Benchmarking large municipal WWTPs using official questionnaires: The case study of Italy

This paper describes the implementation of a benchmarking method applied to large municipal wastewater treatment plants (WWTPs) providing (i) the identification of plants with low environmental performances and technological critical issues, (ii) the definition of appropriate improvement actions and (iii) the simulation of their suitability according to the continuous improvement approach. Moreover, WWTPs quality evaluation for each reference area (the district) was performed. In order to reach these goals the following issues have been addressed: large number of plants to be compared, incomplete data and different sources of information. The use of official questionnaires as those provided by the National Institute of Statistics (ISTAT) was considered the most suitable solution. The process outputs related to the Italian case study highlight the gap between Northern and Southern Italy.