Elimination of Microcystis aeruginosa in water via dielectric barrier discharge plasma: Efficacy, mechanism and toxin release.

Abstract Microcystis aeruginosa (M. aeruginosa), as the representative hazardous algae in cyanobacteria blooms, has long posed a threat to aquatic ecosystems. Here, a self-cooling dielectric barrier discharge plasma (DBDP) reactor was used to eliminate M. aeruginosa in water. The removal efficiency and mechanism of DBDP for M. aeruginosa and its toxin release during the treatment process was investigated. The results showed that over 99% of M. aeruginosa cells were removed by DBDP over 60 min under optimal conditions, and treated M. aeruginosa lost their ability to reproduce entirely. Reactive species generated in the self-cooling DBDP reactor damaged the membrane of M. aeruginosa, leading to leakage and degradation of dissolved organic matter. Increased intracellular reactive oxygen species accelerated the breakdown of protein and enzyme, and causes cell cytolysis. Eventually, M. aeruginosa was mineralized and lost its activity. The ·OH, 1O2 and ·O2- were crucial for inactivating M. aeruginosa. During the treatment process, the toxin microcystin-LR increased in the first 20 min, but declined over time: its concentration fell below 1 μg·mL-1 after 60 min. This study provides insight into M. aeruginosa’ s elimination in water by DBDP and has significant implications for developing a plasma technique to curtail cyanobacteria bloom.