ULTRAVIOLET TREATMENT FOR SWIMMING POOLS

WHY A UV INSTALLATION?

UV treatment offers all the benefits, and more, of ozone at a fraction of the capital and running cost

UV destroys chloramines and reduces THMs producing a brighter sparkling water.

UV produces a more pleasant environment for the bather eliminating eye irritation due to chloramines.

Reduced wear on the building and ventilation  due to corrosive condensation.

Lower chlorine levels can be held, and combined chlorine levels should reduce with the introduction of UV treatment.

A reduction in chlorine consumption has been observed by pool operators.

UV cannot be overdosed and is fully automatic, with  electricity as the only consumable.

POOL DISINFECTION

Most public pools and spas are required to maintain a residual disinfectant in the water.
Chlorine is generally used for reasons of economy and availability, but chlorine brings several disadvantages.

CHLORAMINES & TRIHALOMETHANES (THMs)

When pool waters are chlorinated the chlorine reacts with the ammonia and organics in the water to form chloramines and THMs including chloroform.
Chloramines are associated with the problem of 'red-eye' and chloroform is a known carcinogen. Dichloramine is particularly irritating and tends to concentrate in the air directly above the water surface, explaining why eye irritation is so noticeable.

Table 2 shows the wavelengths capable of oxidising, ie removing, organics by direct photolysis. These wavelengths are produced by our  Medium Pressure UV lamps.
Chloramines absorb UV light at the wavelengths shown, and because the energy levels are sufficiently high, they will be reduced as they pass through the UV unit.

CRYPTOSPORIDIUM
Recent research indicates that this occyst and other similar protozoa are inactivated at UV doses much lower than those used by Willand UV units for pool treatment.  This is a potential major benefit to Pool operators.

UV DOSE & KILL RATE
Table 1 below shows the UV D10 dose required to achieve a 1-log kill (90%) for the micro-organisms associated with swimming and spa pools; and the doses required to achieve higher kill rates.
Our UV units are designed to provide a minimum of 60mj/cm2 at the end of lamp life. Consequently the biocidal reduction will be greater than log4 (>99,99%) per pass through the UV unit.

INSTALLATION
The unit is normally placed in the recirculation loop, after the filter and before chlorination. The entire recirculating flow should be treated in order to fully control levels of THMs and provide optimum disinfection.

TABLE 1.

TABLE 2. UV WAVELENGTHS REQUIRED TO BREAK CHEMICAL BONDS.