In response to strong growth in energy intensive wastewater treatment, public agencies and industry began to explore and implement measures to ensure achievement of the targets indicated in the 2020 Climate and Energy Package. However, in the absence of fundamental and globally recognized approach evaluating wastewater treatment plant (WWTP) energy performance, these policies could be economically wasteful.This paper gives an overview of the literature of WWTP energy-use performance and of the state of the art methods for energy benchmarking. The literature review revealed three main benchmarking approaches: normalization, statistical techniques and programming techniques, and advantages and disadvantages were identified for each one. While these methods can be used for comparison, the diagnosis of the energy performance remains an unsolved issue. Besides, a large dataset of WWTP energy consumption data, together with the methods for synthesizing the information, are presented and discussed. It was found that no single key performance indicators (KPIs) used to characterize the energy performance could be used universally. The assessment of a large data sample provided some evidence about the effect of the plant size, dilution factor and flowrate. The technology choice, plant layout and country of location were seen as important elements that contributed to the large variability observed.

No abstract

Layers composed of catalyst particles of platinum supported on carbon ͑Pt/C͒ and ionomer phase ͑Nafion͒ have been prepared by electrospray deposition. Some properties are studied, such as morphology; porosity; surface area; thermal decomposition; electroactive area; and single cell testing, relevant to their performance as catalyst layer for proton exchange membrane fuel cell ͑PEMFC͒ electrodes. A dendritic morphology is obtained by electrospray deposition, with enhanced meso-and macroporosity. Thermogravimetry analysis shows a specific interaction between Pt/C particles and the ionomer phase involving sulfonic acid groups. The electrochemical active area of Pt/C + Nafion electrosprayed films is larger, till about 30% with the optimized ionomer concentration, compared with films deposited by other common techniques or commercial electrodes. The deposited layers are studied as a cathode in single PEMFC under normalized conditions, showing improved performance due to a lower electric resistance and higher electrochemical active area. These results are explained as a consequence of the optimal mesoporous structure, improved distribution, and interaction of the ionomer film with Pt/C catalyst aggregates. The electrospray deposition may be used to prepare PEMFC catalyst layers with a reduced amount of platinum.The catalyst layer of a proton exchange membrane fuel cell ͑PEMFC͒ electrode is the part of the cell with the highest impact on cost and durability. Both issues are recognized at this moment as the major challenges for the deployment of PEMFC technology. 1,2 Within the catalyst layer, platinum nanoparticles supported on carbon black aggregates form a porous film with mesopores partially filled by a proton conducting polymer, the ionomer. The structure allows for the conduction of gas reactants and water species toward the catalyst platinum particles and the removal of excess water. One possibility for maximizing reactivity and reduce platinum requirements is the implementation of deposition methods able to properly set out the components of the catalyst layer. Appropriate porosity of the catalyst layer and ionomer distribution may increase the utilization factor of the catalyst, and at the same time, improve mass transport properties and electrical conductivity of the layer. These three properties deserve optimization to maximize the performance of the catalyst layer. The utilization factor, i.e., the ratio of the active area to total area of platinum, 3,4 for standard PEMFC electrode configurations, is typically considerably lower than 100%. A recent study by our group based on literature data and the analysis of our own data, shows that most probable platinum utilization falls in a range between 10 and 30% of the available platinum surface. 5

Fuel cells are devices that transform efficiently the chemical energy of hydrogen or another fuel into clean electricity. The fuel cells technology is attractive for its high-energy efficiency and expanded...