Characterizing Navajo Nation water sources for potential use with nanofiltration

Clashin, Dana Nicole (2022) Characterizing Navajo Nation water sources for potential use with nanofiltration. Masters thesis, Northern Arizona University.

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Abstract

This study is motivated by the need to increase access to clean and safe water on the Navajo Nation. Up to 30% of the Navajo Nation lacks access to public water systems; however, the expansion of water infrastructure across the Navajo Nation is not feasible considering its low population density. The natural abundance of uranium and arsenic in the southwest US, the potential for increased mobilization from previous mining activity, and the use of unregulated water for potable purposes can contribute to increased human exposure to uranium and arsenic on the Navajo Nation.A relatively new, decentralized, and affordable technology used in this study is solar nanofiltration (SNF). The SNF systems utilize nanofiltration, a water purification technique that can remove more than 90% of uranium (U) and arsenic (As) from water. Contaminant rejection is, however, variable, and dependent on the speciation of uranium and arsenic and on membrane fouling. Both speciation and membrane fouling are sensitive to pH, cations, and anions present. Additionally, membrane fouling can be affected by total organic carbon and bacteria concentrations. A primary objective of this study was to use analytical techniques (including inductively coupled plasma mass spectrometry) to characterize the Dilkon Chapter House water source that will be filtered by the SNF system located in Dilkon, AZ. The uranium, arsenic, cation, and anion concentrations were below enforceable limits, and no bacterial growth was observed after 48 hours. All measured variables are not considered problematic for the SNF system at this time. To continue monitoring and maintaining the SNF, further analysis is needed. A secondary objective was to survey the water sources in areas surrounding the Dilkon SNF, including water sources in Dilkon and Black Falls. From the seven sources sampled, two exceeded the U MCL and three exceeded the As MCL. Additionally, samples from the Dilkon area had higher TDS concentrations ranging from 300-16,000 mg/L. The final objective was to evaluate the efficiency of the ultraviolet (UV) disinfection attachments in Lupton. The Lupton heterotrophic plate count results showed no bacterial growth after 24 hours, demonstrating that the UV disinfection was effective.

Item Type:	Thesis (Masters)
Publisher’s Statement:	© Copyright is held by the author. Digital access to this material is made possible by the Cline Library, Northern Arizona University. Further transmission, reproduction or presentation of protected items is prohibited except with permission of the author.
Keywords:	Nanofiltration; Navajo Indian Reservation; Uranium; Water supply; Water pollution
Subjects:	Q Science > QD Chemistry
NAU Depositing Author Academic Status:	Student
Department/Unit:	Graduate College > Theses and Dissertations College of the Environment, Forestry, and Natural Sciences > Chemistry and Biochemistry
Date Deposited:	02 Jun 2023 18:31
Last Modified:	02 Jun 2023 18:31
URI:	https://openknowledge.nau.edu/id/eprint/5953

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