Study On Low-voltage Pulsed Electric Field Technology For Tap Water Desinfection Of Water Supply Network Terminal

As the pollution of water environment becomes more serious,the pathogenic microorganism in the tap water has become the major cause of diseases and a serious threat to human health.The existing water-disinfecting process cannot ensure ideal disinfection effect,and the disinfection by-products also become a threat to human health.Normally,tap water is delivered through long-distance water supply network,pathogenic microorganism could reproduce and recolonize in the network,leading to the decline of water quality of water network terminals.Therefore,it is necessary to develop a technology that can disinfect the water at the terminals of water network.As a new type of non-thermal disinfection technology,pulsed electric field(PEF)is a kind of technology with non-toxic by-products,low energy consumption and good effect.In this paper,the application of low voltage pulsed electric field technology to tap water disinfection of water supply network terminals was studied.A small-sized treatment chamber was designed to reduce the pulsed electric voltage,and the gap between electrodes was minimized to 250?m.The disinfection effect and security of low-voltage pulsed electric field technology would be assessed through testing the inactivation rate of bacteria,water quality before and after treatment,electrode corrosion condition.Firstly,the PEF electrodes was designed to be consisted of copper(anode),stainless steel(cathode)and Polytetrafluorethylene(Teflon)as insulating coating.E.coli was selected as the experiment object.The test result suggested that under 200 V voltage,after 15 min treatment,PEF eliminated 82% of E.coli while had no obvious affect on water quality,the insulating coating was still intact.Secondly,a coaxial micro-gap continuous treatment chamber was designed.Micro-filtration membrane was applied between the electrodes to filter more bacteria in the chamber and increase the treating time by PEF.E.coli was selected as the experiment object.The test result suggested,when pulsed voltage was 200 V and water flow was 1L/min,after10 min treatment,PEF eliminated 90% of E.coli,the water quality had not been affected,the micro-filtration membrane filtered 99% of E.coli and water quality was not affected by PEF.Finally,the field test of the treatment chamber was carried out in a hospital,the total number of bacteria in tap water was the experiment object.The test result suggested,when pulsed voltage was 200 V and water flow was 1L/min,after 10 min treatment,90% of bacterial was filtered on the membrane,PEF eliminated 90% of the total bacteria,while the water quality met the drinking water quality standard.