Safety of drinking water has become a concern of Hong Kong people. Not only would they install water purifiers, they also get used to boiling water before drinking. Potable water can be easily contaminated as it travels through building water tanks and pipes, which are the breeding grounds for waterborne pathogens like Legionella bacteria and E coli bacteria.

After successfully developing the world’s first smart anti-microbial coating, Prof King-Lun Yeung, Associate Dean of the School of Engineering, Department of Chemical and Biomolecular Engineering, and Prof Joseph Kwan, Director of Health, Safety and Environment Office, worked together again to bring a revolutionary change to water disinfection with the innovative invention of a mini pulsed electric field device. “Chlorination is the most common method for water disinfection but the gas can also react with organic compounds found in water and produce toxic by-products. By applying physics mechanisms, we hope to create the same results without adding unwanted chemicals into our drinking water,” said Prof Yeung. He added that heating and reverse osmosis were effective but energy consuming and relatively expensive.

The mini pulsed electric field device is made of stainless steel with many small holes on it and installed with tailor-made tiny electrodes. It creates an electric field that destroys cell membranes, killing effectively over 90 percent of waterborne bacteria and does not cause gene mutation in the pathogens. The technology of pulsed electric field has been widely applied in industries for a long time, such as disinfection of fruit juices, but existing technology requires the use of large scale appliances and a gargantuan electricity supply of more than 100,000 volts, which posts potential threats of electrical hazards to operators. The new device can operate for half a year on two AA batteries, creating a current of 30 volts, and is safe and energy saving. “We hope to miniaturize the technology and make it a common and more cost effective one so that it can be used in everyday family life. This mini device can be installed on any water taps, shower heads and water tanks, disinfected water before making contact with users, ,” said Prof Kwan.

The research team is now testing the new technology in local public hospitals. The team expects that with further revision, the technology can be applied to disinfect water used for organ transplant procedures, which holds the most rigorous standards in medical applications. The low price of the device makes it an ideal candidate for mass adaptation in developing countries, serving clean water to the general populace and reduces the number of diseases caused by contaminated water sources.