Volatile Disinfection Byproduct Formation Resulting from Chlorination of Organic−Nitrogen Precursors in Swimming Pools

Abstract

Clinical studies have documented the promotion of respiratory ailments (e.g., asthma) among swimmers, especially in indoor swimming pools. Most studies of this behavior have identified trichloramine (NCl3) as the causative agent for these respiratory ailments; however, the analytical methods employed in these studies were not suited for identification or quantification of other volatile disinfection byproducts (DPBs) that could also contribute to this process. To address this issue, volatile DBP formation resulting from the chlorination of four model compounds (creatinine, urea, L-histidine, and L-arginine) was investigated over a range of chlorine/precursor (Cl/P) molar ratios. Trichloramine was observed to result from chlorination of all four model organic-nitrogen compounds. In addition to trichloramine, dichloromethylamine (CH3NCl2) was detected in the chlorination of creatinine, while cyanogen chloride (CNCl) and dichoroacetonitrile (CNCHCl2) were identified in the chlorination of L-histidine. Roughly 0.1 mg/L (as Cl2) NCl3, 0.01 mg/L CNCHCl2, and 0.01 mg/L CH3NCl2 were also observed in actual swimming pool water samples. DPD/FAS titration and MIMS (membrane introduction mass spectrometry) were both employed to measure residual chlorine and DBPs. The combined application of these methods allowed for identification of sources of interference in the conventional method (DPD/FAS), as well as structural information about the volatile DBPs that formed. The analysis by MIMS clearly indicates that volatile DBP formation in swimming pools is not limited to inorganic chloramines and haloforms. Additional experimentation allowed for the identification of possible reaction pathways to describe the formation of these DBPs from the precursor compounds used in this study.

Effect of pH on the formation of disinfection byproducts in swimming pool water – Is less THM better?

“…This pH dependency was also confirmed by other studies, since NCl 3 is one of the few DBPs where the pH effect on its formation in pool water was previously investigated (Palin, 1950;Schmalz et al, 2011). Other parameters which have been investigated include the chlorine dosing (Cl/N mass ratio) as well as the different N-based compounds found in pool water which can act as NCl 3 precursors (Li and Blatchley III, 2007;Palin, 1950;Schmalz et al, 2011). Each compound was investigated at different pH values to identify its individual effect on NCl 3 formation (Schmalz et al, 2011).…”

“…The BFA consist of four compounds which may act as precursor for HANs. Histidine has been identified as precursor for dichloracetonitrile where as creatinine was found not to form HANs (Li and Blatchley III, 2007). It is important to note, that HANs are the most toxic DBP group examined in this study , and HAN have also been reported to be the DBP group that contributes the most to the toxicity of chlorinated pool water (Kramer et al, 2009).…”

“…NCl 3 is a compound with low solubility in water; it is four times more volatile than chloroform and has a penetrating odor, which makes it one of the most important air pollutants of indoor pools (Schmalz et al, 2011). Studies have shown that urea (the major nitrogen containing component of urine) is the main precursor of NCl 3 formation (Li and Blatchley III, 2007;Palin, 1950;Schmalz et al, 2011). The BFA used in this study consisted of five nitrogen containing compounds besides urea: ammonium, creatinine, L-histidine, hippuric acid, and uric acid.…”

Photolytic removal of DBPs by medium pressure UV in swimming pool water

“…full scale treatment) the EEO for removal of combined chlorine was 1.0 kWh m Irradiation time to achieve 90 % removal of the monochloramine produced was 6.4 min, which is less than the time needed for photolysis of combined chlorine in pool water. The pool water contains organic chloramines which to some extent represents part of the combined chlorine as measured by the DPD method (Li and Blatchley, 2007). From this one can conclude that some organic chloramines are less sensitive to degradation by UV than monochloramine.…”

Potential negative effects of chlorinated swimming pool attendance on health of swimmers and associated staff

“…It must be noted that, even when chlorine and chlorinated compounds are used correctly, reactions leading to DBPs formation are inevitable [3]. The DBPs known at present are shown below [21,57,80]:…”