Program One
Thursday, May 22, 1997

Biofilms and Barriers Kansa A



T.J. Gallegos and B.M. Thomson, Department of Civil Engineering, University of New Mexico, Albuquerque, NM 87131, and D. Marozas, Sandia National Laboratories, Albuquerque, NM 87131 This paper describes the performance of iron foam and steel wool, two alternative forms of zero-valent iron, for application to sub-surface permeable barriers used for contaminant reduction in ground water.

The objectives are to: (l) compare the reducing capabilities of iron foam and steel wool to achieve removal of arsenic, selenium, molybdenum, uranium, sulfate, and nitrate; (2) determine if the products of iron oxidation and precipitation of metals will affect the hydraulic properties of a subsurface zero-valent iron barrier; and (3) determine the removal mechanism of the contaminants of interest.

Properties monitored included concentration of contaminants, Eh, pH, dissolved oxygen, and hydraulic conductivity over time. In a batch experiment conducted for a period of one week, the iron foam exhibited good removal of seleniurn (100%), nitrate (86%), uranium (100%), and arsenic (83%) from solution. The steel wool removed about 80% of uranium, 20% arsenic, and 70% nitrate. Neither the iron foam nor the steel wool significantly removed sulfate or molybdenum.

Column data showed that the hydraulic conductivity decreased slightly over a 70-day period for both the iron foam and the steel wool. However, the limiting values of hydraulic conductivity of 0.08 cm/s for steel wool and O.O9 cm/s for iron foam were sufficiently high that this decrease doesn't appear likely to limit application of this technology to ground water remediation.

The removal mechanism for selenium primarily appears to be retuction/precipitation. However, it seems that in addition to reduction/precipitation, adsorption is also responsible for the disappearance of arsenic and uranium from solution.

Key words: zero-valent iron, hydraulic conductivity, ground water, selenium

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Tuesday, May 20, 1997

Metals Kansa A

Remediation of Munitions Compounds Kansa B

Analytical Methods Kansa C/D

General Topics Kansa B

Wednesday, May 21, 1997

Metals Kansa A

Zero-Valent Metals Kansa A

Remediation Kansa A

Vegetation-based Remediation Kansa B

Partnerships & Innovative Technologies Kansa C/D

Nonaqueous Phase Liquids Kansa C/D

Thursday, May 22, 1997

Biofilms & Barriers Kansa A

Bioremediation Kansa B

Partnerships & Technology Innovations Kansa C/D

Remediation Kansa C/D


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