Study On Treatment Of Wastewater By Pulse Dielectric Barrier Discharge Plasma

Pulsed discharge plasma used to treatment wastewater is a recently developed advanced oxidation technology. It contains multiple oxidative effects, such as high-energy electrons, hydroxyl radicals, ozone, hydrogen peroxide, ultraviolet (UV)and so on. It has advantages of non-selectivity, high efficiency and less secondary pollution. Since the process can degrade the chemical bonds efficiently at the room temperature and require no additives, it is prospective in the industrial application.In this paper, the pulsed dielectric barrier discharge plasma was used to treat landfill leachate and simulated wastewater made by rhodamine B. The main contents of this research are as follows:(1) Established a set of plasma system dealing with wastewater. The system is constituted by the power supply and the reactor. The power supply uses the high-voltage pulse source which can provide a steep rising edge and a small pulse width. Under this circumstance, only the electrons are accelerated to form high-energy electrons. The reactor are in the form of dielectric barrier discharge structure, which can generate a large area of the discharge channels for industrial application. The electrodes are covered with dielectrics to avoid the discharge electrolysis effect and Joule heating.(2) Designed the reactor A for actual wastewater treatment of landfill leachate in the form of mixing gas and liquid phases. The advantage of this structure is that the strong electric field can act directly on the liquid in the process of degradation of wastewater. In addition, using atomizing nozzle in the water recycle can increase the contacts of active oxidants and pollutants. Discharge time, oxygen injection, initial pH value and combined with Fenton reaction were studies to see their influences of COD removal. The results showed that when the discharge treatment was combined with Fenton reaction under oxygen injection, the pH is 3 and the dealing time of 40minutes, the COD removal of landfill leachate reached 60%. At the same time, the decolorization effect was obvious.(3) Designed the reactor B for simulated wastewater treatment of rhodamine B in the form of making liquid phase as one electrode. The main advantage of this system is that the wastewater was employed as one of the electrodes for the degradation of rhodamine B, which made use of high conductivity and lessened its negative influence on the discharge process. The effects of some factors like peak pulse voltage, discharge frequency, pH conditions and synergistic reaction of ultraviolet (UV) were investigated. The results showed that the combination of these reactive species could enhance the degradation of the dye while the ozone played the most important role in the process. The degradation efficiency was enhanced with the increase of energy supplied. The removal of rhodamine B could reach 99.9% under the condition of high solution conductivity.(4) Summarized the generating process and degradation mechanism of the main strong oxidants (hydroxyl radicals and ozone) during the pulsed discharge plasma for water. On this basis, the process of the degradation of rhodamine B and degradation products were inferred. The final degradation products of rhodamine B might be small molecules such as organic acids, alcohols, aldehydes, and so on.