Date of Award

2020

Degree Type

Thesis

Degree Name

Master of Science in Civil and Environmental Engineering

Specialization

Environmental Engineering

Department

Civil and Environmental Engineering

First Advisor

Vinka Oyanedel-Craver

Abstract

Ceramic water filters (CWFs) are manufactured in developing communities worldwide and are designed to remove microorganisms from drinking water. These filters are low cost, point-of-use, and have been shown to reduce the prevalence of diarrheal disease. CWFs are manufactured at 50 locations around the globe, each factory using a different set of raw materials and manufacturing practices. In this study, the state of the literature encompassing CWF manufacturing and performance assessments was reviewed to determine areas of potential improvements. A modified form of one of the potential standard methodologies was then used to analyze the performance of a new style of CWF with ovoid (curved) walls.

The goal of the literature review was to demonstrate the need for a standardized performance assessment procedure in the testing of CWFs. The performance of CWFs can vary greatly between units manufactured in different areas. A standardized methodology for evaluating CWF performance is necessary in order to determine how manufacturing differences could change the performance of the final product. The many variables in manufacturing and testing that can affect the performance of CWFs were reviewed to determine the major contributors to variations in CWF performance. The USEPA and WHO performance assessments procedures that are available for CWFs are discussed and compared. The implementation of a standardized performance assessment procedure has the potential to improve the performance of CWFs, increase stakeholder involvement, and improve health in developing communities.

Experimentally, the performance of a ceramic water filter (CWF) with curved (ovoid) walls developed by Potters without Borders was evaluated. The modified protocol used in this assessment was the USEPA Guide Standard and Protocol for Testing Microbiological Water Purifiers, which has yet to be utilized in the literature. Filters with/without silver nanoparticles (AgNPs) were evaluated for bacterial removal, turbidity removal, flow rate, and silver leaching. Bacterial and turbidity removal were high for the ovoid CWFs compared to previous studies. All the CWFs tested here had flow rates within the acceptable range after they had been saturated. Coated CWFs had a higher total effluent silver concentration compared to uncoated; coated CWFs also had increased silver release during testing phases with a higher concentration of total dissolved solids (challenge phase, 35 ppb). This was compared to the general phase that had a release of 13 ppb. The procedure demonstrated utility as a reproducible performance testing technique. X-ray diffraction and mercury intrusion porosimetry were used to study the ceramic structure in order to explain the high performance of the CWFs. X-ray photoelectron spectroscopy (XPS), was used to determine that the AgNP coating on the exterior of the CWFs leached off by the dissolution of the AgNPs during the general and challenge phases and the release of AgNPs from the ceramic during the leaching phase.

Available for download on Thursday, April 08, 2021

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