Influence of Discharge Gap Parameters on Efficiency of Disinfection of Contaminated Water

High-voltage electric discharge in water initiated by a pulse with nanosecond front may serve as an effective method for microorganism inactivation [1]. We present results on the effect of strong impulse electric fields and discharges on the inactivation degree of E. coli bacteria in drinking and waste water. We use a Marx generator with maximum output voltage of ~ 1 00 kV as an energy source. The pulse duration $(0.3 < \tau < 3\mu \mathrm{s})$ and pulse front (~ 20 ns) were adjusted by varying the capacity of the discharge circuit and shortening the pulses in the output of the generator [2]. We used a pin-plane electrode system, with pin electrodes of both polarities. We find that high voltage pulses of positive polarity are a more effective pulsed mode, because of a higher rate of physical processes and rapid breakdown of water gap. Also, shortening the pulse front facilitates the penetration of the high-frequency electric field directly into the nuclei of biological cells. Microbiological analysis shows that the concentration of E. coli bacteria in treated water decreases from ~10⁸ CFU/cm³ to ~10³ CFU/cm³ after 1000 discharges at a voltage of ~45 kV and positive polarity of the pin electrode. The results of the experiments and calculations confirm the chosen functional dependence of energy released into water on parameters of electrode system. Application of the offered optimized high-voltage, short- front pulsed technology of water treatment seems to be more efficient and environmentally friendly rather than chemical water treatment.