Introduction

Ozone is an unstable gas as it is produced for commercial application and has a pungent characteristic odor, it is formed photochemically in Earth’s Stratosphere, but exist at ground level only in low concentration. It is the most powerful Oxidant used in Swimming Pools and has the ability to destroy algae and bacteria, inactive viruses and to oxidize many organics and inorganic contaminants which are present in the water.
Ozone has a short half life in aqueous solution this Ozonised water can be recycled in Swimming Pools without fear of building high concentration of dissolved Chemicals.

Application of ozone gas
Drinking water/Mineral water
Swimming pools
Cooling tower water
Waste water
Air purification
Hotels, Hospitals etc…

Application of Ozone in Water treatment for Swimming pools

Anybody entering a swimming pool contaminates the water either from secretion or just from washing off. Typical contaminated are
sweat
skin flaks
mucous
hair ointments
urine
In addition there are contaminants and organisms from the environment of the swimming pools such as dust algae and microorganisms therefore the pool water has to be constantly filtered and disinfected.

At the present time only chlorine disinfection is used which means use if chlorine, hypochloride and chlorine dioxide.

However, the disinfection efficiency of chlorine is very much hindered by water contaminants.
For Example : In highly contaminated water even at a concentration of 3.5mg/l of free chlorine, virus bacteria were found while normally a tenth of this amount that is 0.3mg Cl 2/ltrs would be sufficient to destroy the bacteria.

There are several causes for a reduction of Chlorine activity.
●  Colloids may envelope bacteria forming a protective coat against chlorine.
●  Organic are oxidised by chlorine which reduces the concentration of free chlorine.
● Ammonia and other nitrogenous compounds react with Chlorine forming Chlorine-Nitrogen compounds which have slower in activation for virus and bacteria.

These Chlorine compounds known as Chloamines and Chlorourea not only produce that typical unwanted swimming pool odor. But are also highly Irritant poisonous substances that cause Eye Irritation ( Redness of Eyes ) and Skin Allergy. Some of these chlorine compound are found to be highly carciogenic.
The comfort of the swimmer keep a priority aspect is selection of a swimming pool purification process.

Ozone is proved to be the most Advanced & beneficial treatment processes.

Advantage of using Ozone v/s Chlorine

Ozone possesses many advantages over chlorine in the processing of swimming pool water or in conjuction with chlorine.

Basically, ozone is used as a purification agent and chlorine is used for disinfection. Actually, ozone can be used both as a flocculating agent as a disinfectant in addition to its function as a purification agent. The pool water is flocculated to remove various colloidal material and substances that create turbidity, as well as bacteria and virus. The water passes through sand filters to remove the precipitate before being ozonated. By removing the colloidal matter and the cause of turbidity, the ozone is given a better chance of doing a fine job.

Some of the advantages and disadvantages of ozone and chlorine used for swimming pool water purification are:

●  Chlorine is not only highly toxic, it is a poisonous gas
●  Although ozone is rated as toxic at the 1.0 mg/1 level by the United States government, no one has ever been known to have died as a result of inhaling it. Ozone has a very pungent odor, noticeable at the 0.01mg/1 level; is highly irritating at elevated levels; tends to dry out the skin and mucous membrane and can cause temporary throat discomfort.
●  Chlorine is stored in high pressure containers on the premises and can be dangerous. A broken chlorine line could cause serious problems.
●  Ozone is generated on the premises (not stored)
● Chlorine, when mixed with urine and perspiration, will form chloramines that will cause eye irritation and are toxic to aquatic life.
● The cost of chlorine is constantly increasing and has become quite expensive. Ozone, on the contrary, is becoming less expensive due to the increase in efficiency and lower energy consumption. The overall cost of using ozone instead of chlorine will be less costly to the pool owner.
●  Ozone is the most active oxidizing agent that can be used with safety. It is sometimes called “activated oxygen”.
●  Tests have proven that ozone is from 600 to 3000 times more active in the destruction of bacteria and viruses than chlorine in the same concentration. Escherichia Coliform (E. coli) is killed within 5 seconds by ozone at a concentration of 1 mg/1, whereas 15,000 seconds for the same results using chlorine at the same concentration.
●  Ozone is effective against mustiness, mildew, fungus and can be used to eliminate the “locker room” odor in dressing rooms.
●  Due to the flocculation process and the ozonation process, the water in an ozonated pool is very clear. A sky blue color is imparted in the pool water.
●  Chlorine is more effective against algae growth. Outdoor pools using ozone have a problem with algae bloom, under high temperature conditions, that can be eliminated bu chlorine “ shock treatment’ of 5 to 10 mg /1, when needed.
●  Chlorine needs pH control (7.0 to 7.4 pH) for reliable results. Ozone does not not require pH control but some of the other chemicals used may require such control.
●  Ozone is an excellent deodorizing agent for many substances, such as putrefactions, hydrogen sulfide, urine, smoke, cooking, paints, etc.
●  Ozonated pools do not have the “bath tub ring” that is caused by skin oils, grease, ointments, hair dressing and cosmetics used by the swimmers
●  Ozone is used in therapeutic pools and baths for the treatment of skin infection and burns.

CALCULATION FOR OZONE DOSING FOR SWIMMING POOL

Following parameters should be considered before selecting the size of Ozone Generator:

●  Quantity of make up water per day.
●  Water Temperature.
●  Number of swimmers.
●  Type of filteration process.
●  Type of Ozonization.

Generally 2ppm dosage is kept for make up water due to its high ozone demand (Iron/Manganese).
0.4ppm is sufficient for general oxidation of organic contaminant (Urea and other Arial container). And 0.4ppm is used for disinfection and residal protection.
For high ambient temperature or heavily loaded pools (Water parks) a multiplication factor of 1.2 is used.
This works put to about 1 to 1.2ppm higher dosage would lead to high concentration (above 0.2mg/m3) of ozone in air above the pool, which would lead to coughing among the swimmers.

Chlorination