Jar-test is a well-known tool for chemicals selection for physical–chemical wastewater treatment. Jartest
results show the treatment efficiency in terms of suspended matter and organic matter removal.
However, in spite of having all these results, coagulant selection is not an easy task because one coagulant
can remove efficiently the suspended solids but at the same time increase the conductivity or increase
considerably the sludge production containing chemicals and toxic dyes. This makes the final selection of
coagulants very dependent on the relative importance assigned to each measured parameter.
In this paper, the use of multicriteria decision analysis (MCDA) is proposed to help on the selection of the
coagulant and its concentration in the physical–chemicalwastewater treatment, since textilewastewater
contains hazardous substances. Therefore, starting from the parameters fixed by the jar-test results, these
techniques will allow to weight these parameters, according to the judgements of wastewater experts,
and to establish priorities among coagulants. Two well-known MCDA techniques have been used: analytic
hierarchic process (AHP) and preference ranking organization method for enrichment evaluations
(PROMETHEEs) and their results were compared.
Themethod proposed has been applied to the particular case of textilewastewaters. The results obtained
show that MCDA techniques are useful tools to select the chemicals for the physical-technical treatment.