If you're looking for an effective water treatment plan, ozone is a powerful oxidizer and disinfectant. To create ozone for water treatment, however, you'll need a generator on site. What is an ozone generator? It's a device that breaks apart oxygen molecules (O2) and recombines them to form ozone O3. There are several ways this can be done, and each generation method has its pros and cons.
Simply put, ozone generators work by combining oxygen (O2) with energy to produce ozone (O3). When the oxygen molecules are exposed to energy, the two atoms are broken apart. The single oxygen atoms quickly bond in groups of three to form ozone.
Ozone is created in the earth's atmosphere in the same way that an ozone generator works. In sunlight, the ultraviolet (UV) energy splits some of the O2 molecules to create ozone. The ozone layer in the upper atmosphere absorbs certain wavelengths of UV light, helping to protect life on earth, which could be hurt by this type of radiation.
Lightning also creates ozone. The sudden burst of energy in the air splits oxygen molecules, often leaving behind the sharp smell of ozone.
One of the challenges of using ozone in water treatment (and for other purposes) is that it cannot be effectively stored or transported. It decays quickly to form O2, so it must be made where it's going to be used.
Creating ozone seems pretty simple, but to do so on a scale big enough to produce the concentrations and amounts large enough for water treatment is a different matter. The most common ozone generation methods are UV and corona discharge, although cold plasma and electrolytic methods are also used.
What is a UV ozone generator? This type of system works to produce ozone much like it is made in the upper atmosphere. Normal air – a little more than 20% of which is oxygen – is exposed to a narrow-band UV light. This light adds energy to the oxygen, splitting up the atoms so that they can recombine to make ozone.
UV ozone systems are among the least expensive types of ozone generators. They produce ozone relatively slowly, however, and in concentrations of about 0.5% or less.
How does a corona discharge ozone generator work? This type of system works much the same way that lightning makes ozone. Oxygen is exposed to an electrical field, which adds the energy needed to break the atoms apart. One of the challenges of this type of system is that the air needs to be very dry for ozone to be produced efficiently. Humid air not only makes less ozone, it can also lead to the creation of nitric acid, which can corrode the generator parts.
This type of system produces higher concentrations of ozone (3% - 6%) more quickly than the UV method, but it's more expensive and often requires additional equipment to work at its best. In some cases, an oxygen concentrator may also be used to increase production the of ozone.
While UV and corona discharge are the most common ways to generate ozone, there are other methods. A cold plasma ozone generator works by exposing pure oxygen to plasma, a form of matter created between two electrodes separated by an insulating barrier. The plasma causes the O2 to split apart. Ozone can also be generated using electrolytic ozone generation, which divides water molecules instead of oxygen.
Ozone generators do work, but their effectiveness depends on what you're using the ozone for. A UV ozone generator, for example, produces relatively low concentrations of ozone; it's good for smaller systems and doesn't need dry air to work effectively. Corona discharge generators, on the other hand, produce higher concentrations of ozone over a shorter amount of time. They also may require the use of an air dryer, however, and can be more expensive than UV systems. To work effectively, you need to find the right size system that produces the appropriate concentration of ozone for your needs.
According to the EPA and other U.S. government agencies, ozone air purifiers don't work. At concentrations low enough to be safe to breathe, studies show that ozone is not effective at removing air-borne pollutants, odor-causing chemicals, or microorganisms. Learn more from the EPA's report on Ozone Generators that are Sold as Air Cleaners.