Swimming pool disinfection

The use of UV disinfection technology in swimming pools is growing. For many pool operators, the reduction in the use of chlorine is a decisive argument in favour of the installation of a UV disinfection system.

In addition, UV technology can reduce levels of chloramine and trihalomethane. Trihalomethane (THM) and chloramine are produced when substances in the water react with free chlorine. These substances are most frequently brought in by swimmers (urea, skin particles etc.). But the water used to fill the pool may itself contain substances that can react with chlorine to produce undesirable by-products. THM has been shown to be carcinogenic in animals. Chloramines cause red eyes, skin irritations and the typical swimming pool smell, and they are suspected of being carcinogenic.

	Options for incorporating a UV disinfection system in a swimming pool. Use at water input stage, single throughput i.e. the water passes through the UV system only once; the system carries out the required disinfection when fresh water is added. Use in the filtration and return system, circulating  i.e. the continuously circulating water in the pool passes through the UV system at each turnover. The efficiency and effect  of the UV disinfection are continuous.
Savings Reduction in the fill water quantity (when new water is added for the purpose of reducing bound chlorine levels) by approx. 20% - 30% Reduction of chloramine level by approx. 35% - 45% Reduction in chlorination needed Depending on use, the amortisation period is between 0.75 and 3 years
Care needs to be taken both in calculating the radiator output and to choosing the correct radiator, since the different radiators have different effects.  The following formula is used to estimate the throughflow: Pool volume x (0.2 – 0.4)* = throughflow/hour * depending on flow rate Choosing a system - radiators Used to eliminate bound chlorine: Reduction of chloramines, trihalomethane Wavelength required:   254 to 340 (chloramines) and 446 (THM) nm Used for disinfection Destruction of viruses, bacteria, yeasts etc. Wavelength required:  253.7 - 260 nm

The UV system is always installed after the filtration system and before the chlorine injection system.
This ensures that chloramine and THM levels are continuously reduced. If the UV system is installed only in the fresh water input, continuous reduction of chloramine and THM cannot be achieved.

It is only useful to install a UV system in the fresh water input if the water is more than averagely polluted and disinfection is required before it is filtered. In this case installation of additional UV equipment in the circulation system is recommended. If both types are used in the same swimming pool system, the UV system in the fresh water input should be designed for microbiological disinfection and the one in the circulating system should be designed for chloramine and THM reduction.