Date of Award

Spring 1-1-2019

Document Type

Thesis

Degree Name

Master of Science (MS)

First Advisor

Karl G. Linden

Second Advisor

R. Scott Summers

Third Advisor

Roberto Floris

Abstract

The application of low-pressure membrane filtration such as microfiltration (MF) and ultrafiltration (UF) have become progressively well-established in the drinking and wastewater technology industry over the past few decades. While polymeric membranes dominate this sector of the water industry, ceramic membranes have become an increasingly popular and advantageous alternative to polymeric materials. Most importantly, ceramic membranes can be effectively employed to treat high-fouling impaired quality source water because of the inherent material robustness, that can withstand in-situ oxidative cleaning regimes.

Given the ozone (O3)-resistant nature of ceramic membranes, this research demonstrated that preozonation plays a crucial role in both enhancing membrane filterability/permeability due to the oxidation of high molecular weight (HMW) to low molecular weight (LMW) natural organic matter (NOM), allowing the ceramic membranes to be operated at higher flux. The TAMI ceramic membrane exhibited pH-dependent permeate flux decline while filtering synthetic, pH-buffered Suwannee River Humic Acid (SRHA), where reduced fouling was associated with increased pH. However, preozonated SRHA did not follow the same pH-dependent trend. Fluorescence scans showed a pH-dependent trend where a combination of higher pH and O3 led to a greater reduction in both overall and peak intensities. In addition, hydroxyl radical (OH) formation was monitored with a probe compound and showed that the SRHA bulk water in contact with the catalytic membrane surface could further promote OH radical production.

In addition, identical experiments with three secondary effluents of differing dissolved organic carbon (DOC) concentrations were run in order to confirm results found with synthetic water. Preozonation was shown to alleviate organic membrane fouling for all waters. Size exclusion chromatography showed ozonation could shift HMW compounds to LMW which enhanced flux during filtration. It also showed that filtration performance between non-ozonated and preozonated waters behaved differently in the rejection of certain organic fractions. Dissolved ozone in contact with the TAMI ceramic membrane surface accelerated the formation of OH radicals where a higher DOC and ozone dose lead to a greater formation potential.

Consequently, it is expected that ozone prior to ceramic membrane filtration can play a significant role in treating impaired-quality source waters.

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Engineering Commons

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