In the next steps of the treatment (preoxidation/coagulation,
sampling point 2 in Fig. 1) the concentration of the 3 AAs
and N-nitrosodimethylamine was similar to that found in the
raw water samples. This is consistent with previous studies
that have indicated that coagulation steps are not effective in
removing polar nitrogen compounds from surface waters. In
addition, preoxidation with KMnO4 may deactivate precursors
prior to chlorination or chloramination, reducing AAs and
NAms potential formation (Charrois and Hrudey, 2007; Shah
and Mitch, 2012). The next treatments consisted of sedimentation,
filtration and disinfection with a chlorinated agent
(sodium hypochlorite) but, due to the specific location of the
sampling points, it was only possible to take a sample after the