Body fluid analog chlorination: Application to the determination of disinfection byproduct formation kinetics in swimming pool water

Abstract

Disinfection by-products (DBPs) are formed in swimming pools by the reactions of bather inputs with the disinfectant. Although a wide range of molecules has been identified within DBPs, only few kinetic rates have been reported. This study investigates the kinetics of chlorine consumption, chloroform formation and dichloroacetonitrile formation caused by human releases. Since the flux and main components of human inputs have been determined and formalized through Body Fluid Analogs (BFAs), it is possible to model the DBPs formation kinetics by studying a limited number of precursor molecules. For each parameter the individual contributions of BFA components have been quantified and kinetic rates have been determined, based on reaction mechanisms proposed in the literature. With a molar consumption of 4 mol Cl2/mol, urea is confirmed as the major chlorine consumer in the BFA because of its high concentration in human releases. The higher reactivity of ammonia is however highlighted. Citric acid is responsible for most of the chloroform produced during BFA chlorination. Chloroform formation is relatively slow with a limiting rate constant determined at 5.50×10-3 L/mol/sec. L-histidine is the only precursor for dichloroacetonitrile in the BFA. This DBP is rapidly formed and its degradation by hydrolysis and by reaction with hypochlorite shortens its lifetime in the basin. Reaction rates of dichloroacetonitrile formation by L-histidine chlorination have been established based on the latest chlorination mechanisms proposed.

Swimming pool water disinfection by-products profiles and association patterns

“…THMs have been linked with diseases such as bladder and colon cancer, asthma, irritation to the eyes and mucous membrane, and reproductive function [ 1 , 3 , 6 , 46 , 47 ]. Chloroform, bromodichloromethane, dichloroacetic acid, and trichloroacetic acid have been classified as contaminants possibly carcinogenic to humans (Group 2B) by International Agency for Research on Cancer [ 1 , [17] , [18] , [19] , 48 ]. Many DBPs have been demonstrated to be cytotoxic, neurotoxic, genotoxic, with several additionally demonstrating mutagenic, carcinogenic and/or teratogenic nature [ 13 , 25 ].…”

“…In swimming pool waters, nitrogenous DBPs have been shown to be generally more genotoxic (to Chinese hamster ovary cells) compared to most other DBPs [ 13 , 25 ], and greater toxicological effects were found to be associated with HANs than with THMs and HAAs [ 43 , 48 , 53 , 54 ]. Toxicological studies showed that HANs are more genotoxic and cytotoxic than THMs or HAAs [ 2 , 13 , 26 , 31 ].…”

Making Swimming Pools Safer: Does Copper–Silver Ionization with Chlorine Lower the Toxicity and Disinfection Byproduct Formation?

“…Because real pools can have substantial variability due to differences in tap filling water, bather loads, , DBP precursors added by the bathers, temperature, pH, levels of chlorine, air exchange, sunlight, and other conditions, ,, simulated pools using a BFA ,, (Table S2) were also investigated so that the parameters could be carefully controlled and results compared directly. Treatments included a low chlorine target residual (1 mg/L) with CSI, and a higher chlorine residual (5 mg/L), representing a mid-range chlorine dose used for real pools, along with BFA/CSI and BFA controls and two tap water controls.…”

“…This is consistent with previous studies where L-histidine was shown to be a precursor to DCAN. 5,82 However, the largest % increases in real pool samples during the peak swimming seasons were seen in HAAs and HALs, likely because inputs such as sunscreens and lotions act as major precursors to these classes and were not present in the simulated reactors. 3,4 Chlorinated HAAs, including chloroacetic acid, dichloroacetic acid, and trichloroacetic acid, progressively increased from the tap water control to the low Cl 2 /CSI reactor to the high Cl 2 reactor, likely from the reaction of citric acid in the BFA and chlorine.…”

Occurrence of Disinfection By-Products in Swimming Pools in the Area of Thessaloniki, Northern Greece. Assessment of Multi-Pathway Exposure and Risk

“…Yeh et al [28] reported an increasing accumulation of TN in swimming po The organic and nitrogen loads are highly variable and depend on their presence in filli water but mainly from the anthropogenic releases. Human body fluids, sweat, sebu skin particles and hair, and personal care products contribute to both carbon and nitrog load in pools [28][29][30][31].…”