(585z) Drinking Water Disinfection By Low Voltage Micro-Mini Pulsed Electric Field Device

Sim, V., The Hong Kong University of Science and Technology
Lam, K. W., The Hong Kong University of Science and Technology
Kwan, S. M., Hong Kong University of Science and Technology
Hung, P. S., The Hong Kong University of Science and Technology
Lee, O. W., The Hong Kong University of Science and Technology
Kwan, J. K. C., The Hong Kong University of Science and Technology
Yeung, K. L., The Hong Kong University of Science and Technology

The microbial contamination of building water supply systems is very common all over the world. Among the 29 common waterborne pathogens, Legionella pneumophila, Campylobacter jejuni, Shigella spp, and E. Coli have a relatively high infectivity, while non-tuberculous mycobacteria is also reported to be a high chlorine-resisting bacteria. This puts public heath in serious jeopardy. Water disinfection technologies such as chlorination, ozone disinfection, UV exposure and reverse osmosis are now widely used in drinking water disinfection. However, these technologies are not effective. In 2012, the discovery of Legionella in the water from the taps of Hong Kong’s brand new government headquarters illustrates the gravity of the situation and its potential threat to public health. Chemicals such as chlorine and ozone are powerful oxidizing agents that can kill most of the waterborne organisms, at the cost of producing unwanted by-products which are toxic. Reverse osmosis will remove all the minerals and nutrients inside the drinking water while and UV exposure may foster high infectivity microorganisms due to cell mutation. The current disinfection technologies bring a lot of questions other than disinfection effectiveness .

Pulse electric field disinfection is an effective, environmentally benign and safe technology for point-of-use disinfection of tap water. Microbial cell wall will be elongated and suppressed under a pulse electric field. This causes irreversible damage to the microbial cell wall. The inner structures such as cytoplasm of microbial will diffuse out of the cell through the enlarged pores. Thus, the microbial is no longer able survive. This disinfection technology avoids the use of chemical disinfectants that can alter the quality of the drinking water and induce resistance in microorganisms. It requires no heating so the energy consumption is far less than that of current disinfection technology such as ozone generation and reverse osmosis. The technology was first used for non-thermal sterilization pharmaceuticals and food products, eventually extending to sewage and clinical waste disinfection. However, the current technology uses high-input voltage pulse electric field as the key disinfection parameter. This creates a potential electrical hazard to operators. The design in this project is able to use low-input voltage with micro-engineered electrode to attain 99.9% bacteria reduction in the running tap water. The pulse electric field device is portable and small enough for home and public tap water. It believed that this device should be used as the last step for disinfection of drinking water from the water distribution system.