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

• O 3 micro-bombs were surface- and core-modified by coagulant and O 3 , respectively. • Removing cells and in situ degrading microcystin-LR were achieved simultaneously. • Coated coagulant helped to effectively capture cells and dissolved organic matter. • Micro-bombs exploded, released oxidant and facilitated microcystin-LR degradation. • Re-growth of cells was inhibited after the ozone micro-bomb treatment. 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 µm 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 microcystin-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 micro-bombs 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. [ABSTRACT FROM AUTHOR]