School of Civil and Environmental Engineering

Ph.D. Thesis Defense Announcement

Advancing Wastewater-based Epidemiology: Engineered Solutions for Efficient Sampling and RNA Preservation of SARS-CoV-2

By Gyuhyon Cha

Advisor:

Dr. Konstantinos T. Konstantinidis

Committee Members:  Dr. Xing Xie (CEE/Georgia Tech), Dr. Ameet Pinto (CEE/Georgia Tech), Dr. Katherine Graham (CEE/Georgia Tech), Dr. Joe Brown (Gillings School of Global Public Health/UNC-Chapel Hill)

Date and Time:  April 12, 2024. 3:00 PM

Location: Ford Environmental Science & Technology Building, Room L1205

ABSTRACT
Wastewater-based epidemiology (WBE) has long been used to monitor infectious
disease trends in communities and has received special attention during the recent
SARS-CoV-2 pandemic. Composite sampling using autosamplers has been shown
to provide more robust representation of SARS-CoV-2 RNA levels in sewage
compared to traditional grab samples. However, autosamplers have cost- and
operation-related limitations for application for small-scale surveillance (e.g., at
the neighborhood or university campus level), for which identifying specific
infection hotspots is critical. Passive sampling may offer a cost-effective
alternative in such settings but there is limited field data on the efficacy of this
methodology. This thesis describes a study conducted on the Georgia Tech
campus that aimed to monitor SARS-CoV-2 dynamics in the wastewater from four
dormitories using various sampling methodologies. The results suggested that
passive Moore swabs can be as suitable as, if not more than, autosamplers for

sewage surveillance due to their increased sensitivity when wastewater flow is low
or intermittent. Furthermore, bioinformatics analysis of the resulting data offered
early signals of the introduction of new viral variants and guided prevention
strategies. Follow-up in-situ experiments showed that for the campus conditions
studied here the optimal deployment time of Moore swabs is about 6 hours before
they begin to saturate with fecal solids. Finally, the rapid degradation of SARSCoV-
2 RNA in sewage is a major limitation for the wide adoption of WBE,
particularly in remote locations where traditional cold-chain logistics are
challenging. To address this limitation, a novel cold-chain-free RNA preservation
method using porous superabsorbent polymer (PSAP) beads was validated as an
effective means to preserve SARS-CoV-2 RNA at room temperature. Collectively,
these results and methodologies advance the toolbox of WBE and make it more
widely accessible for public health monitoring.