Sterilization by electrohydraulic treatment

Lethal effects of electric current on Escherichia coli

An attempt has been made to use low-voltage alternating current to kill microorganisms such as Escherichia coli. The bactericidal effect depends on the energy passing through the suspension and on the time during which the cells are left standing in the medium after the treatment. Most of the toxicity is due to an indirect effect developed with unalterable electrodes in the presence of chlorides in the medium. This method might be applied to eliminate pollution of natural waters.

Virucidal effect of transient electric arcs in aqueous systems

Bacterial and animal viruses were inactivated by high voltage electrical discharges in water. The sensitivity of phages to the immediate component of this effect was correlated to the sensitivity to ultraviolet radiation. Transient electrical arcs in weak electrolytes also generated chemical compounds which were virucidal against phages T3, T5, and varphiX174 but were only slightly virucidal against phages T2 and T4.

Inactivation of microorganisms by electrohydraulic shock

The electrohydraulic shock treatment of microorganisms was accomplished by discharging high-voltage electricity (8 to 15 kv) across an electrode gap below the surface of aqueous suspensions of the microorganisms. This treatment was effective in destroying Escherichia coli, Streptococcus faecalis, vegetative cells and spores of Bacillus subtilis, and bacteriophage specific for S. cremoris ML1. The presence of added protein in bacterial suspensions resulted in reduced bactericidal action. Water subjected to electrohydraulic treatment retained a certain amount of toxicity when copper-core electrodes were used to apply the treatment. This was caused by copper liberated from the electrode during electrohydraulic discharge.

Disinfection by electrohydraulic treatment

Electrohydraulic treatment was applied to suspensions of Escherichia coli, spores of Bacillus subtilis var. niger, Saccharomyces cerevisiae, and bacteriophage T2 at an input energy that, in most cases, was below the energy required to sterilize. The input energy was held relatively constant for each of these microorganisms, but the capacitance and voltage were varied. Data are presented which show the degree of disinfection as a function of capacitance and voltage. In all cases, the degree of disinfection for a given input energy increases as both capacitance and voltage are lowered.