The particular analysis of each target variable can lead to the
identification of several combinations that seem to work better
regarding the removal of the studied contaminant agents. Graphically,
this aspect can be shown in Fig. 1 where box-and-whisker
plots are presented for each system: metal, dye and surfactant
removal. In addition, homogeneous subsets in Tukey’s test for multiple
comparison gives the idea of functional groups regarding the
elimination of each pollutant.