Disinfection of water using pulsed power technique: Effect of system parameters and kinetic study

• Sequential stress conditions showed better efficiency than continuous stress.
• Effect of voltage, frequency, alkalinity, pH and natural organic matter.
• An empirical model for disinfection was developed using response surface method.
• Kinetic study of bacterial disinfection and kinetics of reactive oxygen species.
• Bacterial inactivation is permanent by adapting pulsed power technique.

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, 17, 1 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. Presence of alkalinity, natural organic matter and turbidity reduced the disinfection efficiency significantly. For 7 log reduction of Escherichia coli, the treatment time was increased from 6 to 10 min, when pH was increased from 4 to 9. Complete disinfection of E. coli was achieved in a short treatment time of 4–10 min, with an energy consumption of 0.0056–0.014 kW h 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. 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.

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