Fast Bacteria Inactivation of Waste Water by Gas-liquid Plasma

The experimental investigations of bacteria inactivation of waste water were carried out in a gas-liquid discharge reactor. Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) were selected as the typical Gram-negative and Gram-positive bacteria to study the sterilization efficiency of the device. The experimental results showed that pulsed discharges had a great effect of fast inactivation on microorganisms in waste water. After only 3 minutes of plasma treatment, the sterilization rates of both E. coli and S. aureus could reach to 99.99%. To investigate the sterilization mechanism of plasma, observations of scanning electron microscopy (SEM) and measurements of protein leakage were made. After plasma treatment, structures and morphologies of both two bacteria cells had undergone significant variations. With the increment of the discharge treatment time, protein leakage of the two bacteria kept increasing. The active radicals, high electric field and shock waves may work together to cause the severe damage of bacteria by interacting with cell walls. This may provide technical guide for the further application of microbial inactivation by gas-liquid plasma in waste water.