Elevating Electrode Durability in Locally Enhanced Electric Field Treatment (LEEFT) for Long-Term Water Disinfection with a Robust Stainless-Steel Brush

Abstract

Locally enhanced electric field treatment (LEEFT) has emerged over the past decade as a new chlorine-free approach for water disinfection. However, the nanowire-modified electrodes for LEEFT remain the bottleneck as they are prone to degradation. This study aims to elevate electrode durability with a robust stainless-steel brush, allowing the long-term operation of the LEEFT systems. A coaxial reactor featuring the brush as the center electrode was developed to combine both macro- and micro-scale electric field enhancements. The system was optimized by testing various waveforms, frequencies, and operational conditions (e.g., voltage, flow rate, and number of reactors in series) to evaluate disinfection performance, including inactivation efficiency and metal release. Control experiments, flow cytometry analysis, and scanning electron microscopy were conducted to clarify the inactivation mechanisms. The results indicate that unipolar pulses with high duty cycle and frequency are optimal, allowing effective operation at low voltages (tens of volts) with a flow rate of 2 mL/min. Electroporation assisted by reactive oxygen species is identified as the main mechanism for microbial inactivation. Notably, the brush electrode has enabled effective inactivation for over one month with minimal electrode corrosion, which is promising for real-world water disinfection applications.