Wastewater treatment plant (WWTP) utilization of combined heat and power (CHP) systems allows for the efficient use of on-site biogas production, as well as increased annual savings in utility costs. In this paper, a review of biogas energy recovery options, CHP prime mover technologies, and the costs associated with biogas cleaning give a broad summary of the current state of CHP technology in WWTPs. Even though there are six different prime mover technologies, the main ones currently being implemented in WWTPs are micro turbines, fuel cells and reciprocating engines. Different prime movers offer varying efficiencies, installation costs, and biogas impurity (H2S, siloxanes, HCl) tolerances. To evaluate the long-term savings capabilities, a techno-economic assessment of a CHP installation at a case study WWTP shows the payback, annual savings, and initial costs associated with the installation of a CHP system. In this case, a study a payback of 5.7 years and a net present value of USD 709,000 can be achieved when the WWTP generates over 2,000,000 m3 of biogas per year and utilizes over 36,000 GJ of natural gas per year.
People in the United States drink almost four times the amount of bottled water than they did 20 years ago, even though tap water supplies in the United States are considered to be among the safest in the world. To understand ‘how do people make a decision on tap or bottled water’, a consumer preferences survey was administered to the Civil and Environmental Engineering students attending a US university. The survey elicited information on participants’ preferences and real life attitude/preferences and included a multi‐criteria pairwise comparison. The pairwise comparison preferences were further analysed by integrating nonparametric bootstrap simulations to determine the underlying uncertainty. The results revealed that although safety issues were deemed most important, participants were also subconsciously aware of other crucial issues related to drinking water. These findings provide useful information for drinking water policy experts and water utilities about consumer perceptions of the relative virtues of tap and bottled water.
Physical, technical, managerial, and environmental factors are all known to influence non-revenue water (NRW) volume, so a better understanding of these factors is important if we are to intervene in water loss problems more effectively. This study therefore identified determinants of NRW for a water utility in California by applying fixed effects panel regression analysis incorporating uncertainty. Network length, connection density, and net operating revenue per cubic meter of water sold were found to be negatively correlated with NRW while a positive relationship between number of leaks and NRW was identified. These findings will inform the water utility's management team/decision-makers regarding the specific impacts of NRW's critical factors and guide them to focus on these factors to further reduce NRW as well as set long-term benchmarks.
Groundwater wells are critical drinking water infrastructure elements that widely support basic system supply needs while also providing supply reliability, better water quality (in some cases), and comparatively lower operational costs. Well rehabilitation and replacement are thus an area where water utilities could benefit from rational decision support frameworks and quantitative tools that enable them to better navigate the complex trade-off relationship(s) that exist among a variety of environmental quality, public health, financial, regulatory, organizational, and technological dimensions. Consistent with these considerations, a business risk-based prioritization tool was developed for this study that augments/extends California Water Service (Cal Water)'s well rehabilitation and the replacement decision-making process. For this derivation, a business risk exposure methodology is combined with an analytical hierarchy process (AHP), with the AHP being utilized to determine the weights of the factors involved in the likelihood of failure and the consequence of failure calculation. It is expected that the new tool will assist in optimizing inspection and action plans and identify the wells requiring attention and/or additional work for water utilities.
Turkey is known to be rich in terms of renewable energy. Efficient use of renewable energy resources requires analysis of their spatial distribution as these resources are not equally distributed throughout the country. The aim of this study is to investigate the current use and the available potential of hydraulic, wind, geothermal, solar, and biomass energy in Turkey on a spatial basis using Geographic Information Systems. The results show that renewable energy resources are distributed over the country, and countrywide utilization of renewable energy is possible. However, a very limited portion of the available potential is currently in use. The eastern part of the country has a remarkable hydraulic energy potential, whereas the western part has high wind and geothermal energy potential. The western and central parts of the country are rich in terms of biomass energy potential, while the southern and southeastern parts have plentiful solar energy. As an energy importing country, Turkey needs to increase the potential and use of its renewable energy resources. For this purpose, a strong renewable energy policy needs to be established, and some enhancements in current implementations need to be made. Spatial analysis is a powerful tool to help policy makers and implementers during the establishment and enhancement processes. V C 2015 AIP Publishing LLC. [http://dx.
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