1. DeNovo Constructors, Inc.
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CHEMICAL AND BIOLOGICAL TREATMENTS

2. 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.

3. 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).

4. Chemical Oxidation – Common Oxidants
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
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
TCA = tricholorethane
MTBE = methyl tertiary butyl ether
There are two common forms of permanganate—potassium permanganate (KMnO4) and sodium permanganate (NaMnO4).
Persulfate activated through iron, elevated pH (lime), heat, hydrogen peroxide
Peroxide (H2O2 ) + Iron (Fenton’s Reagent) – generates hydroxyl radicals and is kinetically faster than hydrogen peroxide
*Activation by iron, hydrogen peroxide, heat, or high pH (lime or NaOH)

5. Chemical Oxidation – Application methods
Direct push injection
Fixed well injection
In situ soil blending application
Ex situ soil blending application

6. 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.

7. Chemical Reduction – Application MEthods
Injection:
Direct injection
Hydraulic/pneumatic fracturing
Placement:
Placement into trenches or excavations
Deep soil mixing

8. 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)

9. 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.

10. 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

11. 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

12. 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.
6300 Cubes
VOC -

13. THANK YOU