Award Date

5-1-2019

Degree Type

Thesis

Degree Name

Master of Science in Engineering (MSE)

Department

Civil and Environmental Engineering and Construction

First Committee Member

Jacimaria Batista

Second Committee Member

David James

Third Committee Member

Daniel Gerrity

Fourth Committee Member

Spencer Steinberg

Number of Pages

203

Abstract

Remediation of contaminated groundwater is becoming increasingly more

important as much of the U.S. population relies on groundwater for their drinking water.

Contaminates such as Chromium, common pollutant at industrial waste sites, and

Hexavalent chromium which is toxic to humans, animals, and plants are major

concerns. Chlorate, another contaminate of concern, has been widely detected in

ground and surface water in the United States and even locally in Henderson Nevada at

the Nevada Environmental Response Trust (NERT) sites. To assist in mitigating this

issue, this research focuses on the removal of high levels of hexavalent chromium (ppm

range) (Cr(VI)) and chlorate (ClO3-) from water using zero valent iron (ZVI).

Zero valent iron is a proven technology for the biotic and abiotic reduction of a

wide variety of environmental contaminants including Cr(VI), nitrate (NO3-), chlorinated

organic compounds, arsenic, ClO3-, and ClO4-. There is a lack of research investigating

the reduction of Cr(VI) using ZVI+Sludge, specifically examining how competing

contaminants, such as chlorate, would affect Cr(VI) remediation. The overall goal of this

research was to determine whether a combination of ZVI+Sludge can improve reduction

kinetics of degradation of high levels of Cr(VI) and chlorate, when they occur together.

A series of batch tests were conducted in which a synthetic groundwater,

containing the contaminants of interest, was added with various concentrations of ZVI,

microbial seed, and an external carbon source (i.e. EOS emulsified oil). Depending on

the method to be tested, varying concentrations of ZVI, Sludge, or a combination of

ZVI+Sludge were added to the vials. Degradation experiments were performed first with

single contaminants followed with the contaminants together. The analysis of the

experiments related to ZVI+Sludge showed a statistically significant increase in the

reduction of Cr(VI) alone over ZVI. The outcome of this research suggests an increase

in contaminant reduction rates when combining chemical and biological treatment

(ZVI+Sludge). Supporting the conclusion that a ZVI+Sludge treatment method could

reduce the amount of ZVI material required and/or increase the longevity of the system.

Keywords

Batch test; Bio-ZVI; Chlorate; Groundwater; Hexavalent chromium; Zero valent iron

Disciplines

Environmental Engineering

Language

English


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