Application of the Analytic Hierarchy Process and the Analytic Network Process for the assessment of different wastewater treatment systems

Multicriteria analyses (MCAs) are used to make comparative assessments of alternative projects or heterogeneous measures and allow several criteria to be taken into account simultaneously in a complex situation. The paper shows the application of different MCA techniques to a real decision problem concerning the choice of the most sustainable wastewatertreatment (WWT) technology, namely Anaerobic digestion, Phytoremediation and Composting, for small cheese factories. Particularly, the AnalyticHierarchyProcess (AHP) and its recent implementation, the AnalyticNetworkProcess (ANP), have been considered for prioritizing the different technologies. The models enable all the elements of the decision process to be considered, namely environmental aspects, technological factors and economic costs, and to compare them to find the best alternative. The AHP and ANP techniques are applied through specific software packages with user-friendly interfaces called Expertchoice and Superdecision, respectively. A comparison of the merits obtained from the different models shows that Phytoremediation results as the most sustainable WWT technology for small cheese factories and that the use of the ANP method, which allows more sophisticated analysis to be made, succeeds in offering better results.