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Ozone is an unstable gas comprising of three oxygen atoms, the gas will readily degrade
back to oxygen, and during this transition a free oxygen atom, or free radical form. The free
oxygen radical is highly reactive and short lived, under normal conditions it will only survive
for milliseconds.
Ozone is a colorless gas that has an odor similar to the smell of the air after a major
thunderstorm.
Ozone has a greater disinfection effectiveness against bacteria and viruses compared to
chlorination. In addition, the oxidizing properties can also reduce the concentration of iron,
manganese, sulfur and reduce or eliminate taste and odor problems. Ozone oxides the iron,
manganese, and sulfur in the water to form insoluble metal oxides or elemental sulfur.
These insoluble particles are then removed by postfiltration. Organic particles and
chemicals will be eliminated through either coagulation or chemical oxidation. Ozone is
unstable, and it will degrade over a time frame ranging from a few seconds to 30 minutes.
The rate of degradation is a function of water chemistry, pH and water temperature.
Ozonation Process
The formation of oxygen into ozone occurs with the use of energy. This process is carried
out by an electric discharge field as in the CDtype ozone generators (corona discharge
simulation of the lightning), or by ultraviolet radiation as in UVtype ozone generators
(simulation of the ultraviolet rays from the sun). In addition to these commercial methods,
ozone may also be made through electrolytic and chemical reactions. In general, an
ozonation system includes passing dry, clean air through a high voltage electric discharge,
i.e., corona discharge, which creates and ozone concentration of approximately 1% or
10,000 mg/L. In treating small quantities of waste, the UV ozonation is the most common
while largescale systems use either corona discharge or other bulk ozoneproducing
methods.
The raw water is then passed through a venturi throat which creates a vacuum and pulls the
ozone gas into the water or the air is then bubbled up through the water being treated.
Since the ozone will react with metals to create insoluble metal oxides, post filtration is
required.
Primary Advantages to Ozone
1. Ozone is effect over a wide pH range and rapidly reacts with bacteria, viruses, and
protozoans and has stronger germicidal properties then chlorination. Has a very strong
oxidizing power with a short reaction time.
2.The treatment process does not add chemicals to the water.
3. Ozone can eliminate a wide variety of inorganic, organic and microbiological problems
and taste and odor problems. The microbiological agents include bacteria, viruses, and
protozoans (such as Giardia and Cryptosporidium).
Disadvantages to Ozone
1. There are higher equipment and operational costs and it may be more difficult to find
professional proficient in ozone treatment and system maintenance.
2. Ozonation provides no germicidal or disinfection residual to inhibit or prevent regrowth.
3. Ozonation byproducts are still being evaluated and it is possible that some byproducts
by be carcinogenic. These may include brominated byproducts, aldehydes, ketones, and carboxylic acids. This is one reason that the postfiltration system may include an activate
carbon filter.
4.The system may require pretreatment for hardness reduction or the additional of
polyphosphate to prevent the formation of carbonate scale.
5.Ozone is less soluble in water, compared to chlorine, and, therefore, special mixing
techniques are needed.
6.Potential fire hazards and toxicity issues associated with ozone generation.
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