36 research outputs found
Theoretical and experimental investigation of liquid droplets flashing for low cost seawater desalination
No full textThe high specific energy consumption from all existing seawater desalination methods has heightened the motivation for having more efficient and greener desalination processes to meet the future goals of sustainable seawater desalination. One of the promising thermally-driven desalination methods is the direct-contact spray evaporation and condensation (DCSEC) where the excess enthalpy between feed and equilibrium states of evaporator chambers is exploited with reasonably high flashing efficiency. Further improvements in energy efficacy of DCSEC are boosted by firstly the incorporation of micro/nano-bubbles (M/NB) where micro or nano size subcooled vapor are embedded in the sprayed liquid droplets of evaporator, thereby lowering the temperature brine in evaporator and minimizing the thermal equilibrium effect of brine. The presence of subcooled bubbles increased the available surface area for heat transfer. Secondly, the concept of an evaporator-condenser pair of DCSEC could be extended to a multi-stage arrangement where the latent heat of vapor condensing on the water droplets sprayed within the condenser is recovered. From the experiments, the effect of incorporating the (M/NB) in the DCSEC at optimum feed flow rate yields more than 34% increase in distillate production at feed temperatures greater 47oC and the cooling inlet temperature set at 35oC. The other salient improvement found from the experiments is the increase in performance ratio (PR) up to 3.3 for a 6-stage configuration. This quantum jump in the PR is attributed to the heat recovery effect by as much as 70% of the total heat input. Arising from the DCSEC design, the implicit benefits are the low capital and operational cost, i.e., low CAPEX and OPEX. The former savings is attributed zero physical interfaces such as tube-based heat exchangers or membranes, whilst the latter savings is contributed by significant lesser use of chemicals in the pre-treatment of seawater feed. Lastly, the accompanied benefit is the robustness of the DCSEC processes where it could within stand high salinity of the brine, typically as high as 200,000 ppm
Experimental Performance of Single-Slope Basin Solar Still Coupled with a Humidification–Dehumidification Cycle
No full textDespite their low distillate yield, single-slope basin solar stills incorporate a simple and cheap technique to secure potable water in arid and rural areas away from fresh water resources and the power grid. Nevertheless, recovering a portion of the inevitable thermal losses from the still will significantly contribute to enhancing its daily distillate productivity and thermal performance. In this manuscript, the latent heat of condensation in single-slope basin solar still was partially recovered and utilized as the thermal energy source for an auxiliary humidification–dehumidification (HDH) distillation cycle. The thermal performance of the resultant SS-HDH distiller was experimentally tested side by side with a separate single-slope basin still of the same basin area. The results showed an increase of about 2 L/m2 in the daily distillate production of the SS-HDH distiller over that of the conventional single-slope basin still. In addition, the thermal efficiency of the SS-HDH distiller was 57% greater than that of the conventional single-slope basin still
A greener seawater desalination method by direct-contact spray evaporation and condensation (DCSEC): Experiments
No full textOwing to the high specific energy consumption of conventional seawater desalination methods available hitherto, there is much motivation for designing greener desalination processes. As a greener desalination process, it should consume lower top-brine temperatures for the seawater feed as well as minimum chemical use for brine treatment. In this paper, a direct-contact spray-assisted evaporation and condensation (DCSEC) is presented that addresses the above-mentioned requirements of greener desalination. We have tested both the single-stage and multi-stage configurations of DCSEC process with seawater (3.5% by weight salinity) from Red Sea. The performance of the system was investigated for a feed flow rate of 6 L/minute when the evaporator chamber temperature was varied from 38 °C to 60 °C. From the experiments, maximum distillate production of 31 L/hr m3 was recorded at 60 °C feed temperature for a single-stage configuration. To further enhance the distillate production of DCSEC, an innovative micro/nano-bubbles (M/NBs) generator device is incorporated in the feed supply system which resulted in 34% increase in potable water production at the corresponding inlet feed temperatures.The authors wish to thank the King Abdullah University of Science & Technology (KAUST) (URF/1/2986-01-01), and Aljouf University (JU)
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Corporate social responsibility reporting amongst petrochemical firms in the Kingdom of Saudi Arabia (KSA): practice and perception
No full textThe purpose of this study is to look into the disclosure of corporate social responsibility (CSRD) in the context of petrochemical companies in the Kingdom of Saudi Arabia (KSA). In doing so, it responds to a gap in the literature by addressing four main research questions including: 1) In the Saudi petrochemical companies' annual reports, what is the extent and nature of CSRD ?. 2) To what extent did CSRD increase in volume over the period 2012-2017 in the annual reports of the Saudi petrochemical companies? 3) What are the institutional drivers which may drive trends of CSR disclosure in KSA petrochemical sector? 4) What is the relationship between CSRD of petrochemical companies operating in KSA and firm performance? The study is the first to examine the Islamic context, particularly the link among CSRD and company performance in the context of the Saudi petrochemical sector to see how the study assess the patterns, drivers and implications of CSR disclosure in KSA petrochemical sector.
The study applied institutional theory to understand the drivers and pressures that may have the impact on CSRD trends by considering the multilevel forces to answer the aforementioned research questions relating to the practice and perception of CSRD in the kingdom of Saudi Arabia. Institutional theory is used to describe a broader aspect of an organisation form used to adopt legitimacy. However, the author focused on the multilevel model of Institutional Forces and the Drivers for KSA' Petrochemical Industry from the institutional theory angle. The Institutional Forces (Coercive, Memetic, and Normative) have demonstrated how pressures interact and interfere with each other at the same level and at times between several levels, as well as how the strength and influence of each pressure varies depending on the level in which it is placed. For instance, in the study the influence of institutional pressures was investigated at four distinct levels including the global industry, national, and company levels. At all the levels, three institutional pressures were evident. Sharia Law emerged as a coercive pressure at all the four levels. On the other hand, reporting initiative, as a mimetic pressure was evident across the levels. Ethics emerged as a normative force at all the levels. The most apparent conclusion is that the Islamic culture, which has its origins in Sharia law, has a significant impact on the petrochemical sector in the Kingdom of Saudi Arabia.
The extent and nature of CSRD in the sector was investigated by applying quantitative content analysis to the annual reports published by six sampled companies over the period 2012-2017. The resulting word counts gave an initial overview of general trends in overall CSRD and the four selected disclosure categories (environmental, social, human resources and products and services disclosure). These data were then subjected to descriptive, correlation and regression analysis to test the hypothesised link between CSRD and financial performance.
The quantitative findings revealed that all the sampled companies engaged in all four categories of disclosure, and that the volume of this disclosure rose over the study period. Furthermore, a significant positive link was found between CSRD and financial performance over six years, as measured in Return on Assets (ROA), Net Profit Margin (NPM) and Tobin's q. The analysis of the link between CSRD and ROA, NPM and TBQ showed that all the disclosure categories impacted on financial performance in different ways, with environmental and social disclosure having the greatest impact on ROA and environmental and human resources disclosure having the greatest impact on ROE. All disclosure categories were positively correlated with TBQ. The positive relationships help to assess the patterns, drivers and implications of CSRD disclosure in KSA petrochemical sector. The results thus support the hypothesis that there is a relationship between CSRD and financial performance over the period 2012 to 2017
Bio-Waste to Bioenergy: Critical Assessment of Sustainable Energy Supply Chain in Egypt
No full textThis study analyses the potential electricity output from different bio wastes using various energy conversion technologies to enhance the share of renewable energy. Furthermore, it evaluates the carbon emissions mitigated by replacing fossil fuels with bioenergy, contributing to efforts to reduce environmental pollution. The findings reveal that Egypt’s annual biomass waste (BW) could total approximately 80 million tons, with the most significant contributions from agricultural crop residues and municipal solid waste (MSW). MSW incineration and crop residue combustion were found to have the highest power generation compared to other techniques. Additionally, the anaerobic digestion of various biomass types offers the benefits of lower greenhouse gas emissions while still generating significant energy. The electricity generation from different BW sources is approximately 49.14 TWh/year. This energy can be predominantly generated through direct combustion of agricultural crop residues (66%), incineration of MSW (29%), anaerobic digestion of sewage sludge (3%), and animal waste (2%). Furthermore, the reduction in carbon emissions from substituting fossil fuels with bioenergy is estimated at up to 30.47 million tons of CO2 annually, supporting efforts to mitigate climate change and combat global warming
Utilizing Marble Wastewater in Cement Pastes and Mortars for Enhanced Physico-Mechanical and Microstructural Properties
No full textThis research explored the potential of marble wastewater (MWW) in cement paste and mortar production, addressing water scarcity, sustainable growth, and resource management. It investigated the physico-mechanical properties and microstructure of cement materials incorporated with varying amounts of MWW. In this study, we utilized tap water and MWW for mortar quality testing, focusing on parameters including setting times, water absorption, and mechanical strength. The viability of MWW in concrete formulations was confirmed by its acceptable total dissolved solids and alkalinity levels. A comprehensive experimental program determined that using marble wastewater in place of tap water reduced the quantity of water required for cement consistency and generated slightly higher compressive strengths (2, 3, 4, and 6%) after 28 days of curing. Analytical techniques, including Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy-dispersive X-ray analysis, and X-ray diffraction (XRD), were employed for molecular and microstructural analyses, which revealed that MWW had a significant influence on portlandite development and CSH formation at higher replacement levels. In short, this research highlights the feasibility of using MWW in cement products, contributing to sustainable water resources, and industrial waste management and utilization
Adsorption of Diphenolic Acid from Contaminated Water onto Commercial and Prepared Activated Carbons from Wheat Straw
No full textThe fabrication of carbon materials from biomass residues can be a promising economical approach for absorbing various target pollutants from aqueous phase. In the study, the adsorption of diphenolic acid (DPA) is investigated on activated carbons fabricated from wheat straw (ACWS) and commercial-activated carbon cloth (CACC). Adsorption kinetics, isotherms, and operational variables (solution pH and ionic strength) are analyzed for the adsorption capacity of the DPA on both carbons. The results show that the ACWS has a higher surface area (1164 m2/g) and volume of micropores (0.51 cm3/g) than those of the CACC. The second-order kinetics model fitted the experiment data better than the first kinetics models with a lower percentage of deviation. The adsorption capacity of the ACWS (264.90 mg/g) is higher than the CACC (168.19 mg/g) because of the higher surface area and volume of micropores of the ACWS. The adsorption isotherm shows that the adsorption of the DPA on the ACWS and CACC is consistent with the Langmuir and Freundlich isotherm models, respectively. The pH has a significant effect on DPA adsorption onto both carbons. The adsorption process is favored at the acidic pH, but the presence of electrolytes has no effect on the adsorption capacity of both carbons due to the screening effect. Thus, the preparation of activated carbon from wheat straw is an attractive option to recycle the wheat straw to added-value materials that can be used for the removal of such pollutants from aqueous solution. These findings can increase the research knowledge about the management of different straws in a sustainable way to produce activated carbon for different applications
Adsorption of Lead (Pb(II)) from Contaminated Water onto Activated Carbon: Kinetics, Isotherms, Thermodynamics, and Modeling by Artificial Intelligence
No full textHeavy metals, extensively used in various industrial applications, are among the most significant environmental pollutants due to their hazardous effects on human health and other living organisms. Removing these pollutants from the environment is essential. In this study, activated carbon (AC) (Carbon C) was employed to eliminate Pb(II) from water. The optimal removal conditions were determined as follows: a 50 mg dose of activated carbon, an initial Pb(II) concentration of 100 mg/L, pH 4, a temperature of 30 °C, and a contact time of 60 min Under these conditions, activated carbon achieved a Pb(II) removal efficiency of approximately 97.86%. The adsorption data for Pb(II) closely aligned with the 2nd-order kinetic model, and the equilibrium data were effectively described by the Langmuir isotherm equation. The maximum adsorption capacity of Pb(II), as determined by the Langmuir model, was 48.75 mg/g. These methods were successfully applied to remove Pb(II) from various environmental and industrial wastewater samples. To accurately predict the percentage of Pb(II) removal based on parameters such as pollutant type, carbon dosage, pH, initial concentration, temperature, and treatment duration, feed-forward neural networks (FFNNs) were utilized. The FFNN model demonstrated outstanding predictive accuracy, achieving a root mean square error (RMSE) of 0.03 and an R2 value of 0.996
Activated Carbon Fabricated from Biomass for Adsorption/Bio-Adsorption of 2,4-D and MCPA: Kinetics, Isotherms, and Artificial Neural Network Modeling
No full textAdsorption is an effective and economical alternative to remove herbicides from polluted water. The aim of this study is to investigate the adsorption of the most common herbicides (2,4-dichlorophenoxy-acetic acid (2,4-D) and 4-chloro-2-methylphenoxyacetic acid (MCPA)) onto activated carbon (AC) fabricated from wheat straw under different conditions. The adsorption of MCPA and 2,4-D onto the selected AC (CLW) and the effects of the ionic strength, the solution pH, and the presence of microorganisms in the medium were investigated. The results showed that the selected AC had a high surface area (1437 m2/g). The adsorption rate increased with an increase in the AC mass. The selected AC had a higher adsorption capacity (1.32 mmol/g) for 2,4-D compared to MCPA (0.76 mmol/g). The adsorption of 2,4-D and MCPA was not affected by variation in the solution pH. However, the presence of electrolytes exerted a major effect on adsorption. The presence of microorganisms enhanced adsorption onto the AC by 17% and 32% for 2,4-D and MCPA, respectively. Moreover, a radial basis function neural network (RBFNN) was employed to accurately predict the adsorption capacity based on the pollutant type, carbon dose, initial concentration, pH, ionic strength, and presence of bacteria. The RBFNN showed excellent accuracy in predicting the adsorption capacity, with an R2 value of 0.96 and a root mean square error (RMSE) of 0.054. These findings showed that the AC fabricated from biomass residues of wheat straw is a promising option to recycle this type of biomass waste and reduce environmental threats, consequently contributing to achieving sustainability
Influence of bio-filter configurations on hydraulic aspects while enhancing the sustainable self-purification of agricultural drainage water
No full textAs global climate change exacerbates water scarcity, recycling agricultural drainage water is emerging as a promising solution in water resources-limited regions. This research investigated the hydraulic impact of using gravel bio-filters in contaminated water-courses, focusing on submerged bioreactors as a sustainable engineering solution. This study assessed the hydraulic impacts of installing these bioreactors in polluted waterways using three-dimensional numerical models based on computational fluid dynamics. Results indicated that relative heading-up will increase with the Froude number, demonstrating a direct relationship between flow velocity and heading-up. Altering the shape of bio-filter inlet is predicted to significantly influence heading-up values, with triangular shapes showing the lowest heading-up values compared to basic, rounded, or sloped upstream U.S face shapes. Relative heading-up values will increase by 10.32%, 10.44%, 24.67%, and 31.86% when changing the bio-filter inlet shape from triangular to sloped U.S. face with respect to horizontal and vertical direction, rounded, and basic bio-filter, respectively. Additionally, the number and orientation of shapes in the bio-filter inlet impact relative heading-up, with varying effects predicted based on the inclination angle. These findings provide valuable guidance for mitigating hydraulic impacts and optimizing the design and operation of bioreactors in water resource management, promoting sustainable water purification approaches in contaminated watercourses and conserving surrounding environments
