Charging for water disinfection – The Physics Congress 2003

A pulsed electric arc could provide an alternative to chlorination and other chemical methods of disinfecting water, according to researchers from the University of Poitiers, France, speaking to the Institute of Physics’ Congress on March 27 at Heriot-Watt University.

Water treatment is usually carried out using chlorine-containing disinfecting agents but these produce by-products that are coming under increasing scrutiny by the European Community. Chemical agents to destroy pollutants are also widely used. The Poitiers team working with a team, from McMaster University in Canada, is looking for an alternative approach that offers a compromise between the efficiency of the process and the environmental impact that it may have.

The researchers have investigated an electrical solution to water treatment as a viable alternative to chemical disinfectants. The approach is based on the remarkable properties of an electrical pulsed arc discharge in water. A high voltage arcing between submerged electrodes creates countless free radicals, highly reactive atoms or groups of atoms with an odd number of electrons, which can cause chain reactions in the water destroying any contaminant, polluting molecules, or pathogen present.

The researchers described a system based on a cylindrical vessel in which an electric arc is created between two rod-type electrodes at high voltage. Professor Hubert Romat and his team from the University of Poitiers are now investigating the optimal voltage and electrode gap required to eradicate potentially harmful compounds in the water. They have also looked at the waveform of the electric current to find the most efficient power and flow rate for the discharge.

The team is busy working on finding the best waveform but does not yet know what the final configuration that might be used in practice will be. Professor Romat suggests that the potential between the electrodes will be likely to be a few thousand volts, the electric current passing between them about 10,000 amps and the duration of each arc 50 microseconds. Whatever configuration works best could one day lead to effective water treatment in a flash, without the chemical by-products.