This paper provides an analytical assessment of the feasibility of wind energy for Saudi Arabia's envisioned NEOM city, which plans to use only renewable energy. A probability density function was ...fit to winds simulated for the NEOM region during 2014‐2018. Using this distribution, the optimal wind turbine was selected as the one with the largest capacity factor and smallest levelized cost of energy (LCOE). Financial, environmental, and risk analysis of a wind farm consisting of 100 of these units was also performed. A Weibull distribution determined by changing the shape and scale parameters to minimize the mean squared error offered the best fit to the measured wind speeds at this location. The estimated power density showed that the NEOM site warrants a Class 3 classification, which means wind energy systems would be suitable for commercial operation. A 3.2‐MW wind turbine, which is optimal for this location, has a capacity factor varying from 31.9% to 41.4% and LCOE that ranges from 6.99¢ to 8.32¢ per kWh. The 320‐MW wind farm has a positive net present value, a simple payback period of 13.8 years, and a LCOE of 6.6¢ per kWh. By installing this farm, potential annual savings of CO2 are around 106 metric tons.
The potential wind energy in the proposed city of NEOM, which will be powered with renewable energy only, is estimated and classified. Simulated wind data are used and modeled because of NEOM's remote location with few measurements. An economic analysis yields the expected levelized cost of energy (LCOE), and because Saudi Arabia does not have existing projects that can show cost trends, an uncertainty analysis is done to see how different assumptions in the cost analysis could lead to different outcomes.
The USEPA's 2010 mercury rule, which would reduce emissions from non-hazardous waste burning cement manufacturing facilities by an estimated 94%, represents a substantial regulatory challenge for the ...industry. These regulations, based on the performance of facilities that benefit from low concentrations of mercury in their feedstock and fuel inputs (e.g., limestone concentration was less than 25
ppb at each facility), will require non-compliant facilities to develop innovative controls. Control development is difficult because each facility's emissions must be assessed and simple correlation to mercury concentrations in limestone or an assumption of ‘typically observed’ mercury concentrations in inputs are unsupported by available data. Furthermore, atmospheric emissions are highly variable due to an internal control mechanism that captures and loops mercury between the high-temperature kiln and low-temperature raw materials mill. Two models have been reported to predict emissions; however, they have not been benchmarked against data from the internal components that capture mercury and do not distinguish between mercury species, which have different sorption and desorption properties. Control strategies include technologies applied from other industries and technologies developed specifically for cement facilities. Reported technologies, listed from highest to lowest anticipated mercury removal, include purge of collected dust or raw meal, changes in feedstocks and fuels, wet scrubbing, cleaning of mercury enriched dust, dry sorbent injection, and dry and semi-dry scrubbing. The effectiveness of these technologies is limited by an inadequate understanding of sorption, desorption, and mercury species involved in internal loop mercury control. To comply with the mercury rule and to improve current mercury control technologies and practices, research is needed to advance fundamental knowledge regarding mercury species sorption and desorption dynamics on materials within cement facilities.
►2010 USEPA cement facility mercury regulations will reduce emissions by 94%. ►Highly variable mercury inputs confound facility assessment. ►Emissions transience caused by an internal mercury loop complicates control design. ►Current emissions models do not distinguish between mercury species. ►Poor understanding of mercury species sorption and desorption limits control plans.
The following review article will serve to elucidate the existing state-of-the-art and breadth of technical understanding related to thermophilic aerobic biological wastewater treatment. The ...advantages of this technology include rapid biodegradation rates, low sludge yields, and excellent process stability. Substrate utilization rates reported in the technical literature are 3–10 times greater than that observed with analogous mesophilic processes, and sludge production rates are generally similar to anaerobic treatment processes. As such, thermophilic aerobic treatment has been used to biodegrade wastewaters from the pulp and paper industry, livestock production, and many other miscellaneous waste streams. Thermophilic aerobic processes are particularly advantageous for the treatment of high-strength wastewaters that can fully benefit from the rapid biodegradation rates and low sludge yields. High-strength wastewaters also contain the necessary energy content to facilitate autothermal operation such that exogenous heat input is not required. A theoretical energy balance is presented which predicts that COD removals of 20,000–40,000
mg
l
−1 coupled with an oxygen transfer efficiency of 10–20% are necessary for autoheating to thermophilic temperatures. Of the bacteria likely to proliferate in thermophilic aerobic bioreactors, relatively unique and specific nutritional requirements are common. In particular, thermophilic
Bacillus spp. commonly exhibit a growth requirement for methionine. Most researchers have reported that thermophilic bacteria fail to aggregate, making biomass separation from the treated effluent a key design criterion. Further work on thermophilic aerobic treatment processes is also needed to identify optimum operating conditions, and determine the best method to accommodate the oxygen uptake rates of these systems.
•Thassos marble used extensively as cool pavement at Al Masjid Al-Haram, Makkah City, Saudi Arabia.•Thassos marble provides unique thermophysical properties due to its dolomitic composition.•Thassos ...marble also offers unique ‘snow white’ color which matches sacred purity of prominent Al Masjid Al-Haram religious site at Makkah City.
This paper presents a thermophysical assessment of the extraordinary ‘snow white’ dolomitic marble material being used for pavement, wall, and even roofing surfaces within the Al Masjid Al-Haram (i.e., Great Mosque) in Makkah City, Saudi Arabia. Extensive use of this extremely white marble with exterior pavements helps maintain a cool surface which is conducive to the site’s religiously obligatory barefoot pedestrian contact. Modelled analysis of this site’s expected diurnal marble pavement surface temperature during both summer and winter periods was derived using local seasonal weather data. These results conceptually confirmed this marble’s remarkable ability to maintain desirable cool-surface conditions even during peak summertime solar insolation periods. Comparative analyses of surface temperatures and energy transfer were also derived for the same site and weather conditions based on the possible alternative use of conventional paving options (e.g., concrete and asphalt). In this case, modelling results indicated that either of the concrete or asphalt options would have generated far hotter surfaces which would be unacceptable, and perhaps even dangerous for bare skin contact, during summer months.
Wastewater disinfection is practiced with the goal of reducing risks of human exposure to pathogenic microorganisms. In most circumstances, the efficacy of a wastewater disinfection process is ...regulated and monitored based on measurements of the responses of indicator bacteria. However, inactivation of indicator bacteria does not guarantee an acceptable degree of inactivation among other waterborne microorganisms (e.g., microbial pathogens). Undisinfected effluent samples from several municipal wastewater treatment facilities were collected for analysis. Facilities were selected to provide a broad spectrum of effluent quality, particularly as related to nitrogenous compounds. Samples were subjected to bench-scale chlorination and dechlorination and UV irradiation under conditions that allowed compliance with relevant discharge regulations and such that disinfectant exposures could be accurately quantified. Disinfected samples were subjected to a battery of assays to assess the immediate and long-term effects of wastewater disinfection on waterborne bacteria and viruses. In general, (viable) bacterial populations showed an immediate decline as a result of disinfectant exposure; however, incubation of disinfected samples under conditions that were designed to mimic the conditions in a receiving stream resulted in substantial recovery of the total bacterial community. The bacterial groups that are commonly used as indicators do not provide an accurate representation of the response of the bacterial community to disinfectant exposure and subsequent recovery in the environment. UV irradiation and chlorination/dechlorination both accomplished measurable inactivation of indigenous phage; however, the extent of inactivation was fairly modest under the conditions of disinfection used in this study. UV irradiation was consistently more effective as a virucide than chlorination/dechlorination under the conditions of application, based on measurements of virus (phage) diversity and concentration. Taken together, and when considered in conjunction with previously published research, the results of these experiments illustrate several important limitations of common disinfection processes as applied in the treatment of municipal wastewaters. In general, it is not clear that conventional disinfection processes, as commonly implemented, are effective for control of the risks of disease transmission, particularly those associated with viral pathogens. Microbial quality in receiving streams may not be substantially improved by the application of these disinfection processes; under some circumstances, an argument can be made that disinfection may actually yield a decrease in effluent and receiving water quality. Decisions regarding the need for effluent disinfection must account for site-specific characteristics, but it is not clear that disinfection of municipal wastewater effluents is necessary or beneficial for all facilities. When direct human contact or ingestion of municipal wastewater effluents is likely, disinfection may be necessary. Under these circumstances, UV irradiation appears to be superior to chlorination in terms of microbial quality and chemistry and toxicology. This advantage is particularly evident in effluents that contain appreciable quantities of ammonia-nitrogen or organic nitrogen.
This paper summarizes the efforts and the outcomes of a pilot student internship program developed jointly in 2012 by the Iowa Department of Transportation (DOT) and the Institute for Transportation ...at Iowa State University. In 2012, Iowa was the only state DOT to use federal funds for the internship program, which was initiated as a summer program with 56 interns assigned to DOT offices and projects across the state. The paid internship program was extended into the fall semester with 22 students assigned to offices in Ames, Iowa. The program had engineering and nonengineering positions and was developed to provide experiential learning opportunities, to address Iowa DOT's workforce needs, and to attract undergraduate students to transportation careers. More than 80% of the interns and more than 90% of the supervisors, choosing from multiple choice responses, rated the program outcomes as great or okay. The interns valued opportunities to work in professional settings where they had responsibilities entrusted to them, interactions with other professionals and practitioners, an opportunity to understand real-world application of their course work, and the chance to gain first-hand experience working on transportation projects, as well as to learn about expectations in a professional setting. Supervisors noted the importance of establishing a continuation of the internship and cooperative education programs for future students. Nearly 100% of the interns and fully 100% of the supervisors said that they would recommend the program to students. Because of the student contributions during the internship, Iowa DOT was able to complete many activities that would not have been completed.
The effect of temperature was studied on the efficiency of soluble COD removal and bacterial community development during the aerobic biological treatment of a pharmaceutical wastewater. Using ...wastewater and bacterial inoculum obtained from the full-scale facility treating this wastewater, batch laboratory cultures were operated at 5°C intervals from 30°C to 70°C. Following four culture transfers to allow for bacterial acclimation, residual soluble COD levels were measured and bacterial community fingerprints were obtained by denaturing gradient gel electrophoresis (DGGE) of polymerase chain reaction (PCR)-amplified 16S rRNA gene fragments. Soluble COD removal efficiency declined as temperature increased from 30°C (62%) to 60°C (38%). Biological treatment of this wastewater failed to occur at temperatures higher than 60°C. Gradual shifts in bacterial community structure were detected as temperature increased, including a concomitant reduction in the number of different bacterial populations. The impact of temperature on a two-stage biological treatment process was also compared. Better soluble COD removal was achieved when both reactors were operated at 30°C compared to a system where the two stages were consecutively operated at 55°C and 30°C. These results indicate that operation of aerobic biological wastewater treatment reactors at elevated temperatures can have adverse effects on process performance.
Radiocarbon activity of fuels is a direct analog to the biogenic fraction of carbon in the fuel. The amount of radiocarbon in a fuel sample may be determined by liquid scintillation direct analysis ...if the sample is relatively transparent to ultraviolet light. However, many biofuels are colorful which adversely affects the counting efficiency of this technique and therefore the precision which the biofuel blend level may be determined. In such cases, decolorization may be an approach to improve measurement precision. Here, we present the effectiveness of several decolorization techniques for different fuel types. For some fuels, decolorization impacted the radiocarbon content of the sample; therefore, caution is necessary to ensure reliable assessment of biofuel blend levels.
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