The microbial contamination of building water supply system is very common worldwide. Among the 29 common waterborne pathogens, Legionella pneumophila, Campylobacter jejuni and Mycobacterium species have a relatively high infectivity, while non-tuberculous mycobacteria is a high chlorine-resistant bacteria. Legionella and Mycobacterium are also reported to be fatal. This puts public heath in serious jeopardy.
Technologies such as chlorination, ozone disinfection, UV exposure and reverse osmosis are now widely used in drinking water disinfection. However, these disinfection technologies are not effective. The discovery of Legionella in the water from the taps of Hong Kong’s brand new government headquarters illustrates the gravity of the situation. The situation is exacerbated by the occurrence of multidrug-resistant genes in microbial biofilms of building pipelines and the ineffectiveness of current disinfection technologies. Thus, it is necessary to minimize the amount of pathogens that affect human health by using a new disinfection technology, pulse electric field disinfection.
Pulse electric field (PEF) disinfection is an effective, environmentally benign and safe technology for point-of-use disinfection of tap water based on the poration of microbial cell wall under the electric field. This new disinfection technology avoids the use of chemical disinfectants that can alter the quality of the drinking water and induce resistance in microorganisms. Current PEF technology, however, uses high-input voltage pulse electric field as the key disinfection parameter. The device in this research is designed to use low-input voltage to attain 99.9 percent bacteria reduction in the running tap water. With the PEF device installed onto taps, most of the waterborne pathogens, including Legionella and Mycobacterium, in building water systems will be killed when they pass the device.
The pulse electric field device in the near future will become portable and compatible to all domestic taps in Hong Kong. It is believed that this device should be used as the final step for disinfection of drinking water from the water distribution system. This is going to prevent disease outbreak by improving the quality of our source of life, water.