Remediation of PAH-Contaminated Soils and Sediments: A ...

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solubility with the additions of: surfactants, sub/supercritical water extraction and electrokinetics (Rivas 2006; Isosaari et al., 2007). Electrokinetic degradation: Use of electrokinetics for PAH remediation is often integrated as an assist in nonbiological or biological oxidation steps. Electrokinetic remediation is the process of inducing an electric current through a body of contaminated sediment. The technology works by placing a series of wells coupled with electrodes around the zone of contamination; connection of the electrodes to a power supply creates cathodic and anodic zones. Inside of this energized zone the cations in the soil solution (electrolyte solution), located beyond the shear zone of soil particles diffuse double layer, begin to flow towards the cathodic zone in a process called electroosmosis or electroosmotic flow. The movement of the electrolytic solution drags uncharged molecules, such as PAHs, into the flow where they can be removed via the wells and treated at wastewater facilities (Figure 7). The charge induced during electroosmosis also increases the dispersion and formation of radical species during treatments utilizing chemical oxidants (i.e. H2O2, Na2S2O8), leading many researchers to suggest that electrokinetic remediation be integrated with other treatment techniques. Some advantages and disadvantages of electrokinetic degradation are listed below: Advantages: � if integrated with chemical oxidants, electrokinetics have the potential to limit the effects of untreated zones � works well in sediments of high clay or organic matter that have small capillary pores � is an effective in-situ remediation strategy for saturated sediments Disadvantages: � high ionic strengths collapse the diffuse double layer and reduce the area prone to electroosmotic flow � low ionic strengths cease electroosmotic flow by removal of the charged particles that facilitate flow � the contaminated zone must be saturated for electroosmosis to occur, which poses PAH leaching hazards � electroosmosis will not occur in compacted sediments with overlapping diffuse double layers 36
Figure 7. Schematic of integrated electrokinetic technique (Saichek and Reddy 2005) Photochemical degradation: Photochemical degradation or photooxidation involving sunlight is an important process for surface and atmospheric degradation of PAHs (Harvey, 1998; Pierzynski et al., 2000). During direct photooxidation the PAH, is directly oxidized after the absorption of sunlight radiation by the PAH. The PAHs must absorb radiation above 290-335 nm (below this level ozone absorbs solar radiation) for photooxidation to occur (Table 7). Chemical transformation rates during direct photooxidation depend upon sunlight intensity, and overlapping spectral characteristics of solar radiation and the PAHs. 37
Page 1 and 2: Remediation of PAH-Contaminated Soi
Page 3 and 4: Abstract Polycyclic aromatic hydroc
Page 5 and 6: soil is the primary environmental r
Page 7 and 8: Solubility Solubility of PAH compou
Page 9 and 10: Figure 1. Structures of US EPA’s
Page 11 and 12: � If you were to add 2 benzene ri
Page 13 and 14: and their mutagenic and carcinogeni
Page 15 and 16: PAH in humans The carcinogenicity o
Page 17 and 18: persist in the soil (Alexander, 199
Page 19 and 20: Figure 3. Relative PAH concentratio
Page 21 and 22: the gas phase was attributed to tem
Page 23 and 24: increasing rainfall intensity or wi
Page 25 and 26: in contaminated soils than uncontam
Page 27 and 28: Ideal biodegradation of PAHs, where
Page 29 and 30: Figure 5. Aerobic degradation of PA
Page 31 and 32: Cometabolism is explained by three
Page 33 and 34: donate electrons. The redox potenti
Page 35: 1. Fenton’s reagent - formation o
Page 39 and 40: Figure 8. Possible mechanism for di
Page 41 and 42: Freundlich adsorption equation: x/m
Page 43 and 44: Diffusion: Weber et al. (1992), Web
Page 45 and 46: Biological Techniques for Enhancing
Page 47 and 48: oot extract resulted in continuous
Page 49 and 50: Composting Composting is a form of
Page 51 and 52: The addition of inorganic nutrients
Page 53 and 54: � Yu et al. (2006) found no effec
Page 55 and 56: Carrot Daucus carota Wild and Jones
Page 57 and 58: Surfactants Mass transfer of PAH co
Page 59 and 60: � Straube et al. (2003) showed th
Page 61 and 62: encountered with biodegradation, an
Page 63 and 64: volatilization of some compounds, s
Page 65 and 66: Regulatory Framework Dredged materi
Page 67 and 68: transition phase between slurried s
Page 69 and 70: In addition to equation manipulatio
Page 71 and 72: Coastal Zone Management Act (CZMA)
Page 73 and 74: EPA Region V NA http://www.epa.gov/
Page 75 and 76: Indiana Department of Environmental
Page 77 and 78: New York State Department of Enviro
Page 79 and 80: Analytical Methods The following is
Page 81 and 82: Sample Cleanup After extraction, cl
Page 83 and 84: Table 13. Detection limits for cert
Page 85 and 86: Citations Accardi-Dey, A., and P.M.
Page 87 and 88:
Cerniglia, C.E., and D.T. Gibson. 1
Page 89 and 90:
EPA. 2008. Integrated Risk Informat
Page 91 and 92:
Harmsen, J. 2007. Measuring bioavai
Page 93 and 94:
Kelsey, J.W., B.D. Kottler, and M.
Page 95 and 96:
Mackay, D., and D. Callcott. 1998.
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O’Mahony, M., A. Dobson, J. Barne
Page 99 and 100:
Saison, C., C. Perrin-Ganier, M. Sc
Page 101 and 102:
Vessigaud, S., C Perrin-Ganier, L.
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