Wastewater treatment is a resource-intensive process that utilises several inputs, such as energy, chemicals and water, to produce an effluent that meets designated environmental standards. Driven by environmental regulations, the focus of wastewater treatment plants (WWTPs) has traditionally been the quality of the effluent and not necessarily the energy or resource efficiency of the plant. Regulations and penalties provide incentives to meet environmental effluent standards; however, to date, there are no such analogous penalties or incentives to expedite a focus on resource efficiency. It is imperative to recognise that resource utilisation and, indeed, sludge management also have significant environmental consequences, and therefore WWTP performance should be viewed holistically. This research sought to address this challenge by adopting a multi-pronged approach to audit and benchmark the resource efficiency of Irish WWTPs, including the use of life-cycle analysis (LCA) and exergy analysis. Ten representative Irish WWTPs were audited in detail. The plants varied in scale, with regard to their design capacities [which were quantified in terms of units of population equivalent (PE)], from 600PE to 186,000PE. Simultaneous energy and resource consumption and water quality audits were undertaken, resulting in the development of benchmarking tools and auditing methodologies, and the detailed performance evaluation of the plants in order to support better resource management and to provide baseline data on the holistic performances of the WWTPs. This work involved several key considerations: (1) the selection of representative plants; (2) the development of an appropriate auditing methodology; (3) the lack of functioning and appropriate monitoring equipment, particularly flow meters; (4) the access to plant data and water quality samples; (5) the identification of essential data requirements for each of the individual approaches and the subsequent development and implementation of data acquisition strategies; and (6) the determination of metrics that allow a fair comparison across WWTPs despite the many variables, such as scale, influent quality, discharge requirements, technology and nutrient removal requirements, that exist. To read the full report please click here.