I.S. Chang, J.H. Lee
Keywords: bromate, carcinogen, disinfection, high-voltage-impulses
Summary:Ozonation, the most common disinfection practice for bottled drinking water, produces various kinds of disinfection byproducts (DBPs). Among the DBPs, bromate (BrO3-) is notorious for its potential carcinogenic nature. It has been known that bromate is generated by the oxidative reaction between ozone and bromide (Br-). World health organization (WHO) limits the bromate to 10 ppb in drinking water. To reduce or minimize this bromate formation during disinfection processes, a high voltage impulse (HVI) technique was applied in this study. HVI has been used as an alternative disinfection process for non-thermal sterilization of foods because it does not alter the nutritional properties of foods such as avoiding loss of flavors and vitamins. Cell membranes of the microorganisms exposed to HVI are damaged and thus, their cells are torn leading to disinfection and/or sterilization. In this study, we designed and assembled a high voltage pulse generating system in our laboratory. The HVI system has consisted of a power supply, high voltage generator, capacitors, and impulse generator. The impulse with 10 to 20 kV/cm of electric fields was introduced to sample waters in order to monitor if bromate is formed or not. As the precursor of bromate, i.e., bromide (Br-) was spiked into the sample waters by 1,000 ppb, Bromate was analyzed by ion chromatography (Metrohm Inc., Swiss). Bromate was not generated at all times, indicating that the bromate formation was completely inhibited. A model microorganism, Escherichia coli is inoculated to the sample waters to test the disinfection efficiency. More than 2-log reduction (99 %) of E.coli was achieved after HVI treatment with 20kV/cm, 100Hz, 4μs pulse width. Consequently, the HVI technique could be used as an alternative strategy for bromate free-disinfection procedure for water disinfection.