Program One
Wednesday, May 21, 1997

Zero-Valent Metals Kansa A



L.L. Zawaideh, C.F. Chew, and T.C. Zhang, Department of Civil Engineering, University of Nebraska-Lincoln at Omaha Campus, Omaha, NE 68182-0178 In this study, zero-valent iron powder was used to remediate nitrate-contaminated water and soil. To simulate remediation of nitrate-contaminated water, bench-scale batch reactors were used. These batch reactors consisted of 150 ml Erlenmeyer flasks sealed with parafilm to reduce evaporation losses.

To determine the effectiveness of using zero-valent iron powder to remove nitrate, several operational parameters and experimental conditions were studied, including the use of an organic buffer (HEPES), weight/volume of Fe°, initial concentration of nitrate-nitrogen, DO, and pH. An amount of 0.01M of HEPES was added to all other tests (except pH tests) since the reaction of iron with water raises the pH. All the samples (except for DO tests) were purged with N2 gas to reduce the dissolved oxygen in the samples.

It was found that (1) nitrate-nitrogen was removed by 94.4% when 0.01M of HEPES and 6% (w/v) of Fe° were used; (2) treatment of a 60 mg NO3--N/L solution with 6% (w/v) Fe° at pH 1.0 completely transformed all NO3- within 24 h; (3) nitrate transformation from solution was inversely related to pH; (4) nitrate was reduced to ammonium; and (5) the optimum removal of nitrate was shown at an initial concentration range of 50-80 mg/l of NO3--N.

Nitrate transformation by iron powder in soil system was investigated using "artificial" soil contaminated with nitrate (10 g clay + 10 g sand + 10 g iron powder + 10 mL of 50 mg-NO3--N/l). Batch tests were conducted under both air-dry and saturated conditions (batch reactors were sealed with parafilm) for three days. The samples were then extracted with 50 mL distilled deionized water (DDW). The transformations were as high as 97% for air-dry samples or 99% for wet samples; while only 2% transformation occurred in control treatments containing 10 g clay + 10 g sand + 10 mL of 50 mg-NO3--N/L without Fe powder.

These results indicate that Fe° can effectively remove nitrate from contaminated water and soil.

Key words: zero-valent iron, nitrate, remediation

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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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