Abstract
Formation potentials of trichloramine (NCl3), one of the major chlorinous odor compounds, in 15 raw waters were evaluated. Effects of co-existing compounds on NCl3 formation by chlorination were also examined. NCl3 formation potentials in 15 raw waters were 6-140 μg Cl2/L. The NCl3 formation potentials were correlated with ammonia concentration in raw water. NCl3 formation potentials in ammonium solution were higher than those in raw waters when ammonia concentrations in the sample solutions were same. NCl3 formation potentials of ammonium and glycine solutions decreased in the presence of natural organic matter (NOM). Thus, it was found that NOM reduced NCl3 formation in chlorination. Among 5 NOMs used, the effects of the Pony Lake fulvic acid (PLFA) on NCl3 formation was smaller than those of other 4 NOMs. This was because PLFA had the portions of the NCl3 precursors by chlorination. NCl3 formation potentials of ammonium and glycine solutions decreased in the presence of bromide ion. However, for ammonium solution, the effects of bromide ion was not observed when NOM was also co-exsited. In case of glycine solution, the effects of 20 and 50 μg/L of bromide ion was not observed, but those of 200 μg/L of bromide ion was observed when NOM was also co-exsited. The effects of bromide ion was not observed when bromide ion was added to raw waters.
