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Abstract A survey of papers on salt gradient solar ponds published in periodicals as well as ISES conferences and other notable solar energy conferences is conducted. The main solar pond R&D areas are identified and classified into 9 main categories and 11 sub-categories. The papers collected for the survey are cross referenced by categories.

Abstract Saline water such as seawater or brackish water is a potential source for drinking water or for non-potable applications, but the existing desalination techniques are energy intensive. Therefore, there is an urgent need to develop sustainable desalination methods. Microbial desalination cells (MDCs) hold great promise for energy-efficient saline water desalination. In MDCs, electrical energy from wastewater is extracted by taking advantages of microbial extracellular respiration and used to drive desalination. Herein, we have comprehensively reviewed and discussed the potential functions of MDCs, including seawater desalination, brackish water desalination, water softening, hydrogen and chemical production, and groundwater remediation along with wastewater treatment. The role of process parameters in improving the MDC performance was also analyzed. We expect to provide insight into the advantages and limitations of this emerging technology from the aspect of its functions, thereby encouraging more research efforts towards further development and commercialization of MDCs.

Rice husk is a bulky byproduct with a high silica content from rice milling. In this study, the application of an acid-catalyzed ionic liquid (IL) pretreatment was studied for processing rice husks with a rugged structure. The pretreatment conditions were 130°C for 30 min with 1.2 wt% HCl. The results of enzymatic hydrolysis demonstrated that cellulose conversion of HCl-BMIMCl-treated at 48 h was increased by 660.05%, 538.81%, and 376.55% compared with the untreated, HCl-treated, and BMIMCl-treated rice husks, respectively. Composition analysis demonstrated that most of the hemicellulose was removed in the acid-IL combined treatment. Moreover, scanning electron microscopy, X-ray diffraction (XRD), and Fourier transform infrared analyses indicated that the crystalline structure and outer silica layer of the rice husks were efficiently broken up. The results revealed that the HCl-catalyzed dissolution is highly favorable for the industrial application of rick husks in the production of fermentable sugar and high-purity silica.

AbstractTwo complexing agents, glycine and citric acid, in hydrogen peroxide based slurries for planarizing copper have been compared. Copper dissolution and polish rates and in situ electrochemical experimental results at various slurry pH values and hydroxyl radical concentrations at pH=8.4 are presented. It was observed that the pH of the slurry has a strong influence on copper dissolution and polish rates. While high copper removal rates were observed with citric acid-peroxide solutions at low pH values, glycineperoxide system yielded high Cu removal rates at alkaline pH values. Copper dissolution rates in both the systems at pH 4 and 8 were consistent with the electrochemical measurements. The concentration of hydroxyl radicals generated in citric acid-peroxide system was less than that of those generated in glycine peroxide system at pH=8.4 indicating low copper removal rates at alkaline conditions in the former system.

The aim of this work is to compare the extra added cost of different new water distillation techniques to the cost of extra collected distilled water. The comparison is between; a traditional single slope solar still, a solar still with installed reflecting mirror, a solar still with replacing the flat water with step wise basin, a solar still with a single axis sun tracking system and a solar still with sun tracking system and replacing the flat water basin with step wise basin. It was found that all cases of modifications have an economical effect except one which is the system with sun tracking. The most feasible system is the step wise design, which gave the shortest pay back period of 2.1 years, followed by the system with sun tracking and step wise, which gave the payback period of 3.6 years, followed by the system with reflecting mirrors, which gave the payback period of 4.6 years.

Abstract An economically sustainable model for water purification and desalination process is presented. This system is designed as a standalone, off-the-grid water purification system. It utilizes a parabolic trough as a heat concentrator, a tube collector filled with heat transfer fluid (HTF), and a boiler to distill sea/brackish water for the desalination process. The paper outlines the process of designing and optimizing the solar-powered distillation system and the process of fabricating the parabolic trough. The current troughs are designed and fabricated to facilitate the necessary energy required to raise the HTF temperature to the design temperature of 120 °C. A non-toxic, non-hazardous HTF is selected as the working fluid for the solar trough hot loop. System performance analysis is conducted through a set of experiments while parametric analysis is performed using a computer model custom built for this system. The computer model simulates the thermodynamic and heat transfer processes where a range of optimum flow rates are determined. An increase in the boiler water temperature is observed experimentally for the new range of HTF flow rates obtained from the computer model. The maximum temperature recorded experimentally is 124 °C exceeding the design temperature of 120 °C. This system is designed to fit into a standard shipping container for ease of transportation worldwide.

Carbon capture and storage (CCS) is an attractive area of research in such fields as CO2 mineral carbonation, global warming and sustainable energy systems. In this study, carbonation efficiency for aqueous mineral carbonation (MC) was achieved through two steps, which include leaching of calcium from cement kiln dust (CKD) followed by the reaction of pure CO2 with the calcium hydroxide precipitates formed by the hydroxylation using NaOH. Response surface methodology (RSM) with a Box-Behnken design (BBD) was applied to optimize the calcium leaching yield, while the carbonation efficiency from CKD was assessed using RSM with central composite design (CCD). Optimization of calcium leaching is highly important, as it is a rate-limiting reaction step in MC and also influences and enhances carbonation efficiency. Different parameters including acid concentration (HNO3), leaching temperature, leaching time, and dose of CKD sample were considered in order to optimize the maximum yield of Ca leaching from the CKD sample. In addition, different CO2 flow rates and temperatures were used as parameters for optimizing carbonation efficiency. Two quadratic regression models were developed for each process, i.e. calcium leaching and carbonation. For calcium leaching, a maximum of 98.55% calcium was extracted under the optimal set of acid concentration 4.13 M, 90 °C, 28 min leaching time, and 13.8 g of CKD sample. For carbonation, the maximum carbonation efficiency of 89.2% was achieved for a CO2 flow rate of 1163 cm3/min at 90 °C. Calcium leaching results indicate that the leaching yield was significantly affected by all the input parameters except leaching time. For carbonation, both factors affected the carbonation efficiency, with the effect temperature shown to be greater than that of the CO2 flow rate. Additionally, the predicted results agreed well with the experimental values for both calcium leaching and carbonation processes, with errors of less than 1% and 5%, respectively.

Dairy cattle treated wastewaters are potential resources for production of microalgae biofuels. A study was conducted to evaluate the capability of Arthrospira platensis cultivated in dairy farm wastewater for biodiesel production. The biomass of Arthrospira platensis was found to be 4.98 g L-1 and produced 30.23 wt% lipids to dry biomass cultivated in wastewater which was found nitrogen stressed in photo bioreactor. The extracted lipid displayed a suitable fatty acid profile for biodiesel, although the content of linolenic acid was found a little higher than the standard EN14214. It was found that nitrogen stressed medium increase the total lipid content but temperature and intensities of light were the most important factors to control the quantity of linolenic acid and hence the quality of biodiesel, while the optimum CO2 helped to achieve maximum biomass and triacylglycerols. The Arthrospira platensis offer a good option for the treatment of wastewater before final discharge.

Abstract Protected Agriculture (PA) presents a sustainable solution for food production in hot and arid environments. Harsh climate and the water deficit are obstacles to all year round cultivation. The greenhouse design should provide adequate control of its microclimate, such as temperature, relative humidity, CO2 concentration, and lightning depending on ambient conditions and the type of cultivation. This paper provides a thorough review of previous research on greenhouses design features, deemed important for efficient operation in hot and arid environments, such as dimensions, orientation, shapes, covering and shading materials. Effective greenhouse cooling methodologies and operation strategies to achieve and maintain satisfactory climate conditions in hot and arid conditions are investigated. Namely, natural and forced ventilation, evaporative cooling and fogging systems. Furthermore, the paper discusses the greenhouse control methods (field, remote, direct and combined) to monitor and regulate the indoor climatic parameters. Finally, the paper focuses on current greenhouse sustainable technologies and clean energy applications that contribute towards minimizing dependency on fossil fuels and leading to efficient water management. Namely, storage systems, humidification/dehumidification systems and Photovoltaic Panels. The future challenges facing the protected agriculture sector are identified. Suggestions of future scientific research and development topics are proposed.