LAUSR

Abstract Underwater pulsed arc discharge is a potential method applying on sewage disinfection. The disinfection effect may be influenced by electrode parameters. In this paper, effects of different electrode materials, gap distances and electrode shapes were studied with underwater pulsed arc discharge. The following results were obtained through experiments. Reactive species production of different materials are arranged from largest to smallest is W, Titanium alloy and Ti. However, the difference of pressure amplitude among three materials is less than 0.88%. Under the influence of these physical and chemical effects, with 800 s’ treatment, the residual Escherichia coli content of W, Titanium alloy, and Ti is 103.77 CFU/L, 104.29 CFU/L, and 104.87 CFU/L. W shows the best disinfection effect, which generated 2.2 orders reduction with an energy density of 0.6 J/mL. It can be found that the disinfection effect has a positive correlation with the electron work function of material. When the voltage is constant, the discharge dispersion increases as the gap distance increases. At a discharge voltage of 4.5 kV, with the gap distance changing from 0.25 to 1.50 mm, the total spectral intensity decreases, and the pressure amplitude increases first and then decreases. The study shows disinfection efficiency keeps the same trend with the change of pressure wave. And there is an optimal distance in sewage disinfection. Under the experimental conditions in this manuscript, the optimal distance is 1 mm. For the three electrode shapes, the pressure amplitude and total spectral intensity of rod shape are higher than hemisphere and cone shape. As a result, the rod electrode presented the highest disinfection effect, which residual Escherichia coli content is 103.63 CFU/L after 800 s’ treatment.