Semester

Spring

Date of Graduation

2026

Document Type

Dissertation

Degree Type

PhD

College

Statler College of Engineering and Mineral Resources

Department

Civil and Environmental Engineering

Committee Chair

Emily Garner

Committee Member

Kevin Orner

Committee Member

Lian-Shin Lin

Committee Member

Leslie Hopkinson

Committee Member

Leigh-Anne Krometis

Abstract

Access to clean and safe drinking water remains one of the most persistent public health and environmental challenges in the United States. Maintaining water quality after leaving the treatment plant in drinking water distribution systems (DWDS) is a complicated and often overlooked challenge. Most research focuses on water treatment and source water quality, but not on the miles of pipe that follow. Aging infrastructure, complex flow patterns in the DWDS, and limited resources make water quality management especially difficult. This dissertation includes three core studies: 1) A system-level analysis of small and rural utilities in the geographically complex region of West Virginia that face unique difficulties due to aging infrastructure, limited workforce capacity, and economic hardship; 2) A lab scale investigation to better understand the impact of flow hydrodynamics on biofilm development and its composition in DWDS; 3) A lab scale investigation to determine the impact of composition of biofilm extracellular polymeric substances (EPS) on the formation of disinfection byproducts (DBP). Together, these studies show how physical conditions, biological growth, and chemical reactions interact to influence water quality. The findings offer practical insights for improving DWDS design and operation strategies to protect public health more effectively

In the first study, to investigate the operational, managerial, technical, and financial challenges that plague particularly vulnerable DWDS located in rural communities, data was compiled from several state and national datasets related to regulatory compliance, infrastructure and workforce characteristics, and affordability of West Virginia DWDS. Relationships among infrastructure metrics (miles of main line, number of storage tanks, number of booster stations, annual water main breaks, annual total number of breaks, and annual total number of leaks), and regulatory compliance were examined. Workforce size and water bill affordability were also assessed to better understand the constraints of small and rural DWDS in West Virginia. Results showed that very small utilities (serving < 500 customers) had more frequent violations, fewer full-time employees, higher unaccounted-for water losses, and longer pipe miles per customer compared to small (serving 501 – 3,300 customers) and medium (serving 3,301 – 10,000 customers) utilities. These issues highlight the relationship between operational capacity of utilities and provision of reliably safe drinking water.

Hydrodynamics play an important role in the production of biofilms that is often neglected in the examination of water quality in DWDSs. In the second study, benchtop biofilm reactors were used to cultivate Pseudomonas fluorescens biofilms under three shear stress conditions (0.317, 1.72, and 3.87 Pa) representing low, medium, and high flow regimes in DWDS. Scanning electron microscopy (SEM) was used to examine biofilm morphology, and proteins and polysaccharides were quantified to characterize EPS composition. Fourier transform infrared (FTIR) spectroscopy was applied to identify functional groups associated with EPS. Results demonstrated a strong relationship between shear stress and biofilm properties. Low shear stress conditions promoted growth of biofilms and production of extracellular proteins and polysaccharides. As shear stress increased in medium flow conditions, concentration of proteins and polysaccharides in EPS was lower compared to the low shear condition and thinner, less cohesive biofilms were observed. High shear stress reduced overall biomass accumulation and slowed biofilm maturation, resulting in less stable films.

Biofilm growth is facilitated by the production of EPS, which consists of proteins, polysaccharides, lipids, and extracellular DNA. These components, particularly proteins and polysaccharides, are known to promote DBP formation when exposed to free chlorine. In the third study, biofilms developed in benchtop reactors were suspended in free chlorine concentrations of 0.5 mg/L to 4 mg/L. Despite the presence of free chlorine, biofilms persisted from all flow conditions and acted as reservoirs for organic matter. SEM images showed the greatest biofilm disruption and EPS degradation under medium shear stress, corresponding to intensified chlorine interaction. FTIR spectra supported this observation, showing lower absorbance intensities in amide and carbohydrate regions under medium shear stress, indicating extensive EPS oxidation. Spearman rank correlation analyses of total trihalomethanes (TTHMs), total haloacetic acids (THAA5s), and EPS constituents revealed significant positive relationships between DBPs formation and both protein and polysaccharide concentrations in biofilms. These findings confirm that EPS components serve as key precursors for DBP generation when chlorinated and provide insight into the flow conditions that may disproportionately result in biofilms prone to facilitate formation of DBPs.

Overall, this research highlights the critical interplay among hydrodynamic conditions, biofilm structure, EPS composition, and DBP formation in DWDS, while highlighting the particular vulnerability of rural DWDS to water quality degradation. Understanding these relationships provides valuable insight that can be applied to optimize flow conditions, improve disinfection efficiency, and minimize DBP formation, thereby ensuring safer and more sustainable drinking water quality.

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