Valence state: The combining capacity of an atom or radical determined by the number of electrons that it will lose, add, or share when it reacts with other atoms.
free product: A NAPL found in the subsurface in sufficient quantity that it can be partially recovered by pumping or gravity drain.
aerobic: Direct aerobic metabolism involves microbial reactions that require oxygen to go forward. The bacteria uses a carbon substrate as the electron donor and oxygen as the electron acceptor. Degradation of contaminants that are susceptible to aerobic degradation but not anaerobic often ceases in the vicinity of the source zone because of oxygen depletion. This can sometimes be reversed by adding oxygen in the form of air (air sparging, bioventing), ozone, or slow oxygen release compound (e.g., ORC(r)).
Aerobic dechlorination may also occur via cometabolism where the dechlorination is incidental to the metabolic activities of the organisms. In this case, contaminants are degraded by microbial enzymes that are metabolizing other organic substrates. Cometabolic dechlorination does not appear to produce energy for the organism. At pilot- or full-scale treatment, cometabolic and direct dechlorination may be indistinguishable, and both processes may contribute to contaminant removal. For aerobic cometabolism to occur there must be sufficient oxygen and a suitable substrate which allows the microbe to produce the appropriate enzyme. These conditions may be present naturally but often in the presence of a source area oxygen and a substrate such as methane or propane will need to be introduced.
Adapted from US. EPA 2006 Engineering Issue: In Situ and Ex Situ Biodegradation Technologies for Remediation of Contaminated Sites
anaerobic: Direct anaerobic metabolism involves microbial reactions occurring in the absence of oxygen and encompasses many processes, including fermentation, methanogenesis, reductive dechlorination, sulfate-reducing activities, and denitrification. Depending on the contaminant of concern, a subset of these activities may be cultivated. In anaerobic metabolism, nitrate, sulfate, carbon dioxide, oxidized metals, or organic compounds may replace oxygen as the electron acceptor.
Anaerobic dechlorination also may occur via cometabolism where the dechlorination is incidental to the metabolic activities of the organisms. In this case, contaminants are degraded by microbial enzymes that are metabolizing other organic substrates. Cometabolic dechlorination does not appear to produce energy for the organism. At pilot- or full-scale treatment, cometabolic and direct dechlorination may be indistinguishable, and both processes may contribute to contaminant removal.
Quoted from US. EPA 2006 Engineering Issue: In Situ and Ex Situ Biodegradation Technologies for Remediation of Contaminated Sites
architecture: "Architecture" refers to the physical distribution of the contaminant in the subsurface. Residuals that take the form of long thin ganglia or small dispersed globules provide a larger surface area that will dissolve much faster than if the same amount of liquid were concentrated in a competent pool.
Sources: For purposes of this discussion, a DNAPL source zone includes the zone that encompasses the entire subsurface volume in which DNAPL is present either at residual saturation or as "pools" of accumulation above confining units. In addition, the DNAPL source zone includes regions that have come into contact with DNAPL that may be storing contaminant mass as a result of diffusion of DNAPL into the soil or rock matrix.
source zone: For purposes of this discussion, a DNAPL source zone includes the zone that encompasses the entire subsurface volume in which DNAPL is present either at residual saturation or as "pools" of accumulation above confining units. In addition, the DNAPL source zone includes regions that have come into contact with DNAPL that may be storing contaminant mass as a result of diffusion of DNAPL into the soil or rock matrix.
focal ulceration: The process or fact of a localized area being eroded away.
metaplasia of the glandular stomach: A change of cells to a form that does not normally occur in the tissue in which it is found.
hyperplasia of the glandular stomach: A condition in which there is an increase in the number of normal cells in a tissue or organ.
histiocytic: Degenerative.
duodenum: First part of the small intestine.
microcytic: Any abnormally small cell.
squamous cell papillomas: A small solid benign tumor with a clear-cut border that projects above the surrounding tissue.
squamous cell carcinomas: Cancer that begins in squamous cells-thin, flat cells that look under the microscope like fish scales. Squamous cells are found in the tissue that forms the surface of the skin, the lining of hollow organs of the body, and the passages of the respiratory and digestive tracts. Squamous cell carcinomas may arise in any of these tissues.
jejunum: The middle portion of the small intestine, between duodenum and ileum. It represents about 2/5 of the remaining portion of the small intestine below duodenum.
ileum: The distal and narrowest portion of the small intestine.
squamous: Flat cells that look like fish scales.
metaplasia: A condition in which there is a change of one adult cell type to another similar adult cell type.
ossification: The process of creating bone, that is of transforming cartilage (or fibrous tissue) into bone.
clastogenesis: Any process resulting in the breakage of chromosomes.
neoplastic: Abnormal and uncontrolled growth of cells.
ulceration: The process or fact of being eroded away.
leucocytosis: An elevation of the total number of white cells in blood.
neutrophils: A type of white blood cell.
chromodulin: A small protein that binds four trivalent chromium ions.
biomagnification: The increased accumulation and concentration of a contaminant at higher levels of the food chain; organisms higher on the food chain will have larger amounts of contaminants than those lower on the food chain, because the contaminants are not eliminated or broken down into other chemicals within the organisms.
exencephaly: Cerebral tissue herniation through a congenital or acquired defect in the skull.
everted viscera: Rotated body organs in the chest cavity.
To Be Considered: Documents, such as federal or state guidances, that are not legally binding but may be relevant to the topic in question.
gaining: A gaining surface water body is one where groundwater flows into it.
losing: A surface water body is losing when there is a permeable sediment bed that is not in contact with the groundwater allowing the surface water to seep through it.
fluvial: Of or pertaining to flow in rivers and streams.
lacustrine: Of or pertaining to a lake as in lacustrine sediments—sediments at the bottom of a lake.
lipid: Any class of fats that are insoluble in water.
lipophilic: Able to dissolve in lipids—in this case fatty tissue.
organelles: A part of a cell such as mitochondrion, vacuole, or chloroplast that plays a specific role in how the cell functions and membranes.
RfD: The RfD is an estimate of a daily exposure of the human population (including sensitive sub-groups) to a substance that is likely to be without "the appreciable risk of deleterious effects during a lifetime." An RfD is expressed in units of mg/kg-day.
autonomic: That part of the nervous system that controls non-conscious actions such as heart rate, perspiration and digestion.
ataxia: Lack of muscle coordination.
funnel-and-gate configuration: A system where low-permeability walls (the funnel) placed in the saturated zone direct contaminated ground-water toward a permeable treatment zone (the gate)
Hekster, F.M., R.W.P.M. Laane, and P. de Voogt. 2003. Environmental and toxicity effects of perfluoroalkylated substances. Reviews of Environmental Contamination and Toxicology 179:99-121.
Higgins, C. and R. Luthy. 2006. Sorption of perfluorinated surfactants on sediments. Environmental Science & Technology 40(23):7251-7256.
Kaiser, M.A., B.S. Larsen, C-P.C. Kao, and R.C. Buck. 2005. Vapor pressures of perfluorooctanoic, -nonanoic, -decanoic, -undecanoic, and -dodecanoic acids. Journal of Chemical and Engineering Data 50(6):1841-1843.
Kauck, E.A. and A.R. Diesslin. 1951. Some properties of perfluorocarboxylic acids. Industrial and Engineering Chemical Research 43(10):2332-2334.
The literature indicates ongoing laboratory work in the investigation and development of in situ flushing of DNAPL mixtures from soil; however, few descriptions of field applications of the technology to coal tar, creosote, or heavy oils are available. In addition to chemical flushing, water alone, both heated and at ambient temperature, has been applied in a flushing process called waterflooding to the mobilization of DNAPL mixtures from the subsurface.
The technology demonstration at the Brodhead Creek Superfund site in Stroudsburg, PA, was a full-scale remediation effort lasting about 20 months. The system used for the demonstration included six hot water injection wells, two recovery wells, an aboveground water treatment system, and a data acquisition and control system. The injection and recovery wells targeted an accumulation of free-phase coal tar within a 40-ft by 80-ft treatment area. The CROW process was successful in removing coal tar from the subsurface; however, it was unable to reduce coal tar concentrations to residual immobile levels. No significant change was observed in the concentration of coal tar in the soil outside the treatment area except for measurements of the amount of coal tar in the layer under the treatment zone, which suggest that some coal tar was pushed down into the underlying confining unit.
See also the project cost and performance report.
The Bell Pole Phase 1 CROW demonstration began in mid-1995 and was operated until January 2001. The operation of the demonstration was satisfactory, though at less than the design conditions. During the demonstration, 25,502,902 gal of hot water were injected and 83,155 gal of organics were transferred to the storage tank. More than 65% of the produced organic material was used in Bell Pole's treating operation. Recycling the produced organic material partially offset the cost of remediation.
At the Koppers Co. Inc., Seaboard Plant, Kearny, NJ, waterflooding (i.e, the use of hydraulic pressure achieved via groundwater injection and recirculation) was used to mobilize coal tar and creosote toward collection trenches.
In a small-scale field demonstration at a private wood treating site in Laramie, WY, 144,000 gallons (28 pore volumes [pv]) of water were cycled between the delivery and recovery drain lines to displace mobile free-phase oil, followed by a second soil flushing step consisting of delivery of 30,000 gallons of flushing solution (alkaline agents, polymer, and surfactants) into the test cell. As part of the soil flushing step, 10,000 gallons (2 pv) of Polystep A-7R were used to produce reusable wood-preserving oil, followed by 10,000 gallons (2 pv) of Makon-10R to achieve lower cleanup levels. After the first 20,000 gallons of flushing solution delivery, 10,000 gallons (2 pv) of water were delivered to continue fluid movement while waiting for the arrival of additional flushing solution. An additional 10,000 gallons (2 pv) of Makon-10R were then delivered to the cell to complete the soil flushing step. In a reconditioning step, the cell was flooded with 150,000 gallons (30 pv) of water to displace mobilized oil and soil-washing solution remaining in the aquifer.
At a Fredricksburg, VA, wood treating site, flushing with a combination of an alkaline agent, surfactant, and polymer was used to recover creosote-based wood-treating oils from soil.
Abstracts of Journal Articles
In-Situ Biosurfactant Flushing, Coupled with a Highly Pressurized Air Injection, to Remediate the Bunker Oil Contaminated Site
Lee, M., J. Kim, and I. Kim.
Geosciences Journal, Vol 15 No 3, p 313-321, Sep 2011
A pilot-scale test of in situ biosurfactant flushing coupled with highly pressurized air injection (HPAI) was performed to remediate a site contaminated with A and C bunker oil in Ulsan, Korea. Twelve injection wells and 2 extraction wells were installed in a 17 m x 12 m x 4 m contaminated area. Addition of a 2% biosurfactant flushing solution into each injection well at 2 L/min was followed by HPAI (20 kgf/sq cm) to accelerate solution mobility in pore spaces. The process was repeated until about 1.9 pore volumes of biosurfactant solution (350 tons) had been flushed, removing ~2.2 tons of TPH (82% of the initial TPH) from the site. The resultant average residual TPH concentration in soil was <500 mg/kg. Longer abstract
In Situ Remediation of Coal Tar-Impacted Soil by Polymer-Surfactant Flooding
C.M. Young, V. Dwarakanath, T. Malik, L. Milner, J. Chittet, A. Jazdanian, N. Huston, and V. Weerasooriya.
Proceedings of the Third International Conference on Remediation of Chlorinated and Recalcitrant Compounds (Monterey, CA; May 2002).
Battelle Press, Paper 2C-33, 8 pp, 2002
In a thermally enhanced polymer/surfactant pilot field test conducted in 2001 at a former manufactured gas plant in Bloomington, IL, 80% of the coal tar DNAPL was removed (10% solubilized, 90% mobilized). Heating the injection solution lowered the viscosity of the coal tar by 50% (from 65 cps to 34 cps) when the temperature was increased from 24 to 38 degrees C. The surfactant— Alfoterra™ 123-8 PO Sulfate (branched propoxylated alcohol sulfates)—was designed for recovery of bunker fuel. Batch and column experiments were conducted to optimize the in situ flushing design for site DNAPL, soil, and temperature. Three pore volumes of surfactant solution were injected. The solution consisted of 4% surfactant, 8% secondary butyl alcohol, 0.13% polymer, and 0.08% CaCl2. The initial saturation of the coal tar was around 35%.
Western Research Institute, Contained Recovery of Oily Waste (CROW) Process: Innovative Technology Evaluation Report
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