Search

In this paper, an atmospheric touchable surface dielectric barrier discharge nonthermal plasma system was introduced. The typical plasma area, pulsed voltage, pulsed current, pulse frequency, and plasma power are 459 cm2, 6 kV, 5.5 A, 10 kHz and 140 W, respectively. Its disinfection performance was evaluated on agar plate, glass, and silicone hand by four bacteria including Escherichia coli, Staphylococcus aureus, Staphylococcus albus , and Pseudomonas aeruginosa . The efficiency of plasma disinfection was enhanced with increasing voltage and frequency, but had no significant difference with bacteria type. For a 10-s treatment of agar and silicone hand, the log reductions of bacteria were 2.35–2.6 and 2.85–3.26, respectively. After a 5-s treatment of glass, 3.3–3.68 log reduction of bacteria could be obtained.

In this paper, a new multiple-needle-cylinder reactor is designed to study the Escherichia coli inactivation with an unstable pulsed arc discharge in water and investigate the influence of several parameters for promoting its industrial application. The results show that the inactivation rate is mainly determined by energy density. About three orders reduction can be obtained with an initial cell count of $3\times 10^{5}$ CFU/mL and energy density around 2 J/mL. The inactivation rate can almost reach 100% when the energy density is around 8 J/mL. For reaching the maximum inactivation rate of this system, the parameters including initial water conductivity below $50~\mu \text{S}$ /cm, initial cell count over $10^{4}$ CFU/mL, and bubbling flow rate around 3.5 L/min are recommended. The water conductivity, pH value, and concentrations of hydrogen peroxide and ozone are also measured during the treatment to evaluate their influence. The transmission electron microscopy images of E. coli indicate that the intracellular morphology changes after plasma treatment.