Award Date

5-1-2020

Degree Type

Thesis

Degree Name

Master of Science in Engineering (MSE)

Department

Civil and Environmental Engineering and Construction

First Committee Member

Erica Marti

Second Committee Member

Daniel Gerrity

Third Committee Member

Eakalak Khan

Fourth Committee Member

Eric Dickenson

Fifth Committee Member

Christy Strong

Number of Pages

101

Abstract

Antibiotic resistance is a prominent issue in the world today. It is said by the Centers for Disease Control and Prevention that it is one of the major public health challenges we face today. Predominantly, antibiotic resistance is growing because conventional wastewater treatment processes are not able to completely break down antibiotics. As bacteria are exposed to such antibiotics, which don’t kill them due to selective pressure, they become immune and develop resistance which is a huge health concern. To prevent this from occurring, antibiotics need to be removed from hospital wastewater. Sonication is a promising technology that can be used to degrade organic matter such as antibiotics in water.

The objective of this research is to study the parameters that influence antibiotics degradation in water via sonolysis. During sonication this was accomplished by varying three parameters: the concentration of H2O2, amplitude, and irradiation method (i.e., pulse or continuous soundwaves). The investigated antibiotics were sulfamethoxazole, trimethoprim, tetracycline, azithromycin, lincomycin, and clarithromycin. Batch experiments were conducted with a mixture of antibiotics (each individual antibiotic at an initial concentration of approximately 20 ppb) in a jacketed beaker using the QSonica Sonicator, Q500. An attempt was made to keep the temperature constant (30±5 °C) with the use of a chiller and ethylene glycol.

During the sonication process, there were minimal hydroxyl radicals produced. Under pulsing conditions, azithromycin and clarithromycin, which are slightly hydrophobic, were expected to have improved removal efficiency when compared to continuous irradiation. Pulse irradiation was expected to increase their accumulation at the bubble interface, causing more degradation during bubble collapse but it did not. Potentially, the presence of the remaining 4-four antibiotics sulfamethoxazole, trimethoprim, tetracycline, and lincomycin) could have prevented azithromycin and clarithromycin from migrating towards the bubble interface zone. The most efficient amplitude for antibiotic removal was 75% (approximately 85 W). Further increasing the amplitude to 100% (approximately 120 W) did not result in increased percent removal. Overall, the most efficiently removed antibiotic was tetracycline with over 90% removal, and the least efficiently removed was trimethoprim (12%). To maximize the removal of antibiotics under the tested conditions, it is recommended to sonicate water at 75% amplitude at constant irradiation for at least 30 minutes.

Keywords

Acoustic; Antibiotics; Cavitation; Sonication; Sonolysis; Water

Disciplines

Civil Engineering | Environmental Engineering

File Format

pdf

File Size

2.9 MB

Degree Grantor

University of Nevada, Las Vegas

Language

English

Rights

IN COPYRIGHT. For more information about this rights statement, please visit http://rightsstatements.org/vocab/InC/1.0/

Download


Share

COinS