28.02.2013 Views

Handbook of Solvents - George Wypych - ChemTech - Ventech!

Handbook of Solvents - George Wypych - ChemTech - Ventech!

Handbook of Solvents - George Wypych - ChemTech - Ventech!

SHOW MORE
SHOW LESS

You also want an ePaper? Increase the reach of your titles

YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.

1620 Barry J. Spargo, James G. Mueller<br />

Figure 23.2.2. Anaerobic degradation <strong>of</strong> carbon tetrachloride. An example <strong>of</strong> anaerobic dehalogenation, using carbon<br />

tetrachloride as the model compound. In many cases, these reactions occur under cometabolic conditions<br />

meaning that an alternative growth substrate must be present to serve as an electron donor to drive the reduction reactions<br />

whereby carbon tetrachloride is used as the electron acceptor. Three known pathways for microbial degradation<br />

<strong>of</strong> carbon tetrachloride have been identified [U.E. Krone, R.K. Thauer, H.P. Hogenkamp, and K. Steinbach,<br />

Biochemistry, 30(10), 2713 (1991); C.H. Lee, T.A. Lewis, A. Paszczynski, and R.L. Crawford, Biochem Biophys<br />

Res Commun, 261(3), 562 (1999)]. These pathways are not enzymatically driven but rely on corrinoid and<br />

corrinoid-like molecules to catalyze these reactions.<br />

ical <strong>of</strong> those prevalent in the dissolved phase, including PAH constituents, has also been<br />

demonstrated. 21-28<br />

It is therefore accepted that aerobic and anaerobic biodegradation <strong>of</strong> organic compounds<br />

occurs through the action <strong>of</strong> natural, indigenous micr<strong>of</strong>lora. As a result <strong>of</strong> these natural<br />

in situ microbial processes, many sites with elevated concentrations <strong>of</strong> biodegradable<br />

organics exhibit highly reducing and anaerobic conditions in areas containing elevated concentrations<br />

(i.e., suspected source areas). Moving outward laterally and down-gradient<br />

within the plume, the aquifers tend to become more oxidizing as a result <strong>of</strong> lower constituent<br />

levels, infiltration, and recharge with oxygenated water.<br />

23.2.2.1.1 Case study - Cooper River Watershed, Charleston, SC, USA<br />

The Cooper River Watershed empties into the Charleston Harbor on the southern Atlantic<br />

coast <strong>of</strong> the United States. In the lower reaches, the Cooper River is a highly industrialized<br />

and urbanized watershed with storm sewer and surface run-<strong>of</strong>f impact. The river supports<br />

industries such as a wood pulp processing plant, a former naval shipyard, and a chromium<br />

mining/processing facility. In addition a number <strong>of</strong> fossil fuel refineries, storage facilities,

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!