TCE degradation in groundwater using zero-valent iron
- Univ. of Waterloo, Ontario (Canada)
- EnviroMetal Technologies, Inc., Guelph, Ontario (Canada)
Column testing and field demonstration studies of the degradation of chlorinated compounds by iron are presented. Granular iron was the main material for column testing. Of 14 halogenated methanes, ethanes, and ethenes tested, 13 clearly showed enhanced degradation with normalized half lives ranging from 5 to 15 orders of magnitude lower than values reported for natural abiotic degradation rates. Column test results for trichloroethene (TCE) showed a decline in TCE accompanied by an increase in chloride, indicating the decline to be a consequence of dechlorination. Degradation rates of TCE appeared to be relatively independent of both initial organic concentration and the ionic strength of the groundwater. Half-lives of 0.5 to 1 hour were commonly observed in laboratory tests using 100% granular iron as the reactive material and waters from numerous hazardous waste sites. A field demonstration resulted in upgradient concentrations that were much higher than normally encountered at contaminated sites. Complete mass removal could have been achieved if a higher proportion of iron had been used in the reactive mixture. Mass removal was consistent over the monitoring period of 1600 days. Core samples of the reactive material collected 13 months and 25 months after installation showed only minor alteration of physical charecteristics of the iron. Low operating and maintenance costs are a potential advantage of the system; however, long-term integrity of the treatment system at commercial sites remains uncertain.
- OSTI ID:
- 210187
- Report Number(s):
- CONF-9509139--
- Country of Publication:
- United States
- Language:
- English
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