Use of medium pressure UV systems to remove the harmful tri-chloramine from pool water

3 min

True and False

Tri-chloramine NCl3 is the most harmful by-product of chlorine waterdisinfection. It is formed by the reaction of chlorine with substancescontained mainly in the sweat and urine of swimmers. Tri-chloramine isvery poorly soluble in water and is therefore easily released as a gas intothe air. Tri-chloramine causes asthma, redness of the eyes, a typical poolodour and various allergies. It causes corrosion of interior equipment ofhalls. For example, in 1985, 12 people died in the Swiss city of Uster as aresult of the collapse of a corroded pool hall construction.For these reasons, it is necessary to pay serious attention to the possibilityofremovingtri-chloramine from the pool water and not to play with the health, andsometimes life, of people visiting public and private pools, spreading half-truths and lies.Lifetech manufactures low-pressure UV systems (mercury and amalgamlamps) and medium-pressure UV systems, as well as ozone generators.We have more than 40 years of experience with these technologies andtherefore know which technologies are most suitable for these purposes.Alas, in the pursuit of profit, one can often see the manipulation ofscientifically proven facts and, despite them, promote low-pressureamalgam ultraviolet systems to remove tri-chloramine. Although it is clearthat the combination of medium-pressure UV and ozone used in theunique LifeOX®-M unit is currently the most effective pool watertreatment technology.

False: To remove Tri-chloramine from pool water, it is sufficient to use thelow pressure UV systems (mercury or amalgam).

True: Due to the different design of the UV lamp, UVM systems not onlydisinfecting water, but they also decompose harmful trichloramine. UVLsystems cannot do this. For these reasons, the updated German standard DIN19643 (November 2012) allows the use only ofmedium-pressure UV systems for public swimming pools.

Since low-pressure UV systems do not remove trichloramine, there is noneed to deal with other pseudo-arguments against medium-pressure UVsystems. When something doesn’t work, it can’t be compared withsomething what works! However, let’s clarify other false claims aboutmedium-pressure UV systems.

False: The lifetime of the medium pressure UV lamps is only 8 000 hours,while the lifetime of the amalgam UV lamps is 16 000 hours.

True:The lifetime of the medium pressure UV lamps at the most of themedium pressure UV systems is actually around 8 000 hours. However,LIFETECH company has developed the unique LifeAGE® technology forpower supply of the medium pressure UV lamps, and that’s why thelifetime of the medium pressure UV lamps in our medium pressure LifeUVM® systems reach the same lifetime as amalgam UV lamps. Wehave installations of our LifeUVM® systems where the lifetime of themedium pressure UV lamps has reached 20 000 to 30 000 hours.

False: Using the medium pressure UV lamps to treat the pool water isenergy disadvantageous, because in the case of the low pressureamalgam UV lamp, about 30-35% of the electrical energy is converted toUV radiation, while in the case of the medium pressure UV lamp it is onlyaround 15%.

True: If we compare the energy efficiency of the low pressure and themedium pressure UV systems for pool water treatment, then it isnecessary to compare not only the energy efficiency of conversion to UVradiation. It should be noted that the second part of the supplied electricalenergy is converted into thermal radiation, which heats the flowing poolwater. The medium pressure UV systems therefore use 100% of thesupplied electric power to treat the pool water.

False: Tri-chloramine may not be formed in pool water. This is due to thepoorly designed filters. All you have to do is repair the filters and then youonly need to install the low pressure amalgam UV systems.

True: Tri-chloramine is formed mainly by the reaction of chlorine with theurine and sweat of swimmers, directly in the pool where they swim. Thisproduction of tri-chloramine is independent of filtration. Reducing theconcentration of existing tri-chloramines is also possible by sorption oncarbon or by reverse osmosis water filtration. However, it is much moreadvantageous to use the medium pressure UV systems for waterdisinfection and tri-chloramine destruction.

False: The by-product of chlorination is not only Tri-chloramine, but alsoMono- and Di-chloramine, the concentration of which is higher than tri-chloramine. Therefore, it is more important to remove only mono- and di-chloramine from the pool water.

True: The concentration of tri-chloramine in pool water is lower than concentration of mono- and di-chloramine, but unlike them a) trichloramine is very poorly soluble in water and therefore very easily diffuses into the air from the water above its level, where it is inhaled by the swimmerb) tri-chloramine is much more harmful to human health. Scientific studies have clearly proved that the greatest danger to the health of bathers is trichloramine. In addition, it is so aggressive that it causes corrosion of theload-bearing floors of the building and caused the death of visitors to many water parks due to the collapse of the walls and ceiling of the halls.

In conclusion, we once again state: mercury or amalgam low-pressure UV systems do not remove trichloramine. To remove trichloramineand decontaminate water, it is necessary to use systems with medium-pressure UV lamps.