DeNovo Constructors, Inc. WELCOME CHEMICAL AND BIOLOGICAL TREATMENTS

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.

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).

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)

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

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.

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

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)

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.

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

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

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 -

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