Fig. 10. The generation of bulk nanobubbles in a semi-continuous system using a centrifugal multiphase pump (CMP). Atmospheric air is injected into the CMP (item 4 in the figure) and passed through the pump impellers. The impeller's shear forces cause a multiphasic (air/liquid) flow, which is then subjected to different operating pressures to saturate the air in the water. Then, the saturated water is forced through the needle valve (item 9) for bubble generation through hydrodynamic cavitation.¹¹⁹.