated with chemicals.

• Grout slurry mixture consisting of Zero valent Iron and bentonite – produced in onsite mixing plant.

• Overlapping soil columns mixed with deep-soil auger using a hollow Kelly bar

• Slurry pumped through Kelly bar to the auger/mixer equipped with injection ports.

(NTS)

MANITOWAC 4000 W SERIES

IN-SITU SOIL

12" SQUARE, HOLLOWKELLEY BAR

10-FOOT DIAMETERAUGER / MIXER

SYSTEM

14-FOOT DIAMETER OFF GAS CONTAINMENT SHROUD

CRANE (150 TONS)

HAIN TURN TABLE WITH 300,00 FOOT-POUNDS OF TORQUE

CONTROL VALVES

L-12 MOYNO PUMP

SLURRY FLOW METER

CONTROL VALVE

WATER METER4" HDPE PIPE

WATER FROM FIRE HYDRANT

5 CY HIGH-SHEAR LIGHTNING MIXER

PRESSURE METER

TO AIR TREATMENT

IN-SITU SOIL MIXING & TREATMENT SYSTEM

CONTROL VALVE

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THANK YOU