Study On Removal Of Microcystin By Dielectric Barrier Discharges

The safety problem of potable water is vital for the survival of human being. Water blooms caused by cyanobacteria, is going more and more serious, and microcystin produced by cyanobacteria creats a severe theat against the safty of potable water. Since the structures of microcystins are very stable, it is extremely difficult to remove them from drinking water by conventional water treatment technologies. Pulsed discharge non-thermal plasma process is one of innovative advanced oxidation technologies for water treatment, with many advantages such as high removal efficiency, nonselective, no secondary pollution and so on. This paper investigated the removal of microcystin-LR (MC-LR) by non-thermal plasma induced from bipolar narrow pulse power in a multi-high-electrode dielectric barrier discharge reactor.MC-LR is extracted from Microcystic aeruginosa cultured in the laboratory. Among several extraction methods, 5% acetic acid solution is chosen. Moreover, solid phase extraction and high performance liquid chromatography are adopted to analyze MC-LR after comparing the effects of washing and eluting solutions with different concentration of methanol on the enrichment process of solid phase extraction.MC-LR in water has been removed by non-thermal plasma generated by dielectric barrier discharge. The effect of electric parameters on the removal of MC-LR is investigated. An increase in the peak voltage and pulse repetitive rate improves the removal of MC-LR because of the increased energy inputted into the reactor. The results show an increase in gas flow rate is beneficial to remove MC-LR by non-thermal plasma. The effect of solution properties on the removal of MC-LR is also investigated. Solutions with higher electric conductivity inhibit the removal of MC-LR, while higher pH and lower initial concentration facilitate the removal of MC-LR. What's more, the removal of MC-LR can be expedited by adding Fe²⁺ in the reaction system, because Fe²⁺ can catalyze H₂O₂ and O₃ to form OH radicals.Removal mechanism of MC-LR by discharge is also discussed. In dielectric barrier discharge reactor, H₂O₂ and O₃ can be detected. And in the presence of MC-LR, the concentrations of H₂O₂ and O₃ decline, which implies that H₂O₂ and O₃ produced by discharge participate in the removal process of MC-LR. The experimental results by the addition of n-butanol as radical scavenger indicate that hydroxyl radicals play a predominant role in the removal process of MC-LR. According to total organic carbon results, MC-LR has been mineralized.