To maximize ozone's effectiveness as an oxidizer, the transfer of ozone into the water must be optimized. In order to do so, the surface exchange area of gas bubbles entering the water must be maximized. Increasing the number of gas bubbles while decreasing the diameter of each increases the total surface exchange area, enhancing mass transfer.

There are two basic ways to accomplish the transfer of ozone into water. One pushes the gas through a diffuser and the other draws it into the water through a venturini injection system. Diffusers are available in a variety of shapes and sizes, and are typically made from ceramic, plastic or metal. Optimum transfer efficiency is obtained when the bubble size is between 2 and 5 millimeters in diameter. Challenges to minimizing bubble size include the water's surface tension and the natural tendency of gas bubbles to reform into larger ones.

Venturini injection systems employ the principle of vacuum to get the ozone gas into the water. Water is forced through a small orifice in the venturim, creating a pressure differential between an area of high pressure on the inlet side of the venturi and the lower pressure area on the outlet side. The pressure differential creates a vacuum, which aggressively pulls the gas from the ozone generator into the water. A correct balance of air and water flow - achieved by properly sizing the venturi and adjusting the water flow through the injector manifold - will provide very high ozone mass transfer efficiencies (>95%).

The volume of water being treated and the types and concentrations of contaminants affect which type of system should be employed. Diffusers are used when long-term, passive contact will achieve the water treatment goals. Venturi systems are used in a much wider variety of applications, when lower volumes of water are involved and when more precise dosages must be maintained.

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