Implementing a composite indicator approach for prioritizing activated sludge-based wastewater treatment plants at large spatial scale

Successful implementation of the European Urban Wastewater Treatment Directive requires a deepened and multidisciplinary knowledge of the wastewater systems. The development of ready-to-use tools for decision makers is, in this sense, a challenge. This paper proposes a methodology to efficiently prioritize wastewater treatment plants (WWTPs) on the basis of the relative environmental, social and public health impacts, taking into account the territorial context issues. The proposed methodology has led to the implementation of a composite indicator. The several choices made for its development, from the definition of framework to the final outcomes, have been evaluated in depth and are supported through methodological and statistical techniques. The potential use of the composite indicator with the inherent advantages and limitations are discussed in order to provide a ready-to-use tool for final users for WWTPs prioritization. Moreover, a concise methodology for composite index implementation is described. © 2016 Elsevier Ltd