THMs and HAAs did not behave the same way. According to Table 7,
the difference of residual free Cl has a positive correlation with THM4
concentration. This means that a permanent formation of THMs occurs
in the DS, and maximal concentrations are observed at the end of the
DS. Other studies also reported a positive association between water
residence time, free chlorine consumption and THM levels (Reckhow
and Singer, 1990; Pieri et al., 2014). On the other hand, HAA5 is also influenced
by the residence time(expressed by the difference of free chlorine
level of the beginning of the DS and chosen point), but the
correlation is negative. This result suggests that a degradation of HAA5
occurswith residence time.