 Chlorination
is still the most widely used method of water disinfection for swimming
pools, principally thanks to its cost, the ease of use and the huge
range of products that are available.
However, many believe it would be
desirable if chlorination of water could be phased out because of the
known health and environmental risks. Chlorination byproducts have been
linked in some studies to cancer risks, and chlorine might be corrosive
to some types of swimming pools.
High THM levels
Recently,
researchers at Imperial College London said they found levels of
trihalomethanes (THMs), a byproduct of chlorine, in London swimming
pools that were higher than amounts found in tap water which had been
associated with health problems.
Studies from the
United States have suggested a correlation between the number of glasses
of chlorinated tap water drunk daily by pregnant women and the risk of
spontaneous abortion, stillbirths and congenital malformations.
The presence of
chloroform and other THMs in water has been blamed by some experts. The
Imperial College team reported that the chloroform content of water in
eight pools in London was on average 20 times higher than that of
drinking water.
THMs are formed
when chlorine, which is added to swimming pools to keep them clean,
reacts with organic matter such as skin or hair. THMs can be absorbed
through the skin, swallowed or inhaled.
To reduce THM
formation, scientists recommended making sure people clean themselves
before swimming and filtering the water.
Additional links
September
2001 also saw high levels of THMs linked to lung damage. Children who
swim in a chlorinated pool once a week scored the same on one measure of
lung damage as adult smokers, announced Belgian researchers.
The team took
blood samples to measure levels of three surface proteins that indicate
lung damage resulting from exposure to a high level of oxidants. They
found the level of the proteins increased with higher exposure to
chlorinated water.
This oxidative
damage also increases the amount of 'surfactant' proteins, which the
team measured after the children had been swimming. The highest levels
detected were similar to those seen in adult smokers.
Other researchers
have found an increased incidence of asthma in lifeguards who work in
indoor pools, although further research will be carried out.
The bottom line
is that although chlorine is still an essential step in the pool
disinfection process, levels in pools can be decreased significantly.
This can be
achieved by using low chlorine doses in conjunction with ultraviolet
(UV) or ozone treatment.
Ozonation
Ozone has
been used as a treatment for swimming pool water for over 30 years. It
is a very powerful oxidizer of most organic materials, including
swimming pool contaminants such as soaps, body oils, perspiration and
chloramines.
In the presence
of halogens such as chlorine, ozone will also oxidise ammonia, urea and
amino acids. Therefore, it is also extremely effective for killing
bacteria, viruses, spores and cysts.
Considering its
powerful qualities as an oxidizer of a broad range of waterborne
contaminants, ozone is more effective than chlorine. It also helps to
add great clarity to the water, as it acts as a microflocculent,
enhancing the pool filter system.
Frost & Sullivan
expects as that the public will push commercially owned pools to invest
in systems that ensure that they have the safest pool conditions.
Future years will
see continued investment in chlorine dosing equipment, but the increased
use of alternative techniques such UV and ozonation will become far more
popular to both the domestic and commercial customer. |
Envron
Ozone 
