4 results
7 - Treatability studies: microcosms, mesocosms, and field trials
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- By Ian Snape, Contaminants Geochemist Working for the Australian, Antarctic Division in Tasmania, C. Mike Reynolds, US Army Engineer Research and Development Center, Cold Regions Research and Engineering Laboratory, 72 Lyme Road, Hanover NH 03755, USA, James L. Walworth, Dept. of Soil Water and Environmental Science, University of Arizona, 429 Shantz Bldg. #38, Tucson AZ 85721, USA, Susan Ferguson, Environmental Protection and Change Program, Australian Antarctic Division, Channel Highway, Kingston, Tasmania 7050, Australia
- Edited by Dennis M. Filler, University of Alaska, Fairbanks, Ian Snape, David L. Barnes, University of Alaska, Fairbanks
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- Book:
- Bioremediation of Petroleum Hydrocarbons in Cold Regions
- Published online:
- 22 August 2009
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- 21 February 2008, pp 125-153
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Summary
Introduction
Treatability assessments are used to identify limitations to the rate or endpoint of bioremediation for a specific soil-contaminant combination. For treatability studies, the degradation pathways for the contaminant are generally known (see Chapter 4, Section 4.2.1), but the limitations in a particular soil or at a specific site are less well understood. The tremendous utility of treatability studies is in evaluating practical treatment regimes prior to full-scale implementation. The goal is to demonstrate practicability, optimize treatment design, and provide information for project planning. Sometimes this is an essential proving step for clients or regulators because choice of treatment depends primarily on urgency of remediation and cost. The cost-time relationship for different treatment types is illustrated in Chapter 1, Figure 1.1. The ability to predict the rate of bioremediation progress for a treatment scheme is particularly important in cold regions where costs are higher and treatment times are longer than in temperate regions.
In an effort to understand and improve the bioremediation process in cold regions, researchers have used treatability experiments to:
identify the presence or absence of microbial activity for a particular contaminant or group of contaminants;
determine optimum requirements, such as temperature, nutrients, oxygen, and water, for bacteria and fungi to metabolize contaminants in the soil regime;
examine the effects that natural cycles, such as freezing-thawing and wetting-drying, have on microbial activity and degradation rate;
estimate achievable endpoints;
predict and compare treatment times and costs.
Treatability studies can involve in vitro microcosms with individual bacterial species or consortia from the soil incubated in liquid or slurry media, mesocosm studies with soils and natural microfauna, or field trials.
1 - Contamination, regulation, and remediation: an introduction to bioremediation of petroleum hydrocarbons in cold regions
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- By Ian Snape, Contaminants Geochemist Working for the Australian Antarctic Division in Tasmania, Larry Acomb, Geosphere Inc., 3055 Seawind Drive, Anchorage AK 99516, USA, David L. Barnes, Dept. of Civil and Environmental Engineering, University of Alaska Fairbanks, PO Box 755900, Fairbanks AK 99775, USA, Steve Bainbridge, Contaminated Sites Program, Division of Spill Prevention and Response, Department of Environmental Conservation, 610 University Avenue, Fairbanks AK 99709–3643, USA, Robert Eno, Department of Sustainable Development, Government of Nunavut, PO Box 1000, Stn 1195, Iqaluit NU X0A 0H0, Canada, Dennis M. Filler, Dept. of Civil and Environmental Engineering, University of Alaska Fairbanks, PO Box 755900, Fairbanks AK 99775, USA, Natalie Plato, Department of Sustainable Development, Government of Nunavut, PO Box 1000, Stn 1195, Iqaluit NU X0A 0H0, Canada, John S. Poland, Analytical Services Unit, Queens University, Kingston ON K7L 3N6, Canada, Tania C. Raymond, Environmental Protection and Change Program, Australian Antarctic Division, Channel Highway, Kingston, Tasmania 7050, Australia, John L. Rayner, Environmental Protection and Change Program, Australian Antarctic Division, Channel Highway, Kingston, Tasmania 7050, Australia, Martin J. Riddle, Environmental Protection and Change Program, Australian Antarctic Division, Channel Highway, Kingston, Tasmania 7050, Australia, Anne G. Rike, Dept. of Environmental Technology, Norwegian Geotechnical Institute, PO Box 3930, Ullevaal Stadion, N-0806 Oslo, Norway, Allison Rutter, Analytical Services Unit, Queens University, Kingston ON K7L 3N6, Canada, Alexis N. Schafer, University of Saskatchewan, 51 Campus Drive, Saskatoon, Canada S7N 5A8, Steven D. Siciliano, University of Saskatchewan, 51 Campus Drive, Saskatoon SK S7N 5A8, Canada, James L. Walworth, Dept. of Soil Water and Environmental Science, University of Arizona, 429 Shantz Bldg. #38, Tucson AZ 85721, USA
- Edited by Dennis M. Filler, University of Alaska, Fairbanks, Ian Snape, David L. Barnes, University of Alaska, Fairbanks
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- Book:
- Bioremediation of Petroleum Hydrocarbons in Cold Regions
- Published online:
- 22 August 2009
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- 21 February 2008, pp 1-37
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Summary
Introduction
Oil and fuel spills are among the most extensive and environmentally damaging pollution problems in cold regions and are recognized as potential threats to human and ecosystem health. It is generally thought that spills are more damaging in cold regions, and that ecosystem recovery is slower than in warmer climates (AMAP 1998; Det Norske Veritas 2003). Slow natural attenuation rates mean that petroleum concentrations remain high for many years, and site managers are therefore often forced to select among a range of more active remediation options, each of which involves a trade-off between cost and treatment time (Figure 11). The acceptable treatment timeline is usually dictated by financial circumstance, perceived risks, regulatory pressure, or transfer of land ownership.
In situations where remediation and site closure are not urgent, natural attenuation is often considered an option. However, for many cold region sites, contaminants rapidly migrate off-site (Gore et al. 1999; Snape et al. 2006a). In seasonally frozen ground, especially in wetlands, a pulse of contamination is often released with each summer thaw (AMAP 1998; Snape et al. 2002). In these circumstances natural attenuation is likely not a satisfactory option. Simply excavating contaminants and removing them for off-site treatment may not be viable either, because the costs are often prohibitive and the environmental consequences of bulk extraction can equal or exceed the damage caused by the initial spill (Filler et al. 2006; Riser-Roberts 1998).
8 - Nutrient requirements for bioremediation
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- By James L. Walworth, Dept. of Soil Water and Environmental Science, University of Arizona, 429 Shantz Bldg. #38, Tucson AZ 85721, USA, Susan Ferguson, Environmental Protection and Change Program, Australian Antarctic Division, Channel Highway, Kingston, Tasmania 7050, Australia
- Edited by Dennis M. Filler, University of Alaska, Fairbanks, Ian Snape, David L. Barnes, University of Alaska, Fairbanks
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- Book:
- Bioremediation of Petroleum Hydrocarbons in Cold Regions
- Published online:
- 22 August 2009
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- 21 February 2008, pp 154-169
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Summary
Introduction
Nutrients are required to support biological activity, and hence bioremediation. It is recognized that, although the microbial community requires numerous nutrients, nitrogen and phosphorus are the nutrients most often lacking, and thus limiting to biological hydrocarbon degradation in cold region soils (Mohn and Stewart 2000). Numerous studies have reported that biodegradation of hydrocarbon contaminants in cold region soils has been enhanced by the addition of one or both of these nutrients (Walworth and Reynolds 1995; Braddock et al. 1997; Walworth et al. 1997; Braddock et al. 1999; Mohn and Stewart 2000; Mohn et al. 2001; Ferguson et al. 2003a).
Nitrogen most often provides positive responses, although methodologies for determining application levels are not well defined. Proper nitrogen management can increase cell growth rate (Hoyle et al. 1995), decrease the microbial lag phase (Lewis et al. 1986; Ferguson et al. 2003a), help to maintain populations at high activity levels (Lindstrom et al. 1991), and increase the rate of hydrocarbon degradation (Braddock et al. 1997; Braddock et al. 1999). Whereas many studies indicate positive effects of supplemental nitrogen (Rasiah et al. 1991; Allen-King et al. 1994; Walworth and Reynolds 1995), a surprisingly large number report no benefit, or even deleterious effects when excessive levels of nitrogen are applied (Watts et al. 1982; Brown et al. 1983; Huntjens et al. 1986; Morgan and Watkinson 1990; Genouw et al. 1994; Zhou and Crawford 1995; Braddock et al. 1997; Walworth et al. 1997; Braddock et al. 1999; Mohn et al. 2001; Ferguson et al., 2003a).
9 - Landfarming
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- By James L. Walworth, Dept. of Soil Water and Environmental Science, University of Arizona, 429 Shantz Bldg. #38, Tucson AZ 85721, USA, C. Mike Reynolds, US Army Engineer Research and Development Center, Cold Regions Research and Engineering Laboratory, 72 Lyme Road, Hanover NH 03755, USA, Allison Rutter, Analytical Services Unit, Queens University, Kingston ON K7L 3N6, Canada, Ian Snape, Environmental Protection and Change Program, Australian Antarctic Division, Channel Highway, Kingston, Tasmania 7050, Australia
- Edited by Dennis M. Filler, University of Alaska, Fairbanks, Ian Snape, David L. Barnes, University of Alaska, Fairbanks
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- Book:
- Bioremediation of Petroleum Hydrocarbons in Cold Regions
- Published online:
- 22 August 2009
- Print publication:
- 21 February 2008, pp 170-189
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Summary
Introduction
Landfarming has been described as “a simple technique in which contaminated soil is excavated and spread over a prepared bed and periodically tilled until pollutants are degraded” (Vidali 2001) but, in practice, it can be either an ex situ or in situ technique. Landfarming generally uses a combination of volatilization and biodegradation to reduce hydrocarbon concentrations. For biodegradation to be effective, stimulating aerobic soil microorganisms is essential; this is commonly accomplished by adding nutrients and mixing the soil to increase aeration. Aerating the soil in this way also increases the loss of hydrocarbon contaminants to the atmosphere via volatilization. Volatilization of diesel and lighter hydrocarbons greatly assists the remediation process but it is less effective for heavier molecular weight hydrocarbons such as crude oil.
For in situ landfarming it is possible to treat only relatively shallow layers of soil where reasonable oxygenation can be maintained. In ex situ landfarming, excavated contaminated soil is spread as a thin layer in a treatment bed that is often lined with an impermeable layer to control leaching and runoff. Ex situ landfarming can be as simple as soil spread in a cleared area or it can be a major construction with contouring or drainage systems or both for removal of excess water. Plumbing can also be used for the application of water, either alone or in combination with nutrients or other amendments, to the landfarm surface.