An isolation ward requires a highly controlled and contamination-free environment since the settling of bacteria-carrying particles (shed by medical staff) on patients’ wounds could cause infections. The present study examines the effect of medical staff’s walking movement on airflow distribution and particle dispersion. Three different walking speeds of 0.25 m/s, 0.5 m/s, and 1.0 m/s were assigned to the medical staff. An RNG k-ɛ model based on the Reynolds-Averaged Navier-Stokes (RANS) equation was adopted to predict the airflow, while a Lagrangian tracking approach was selected to track particle dispersion. The reliability of the selected airflow turbulent model and particle tracking approach was validated using published data. The present study showed that the low-pressure region behind the moving medical staff’s body has induced wake. The higher walking speed of 1.00 m/s produced a significant secondary airflow of 1.12 m/s, while 0.25 m/s and 0.5 m/s generated lower secondary airflow of 0.41 m/s and 0.53 m/s, respectively. The number of particles settled on the patient at 0.25 m/s, 0.50 m/s, and 1.00 m/s were 31, 18 and 5, respectively. Present finding indicated that a higher walking speed reduces the number of particles settled on the burn patient, therefore potentially reducing the associated nosocomial infection risk.
This chapter describes the application of silica-based hollow fiber membrane for water treatment. There are two types of common hollow fiber membrane for water treatment: polymer and ceramic membrane. A well-known phase inversion method was used to prepare these membranes. Accordingly, silica (SiO2) is a well-known glass forming oxide, which can be microporous, mesoporous, and macroporous material. In membrane technology, SiO2 plays an important role in enhancement of the membrane properties as well as performance. For example, addition of silica in polymer membrane matrix could induce higher hydrophilicity behavior, thus increasing membrane flux. However, in terms of geometry, polymer hollow fiber membrane is rarely studied as it offers some drawback. Alternatively, silica-based ceramic hollow fiber membrane has been successfully fabricated from cheap materials such as clays and waste ashes. This kind of technology offers advantages in water treatment as it could not only be used for separation only, but combined separation-absorption application for water treatment like heavy metal removal. Finally, some case studies in water treatment (i.e., oily wastewater separation) are discussed, with potentialities, drawbacks, and future trends.
Background Developing durable superhydrophobic ceramic membranes capable of withstanding harsh operating conditions and maintaining their properties over an extended period poses a challenge due to the limited robustness and stability of superhydrophobic membranes. Methods In this study, a two-step technique, previously unreported, was successfully used to prepare superhydrophobic mullite-based kaolinite (MK) and stainless steel (SS) composite hollow fibre membranes (HFMs). The surface roughening step was attained through the hydrothermal treatment of copper oxide nanoparticles (CuO) at different reaction times (2- 5 h) on the MK-SS HFM surface. The fluorinating process was achieved using 1H, 1H, 2H, 2H perfluorooctyltriethoxysilane (C8, 97%) through a dip-coating technique. A seawater desalination experiment by a membrane distillation (MD) system evaluated the performance of MK-SS HFM for 500 min. Significant findings The results revealed that the MK-SS/4 h HFM, characterized by its flake-like structure, exhibited optimal superhydrophobic behavior. It displayed contact angles (CAs) of 155.9° for water, 144° for water/ethanol, 129° for palm oil, and 112° for engine oil, with a liquid entry pressure (LEP) of 5.2 bar Furthermore, the membrane performance was tested in a direct contact membrane distillation (DCMD) at 70 °C using a solution that simulated real seawater conditions, including sodium chloride (NaCl) at 35 g/L, sodium sulfate (Na2SO4) at 1.2 g/L, sodium carbonate (Na2CO3) at 1 g/L, and humic acid at 8 mg/L. Remarkably, a rejection rate of about 99.91% and a permeate flux of 24.3 L/(m².h) were achieved. Despite the presence of organic contaminants and various salts, this superhydrophobic HFM, prepared using a two-step technique, exhibited higher contact angles, rejection rates, and permeate flux than other superhydrophobic HFMs reported in the literature due to its superior superhydrophobic and antiwetting properties. This robust superhydrophobic membrane holds promise for developing effective superhydrophobic HFMs that can be applied in various real MD applications.
Availability of alternate fuels for cogeneration helps to limit the amount of bagasse as fuel at sugar plants and make them available for other uses such as paper manufacture or ethanol production.Due to the increased awareness on the adverse effects of carbon dioxide emission on the environment, power plant operators are compelled to reduce emissions of pollutants during cogeneration.Selection of low pollutant fuels, tapping of renewable energy and use of efficient operating policies can help to reduce the emissions at sugar plants to some extent.This paper reports on an optimization study where a combination of bagasse, coal, other biomass and solar energy are used.Dried bagasse is more efficient and a less pollutant fuel.The bagasse at different levels of moisture content (MC) is also analyzed here.Minimization of the emissions and bagasse utilization are taken as the objectives with the combined use of coal and biomass along with the bagasse.The problem is formulated as environmental friendly power dispatch with optimum bagasse (EFDOB) and the optimization is performed for this multi-objective problem using sequential quadratic programming (SQP) algorithm in MATLAB.The results discuss the strategy for an economical and environmental friendly utilization of bagasse and other biomasses for sugar plants.
Ceramic membranes have received more attention currently from researchers in membrane distillation (MD) applications due to their outstanding properties. However, despite their superior mechanical, thermochemical stability, and resistance to harsh operating conditions, several bottlenecks still limit their applications in MD. Although there are several published articles on ceramic membranes in MD, the uniqueness of this review lies in the fact that it discusses the critical bottlenecks that significantly affect the performance of ceramic membranes in long-term operation and limit their scale-up to commercial MD applications. Furthermore, recent advances, strategies, and techniques to mitigate these limitations have also been discussed. A discussion on high ceramic membrane fabrication costs and mitigation strategies using alternative low-cost ceramic materials to erstwhile conventional ceramic materials has been presented. In addition, the inherent problems of the brittleness and wetting/fouling of ceramic membranes and recent advances in strengthening ceramic membranes and fouling/wetting control via the development of superhydrophobic and omniphobic ceramic surfaces in MD have been addressed. Consequently, technical bottlenecks that still exist despite recent development in ceramic membranes for MD applications have been highlighted and future research direction in developing robust ceramic membranes in MD applications has been elaborated.
Asymmetric, porous ultrafiltration polysulfone (PSf) hollow fiber membranes were fabricated via the dry-wet phase inversion spinning technique specifically for haemodialysis membrane. The objective was to discover the suitable spinning condition for the fabrication of ultrafiltration hollow fiber membrane with desired sponge-like structure. During haemodialysis procedure, uremic toxins such as urea and creatinine range from size 10,000-55,000 Da needs to be excreted out from the blood. While, proteins such as albumin (66,000 Da) need to be retained. The physical structure or morphology of a fabricated membrane is a major concern in determining the efficiency of a dialysis membrane. Different type of membrane morphology will give a different result in term of its permeability and clearance efficiency. The phase inversion spinning technique is suitable in producing ultrafiltation (UF) membrane where the average pore size of the fabricated membrane is in the range of 0.001 – 0.1 µm. However, there is many factors need to be controlled and manipulated in the phase inversion technique. In this study, the effect of the PVP on membrane pore size and performances were analysed. The contact angle measurement was measured to determine the hydrophilicity of the fibers. The hydrophilic polymer is favorable to avoid fouling and increase its biocompatibility. Furthermore, the diameter of the hollow fibers was determined using a scanning electron microscope (SEM). The effects of different morphology of the hollow fibers on the performance of the membranes were evaluated by pure water flux and BSA rejection. Both techniques were tested using permeation flux system. Based on the results obtained, it is found that the finger-like macrovoids in PSf hollow fiber membranes were suppressed by adding 8% PVP (Mw of 360 kDa) into the spinning dope solution as the result of a drastic increase in dope viscosity. On top of that, fiber spun with 8% PVP show more porous structure which contribute to higher permeability of the membrane. The result of this study can benefit to the membrane field of research especially in membrane technology for haemodialysis application.
Among wide range of membrane-based operations, membrane contactors, as they reify comparatively modern membrane-based mechanism are gaining quite an attention in both pilot and industrial scales. In recent literature, carbon capture is one of the most researched applications of membrane contactors. Membrane contactors have the potential to minimize the energy consumption and capital cost of traditional CO2 absorptions columns. In a membrane contactor, CO2 regeneration can take place below the solvent boiling point, resulting into lower consumption of energy. Various polymeric as well as ceramic membrane materials have been employed in gas liquid membrane contactors along with several solvents including amino acids, ammonia, amines etc. This review article provides detailed introduction of membrane contactors in terms of CO2 removal. It also discusses that the main challenge that is faced by membrane contactors is membrane pore wetting caused by solvent that in turn can reduce the mass transfer coefficient. Other potential challenges such as selection of suitable solvent and membrane pair as well as fouling are also discussed in this review and are followed by potential ways to reduce them. Furthermore, both membrane gas separation and membrane contactor technologies are analysed and compared in this study on the basis of their characteristics, CO2 separation performances and techno economical transvaluation. Consequently, this review provides an opportunity to thoroughly understand the working principle of membrane contactors along its comparison with membrane-based gas separation technology. It also provides a clear understanding of latest innovations in membrane contactor module designs as well as challenges encountered by membrane contactors along with possible solutions to overcome these challenges. Finally, semi commercial and commercial implementation of membrane contactors has been highlighted.
Sensitivity and mechanical properties are the key factors that affect the performance of strain-sensitive etched fiber Bragg grating (EFBG) sensors. Typically, EFBG sensors are fabricated via solvent etching. The manipulation of etching temperature and hydrofluoric acid (HF) concentration during the solvent etching process is particularly crucial to control the surface and mechanical properties of the sensors. In this study, the effects of these two etching conditions on the surface and mechanical properties of the etched fiber surface were investigated. It is found that higher etching temperature and higher HF concentration can cause rougher fiber surface with lower Young’s modulus, fracture stress and strain. EFBG produced at 20 °C temperature and 30% HF concentration exhibits smooth surface and high mechanical properties. Under these optimized etching conditions, the sensitivity of EFBGs was improved by reducing the fiber diameter. The results show that EFBGs with smaller diameters demonstrate higher strain sensing performance due to lower fiber stiffness. EFBG with a diameter of 15 μm has Young modulus of 7.21 GPa and achieves the highest strain sensitivity of 52.74 pm/με. To conclude, EFBG with excellent strain sensing performance can be obtained by tailoring the surface structures and fiber’s diameter during the etching process.
Anode-supported micro-tubular solid oxide fuel cell (MT-SOFC) made from lithium (Li) doped cerium gadolinium oxide (CGO) electrolyte was prepared via phase inversion based co-extrusion/co-sintering technique. In this study, the co-sintering temperature of CGO electrolyte with anode layer was reduced by adding Li that acts as sintering additive. The prepared Li doped CGO (Li-CGO) were characterized by shrinkage analysis, atomic resolution analytical microscope (ARM) observation and X-ray photoelectron spectroscopy (XPS) spectra. Meanwhile, the developed half-cell of MT-SOFC which was co-sintered at 1350–1500°C with interval of 50°C were characterized by its mechanical strength, gas tightness and microstructural analysis. The electrochemical performances of the cells were tested in anode-supported MT-SOFCs with configuration of Ni-CGO anode, Li-CGO electrolyte and LSCF-CGO cathode using humidified hydrogen as fuel and oxygen air as oxidant. MT-SOFCs fabricated with Li-CGO electrolyte were found to exhibit maximum power density of 60Wm−2 at 500°C compared to 200Wm−2 for cells with unmodified CGO electrolyte. The poor performance of cell with Li-CGO electrolyte is probably due to the combined effects of (i) moderately dense electrolyte layer and (ii) appearance of electronic conductivity in Li-CGO electrolyte. Nevertheless, lowering the sintering temperature has shown good properties of the electrolyte materials, which allows the electrolyte materials and anode can be co-sintered together at lower temperature.
Herein, we report the synthesis of few-layered graphene oxide (GO), reduced graphene oxide (rGO), and rGO/ZnO thin films on a glass substrate.
Abstract Rigless temporary well abandonment (TWA) is an increasingly adopted method in the oil and gas industry, offering cost-effective solutions while ensuring well integrity and environmental protection. This paper explores best practices to minimize environmental risks associated with rigless TWA, focusing on barrier placement, verification techniques, and compliance with regulatory requirements. Key considerations include selecting appropriate plugging materials, ensuring zonal isolation, and monitoring well integrity through remote surveillance technologies. Well plugging and abandonment (P&A) poses significant long-term risks for the industry with thousands of onshore and offshore wells requiring P&A in the coming decades. Due to the high cost required for the permanent P & A of wells, it has become expedient to temporarily abandon these wells by rigless means (use of Coiled tubing cementing, Slickline & E-line isolation plugs with perforation techniques) to ensure integrity of the asset and prevent environmental pollution pending approval of main budget for permanent abandonment. Case studies highlight successful implementations that have mitigated risks such as hydrocarbon leaks and groundwater contamination. Proper isolation of hydrocarbon-bearing zones, overpressured formations, uncemented annuli, and freshwater intervals encountered in the wellbore is essential for a successful abandonment. The abandonment strategy should be designed based on the reservoir fluids present and the well's mechanical condition at the time of abandonment. By adopting standardized best practices and advanced monitoring techniques, operators can enhance environmental stewardship and maintain well integrity during temporary abandonment periods.
The excessive amount of ammonia presents in water streams has led to a serious potable water scarceness worldwide. The application of conventional methods in removing ammonia suffers from many drawbacks. To this end, the shift towards adsorptive membrane application in eliminating ammonia has gained a great attention due to its outstanding performance attributable to the hybrid process, i.e., adsorption and filtration approaches, as a single step. Thus, this review critically discusses the current trend of ammonia removal means and the approach of fabricating adsorptive membrane. The future prospective on the utilisation of natural zeolite as adsorptive membrane is also conferred.
This review examines self-cleaning dual-layer membrane systems, which have demonstrated unprecedented efficacy in wastewater treatment by overcoming traditional membrane limitations such as fouling, scaling, and chemical degradation. These innovative membranes boast enhanced selectivity, increased flux, and prolonged durability, thereby transforming the efficiency and sustainability of water treatment and separation technologies. The integration of photocatalytic materials further reduces operating costs and amplifies effectiveness. This paper aims to explore the benefits and drawbacks of self-cleaning membrane technology, providing valuable insights into material selection, design, and configuration. By minimizing maintenance needs and ensuring consistent operation, self-cleaning membrane systems emerge as a promising solution to revolutionize wastewater treatment, addressing fouling issues and significantly improving efficiency.
