PURPOSE: To make it possible to dissolve the whole or the most of the ozone to be injected into the prescribed aq. soln. used for a cooling or recirculating system by compounding another aq. soln. with ozone-contg. flow to form a compounded soln. and regulating the velocity of this compounded soln. to at least a specific value or slightly higher value.

CONSTITUTION: The ozone-contg. flow is formed by injecting the ozone via an ozone injecting means 28 operated to be accompanied with a prescribed drop of at least about 35 psi. Another aq. soln. is then compounded with the ozone-contg. flow. The resulted flow, i.e., the ozone-contg. flow or the compounded flow is fluidized or progressed in a conduit 33 at least at about 7 ft/sec for a distance sufficient for dissolving at least about 70% of the injected ozone. This distance is adjusted in accordance with only the underwater ozone material transfer rate.