Potential of ozone micro-bombs in simultaneously fast removing bloom-forming cyanobacteria and in situ degrading microcystins

Aiming at effectively controlling the worldwide proliferation of cyanobacterial blooms, this study proposed a novel microbubble system - ozone micro-bombs for simultaneously fast removing cyanobacterial cells and in situ oxidatively degrading cyanotoxins. For producing the surface- and core-functionalized microbubbles - ozone micro-bombs, the zwitterionic surfactant-based bubble generation solution was modified with inorganic polymeric coagulant, and meanwhile, the bubble generation method was improved by injecting ozone during bubble creation. Featured as high gas holdup (>38%) and large specific surface area (<90 mu m in diameter), the ozone micro-bombs efficiently eliminated Microcystis aeruginosa cells (>93.2%) within 3-5 min; and simultaneously, approximately 88.9-98.4% and 66.1-79.1% of intracellular and extracellular micmcystin-LR (MC-LR) were removed, respectively. The efficient performance of cell separation by ozone micro-bombs ensured the high total MC-LR removal in spite of the cell lysis and the intracellular MC-LR release. During the treatment process, the surface-coated coagulant reinforced the capacity of microbubbles in capturing cells and dissolved organic matter; the ozone encapsulation in microbubbles enhanced the ozone transfer in water; the explosion of those microbombs released the oxidant of ozone and facilitated the degradation of MC-LR. Moreover, the cell re-growth was inhibited and the dissolved organic carbon got apparently decreased after treatment. With high feasibility and sound performance, the ozone micro-bomb technology is of great potential in in situ and thoroughly treating cyanobacterial blooms.

Automated summary

This study introduced a novel ozone micro-bomb system for effectively removing cyanobacterial cells and degrading cyanotoxins, demonstrating great potential in in situ and thorough treatment of cyanobacterial blooms.