Study On Degradation Of Organic Pollutants And Inactivation Of Algae And Bacteria Induced By Glow Discharge Plasma

Rapid industrialization bring large amount of pollutants into water, which deteriorateswater quality and treats the safety of ecosystem and health of human being. In recent years,much attention has paid to the the development of technology for the purification ofwastewater. Glow discharge plasma （GDP） is a novel electrochemical process, where plasmais sustained around the anode and the gas/liquid interface. In plasma, there are a lot of activespecies such as·OH and H2O2and both of them are oxidative substances, which can oxidizenearly all of organic pollutants into harmless substance carbon dioxide and water. Therefore,GDP is much suitable for the purification of wastewater. This paper study the degradation oforganic pollutants and inactivation of algae and bacteria induced by GDP, in order to providetheretical support for its application on purification of water.First of all, this paper investigated the effect of conductivity, electrolyte constituents andmetal ions on the degradation of organic pollutants such as phenol、cationic blue （CB） andacid orange 7 （AO） in GDP treatment. The results indicated that the discoloration rate of AOincreased with increasing conductivity of the Na2SO4solution and then decreased. Thediscoloration rate of AO was higher in the NaCl solution than in Na2SO4solution. Fe²⁺, Fe³⁺and Cr（VI） demonstrated apparent enhancing effects on the degradation of phenol and AO. Itwas because Fe²⁺, Fe³⁺can decompose H2O2into·OH, and Cr（VI） can capture·H, whichmake more·OH available for substrate.In addition, this work investigated the inactivation of Microcystis aeruginosa （MA）induced by GDP. The effects of electrode material、applied voltage, current and treatmenttime on the inactivation rate are critically examined. Based on the above results, the optimalconditions were chosen to sufficiently utilize chemically active species and enhance theinactivation of MA. Under the optimal conditions （voltage: 530 V; current: 30 mA;treatment time: 20 min）, the inactivation rate of algae was more than 90%. Nearly all ofdehydrogenase and chlorophyll-a of MA are removed within 5 days incubation afterinoculating. GDP can inactivate the MA, but it is found that H2O2and the change of pH arenot the key factors for the inactivation of MA.Furthermore, this work investigated the inactivation of Bacteria induced by GDP. Theinfluences of electrode material、applied voltage, current and treatment time on theinactivation rate were critically examined. Under the optimal conditions （voltage: 530 V;current: 30 mA; treatment time: 15 min）, the inactivation rates of these two bacteria reach100%. The concentration of protein increases to 25.99 mg/L, which demonstrates that GDPdeteriorate the integrity of bacteria’s cell.