Date of Award

Spring 2021

Project Type

Thesis

Program or Major

Civil Engineering

Degree Name

Master of Science

First Advisor

M. Robin Collins

Second Advisor

Thomas P. Ballestero

Third Advisor

Peter Dwyer

Abstract

Arsenic contamination in drinking water is a worldwide public health concern. Contamination occurs from both natural and anthropogenic sources and is associated with serious acute and chronic health effects. In 2001, the Environmental Protection Agency (EPA) changed the maximum contaminant level (MCL) of arsenic from 50 to 10 μg/L. Because of this, there have been incentives for further research and development of cost-effective technologies to help meet these new standards, especially in small community water systems.Over the past decade, attention has turned to zero-valent iron (ZVI) as a possible arsenic removal material because of its efficient, inexpensive, and locally available qualities. Previous studies using ZVI have demonstrated that it can be very effective in the removal of arsenic by adsorption, with bench-scale studies achieving greater than 95% removals at equilibrium. Pilot-scale studies, which implemented a diatomaceous earth (DE) precoat filtration scheme, achieved over 70% removals with initial arsenic concentration of 2 mg/L and a ZVI dose of 200 mg/L (Little, 2011). Moreover, dissolved iron concentrations must not exceed the EPA’s secondary standard of 0.3 mg/L; previous research has shown by maintaining an aerobic environment with pH levels above 7, the issue is alleviated (Little, 2011). The primary focus of this research continues with the examination of enhancing these removals with a smaller initial concentration of arsenic (0.2 mg/L), while also enhancing the removals of select contaminants, such as MS2 bacteriophage (MS2) as well as natural organic matter (NOM), by using ZVI as an adsorptive and amending the DE aluminum-coated diatomaceous earth (DEAL), and iron-oxide/aluminum-coated diatomaceous earth (FEOOH-DEAL) media. Conclusions from these studies have shown that using ZVI, as well as the proprietary coated DE, as an adsorptive media in a precoat filtration system is an effective way of removing arsenic. In addition, ZVI and the proprietary coated DE have shown to produce measurable removal rates of NOM and MS2 using this treatment scheme.

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