Document Type

Dissertation

Date of Award

1-1-2017

Degree Name

Doctor of Philosophy in Environmental Engineering - (Ph.D.)

Department

Civil and Environmental Engineering

First Advisor

Lisa Axe

Second Advisor

Michel Boufadel

Third Advisor

Edgardo Tabion Farinas

Fourth Advisor

Wen Zhang

Fifth Advisor

Robert F. Raczko

Abstract

With the increasing concern of pharmaceuticals and personal care products (PPCPs) in source water, this study examines the hypothesis that existing filters and adsorbents in water treatment plants can be converted to biologically active filters (BAFs) to treat these compounds. Removals through bench-scale BAFs are evaluated as a function of media, granular activated carbon (GAC) and dual-media, empty bed contact time (EBCT), and pre-ozonation. For GAC BAFs, greater oxygen consumption, increased pH drop, and greater DOC removal normalized to adenosine triphosphate (ATP) are observed indicating a different microbial community compared to dual-media BAFs. ATP concentrations in the upper portion of the BAFs are as much as four times greater than the middle and lower portions. Sixteen PPCPs are spiked in the source water. At an EBCT of 18 min, GAC BAFs are highly effective with overall removals greater than 80% without pre-ozonation; exceptions include tri(2-chloroethyl) phosphate (TCEP) and iopromide with removals at 76% and 59%, respectively. With the application of pre-ozonation, all indicator compounds are removed at greater than 75%. Reducing the EBCT to 10 min, the degree of PPCP removal is reduced with less than half of the compounds removed at greater than 80%. The dual-media BAFs show limited PPCP removal with only four compounds removed at greater than 80%, and 10 compounds are reduced by less than 50% with either EBCT. To further improve the removals, the application of pre-ozonation is needed and compounds removed at greater than 75% increase to 11 for the 10 min EBCT and 9 for the 18 min EBCT. DOC removal normalized to ATP is an important indicator for BAF performance. With DOC removals ranging from 200 to 600 mg/g ATP in BAFs, GAC shows significant removal efficiency (>80%) for PPCPs. On the other hand, with DOC removals of 100 to 200 mg/g ATP in dual media BAFs, limited removals are observed. Proteobacteria and Planctomycetes phyla are dominant in both GAC and dual-media BAF. In the filter influent and effluent the dominant phylum is Proteobacteria. Based on a factorial analysis, media type significantly affects the abundance of five bacterial phyla and ten bacterial classes. EBCT impacts the abundance of the dominant bacteria phylum Proteobacteria. The effect of pre-ozonation is observed at class level. This study demonstrates that GAC BAFs are an effective and advanced technology for treating emerging contaminants. On the other hand, pre-ozonation is needed for dual media BAFs to remove PPCPs.

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