Dissolved Ozone Measurement In Pharmaceutical Water

By Mettler-Toledo AG, Process Analytical, Inc.

Ozone (O3) is an unstable tri-atomic form of oxygen. It is a very strongly oxidizing gas that is injected into water to remove organics that may contribute color, odor or taste. Most importantly, ozone sanitizes the water, rapidly destroying any microbiological contamination. Dissolved ozone reverts back to harmless oxygen in a matter of minutes, depending on the temperature and pH of the water, so it must be generated and measured right next to the process. Ozone leaves virtually no harmful breakdown products.

Ozone generators operate by passing dry air or oxygen next to high voltage electrodes where a corona discharge converts some of the oxygen to ozone, similar to the reaction caused by a lightning storm. The gas mixture is then contacted with the water, either in a tank diffusion system or in a pipe with venturi injector. Intimate contact is made to maximize the dissolution. There are newer generation techniques that can produce ozone directly in the water and reduce the possibility of atmospheric losses.

Ozone is an excellent material for disinfecting pharmaceutical water systems. However, it is an undesirable addition to point of use pharmaceutical water. In order to eliminate the ozone, a UV light source is employed to effectively destroy it after the disinfection process is complete. The UV light also has the added benefit of providing further disinfection.