NAMS 2002 Workshop - ICOM 2008

Drinking and Wastewater Applications III – 4
Wednesday July 16, 11:15 AM-11:45 AM, Maui
Improvement of Swimming Pool Water Quality by Ultrafiltration -
Adsorption Hybrid Process
E. Barbot (Speaker), Aix-Marseille University, UMR 6181, France - elise.barbot@univ-cezanne.fr
P. Moulin, Aix-Marseille University, UMR 6181, France
Disinfection by-products can be rapidly formed when organic matter is in contact
with chlorine (i.e. disinfection of drinking water). Among those compounds,
trihalomethanes and haloacetic acids are primarily formed. Since the current
standard swimming pool water treatment method involves disinfection by
chlorinated compounds, pools are highly susceptible to these reactions.
Swimmers introduce a non negligible amount of organic matter, coming from
body fluids, skin, hair and cosmetics. Nitrogenous compounds, typically
originating from urine and sweat, easily react with hypochlorous acid and lead to
the formation of chloramines (NH2Cl and NCl3). The presence of carbonaceous
compounds leads to the formation of trihalomethanes, especially chloroform and
chloroacetic acids. Chloroform and chloramines are toxic and highly volatile,
which means they can rapidly pollute not only the water but also the atmosphere
of the pool. Chloramines concentration has been reported to reach 1.85 mg.m -3
in pool air, when the standard long term exposure value is leveled at 0.5 mg.m -3 .
This chemical pollution is of great concern for the swimming pool staff, who can
suffer from pulmonary or ocular irritation and asthma. Early age children are also
highly exposed, especially through baby swimmer activities. Specific conditions,
such as higher temperature of the water and high pool usage, coupled with
physiological characteristics of babies (i.e. very permeable skin) mean that a
baby can absorb as much chloroform in one hour than a lifeguard in three weeks.
Thus, this study develops a new process for swimming pool water treatment to
meet the three legislation standards of water quality: bacteriological, visual and
chemical. Ultrafiltration by hollow fiber was chosen because of its ability to both
clarify the water by simultaneously removing bacteria and viruses without
chemical compound addition. Molecular weight cut-off (MWCO) of ultrafiltration
hollow fiber membrane does not enable the retention of the major part of organic
matter introduced into the water, nor the disinfection by-products. Thus it was
necessary to couple the ultrafiltration process with an additional one, which could
retain organic matter or chlorinated compounds. Adsorption on a specific
activated carbon was the process selected for that purpose. Experiments were
performed for 18 months in a municipal swimming pool located in Marseille
(France). During that time the 100 m 3 pool was subjected to a high usage
frequency, aquagym and baby swimmer activities. An industrial ultrafiltration unit,
with a 115 m 2 membrane surface and cellulose acetate hollow fibers was set on