Ozone in Swimming pool

Ozone Application – Swimming Pool

Swimming pool water purification using ozone is one of the most advanced and modern methods available. Among all disinfecting agents indicated for water disinfection by current regulations, ozone has the highest oxidation power.

Thanks to this characteristic, ozone acts quickly and effectively against bacteria, algae and viruses, guaranteeing the highest possible microbiological safety.

Ozone is produced from the oxygen present in the air and, within a few minutes, after purifying the water, it decomposes back into oxygen without leaving any trace.

Substances Present in Swimming Pools

It has been found that each swimmer, when entering a swimming pool, disperses not only 300 to 400 million bacteria, but also 0.5 g of organic materials in the form of small skin particles, grease, sweat, saliva, urine, cosmetics, etc. From a quantitative point of view, average estimates show that a swimmer releases 30 to 50 ml of urine and 3 g of organic materials, of which 0.8 g to 1.1 g consist of organic carbon.

• Urea (1.5 g per swimmer);
• Uric acid;
• Carbamine (contained in saliva);
• Phosphates;
• Ammonia;
• Nitrates;
• Chlorides.

During purification with the traditional method based on chlorine compounds, organic material and ammonia react with the chlorine itself, forming chlorinated compounds known as chloramines.

These substances not only irritate the eyes and mucous membranes, but are also responsible for the typical and unpleasant smell of indoor swimming pools. Chlorine makes the water yellowish and requires pH correction.

Ozone, on the other hand, is able to tangibly improve water quality. Due to its high oxidation-reduction power, it is effective at low concentrations and guarantees rapid, broad-spectrum water sanitization.

Other advantages include the elimination of odor problems and yellowing of the water. Oxygen is added to the water and BOD and COD values are reduced.

Another important aspect is that the formation of harmful products is avoided.

Swimming pool water sterilized with ozone is crystal clear, contains no unpleasant-smelling substances and is completely tasteless.

The use of ozone reduces pool maintenance, avoids the supply of salts and chemicals, and prevents the dispersion of pollutants.

Water property	Chlorine	Ozone
Odor and taste	Unpleasant	None
Color	Water tends to yellow	None
Antiviral activity	None	High
Antibacterial activity	Variable depending on species	Total
Activity on algae and protozoa	Low	High
Activity on fungi	Low	High
Activity on spores and cysts	Low	High

Ozone is a very unstable gas under normal environmental conditions, so it cannot be stored but must be “created” in the place and at the moment it is needed. This result is achieved with equipment that transforms part of the oxygen in the air into ozone and is installed in the swimming pool technical rooms together with the filtration systems.

Reference Standard

For swimming pools in Italy, there is a UNI standard that regulates the amount of ozone to be introduced into the pool.

The standard prescribes the use of ozone in order to minimize chlorine dosage: from a value of 4-5 mg/l when only chlorine is used to a value of 0.5-0.6 mg/l when a combined ozone-chlorine system is used.

The reference standard is UNI 10637:2015 – Swimming pools – Requirements for circulation, filtration, disinfection and chemical treatment systems for swimming pool water.

Paragraph 5.5.4 of this standard identifies the design, construction and management requirements for ozone generation systems for swimming pools.

Sepra is able to provide systems that meet all required standards, such as:

• Presence of a hydrokinetic system for correct water/ozone mixing;
• Reaction chamber sized to guarantee contact between ozone and water > 1 min;
• System for removing exhaust gases and reducing these gases;
• System for eliminating dissolved ozone using UV lamps.

Our systems can be installed both in new facilities and in existing, operating swimming pools; only a small space is required in the technical room where the equipment is housed.

Below are some examples of ozone systems for swimming pools. The system mainly consists of the following components:

• The generator transforms oxygen O₂, present in the air, into ozone O₃ through an electrical discharge; the machine is supplied with compressed air or pure oxygen;
• The ozone produced is injected into the loop water through dynamic mixers driven by a booster pump;
• The water/ozone flow is introduced into a pressurized tank with an internal mixing system, ensuring adequate contact time;
• The plant includes a system that allows gas/liquid separation in order to completely remove the exhaust gas; the exhaust gas is conveyed and converted back into oxygen through a thermo-catalytic destructor;
• The gas-free flow is reintroduced into the loop and filtered with a traditional system;
• The plant includes a control instrument that reads the concentration of dissolved ozone before returning the water flow to the pool;
• The provision of a possible UV system on the flow guarantees the removal of dissolved ozone.

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