Abstract:
Performance assessment is essential to effectively evaluate and monitor the activity of water
utilities, support decision making, and encourage continuous improvement. Performance assessment
systems (PAS), covering several service objectives and criteria, have been successfully applied in
water supply and wastewater systems. Tailored approaches focusing on the assessment of the energy
use and efficiency in wastewater systems are still limited. This paper aims at the development
and demonstration of a comprehensive PAS for energy efficiency, tailored for wastewater systems,
incorporating criteria related to energy consumption, operation and maintenance (O&M) costs, and
environmental impacts, such as untreated discharges and greenhouse gases emissions, among others.
Management and control of excessive or undue inflows to these systems is specifically addressed by
several novel criteria and metrics. The proposed PAS should be adapted by each utility to be aligned
with the objectives of the organisation and with the implemented asset management strategy. The
proposed approach and the resulting consolidated PAS are thoroughly described. Results from the
application of the PAS to several Portuguese utilities are discussed. This PAS aims at contributing to
a reliable and replicable process to assess energy efficiency in wastewater systems and to encourage
a more rational energy management.