Advanced oxidation technologies (AOTs) such as ultraviolet photolysis, photocatalysis, sonochemistry, supercritical water oxidation, discharge plasma technology, and electron beam irradiation have been widely used in the field of wastewater treatment. In the application of discharge plasma technology, glow discharge, dielectric barrier discharge and pulsed corona discharge are the three main discharge types used for water treatment purposes [5]. Most of the previous works were studied in pulsed corona discharge plasma systems [6]. Due to the extremely short pulse width (approximately 500–1000 ns) and fast pulse rise time (nanosecond), this technique is more energy efficient than other AOTs and can generate a wider variety of reactive chemical free groups, such as ·OH, ·O , ·O2, and molecular species such as H2O2, O3[7, 8]. All these active substances have a high oxidation potential to oxidize ammonium sulfite. Therefore, pulsed corona discharge technology can be considered as a promising candidate for low operating cost ammonium sulfite oxidation. Ammonium sulfite oxidation reaction is a series of free radical chain reactions. The net reaction can be written as:
In pulsed high-voltage discharge systems, the structure of the discharge reactor (for wire, for plate, wire-to-plate, and ring-to-barrel) is determined by the configuration of the discharge electrode and the ground electrode, which may affect the formation of active species and the degradation of organic matter [9 , 10]. The multi-needle discharge reactor has been used in wastewater treatment for many years, showing that it can induce oxidation processes for the degradation of organic pollutants in aqueous solutions [6, 11]. In liquid discharge reactors, the effect of conductivity is crucial for the formation of discharge in water. In contrast to this reactor, gas phase reactors are not affected by conductivity.
In this paper, we investigate the feasibility of ammonium sulfite oxidation using a multi-anode pulse discharge reactor. Experiments were performed to determine the effects of capacitance, peak pulse voltage, electrode gap, and bubbling gas flow rate on the ammonium sulfite oxidation rate. This research can provide some experimental support for further improving the oxidation of ammonium sulfite by non-thermal plasma technology.