As we answer inquiries regarding ozone generators and advanced oxidation processes, we find that many people new to these technologies are interested in learning what equipment goes into an ozone water treatment system. We have developed a number of web pages on our site that address this issue (www.spartanwatertreatment.com/ozone-water-treatment-systems.html), but we thought that a few postings on the subject may be valuable as well.
When most people think of an ozone system, they initially think about an ozone generator. An ozone water treatment system, however, requires more components than just the ozone generator. A complete system requires a gas feed to supply oxygen, equipment to mix water and the ozonated gas, and possibly instruments/controls.
Ozone is made in the corona discharge process from oxygen found in air or from some other oxygen source, such as purchased liquid oxygen. The generator depending on design and gas will produce a stream that contains anywhere from 2-10% ozone by weight. The gas has to be very dry in order not to cause damage to the ozone generator, typically -70 degrees C (-100 Degrees F) dew point. This is only a 1 ppm of water in the gas. Purchased LOX is already dry, but if air is used as a source it must be dried thoroughly.
Ozone is more soluble in water than oxygen, but less soluble than chlorine. It is usually mixed with water using fine bubble diffusers or venturi injectors. Depending on the approach and design 75-95% of the ozone can be transferred in to the water. For most applications, such as disinfection, a certain amount of contact time is required to insure proper reaction. The contact vessel needs to be properly designed to provide the correct hydraulic detention time for the specific application, especially disinfection of drinking water.
Since less than 100% of the ozone is transferred to the water, provisions normally need to be made for treating the vent gas, EPA regulations indicate that the off gas should be less than 0.08 ppm ozone.
Depending on the critical nature of the application or the cost of the equipment, certain kinds of instruments may be used to monitor the process and protect the system. At a minimum, ambient ozone monitors must be used to detect leaks of ozone and shut down the generator in case of such leaks. Other instruments include dissolved ozone monitors, dew point monitors, high concentration ozone monitors, ORP monitors, etc.
In subsequent postings we will go into detail on each of these segments of an ozone water treatment system. Spartan Environmental Technologies is an ozone system integrator and can provide complete system packages for your applications contact us at (info@spartanwatertreatment.com or 800-492-1252).