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Cylindrical graphite microbial fuel cell (MFC) configuration designed by eliminating distinct casing and membrane was evaluated for bioelectrogenesis and treatment of real-field wastewaters. Both petroleum refinery wastewater (PRW) and Labanah whey wastewater (LW) were used as substrates, and investigated for electricity generation and organic removal under batch mode operation. PRW showed higher bioelectricity generation (current and power generation of 3.35mA and 1.12mW at 100Ω) compared to LW (3.2mA and 1.02mW). On the contrary, higher substrate degradation efficiency was achieved using LW (72.76%) compared to PRW (45.06%). Superior function of MFC operation in terms of volumetric power density (PRW, 28.27W/m3; LW, 23.23W/m3) suggesting the feasibility of using these wastewaters for bioelectricity generation. Large sources of wastewater that generating in the Middle-East countries have potential to produce renewable energy from the treatment, which helps for the sustainable wastewater management and simultaneous renewable energy production.

Abstract Four different anionic surfactants, sodium dodecyl sulfate, dodecyl benzene sulfonic acid (DBSA), dodecyl phosphate and Sodium lauroyl sarcosine, selected from the sulfate, phosphate, and carboxylic family, were investigated as additives in silica dispersions for selective polishing of silicon dioxide over silicon nitride films. We found that all these anionic surfactants suppress the nitride removal rates (RR) for pH ≤4 while more or less maintaining the oxide RRs, resulting in high oxide-to-nitride RR selectivity. The RR data obtained as a function of pH were explained based on pH dependent distributions of surfactant species, change in the zeta potentials of oxide and nitride surfaces, and thermogravimetric data. It appears that the negatively charged surfactant species preferentially adsorb on the positively charged nitride surface below IEP through its electrostatic interactions and form a bilayer adsorption, resulting in the suppression of nitride RRs. In contrast to the surfactants, K2SO4 interacts only weakly with the nitride surface and hence cannot suppress its RR.

This publication was made possible by the NPRP grant (NPRP8-370-2-154) from the Qatar National Research Fund (a member of Qatar Foundation). The statements made herein are solely the responsibility of author(s).

AbstractReducing emissions requires transitioning towards decarbonized systems through avoiding, processing, or offsetting. Decisions on system design are associated with high costs which can be reduced at the planning stage through optimization. The temporal variations in power demand and renewable energy supply significantly impact the design of a low‐emissions energy system. Effective decision‐making must consider such impact in a comprehensive framework that accounts for the potential synergies between different options. This work presents a mixed integer linear programming model that considers the impacts of energy supply and demand dynamics to optimize the design and operation of an integrated energy system while adhering to a set emissions limit. The model integrates renewable power with CO2 capture, utilization, and sequestration by considering H2 production and storage. The case study showed including negative emissions technologies and CO2 capture and processing with renewable energy allows achieving net zero emissions power.

This paper describes a study of the combustion process in an industrial radiant tube burner (RTB), used in heat treating furnaces, as part of an attempt to improve burner performance. A detailed three-dimensional Computational Fluid Dynamics model has been used, validated with experimental test furnace temperature and flue gas composition measurements. Simulations using the Eddy Dissipation combustion model with peak temperature limitation and the Discrete Transfer radiation model showed good agreement with temperature measurements in the inner and outer walls of the burner, as well as with flue gas composition measured at the exhaust (including NO). Other combustion and radiation models were also tested but gave inferior results in various aspects. The effects of certain RTB design features are analysed, and an analysis of the heat transfer processes within the burner is presented.

Abstract To help address this emergency, an atmospheric water extracting (AWE) device is developed and investigated as a part of present work. The AWE device is working on vapour compression refrigeration cycle. The air moisture condenses over the evaporator coil. The amount of condensate depends on psychrometric condition of incoming air. In this paper, the performance investigations are presented of an AWE device under different climatic conditions. The machine is integrated with a climatic chamber to from different climatic conditions in the laboratory to obtain the performance characteristics of AWE device. Total seven different climatic conditions were replicated as: humid and warm, humid and mild, humid and cold, dry and warm, dry and mild, mild and the last was mild humid and warm. The results indicated that the minimum energy intensity is found as 0.75 kWh per liter of water at the rate of 1.78 L per hour for warm- humid condition and maximum energy intensity is found as 4.71 kWh per liter of water at the rate of 0.28 L per hour for mild and dry condition. The present study concludes that AWE devices are most effective in hot and humid regions.

Achieving carbon-neutrality has become a global agenda following the ratification of the Paris Agreement. For the developing countries, in particular, attaining a low-carbon economy is particularly important since these economies are predominantly fossil-fuel dependent, to which Bangladesh is no exception. Therefore, this study specifically aimed at evaluating the environmental impacts associated with energy consumption and other key macroeconomic variables in the context of Bangladesh over the 1975-2016 period. As opposed to the conventional practice of using carbon dioxide emissions to proxy environmental quality, this study makes a novel attempt to use the carbon footprints to measure environmental welfare in Bangldesh. The outcomes from this study are expected to facilitate the carbon-neutrality objective of Bangladesh and, therefore, enable the nation to comply with its commitments concerning the attainment of the targets enlisted under the Paris Agreement and the United Nations Sustainable Development Goals declarations. The econometric analysis involved the application of methods that are suitable for handling the structural break issues in the data. The overall findings from empirical exercises reveal that aggregate energy consumption, fossil fuel consumption, and natural gas consumption boost the carbon footprint figures of Bangladesh. In contrast, nonfossil fuel consumption and hydroelectricity consumption are witnessed to abate the carbon footprint levels. Besides, economic growth and international trade are also evidenced to further increase the carbon footprints. Hence, these findings suggest that a clean energy transition within the Bangladesh economy can be the panacea to the nation's persitently aggravating environmental hardships. Furthermore, the causality analysis confirmed the presence of unidirectional causalities stemming from total energy consumption, fossil fuel consumption, natural gas consumption, hydroelectricity consumption, economic growth, and international trade to the carbon footprints. On the other hand, nonfossil fuel consumption is found to be bidirectionally associated with carbon footprints. In line with these aforementioned findings, several key policy suggestions are put forward regarding the facilitation of the carbon-neutrality agenda in Bangladesh.

Abstract Using a sample of 100 countries from 1980 to 2015, this paper investigates the impact of Foreign Direct Investment (FDI), imports, gross capital formation, and industry value-added on energy efficiency before and after the 2008 global financial crisis. Our findings reveal that failing to control for economic downturns may lead to misleading results. Moreover, we find that the effects of these channels are different between low, middle and high-income countries. Our study also shows that the effect of FDI on energy savings is inverted U-shaped whereas the effect of imports on energy savings is U-shaped when we control for the income level of the countries.

With objective to design cyanobacterial biorefinery, taking Lyngbya as a model organism, a detail sequential protocol has been developed for production of UV protectant and lipids. This study addresses ultra violet radiations (UVR), exposure time of UVRT, nitrogen stress, salinity, oxidative stress to produce UV protectant and lipid in cyanobacteria. To evaluate these parameters a design of experiment (DOE; using a 2 k design) was performed. Based on chemical solubility property of UV protectant in form of mycosporine like amino acid (MAAs) and lipids were extracted. Quantitative and qualitative assay of UV protectant was confirmed by spectrophotometric scanning and Fourier-transform infrared spectroscopy and lipid through fatty acid methyl esters analysis. Nitrogen abundance and high oxidative stress is helpful in the synthesis of UV protectant. This study concluded, UV exposure is good strategy to induce synthesis of UV protectant and saturated lipid productivity. This biorefinery approach encourages economical and environmentally sustainable options.