Disinfection of deionised water using AC high voltage

Abstract

A new type of water purification device that uses a high-magnitude electric field to kill micro-organisms has been developed (Johnstone and Bodger, 1997). This device uses a 6000 V, 50 Hz high-voltage supply applied directly across a flow of deionised water. The area of high-magnitude electric field causes disruption of cellular membranes and leads to a loss of cell viability and infectiveness. This disinfection process required some technical changes to enable its commercial development. A new prototype model of a domestic drinking water device has been constructed with these changes in mind. The initial electrode system and power supply were redesigned to enable them to be easily manufactured. The redesigned system uses a different electrode shape, material and dimensions, although the critical parameters of electric field strength and flow rate remain unchanged. To verify that the electrical and biological performances were still valid, tests were undertaken on the new design. It is shown that the new electrode system is more electrically robust, is easily and cheaply manufactured, and provides a similar disinfection performance. The device was tested on a common bacteria Serratia marcescens and proved close to a three log reduction in viability. The device was also tested on a parasitic protozoan Giardia lamblia. No viable Giardia cysts were detected following treatment.