School of Civil and Environmental Engineering

Ph.D. Thesis Defense Announcement

Locally Enhanced Electric Field Treatment with Copper for Practical Water Disinfection

By Mourin (Mo) Jarin

Advisor: Dr. Xing Xie

Committee Members:  Dr. Ching-Hua Huang (CEE), Yongsheng Chen (CEE), Dr. Sotira Yiacoumi (CEE), Dr. Nirupam Aich (Civil and Environmental Engineering, University of Nebraska-Lincoln)

Date and Time:  April 15th, 2025.  11am-1pm EST

Location: Ford ES&T L1205

ABSTRACT
Today, there are still ~800 million people worldwide who lack access to clean drinking water and over 2 billion without access to a safe water supply. Because of the challenges and concerns associated with current chemical water disinfection approaches, it is necessary to continue developing safe, and sustainable alternatives to disinfect our drinking water. Locally enhanced electric field treatment (LEEFT) has demonstrated great performance previously with low applied voltage and energy consumption. LEEFT with Cu (LEEFT-Cu) has also previously reported significant results with >6 log inactivation when the electric field treatment (EFT) was combined with in situ Cu release. This thesis aims to improve the fundamental understanding, elucidate the mechanisms, optimize the prototype performance, and perform the necessary market research for LEEFT-Cu to be commercialized for real-world application.
First, to elucidate the mechanisms of LEEFT-Cu, the inactivation of S. epidermidis is studied in situ at the single-cell level using a lab-on-a-chip (LOAC) device. The main mechanism is confirmed to be increased membrane permeability caused by the electric field, and then further damage through Cu ion penetration, ultimately leading to cell death. This work sets the foundation for synergistic success in LEEFT-Cu and establishes the fundamental understandings at which the technology can further mature for realistic application. Second, the synergy between EFT and copper (Cu), silver (Ag), and zinc (Zn) is further studied using an LOAC to understand the abilities of the antimicrobial metals in combination with EFT to inactivate S. epidermidis. Third, after understanding the fundamental synergies, the practical applicability of the LEEFT-Cu device for water disinfection is studied using 8 different bacteria species (4 gram-negative (G-) and 4 gram-positive (G+)), each grown in both stable and exponential phases. LEEFT-Cu achieved > 3 log inactivation for most bacteria (7/8) species using < 0.7 mg/L Cu. Additionally, the calculated degree of improvement using LEEFT-Cu in comparison to Cu ions alone indicated > 20 times increase in disinfection performance. This study sets the stage for LEEFT-Cu to be successfully commercialized within the water disinfection market. Fourth, market research and customer discovery of LEEFT-Cu was conducted for promising markets like decentralized treatment systems for remote areas and developing communities, large scale domestic hot water lines, and swimming pools and spas. Over 160 customer discovery interviews were accomplished, finding pools and spas the most promising first market for entry. Fifth, the culmination of literature and market research findings for LEEFT-Cu’s target market of pools and spas was accomplished. The current status of water disinfection technologies in the pool/spa industry (including chlorine, bromine, ozone, UV, and antimicrobial metals) was reviewed and summarized for its methods, trends, advantages, and disadvantages from a health and consumer viewpoint. Finally, the broad application-based findings in this thesis improve not only the fundamental understanding of LEEFT-Cu, but also enhance our abilities to further mature the technology for commercialization and change the outlook on the future of water disinfection.