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Trihalomethanes (THM) are the most typical disinfection by-products (DBPs) found in public swimming pool water. DBPs are produced when organic and inorganic matter in water reacts with chemical disinfectants. The irregular contribution of substances from pool visitors and long contact time with disinfectant make the forecast of THM in pool water a challenge. In this work occurrence of THM in a public indoor swimming pool was investigated and correlated with the dissolved organic carbon (DOC). Daily sampling of pool water for 26 days showed a positive correlation between DOC and THM with a time delay of about two days, while THM and DOC didn't directly correlate with the number of visitors. Based on the results and mass-balance in the pool water, a simple simulation model for estimating THM concentration in indoor swimming pool water was proposed. Formation of THM from DOC, volatilization into air and elimination by pool water treatment were included in the simulation. Formation ratio of THM gained from laboratory analysis using native pool water and information from field study in an indoor swimming pool reduced the uncertainty of the simulation. The simulation was validated by measurements in the swimming pool for 50 days. The simulated results were in good compliance with measured results. This work provides a useful and simple method for predicting THM concentration and its accumulation trend for long term in indoor swimming pool water.

The transport of metal ions (Al, Fe, Zn, Pb) complexed by natural organic matter (NOM) was investigated by column experiments. Direct breakthrough of metal-NOM complexes was observed after elution of one bed volume for Al, Fe, and Pb, but not for Zn. This observation cannot be understood assuming local thermodynamic equilibrium in the columns. Hence, a model was developed, taking into account the kinetics of the interactions of metal ions with NOM and the solid phase. Of all possible reactions during passage through the column, the dissociation of the metal-NOM complexes was assumed to be the rate-determining step. Dissociation-rate constants were determined by cation-exchange experiments with a non-NOM-adsorbing cation-exchange resin (Chelex-100). These rate constants were used to predict the migration of metal-NOM complexes in the column experiments. Experimental and modeling results were in good agreement for the bivalent metal ions. Also, the model well predicted the pH dependence of breakthrough of trivalent metal ions and the differences between Al and Fe breakthrough on a qualitative basis. This leads to the conclusion that the dissociation kinetics of metal-NOM complexes is an essential parameter for the estimation of NOM-facilitated metal transport. However, for the trivalent metals, Al and Fe, the model overestimated the direct breakthrough, thus giving a worst case prediction of metal transport. With the help of coupling size-exclusion chromatography to inductively coupled plasma-mass spectrometry, the formation of Al-hydroxide and Fe-hydroxide colloids in addition to NOM complexes was detected. These colloids, which were not considered in the model, were partially filtered off in the column, thus leading to overestimation of metal breakthrough.