Ask a Librarian

Threre are lots of ways to contact a librarian. Choose what works best for you.

HOURS TODAY

10:00 am - 3:00 pm

Reference Desk - Virtual

CONTACT US BY PHONE

(802) 656-2022

Voice

(802) 503-1703

Text

MAKE AN APPOINTMENT OR EMAIL A QUESTION

Schedule an Appointment

Meet with a librarian or subject specialist for in-depth help.

Email a Librarian

Submit a question for reply by e-mail.

WANT TO TALK TO SOMEONE RIGHT AWAY?

Library Hours for Wednesday, August 10th

All of the hours for today can be found below. We look forward to seeing you in the library.
HOURS TODAY
8:00 am - 8:00 pm
MAIN LIBRARY

SEE ALL LIBRARY HOURS
WITHIN HOWE LIBRARY

MapsClosed

Media Services8:00 am - 4:30 pm

Reference Desk10:00 am - 3:00 pm

OTHER DEPARTMENTS

Special Collections10:00 am - 5:00 pm

Dana Medical Library7:30 am - 11:00 pm

 

CATQuest

Search the UVM Libraries' collections

UVM Theses and Dissertations

Browse by Department
Format:
Online
Author:
Shen, Yuxiang
Dept./Program:
Civil and Environmental Engineering
Year:
2022
Degree:
Ph. D.
Abstract:
Membrane processes have been a promising purification and separation technique as it can potentially remove any ions, particles, and colloids by size selection. Membrane processes are still limitedly used in the real-world industrial application due to its relatively cost prohibitive maintenance and operation, which is attributed to membrane fouling and concentration polarization under pressurized conditions. To improve the efficiency of membrane filtration, alternatives to the traditional cleaning methods have been investigated to mitigate the fouling and concentration polarization problems. Among the alternatives, application of an external field, e.g., electric field or acoustic field, to the mitigate fouling during membrane filtration has been gaining increased attention in recent years. However, simultaneous application electric and acoustic fields to mitigate membrane are limited or lacking. This research focuses on the investigation of simultaneous application of electric and acoustic fields as a means to further enhance the fouling mitigation by providing additional foulant-foulant, and foulant-membrane interactions under combined fields conditions. There is a critical need for in situ characterization methods that could reveal effects of external fields on foulants during membrane filtration. In this dissertation the author presents (1) an apparatus designed and customized for simultaneous application of electric field and acoustic field during membrane filtration experiments; (2) experiment results based on microfiltration that confirm the synergistic effect under the given setup of combined fields; (3) mapping methods and results of enhanced darkfield hyperspectral microscopy (ED-HSI) applied to various foulants common in water and wastewater environment, including (i) pharmaceutical and personal care products (PPCP) molecular foulants and their adsorption to different types of carbon nanotubes (CNT), and (ii) Gram-negative and Gram-positive bacteria in planktonic conditions and in biofilms. The research in this dissertation investigates the application of electric field and acoustic field both individually and simultaneously to mitigate fouling during microfiltration. Under simultaneous application of fields: (1) the rate of fouling mitigation was larger than the numerical sum of each field when applied solely for synthetic wastewater matrix containing colloidal foulants, and (2) 25.1% of initial flux was recovered. The results suggest that electric field and acoustic fields can synergistically act to mitigate fouling while enhancing the flux recovery. A protocol based on ED-HSI was developed to characterize aqueous foulants relevant to membrane filtration. The mapping results revealed (i) adsorption mechanism of PPCP molecular foulant onto CNTs, and (ii) identification of different bacteria species in planktonic conditions and in biofilms.
Note:
Access to this item embargoed until 03/15/2023.