Award Date

December 2023

Degree Type

Thesis

Degree Name

Master of Science in Engineering (MSE)

Department

Civil and Environmental Engineering and Construction

First Committee Member

Jacimaria Batista

Second Committee Member

David James

Third Committee Member

Daniel Gerrity

Fourth Committee Member

Boo Shan Tseng

Number of Pages

179

Abstract

Virus removal is paramount to water reuse applications and nearly all water reuse applications require extensive pathogen reduction because of high influent concentration, difficulty of detection and distinguishing infectivity. Typically, regulations stipulate virus attenuation that require the implementation of multi-barrier advanced treatment trains and award these reductions in log notation called log reduction values (LRVs). Reduction of virus concentrations are not awarded for virus removal that may occur in wastewater treatment steps which precede water reuse units such as activated sludge secondary biological treatment. A systematic literature review was performed and virus reduction at full-scale wastewater treatment plan was monitored to gain a better understanding of the mechanisms of virus attenuation during secondary biological treatment of activated sludge. The literature review was conducted according to the PRISMA guidelines with a uniform search method through Scopus, PubMed and Web of Science databases. The full-scale plant monitoring consisted of a 12-week composite sampling event, 3-week aeration basin grab sampling event and a follow-up grab sample event in the same aeration basin to determine virus partitioning. Viruses were quantified by both culture methods and through qPCR during each sampling event and wastewater quality parameters were provided by the plant operators. The literature review found mostly weak correlation between removal efficiencies and the existing literature did not support the recommendation of awarding virus concentration reduction credits to activated sludge secondary treatment. CrAssphage, f-specific coliphages and somatic coliphages all had the highest reported LRVs during secondary treatment at the full-scale plant of 2.5-log reduction. The lowest LRVs reported were 0.6-log for pepper mild mottle virus (PMMoV) and Cucumber Green mottle mosaic virus (CG). The variability in virus reduction during the secondary treatment was mostly due to virus quantification methodology and there was less desorption of viruses from solids due to the addition of Tween 80 surfactant as aeration progressed.

Keywords

Activated Sludge; Virus Reduction; Wastewater; Water Reuse

Disciplines

Environmental Engineering

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/

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