Disinfection of Water Using Pulsed Power Technique: Effect of System Parameters and Kinetic Study

Abstract

The present study investigated the use of pulsed power technique for disinfection of water under different operating and environmental conditions. Final concentrations of reactive oxygen species (ROS) like hydroxyl radical, hydrogen peroxide, ozone and superoxide radicals generated in the system were found to be 56 mg/L, 17 mg/L, 1 mg/L and 18 mg/L, respectively, for an applied voltage of 23 kV, frequency of 25 Hz and a streamer discharge time of 12 min. It was observed that disinfection efficiency was high with sequential stress compared to continuous stress. The disinfection efficiency increased with increasing applied voltage and frequency. Disinfection efficiency was high when pH was less than 7. The presence of alkalinity, natural organic matter and turbidity reduced the disinfection efficiency significantly. For 7 log reduction of E. coli, the treatment time was increased from 6 min to 10 min, when pH was increased from 4 to 9. Complete disinfection of E. coli was achieved in a short treatment time of 4 min to 10 min, with an energy consumption of 0.0056 kWh to 0.014 kWh for 50 mL of contaminated water. An empirical model for optimum disinfection efficiency was developed using Box-Behnken design (BBD). As per the model, applied voltage, time of treatment and alkalinity were found to be the most significant factors affecting the disinfection efficiency. The model predicted values were in good agreement with the experimental values. Rate constant for disinfection and ROS formation was also evaluated. Rate of disinfection was between 0.59 and 1.68 log(cfu/mL)/min.