|The locally enhanced electric field treatment, or LEEFT, inactivates pathogens by irreversible electroporation from an enhanced electric field near the tips of the nanowires.|
By Polly Wilson
Researchers in the School of Civil and Environmental Engineering have developed a device that kills pathogens in drinking water using an electric field. The tubular system can fit inside water distributions systems to deliver safe drinking water.
Drinking water typically goes through two disinfection phases. The first occurs at a treatment plant. The second combats pathogen regrowth and takes place in the pipe distribution system. Chlorination is a common part of this disinfection process. It is cheap, efficient and residual chlorine acts as a secondary treatment. It also has challenges to do with transport, storage and carcinogenic byproducts. Alternative disinfection techniques include membrane filtration, ozonation and UV. However, high costs, bromate byproducts and microbial regrowth in pipelines are the respective drawbacks of those alternatives. The ideal solution combines continuous disinfection with minimal maintenance, low power requirements and low costs.
That's where Xing Xie, Carlton S. Wilder Assistant Professor of Environmental Engineering, comes in. Xie and his fellow researchers devised another disinfection system, which uses locally enhanced electric field treatment to kill pathogens. Central to the system are electrodes comprised of vertically aligned copper oxide nanowires coated with a protective polydomamine layer. Commercially available aluminium or copper tubing can serve as outer electrodes, making this tubular coaxial configuration scalable and compatible with current pipes.
The system creates a strong localised electric field around the nanowire tips – known as the lightening rod effect. Electrophoresis drives cells towards the centre of the device where irreversible electroporation kills them. Bulk water only encounters the background electric field. The system consumes just 1.4Jl–1 at an applied voltage of 1V, a power level that flowing water can generate in situ.
"In a real-world scenario, segments of pipelines can be replaced with the locally enhanced electric field device every certain distance to provide consecutive antimicrobial power,’ Xie said.