CAREER: Locally Enhanced Electric Field Treatment (LEEFT) for Chemical-Free Water Disinfection

Over 800 million people worldwide do not have adequate supply of safe drinking water. In many areas serviced by drinking water treatment plants, chlorine is used to kill harmful microbes. However, chlorination can produce chemicals that are known human carcinogens. An innovative technology that can provide point-of-service treatment to areas without adequate drinking water supply is locally enhanced electric field treatment (LEEFT). High disinfection has been achieved by LEEFT operated at low voltages with a short treatment time of a few seconds. LEEFT has the added benefits of being relatively inexpensive, chemical-free, robust, and easy to operate. In this project, the PI will study how harmful microbes in drinking water are killed during LEEFT treatment. This work has the goal of developing LEEFT for wide-scale adoption for drinking water treatment to protect public health. The educational plan of this project focuses on training future environmental engineering leaders at the high school, undergraduate, and graduate level. This effort will be complimented by public outreach to increase awareness of water safety and better prepare the public to respond to disruptions in water supply due to unexpected natural disasters.<br/><br/>LEEFT is a physical treatment process that aims to utilize a strong electric field to disrupt cell membranes and thus inactivate pathogens in drinking water. The electrodes installed in a LEEFT device are typically modified with one-dimensional nanostructures so that the electric field is not uniform but enhanced locally near the tips of the nanostructures. This project will systematically investigate the behavior of bacteria during LEEFT with four specific objectives: i) obtaining LEEFT platforms that are suitable for mechanistic study, ii) understanding the mechanisms for bacteria inactivation during LEEFT, iii) revealing the processes for cell transportation in LEEFT devices, and iv) developing a mechanistic model of LEEFT for performance prediction. The core hypothesis is that during LEEFT, bacteria are transported to the regions with strong electric field by a combination of hydrodynamic-, electrophoretic-, and dielectrophoretic-forces, and then inactivated primarily due to irreversible electroporation. Some platforms in this project will be constructed on lab-on-a-chip devices fabricated using micro-electro-mechanical-systems (MEMS) technologies. LEEFT experiments will be performed under various conditions, e.g., electrode materials, frequency of the electric pulses, mixing conditions, and model bacteria. The model will be built based on experimental results using COMSOL Multiphysics, a software using advanced numerical methods to analyze, solve, and simulate physics-based problems. The integrated educational activities involve a program entitled WE-HUG (Water-safety Education and training for High school, Undergraduate, & Graduate students), where a vertical team of high school teachers and students are recruited to develop and deliver education modules that reflect the scientific and engineering aspects of the project.<br/><br/>This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.