Search results for: membrane wall

Authors: M. N. Abu Seman, L. M. Kei, M. A. Yusoff

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Forward Osmosis (FO) polyamide thin-film composite membranes have been prepared by inter facial polymerization using commercial UF polyethersulfone as membrane support. Different inter facial polymerization times (10s, 30s and 60s) in the organic solution containing trimesoyl chloride (TMC) at constant m-phenylenediamine (MPD) concentration (2% w/v) were studied. The synthesized polyamide membranes then tested for treatment of natural organic matter (NOM) and compared to commercial Cellulose TriAcetate (CTA) membrane. It was found that membrane prepared with higher reaction time (30 s and 60 s) exhibited better membrane performance (flux and humic acid removal) over commercial CTA membrane.

Keywords: cellulose triacetate, forward osmosis, humic acid, polyamide

Procedia PDF Downloads 487

Authors: Ayodele Oluwole Alejo

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Wall finishes are the term to describe an application over a wall surface to provide a suitable surface. Wall finishes are smelt, touched and seen by building occupiers even colour and design affects the user psychology and the atmosphere of our building. Building users/owners seem not to recognize the function of various wall finishes in building and factors to be considered in selecting them suitable for the type and purpose of proposed buildings. Therefore, defects such as deterioration, dampness, and stain may occur when comparisons of wall finishes are not made before the selection of appropriate materials at the design stage with knowledge of the various factors that may hinder the performance or maintenance culture of proposed building of a particular location. This research work investigates and compares various wall finishes in building. Buildings in Ondo state, Nigeria were used as the target area to conduct the research works. The factors bearing on various wall finishes were analyzed to find out their individual and collective impact using suitable analytical tools. The findings revealed that paint with high percentage score was the most preferred wall finishes, whereas wall paper was ranked the least by the respondent findings, Factors considered most in the selection of wall finishes was durability with the highest ranking percentage and least was the cost. The study recommends that skilled worker should carry out operations, quality product should be used and all of wall finishes and materials should be considered before selection.

Keywords: building, construction, design, finishes, wall

Procedia PDF Downloads 136

Authors: Kun Liang Ang, Eng Toon Saw, Wei He, Xuecheng Dong, Seeram Ramakrishna

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Ester solvents are widely used in pharmaceutical, printing and flavor industry due to their good miscibility, low toxicity, and high volatility. Through pervaporation, these ester solvents can be recovered from industrial wastewater. While metal-doped silicalite 1 zeolite membranes are commonly used in organic solvent recovery in the pervaporation process, these ceramic membranes suffer from low membrane permeation flux, mainly due to the high thickness of the metal-doped zeolite membrane. Herein, a simple method of fabricating an ultrathin tin-silicalite 1 membrane supported on alumina tube is reported. This ultrathin membrane is able to achieve high permeation flux and separation factor for an ester in a diluted aqueous solution. Nanosized tin-Silicalite 1 seeds which are smaller than 500nm has been formed through hydrothermal synthesis. The sn-Silicalite 1 seeds were then seeded onto alumina tube through dip coating, and the tin-Silicalite 1 membrane was then formed by hydrothermal synthesis in an autoclave through secondary growth method. Multiple membrane synthesis factors such as seed size, ceramic substrate surface pore size selection, and secondary growth conditions were studied for their effects on zeolite membrane growth. The microstructure, morphology and the membrane thickness of tin-Silicalite 1 zeolite membrane were examined. The membrane separation performance and stability will also be reported.

Keywords: ceramic membrane, pervaporation, solvent recovery, Sn-MFI zeolite

Procedia PDF Downloads 187

Authors: Deniz Sahin

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This study provides a literature review of the special issue on wastewater treatment technologies, especially membrane technologies. Currently, wastewater is a serious and increasing worldwide problem with an adverse effect on the environment and living organisms. For this reason, many technologies have been developed to treat wastewater before discharging it to water bodies. We have been discussed membrane technologies to remove contaminants from wastewater such as heavy metals, dyes, pesticides, etc., which represent the main pollutants in wastewater. All the properties of these technologies including performance, economics, simplicity, and operability are also compared with other wastewater treatment technologies. The conventional water treatment technologies have the disadvantages of low separation efficiency, high energy consumption, and strict operating temperature. To overcome these difficulties, membrane technologies have been developed and used in wastewater treatment. Membrane technology uses a selectively permeable membrane to remove suspended and dissolved solids from water. This membrane is a very thin film of synthetic organic or inorganic materials, that can allow a very selective separation between a mixture and its components. Examples of membrane technologies include microfiltration (MF), ultrafiltration (UF), nanofiltration (NF), reverse osmosis (RO), electrodialysis (ED), gas separation, etc. Most of these technologies have been used extensively for the treatment of heavy metal wastewater. For instance, wastewater that contains Cu²⁺, Cd²⁺, Pb²⁺, Zn²⁺ was treated by ultrafiltration technology. It was shown that complete removal of metal ions could be achieved.

Keywords: industrial pollution, membrane technologies, metal ions, wastewater

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Authors: Jaibir Sharma, Lee JaeWung, Merugu Srinivas, Navab Singh

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This paper presents thermal annealing dewetting technique for the preparation of porous metal membrane for thin film encapsulation application. Thermal annealing dewetting experimental results reveal that pore size in porous metal membrane depend upon i.e. 1. The substrate on which metal is deposited for formation of porous metal cap membrane, 2. Melting point of metal used for porous metal cap layer membrane formation, 3. Thickness of metal used for cap layer, 4. Temperature used for porous metal membrane formation. Silver (Ag) was used as a metal for preparation of porous metal membrane by annealing the film at different temperature. Pores in porous silver film were analyzed using Scanning Electron Microscope (SEM). In order to check the usefulness of porous metal film for thin film encapsulation application, the porous silver film prepared on amorphous silicon (a-Si) was release using XeF2. Finally, guide line and structures are suggested to use this porous membrane for thin film encapsulation (TFE) application.

Keywords: dewetting, themal annealing, metal, melting point, porous

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Authors: Jenny Radeva, Anke-Gundula Roth, Christian Goebbert, Robert Niestroj-Pahl, Lars Daehne, Axel Wolfram, Juergen Wiese

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Ceramic membranes for water purification combine excellent stability with long-life characteristics and high chemical resistance. Layer-by-Layer coating is a well-known technique for customization and optimization of filtration properties of membranes but is mostly used on polymeric membranes. Ceramic membranes comprising a metal oxide filtration layer of Al2O3 or TiO2 are charged and therefore highly suitable for polyelectrolyte adsorption. The high stability of the membrane support allows efficient backwash and chemical cleaning of the membrane. The presented study reports metal oxide/organic composite membrane with an increased rejection of bivalent salts like MgSO4 and the organic micropollutant Diclofenac. A self-build apparatus was used for applying the polyelectrolyte multilayers on the ceramic membrane. The device controls the flow and timing of the polyelectrolytes and washing solutions. As support for the Layer-by-Layer coat, ceramic mono-channel membranes were used with an inner capillary of 8 mm diameter, which is connected to the coating device. The inner wall of the capillary is coated subsequently with polycat- and anions. The filtration experiments were performed with a feed solution of MgSO4 and Diclofenac. The salt content of the permeate was detected conductometrically and Diclofenac was measured with UV-Adsorption. The concluded results show retention values of magnesium sulfate of 70% and diclofenac retention of 60%. Further experimental research studied various parameters of the composite membrane-like Molecular Weight Cut Off and pore size, Zeta potential and its mechanical and chemical robustness.

Keywords: water purification, polyelectrolytes, membrane modification, layer-by-layer coating, ceramic membranes

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Authors: Masataka Inada, Masanao Kinoshita, Nobuaki Matsumori

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It has been demonstrated that lipid molecules in biological membranes are responsible for the functionalization and structuration of membrane proteins. However, it is still unclear how the interaction of lipid molecules with membrane proteins is correlated with the function of the membrane proteins. Here we first developed an evaluation method for the interaction between membrane proteins and lipid molecules via surface plasmon resonance (SPR) analysis. Bacteriorhodopsin (bR), which was obtained by the culture of halobacteria, was used as a membrane protein. We prepared SPR sensor chips covered with self-assembled monolayer containing mercaptocarboxylic acids, and immobilized bR onto them. Then, we evaluated the interactions with various lipids that have different structures. As a result, the halobacterium-specific glycolipid S-TGA-1 was found to have much higher affinity with bRs than other lipids. This is probably due to not only hydrophobic and electrostatic interactions but also hydrogen bonds with sugar moieties in the glycolipid. Next, we analyzed the roles of the lipid in the structuration and functionalization of bR. CD analysis showed that S-TGA-1 could promote trimerization of bR monomers more efficiently than any other lipids. Flash photolysis further indicated that bR trimers formed by S-TGA-1 reproduced the photocyclic activity of bR in purple membrane, halobacterium-membrane. These results suggest that S-TGA-1 promotes trimerization of bR through strong interactions and consequently fulfills the bR’s function efficiently.

Keywords: membrane protein, lipid, interaction, bacteriorhodopsin, glycolipid

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Authors: Adnan Alhathal Alanezi

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The performance of vacuum membrane distillation (VMD) process for water desalination was investigated utilizing a new design membrane module using two commercial polytetrafluoroethylene (PTFE) and polyvinylidene fluoride (PVDF) flat sheet hydrophobic membranes. The membrane module's design demonstrated its suitability for achieving a high heat transfer coefficient of the order of 103 (W/m2K) and a high Reynolds number (Re). The heat and mass transport coefficients within the membrane module were measured using VMD experiments. The permeate flux has been examined in relation to process parameters such as feed temperature, feed flow rate, vacuum degree, and feed concentration. Because the feed temperature, feed flow rate, and vacuum degree all play a role in improving the performance of the VMD process, optimizing all of these parameters is the best method to achieve a high permeate flux. In VMD desalination, the PTFE membrane outperformed the PVDF membrane. When compared to previous studies, the obtained water flux is relatively high, reaching 43.8 and 52.6 (kg/m2h) for PVDF and PTFE, respectively. For both membranes, the salt rejection of NaCl was greater than 99%.

Keywords: desalination, vacuum membrane distillation, PTFE and PVDF, hydrophobic membranes, O-ring membrane module

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Authors: Musa Najimu, Isam Aljundi

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In this study, the development of mixed matrix membrane (MMM) containing carbide-derived carbon (CDC) for the separation of CO₂ was investigated. MMM with four different loadings (0.1 to 2 wt%) were prepared by the dry/wet phase inversion technique. Prior to this, the formula of the control polysulfone (PSF) membrane was optimized in terms of the PSF concentration in a mixture of NMP/THF solvents and ethanol. Prepared samples were characterized and tested for CO₂ and CH₄ gas permeation. The optimization of the control PSF membrane revealed that 30 wt% PSF is the critical polymer concentration in the formulation. Characterization results unveiled reinforcement of thermal stability and improved polarity imparted by CDC in the MMM, in addition to uniform dispersion of filler up to 1 wt% loading. Furthermore, the incorporation of CDC in PSF membrane formulation enhanced both the CO₂ permeance and ideal selectivity over the control membrane. A CDC loading of 0.5 wt% resulted in the highest CO₂ permeance of 5.5 GPU corresponding to 120% increase in permeance while a CDC loading of 1 wt% resulted in the highest selectivity (CO₂ /CH₄) of 27 corresponding to 29% increase in selectivity. Studies of operating temperature effect showed that an optimum operating temperature for M1.0 membrane is 20 ⁰C. In addition, the feed pressure studies showed that high pressure feeds will favor high performance of the membrane and a good CO₂ /CH₄ separation.

Keywords: carbide derived carbon, mixed matrix membrane, CO₂ separation, polysulfone

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Authors: Ngozi Nwogu, Mohammed Kajama, Emmanuel Anyanwu, Edward Gobina

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With the objective to create technologically advanced materials to be scientifically applicable, multi-layer silica alumina membranes were molecularly fabricated by continuous surface coating silica layers containing hybrid material onto a ceramic porous substrate for flue gas separation applications. The multi-layer silica alumina membrane was prepared by dip coating technique before further drying in an oven at elevated temperature. The effects of substrate physical appearance, coating quantity, the cross-linking agent, a number of coatings and testing conditions on the gas separation performance of the membrane have been investigated. Scanning electron microscope was used to investigate the development of coating thickness. The membrane shows impressive perm selectivity especially for CO2 and N2 binary mixture representing a stimulated flue gas stream

Keywords: gas separation, silica membrane, separation factor, membrane layer thickness

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Authors: P. Chultheera, T. Rirksomboon, S. Kulprathipanja, C. Liu, W. Chinsirikul, N. Kerddonfag

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Gas separation by selective transport through polymeric membranes is one of the rapid growing branches of membrane technology. However, the tradeoff between the permeability and selectivity is one of the critical challenges encountered by pure polymer membranes, which in turn limits their large-scale application. To enhance gas separation performances, mixed matrix membranes (MMMs) have been developed. In this study, MMMs were prepared by a solution-coating method and tested for CO₂/CH₄ separation through permeability and selectivity using a membrane testing unit at room temperature and a pressure of 100 psig. The fabricated MMMs were composed of silicone rubber dispersed with the activated carbon individually absorbed with polyethylene glycol (PEG) as a liquid additive. PEG emulsified silicone rubber MMMs showed superior gas separation on cellulose acetate membrane with both high permeability and selectivity compared with silicone rubber membrane and alone support membrane. However, the MMMs performed limited stability resulting from the undesirable PEG leakage. To stabilize the MMMs, PEG was then incorporated into activated carbon by adsorption. It was found that the incorporation of solid and liquid was effective to improve the separation performance of MMMs.

Keywords: mixed matrix membrane, membrane, CO₂/CH₄ separation, activated carbon

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Authors: Eun Kyung Kim, Kyehan Rhee

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Viscoelastic wall properties of the arterial plaques change as the disease progresses, and estimation of wall viscoelasticity can provide a valuable assessment tool for plaque rupture prediction. Cross section of the stenotic coronary artery was modeled based on the IVUS image, and the finite element analysis was performed to get wall deformation under pulsatile pressure. The effects of viscoelastic parameters of the plaque on luminal diameter variations were explored. The result showed that decrease of viscous effect reduced the phase angle between the pressure and displacement waveforms, and phase angle was dependent on the viscoelastic properties of the wall. Because viscous effect of tissue components could be identified using the phase angle difference, wall deformation waveform analysis may be applied to predict plaque wall composition change and vascular wall disease progression.

Keywords: atherosclerotic plaque, diameter variation, finite element method, viscoelasticity

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Authors: Eng Toon Saw, Kun Liang Ang, Wei He, Xuecheng Dong, Seeram Ramakrishna

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Solvent recovery process is receiving utmost attention in recent year due to the scarcity of natural resource and consciousness of circular economy in chemical and pharmaceutical manufacturing process. Solvent dehydration process is one of the important process to recover and to purify the solvent for reuse. Due to the complexity of solvent waste or wastewater effluent produced in pharmaceutical industry resulting the wastewater treatment process become complicated, thus an alternative solution is to recover the valuable solvent in solvent waste. To treat solvent waste and to upgrade solvent purity, membrane pervaporation process is shown to be a promising technology due to the energy intensive and low footprint advantages. Ceramic membrane is adopted as solvent dehydration membrane owing to the chemical and thermal stability properties as compared to polymeric membrane. NaA zeolite membrane is generally used as solvent dehydration process because of its narrow and distinct pore size and high hydrophilicity. NaA zeolite membrane has been mainly applied in alcohol dehydration in fermentation process. At this stage, the membrane performance exhibits high separation factor with low flux using tubular ceramic membrane. Thus, defect free and ultrathin NaA membrane should be developed to increase water flux. Herein, we report a simple preparation protocol to prepare ultrathin NaA zeolite membrane supported on tubular ceramic membrane by controlling the seed size synthesis, seeding methods and conditions, ceramic substrate surface pore size selection and secondary growth conditions. The microstructure and morphology of NaA zeolite membrane will be examined and reported. Moreover, the membrane separation performance and stability will also be reported in isopropanol dehydration, ketone dehydration and ester dehydration particularly for the application in pharmaceutical industry.

Keywords: ceramic membrane, NaA zeolite, pharmaceutical industry, solvent recovery

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Authors: Seung Moon Woo, Youn Suk Chung, Sang Yong Nam

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In the present time, we need advanced water treatment technology for separation of virus and bacteria in effluent which occur epidemic and waterborne diseases. Water purification system is mainly divided into two categorizations like reverse osmosis (RO) and ultrafiltration (UF). Membrane used in these systems requires higher durability because of operating in harsh condition. Of these, the membrane using in UF system has many advantages like higher efficiency and lower energy consume for water treatment compared with RO system. In many kinds of membrane, hollow fiber type membrane is possible to make easily and to get optimized property by control of various spinning conditions such as temperature of coagulation bath, concentration of polymer, addition of additive, air gap and internal coagulation. In this study, polysulfone hollow fiber membrane was successfully prepared by phase inversion method for separation of virus and bacteria. When we prepare the hollow fiber membrane, we controlled various factors such as the polymer concentration, air gap and internal coagulation to investigate effect to membrane property. Morphology of surface and cross section of membrane were measured by field emission scanning electron microscope (FE-SEM). Water flux of membrane was measured using test modules. Mean pore diameter of membrane was calculated using rejection of polystyrene (PS) latex beads for separation of virus and bacteria. Flux and mean flow pore diameter of prepared membrane show 1.5 LPM, 0.03 μm at 1.0 kgf/cm2. The bacteria and virus removal performance of prepared UF membranes were over 6 logs.

Keywords: hollow fiber membrane, drinking water, ultrafiltration, bacteria

Procedia PDF Downloads 246

Authors: Ahmed Rouili

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Cantilever L-shaped walls are known to be relatively economical as retaining solution. The design starts by proportioning the wall dimensions for which the stability is checked for. A ratio between the lengths of the base and the stem, falling between 0,5 to 0,7, ensure the stability requirements in most cases. However, the displacement pattern of the wall in terms of rotations and translations, and the lateral pressure profile, do not have the same figure for all wall’s proportioning, as it is usually assumed. In the present work, the results of a numerical analysis are presented, different wall geometries were considered. The results show that the proportioning governs the equilibrium between the instantaneous rotation and the translation of the wall-toe, also, the lateral pressure estimation based on the average value between the at-rest and the active pressure, recommended by most design standards, is found to be not applicable for all walls.

Keywords: cantilever wall, proportioning, numerical analysis, lateral pressure estimation

Procedia PDF Downloads 323

Authors: Seul Ki Min, Gwang Heum Yoon, Jung Hyun Joo, Hwa Sung Shin

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Cellular membrane distortion is known as a factor to change intracellular signaling. However, progress of relevant studies is difficult because there are no facilities that can control membrane distortion finely. In this study, we developed microfluidic device which can inflict mechanical stress on cell membrane of Chlamydomonas reinhardtii using regular height of the channels. And cellular physiological changes were analyzed from cells cultured in the device. Excessive calcium ion influx through into cytoplasm was induced from mechanical stress. The results revealed that compressed cells had up-regulated Mat3 mRNA which regulates cell size and cell cycle from a prolonged G1 phase. Additionally, TAG used for the production of biodiesel was raised rapidly from 4 h after compression. Taken together, membrane distortion can be considered as an attractive inducer for biofuel production.

Keywords: mechanical stress, membrane distortion, Chlamydomonas reinhardtii, deflagellation, cell cycle, lipid metabolism

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Authors: Lenka Morávková, Zuzana Sedláková, Jiří Vejražka, Věra Jandová, Pavel Izák

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The need to minimize the costs of biogas upgrading leads to a continuous search for new and more effective membrane materials. The improvement of biogas combustion efficiency is connected with polar gases removal from a feed stream. One of the possibilities is the use of water–swollen polyamide layer of thin film composite reverse osmosis membrane for simultaneous carbon dioxide and hydrogen sulphide removal. Transport properties and basic characteristics of a thin film composite membrane were compared in the term of appropriate water-swollen membrane choice for biogas upgrading. SEM analysis showed that the surface of the best performing composites changed significantly upon swelling by water. The surface changes were found to be a proof that the selective skin polyamide layer was swollen well. Further, the presence of a sufficient number of associative centers, namely amido groups, inside the upper layer of the hydrophilic thin composite membrane can play an important role in the polar gas separation from a non-polar gas. The next key factor is a high porosity of the membrane support.

Keywords: biogas upgrading, carbon dioxide separation, hydrogen sulphide separation, water-swollen membrane

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Authors: Soo-yeon Seo, Su-jin Jung

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In recent years, the need for remodeling of many apartments built 30 years ago is increasing. Therefore, researches on the structural reinforcement technology of existing apartments have been conducted. On the other hand, there is a growing need for research on the existing underground space expansion technology to expand the parking space required for remodeling. When expanding an existing underground space, for earthworks, an earth retaining wall must be installed between the existing apartment building and it. In order to maximize the possible underground space, it is necessary to minimize the thickness of the portion of earth retaining wall and underground basement wall. In this manner, the calculation procedure is studied for the evaluation of shear strength of the composite basement wall corresponding to shear span-to-depth ratio in this study. As a result, it was shown that the proposed calculation procedure can be used to evaluate the shear strength of the composite basement wall as safe. On the other hand, when shear span-to-depth ratio is small, shear strength is very underestimated.

Keywords: underground space expansion, combined structure, temporary retaining wall, basement wall, shear connectors

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Authors: Gokhan Kilic, Pelin Celik

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Structural health monitoring (SHM) is widely used in evaluating the state and health of membrane structures. In the past, in order to collect data and send it to a data collection unit on membrane structures, wire sensors had to be put as part of the SHM process. However, this study recommends using wireless sensors instead of traditional wire ones to construct an economical, useful, and easy-to-install membrane structure health monitoring system. Every wireless sensor uses a software translation program that is connected to the monitoring server. Operational neural networks (ONNs) have recently been developed to solve the shortcomings of convolutional neural networks (CNNs), such as the network's resemblance to the linear neuron model. The results of using ONNs for monitoring to evaluate the structural health of a membrane are presented in this work.

Keywords: wireless sensor network, non-destructive testing, operational neural networks, membrane structures, dynamic monitoring

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Authors: M. Yusuf Ansari, Asad Abbas

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Proton exchange membrane (PEM) fuel cell is a very efficient and promising energy conversion device. Although Nafion® is considered as benchmark materials for membrane used in PEM fuel cell, it has limitations that restrict its uses. Alternative materials for the membrane is always a challenging field for researchers. Sulfonated poly(ether ether ketone) (SPEEK) is one of the promising material for membrane due to its chemical and mechanical stability and lower cost. In this work, SPEEK is synthesized, and property booster such as silica nanoparticles and polyvinyl alcohol (PVA) are also added to analyse changes in properties such as water uptake, IEC, and conductivity. It has been found that adding PVA support high water uptake and proton conductivity but at large amount of PVA reduces the proton conductivity due to very high water uptake. Adding silica enhances water uptake and proton conductivity.

Keywords: PEM Membrane, sulfonated poly (ether ether ketone) (SPEEK), silica fumes (SiO2), polyvinyl alcohol (PVA)

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Authors: Yuri Seu, Seong-Kyu Choi, Hyun Jin Park, Jin Seo Park, HongtaeKim, Mi-Sun Hur

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The aim of this study was to clarify the attachments of the distal oblique membrane (DOM) and distal oblique bundle (DOB) of the interosseous membrane of the forearm. The distal oblique membrane was investigated in the 21 specimens of 11 Korean cadavers. The muscles in the forearms were removed to observe the DOB. The DOB was found in 13 of 21 specimens (61.9 %). The DOB was attached to the distal radioulnar joint capsule and the septum between the tendons of the extensor digiti minimi (EDM) and extensor carpi ulnaris (ECU) as well as the radius and ulna. In the cases that the DOB was absent, a part of the DOM extended to the distal radioulnar joint capsule and the septum between the tendons of the EDM and ECU, as well as the radius and ulna in all specimens (100%). The DOM, including the DOB, was arranged obliquely in the anteroposterior direction, whereas the intermediate part of the interosseous membrane was arranged in the same plane between the radius and ulna. The extension of the DOM and DOB to the wrist region may stabilize the distal radioulnar joint during supination and pronation. These data will be useful when performing reconstructive surgeries.

Keywords: distal oblique membrane, distal oblique bundle, distal radioulnar joint capsule, interosseous membrane

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Authors: Remzi Şahin, Sadık Ata, Kevser Dincer

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In this study, performance of proton exchange membrane (PEM) fuel cell was experimentally investigated. The efficiency of energy conversion in PEM fuel cells is dependent on the catalytic activities of the catalysts used in the cathode and anode of membrane electrode assemblies. Membrane is considered the heart of PEM fuel cells without which they cannot produce electricity. PEM fuel cell performance increased with coating carbon nanotube (CNT). CNT show a unique combination of stiffness, strength, and tenacity compared to other fiber materials which usually lack one or more of these properties. Two different experiments were performed and the membrane performance has been determined by repeating the two experiments that were done before coating. The purposes of these experiments are the observation of power change due to a temperature change in the same voltage value.

Keywords: carbon nanotube (CNT), proton exchange membrane (PEM), fuel cell, spin method

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Authors: Dhahri Maher, Aouinet Hana

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The presence of bubbles in the boundary layer introduces corrections into the log law, which must be taken into account. In this work, a logarithmic wall law was presented for bubbly two phase flows. The wall law presented in this work was based on the postulation of additional turbulent viscosity associated with bubble wakes in the boundary layer. The presented wall law contained empirical constant accounting both for shear induced turbulence interaction and for non-linearity of bubble. This constant was deduced from experimental data. The wall friction prediction achieved with the wall law was compared to the experimental data, in the case of a turbulent boundary layer developing on a vertical flat plate in the presence of millimetric bubbles. A very good agreement between experimental and numerical wall friction prediction was verified. The agreement was especially noticeable for the low void fraction when bubble induced turbulence plays a significant role.

Keywords: bubbly flows, log law, boundary layer, CFD

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Authors: B. Daee, H. M. El Naggar

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This paper presents an experimental study on structural performance of an innovative noise barrier consisting of poly-block, light polyurethane foam (LPF) and polyurea. This wall system (flexi-wall) is intended to be employed as a vertical extension to existing sound barriers in an accelerated construction method. To aid in the wall design, several mechanical tests were conducted on LPF specimens and two full-scale walls were then fabricated employing the same LPF material. The full-scale walls were subjected to lateral loading in order to establish their lateral resistance. A cyclic fatigue test was also performed on a full-scale flexi-wall in order to evaluate the performance of the wall under a repetitive loading condition. The result of the experiments indicated the suitability of flexi-wall in accelerated construction and confirmed that the structural performance of the wall system under lateral loading is satisfactory for the sound barrier application. The experimental results were discussed and a preliminary design procedure for application of flexi-wall in sound barrier applications was also developed.

Keywords: noise barrier, polyurethane foam, accelerated construction, full-scale experiment

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Authors: Habtamu Abdisa

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In nature, water may not be free from contaminants due to its polar nature. But, more than this, the environmental water is highly polluted by manmade activities from industrial, agricultural, recreation, shipping, and domestic sites, thereby increasing the shortage of freshwater for designated purposes. Therefore, in the face of water scarcity, human beings are enforced to look at all the existing opportunities to get an adequate amount of freshwater resources. The most probable water resource is wastewater, from which the water can be recovered to serve designated purposes (for industrial, agricultural, drinking, and other domestic uses). Present-day, the most preferable method for recovering water from different wastewater streams for re-use is membrane technology. This paper looks at the progressive development of membrane technology in wastewater treatment. The applications of pressure-driven membrane separation technology (microfiltration, ultrafiltration, nano-filtration, reverse osmosis, and tissue purification) and no pressure membrane separation technology (semipermeable membrane, liquefiedfilm, and electro-dialysis) and also ion-exchange were reviewed. More than all, the technology for converting environmental water pollutants into energy is of considerable attention. Finally, recommendations for future research relating to the application of membrane technology in wastewater treatment were made. Also, further research recommendation about membrane fouling and cleaning was made.

Keywords: environmental pollution, membrane technology, water quality, wastewater

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Authors: Chia-Yu Chang, Yi-Feng Lin

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CO2 capture has attracted significant research attention due to global warming. Among the various CO2 capture methods, membrane technology has proven to be highly efficient in capturing CO2 due to the ease at which this technology can be scaled up, its low energy consumptions, small area requirements and overall environmental friendliness for use by industrial plants. Capturing CO2 is to use a membrane contactor with a combination of water-repellent porous membranes and chemical absorption processes. In a CO2 membrane contactor system, CO2 passes through a hydrophobic porous membrane in the gas phase to contact the amine absorbent in the liquid phase. Consequently, additional CO2 gas is absorbed by amine absorbents. This study examines highly porous Polydimethylsiloxane (PDMS)/Polystyrene (PS) Nanofibrous Membranes and successfully coated onto a macroporous Al2O3 membrane. The performance of these materials in a membrane contactor system for CO2 absorption is also investigated. Compared with pristine PS nanofibrous membranes, the PDMS/PS nanofibrous membranes exhibit greater solvent resistance and mechanical strength, making them more suitable for use in CO2 capture by the membrane contactor. The resulting hydrophobic membrane contactor also demonstrates the potential for large-scale CO2 absorption during post-combustion processes in power plants.

Keywords: CO2 capture, polystyrene, polydimethylsiloxane, superhydrophobic

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Authors: Karan R. Chavan, Srivats Gopalan, Kumudini V. Marathe

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In the current work, the comparison of degradation of malathion by single species, Pseudomonas Stutzeri, and Activated Sludge/Mixed Microbial Culture is studied in a Membrane Bioreactor. Various parameters were considered to study the effect of single species degradation compared to degradation by activated sludge. The experimental results revealed 85-90% reduction in the COD of the Malathion containing synthetic wastewater. Complete reduction of malathion was observed within 24 hours in both the cases. The critical flux was 10 LMH for both the systems. Fouling propensity, Cake and Membrane resistances were calculated thus giving an insight regarding the working of Membrane Bioreactor-based on single species and activated sludge.

Keywords: fouling, membrane bioreactor, mixed microbial culture, single species

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Authors: Harshada Lohokare

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Biofouling is major issue in Reverse Osmosis (RO) membranes operation. To address the biofouling issue in raw water as well as wastewater recycle / reuse application requires effective biofouling control program. Current biocides (2,2-dibromo-3-nitrilopropionamide, isothiazolinone) are costly and hence often under-dosed. The membrane compatibility, as well as the microbio efficiency of the RO membrane biocide was studied. Based on the biofouling potential, the biocide product and it’s dosage was studied. It was found that these products need to be dosed continuous as well as intermittent dosage based on the microbio load. This study shows that depending on the application and microbio fouling potential, products can be chosen to mitigate the biofouling issues and improve the RO membrane performance.

Keywords: reverse osmosis membrane, biofouling, biocide, stabilized halogen

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Authors: Fadi Eleiwi, Taous Meriem Laleg-Kirati

Abstract:

This paper presents a complete dynamic modeling of a membrane distillation process. The model contains two consistent dynamic models. A 2D advection-diffusion equation for modeling the whole process and a modified heat equation for modeling the membrane itself. The complete model describes the temperature diffusion phenomenon across the feed, membrane, permeate containers and boundary layers of the membrane. It gives an online and complete temperature profile for each point in the domain. It explains heat conduction and convection mechanisms that take place inside the process in terms of mathematical parameters, and justify process behavior during transient and steady state phases. The process is monitored for any sudden change in the performance at any instance of time. In addition, it assists maintaining production rates as desired, and gives recommendations during membrane fabrication stages. System performance and parameters can be optimized and controlled using this complete dynamic model. Evolution of membrane boundary temperature with time, vapor mass transfer along the process, and temperature difference between membrane boundary layers are depicted and included. Simulations were performed over the complete model with real membrane specifications. The plots show consistency between 2D advection-diffusion model and the expected behavior of the systems as well as literature. Evolution of heat inside the membrane starting from transient response till reaching steady state response for fixed and varying times is illustrated.

Keywords: membrane distillation, dynamical modeling, advection-diffusion equation, thermal equilibrium, heat equation

Procedia PDF Downloads 271

Authors: Mehrdad Ebrahimi, Oliver Schmitz, Axel Schmidt, Peter Czermak

Abstract:

“Produced water” (PW) is any fossil water that is brought to the surface along with crude oil or natural gas. By far, PW is the largest waste stream by volume associated with oil and gas production operations. Due to the increasing volume of waste all over the world in the current decade, the outcome and effect of discharging PW on the environment has lately become a significant issue of environmental concerns. Therefore, there is a need for new technologies for PW treatment due to increase focus on water conservation and environmental regulation. The use of membrane processes for treatment of PW has several advantages over many of the traditional separation techniques. In oilfield produced water treatment with ceramic membranes, process efficiency is characterized by the specific permeate flux and by the oil separation performance. Apart from the membrane properties, the permeate flux during filtration of oily wastewaters is known to be strongly dependent on the constituents of the feed solution, as well as on process conditions, e.g. trans-membrane pressure (TMP) and cross-flow velocity (CFV). The research project presented in these report describes the application of different ceramic membrane filtration technologies for the efficient treatment of oil-field produced water and different model oily solutions.

Keywords: ceramic membrane, membrane fouling, oil rejection, produced water treatment

Procedia PDF Downloads 180