Air gap membrane distillation: A detailed study of high saline solution

An experimental study is used to examine the effect of high concentration of several salts, i.e., NaCl, MgCl2, Na2CO3 and Na2SO4 on permeate flux and rejection factor by air gap membrane distillation (AGMD). A comparative study involving three different membrane pore sizes (0.2, 0.45 and 1.0 μm) were performed to investigate the influence of pore size on energy consumption, permeate flux and rejection factor. The permeate flux decline is higher than that predicted from the vapour pressure reduction. Furthermore, the energy consumption was monitored at different membrane pore size and was found to be increased when the concentration increased

Utilization for a triple-layer phoswich detector for beta spectral stripping

To quantify the relative activity contributions of beta emitters in mixed emission source spectra, the triple-layer phoswich detector was modeled to generate beta energy absorption spectra from mixed beta sources. These mixed sources include four pure beta emitters (C-14, Tc-99, Sr-90, and Y-90). Monte Carlo N-Particle (MCNP) computer code was used to simulate electron energy absorption in the first and second layers (beta detector). A spectral stripping technique was developed to de-convolve the multi-response distribution (beta energy absorption spectrum) into its component parts for the identification and quantification of its constituent radionuclides. The method provided reliable results in identifying the studied radionuclides and determining their relative combination of source activity. The results revealed variations in percentages between the original emission and collected spectra that was found to be less than 2% in all studied spectra. Those variations were believed to be attributed to some degree of uncertainty in the spectral stripping method and some energy loss prior to detection

Towards a Sustainable Water Supply: Humic Acid Removal Employing Coagulation and Tangential Cross Flow Microfiltration

Synthetic solutions assimilating irrigated groundwater containing varying concentrations of humic acid (10 -40 mg/L) and saline (10-35 g/L) and metal agents (5 mg/L) , were processed through a ceramic microfiltration membrane (Sterilox Ltd.,0.5 μm). This was done with enrichment schemes using polymeric coagulants (PDADMAC) applied to enhance the removal of the above-mentioned pollutants. The study was conducted with the scope of investigating the feasibility of sequential and hybrid coagulation and microfiltration as a method of choice for drinking water treatment. Membrane microfiltration is easily scalable into various arrangements, allowing versatility in operation and enrichment treatments, with a relatively lower cost which other treatment practices do not allow. The highest humic acid removal, 91.11 % was achieved with hybrid coagulation

Silica nanofibrous membranes for the separation of heterogeneous azeotropes

Nanofibrous materials produced through electrospinning are characterized by a high porosity, large specific surface area, and high pore interconnectivity and, therefore, show potential for, e.g., separation and filtration. The development of more inert nanofibers with higher thermal and chemical resistance extends the application field to high-end purification. Silica nanofibrous membranes produced by direct electrospinning of a sol-gel solution without a sacrificing carrier, starting from tetraethoxysilane, meet these challenging requirements. After electrospinning the membrane is highly hydrophobic. Storage under dry conditions preserves this property. Oppositely, a superhydrophilic membrane is obtained by storage under high humidity (month scale). This switch is caused by the reaction of ethoxy groups, present due to incomplete hydrolysis of the precursor, with moisture in the air, resulting in an increased amount of silanol groups. This transition can be accelerated to hour scale by applying a heat treatment, with the additional increase in cross-linking density for temperatures above 400 degrees C, enabling applications that make use of hydrophobic and hydrophilic membranes by tuning the functionalization. It is showcased that upon designing the water repellent or absorbing nature of the silica material, fast gravity-driven membrane separation of heterogeneous azeotropes can be achieved

Exploring the current state of play for cost-effective water treatment by membranes

This article presents a perspective on the current development and application of membranes for the treatment of water. We examine how membranes contribute to the global challenge of sustainable supply of clean water. The main theme is on desalination and how innovative science and emerging technology is being applied. Thus, we appraise how techniques such as advanced membrane materials, biomimetic membranes, hybrid systems, forward osmosis, and membrane distillation are being used to improve production to meet the increasing global demand for water

Mercury, Arsenic and Lead Removal by Air Gap Membrane Distillation: Experimental Study

Synthetic industrial wastewater samples containing mercury (Hg), arsenic (As), and lead (Pb) ions in various concentrations were prepared and treated by air gap membrane distillation (AGMD), a promising method for heavy metals removal. Three different membrane pore sizes (0.2, 0.45, and 1 μm) which are commercially available (TF200, TF450, and TF1000) were tested to assess their effectiveness in combination with various heavy metal concentrations and operating parameters (flow rate 1–5 L/min, feed temperature 40–70 °C, and pH 2–11). The results indicated that a high removal efficiency of the heavy metals was achieved by AGMD. TF200 and TF450 showed excellent membrane removal efficiency, which was above 96% for heavy metal ions in a wide range of concentrations. In addition, there was no significant influence of the pH value on the metal removal efficiency. Energy consumption was monitored at different membrane pore sizes and was found to be almost independent of membrane pore size and metal type

Twitter usage in Saudi Arabia: An empirical study on the challenges faced by the government

During the last decade, Twitter has emerged as a prominent platform for digital governance in Saudi Arabia, offering a space for millions of users to engage in public conversations on a daily basis. At the same time, this growth has presented significant challenges for Saudi state institutions as they seek to optimize the platform’s potential while mitigating its associated risks. This empirical study sheds light on the challenges faced by the Saudi government in managing Twitter usage within the context of digital governance. Before formulating the research goals and questions, an extensive literature review was conducted to ensure the relevance of the topic and the theoretical and practical value of the results. It highlighted that Saudi Arabia is at the forefront of digital innovations in the MENA region, including the development of e-government. Despite the traditionally conservative nature of the Saudi government and society, the use of social media, especially Twitter, is very high. Thanks to the Vision 2030 national development plan and the digital development initiatives of Saudi leaders, almost all public institutions have started to provide digital services to clients. This has turned social media into one of the most effective channels of communication with citizens. Nevertheless, the knowledge on this topic is limited, particularly regarding the use of Twitter by Saudi public institutions. To address this gap, the present study provides a thorough analysis of the pace of development and key advancements of digital governance through Twitter among Saudi public institutions. The study relied on qualitative and quantitative methodologies (interviews and questionnaires) to obtain a holistic understanding of the challenges and opportunities associated with digital governance. The researcher conducted 19 11-question interviews with representatives of Saudi public institutions regarding their use of Twitter for digital governance. In addition, 434 regular Saudi citizens participated in a questionnaire assessing their opinions about and satisfaction with these services. The combination of these methods produced a rich and diverse set of perspectives on the topic. The interviews, questionnaires, and secondary data analysis uncovered numerous challenges with the implementation of digital governance. The findings revealed the need to invest in infrastructure and digital skills development, address cultural barriers, and promote citizen engagement in the design and implementation of digital governance services. Additionally, the results showed the potential of social media and Twitter as a platform for social activism and their impact on public discourse in general. Digital governance has significantly enhanced the provision of services to citizens in Saudi Arabia. The use of Twitter has been instrumental in this regard, but there is still room for improvement. Therefore, this study provides recommendations that could help Saudi public organizations provide better digital governance services in the future. As the world is increasingly online, this study offers valuable implications not only for Saudi Arabia but also for other countries seeking to improve their approach to digital governance services