Feed Spacer Research Articles

3d Cfd Study on Hydrodynamics and Mass Transfer Phenomena for Swm Submerged Type Feed Spacer with Different Nodes Geometries and Sizes

3d Cfd Study on Hydrodynamics and Mass Transfer Phenomena for Swm Submerged Type Feed Spacer with Different Nodes Geometries and Sizes

Membrane module autopsy used in the reverse osmosis process

This research was done to get acquainted with the characteristic of the membrane module in spiral, used in the osmosis reverse process. The goal to know its measure, components, hydrophilic, topography, materials and performance. The membranes of the module were characterized by the next techniques: atomic force microscopy (AFM), infrared spectroscopy by ATR (Attenuated Total Reflectance), contact angle and cross- flow equipment. Agree with the autopsy, the infrared spectrums indicate that the membrane is constituted by support of polyester paper, a polysulfone layer, a cellulose acetate layer and polyamide layer. The feed spacer is polypropylene and the permeate spacer is polyethylene terephthalate. All the measures did the membrane module were the same as the technical sheet from the manufacturer. The contact angle was 22.4±3.55° and roughness of 182.43±42 nm. The performance of the membrane was 70% to reject salts of feed 1000 ppm Na2SO4.

Three-dimensional numerical investigation of the displacement of shear-thinning milk protein concentrates in spacer-filled channel

Rinsing is an important part of the cleaning procedure applied to the spiral-wound membrane (SWM) modules in the dairy industry. In this work, we numerically investigated the displacement of non-Newtonian reconstituted milk protein concentrates in a feed spacer channel using OpenFOAM and compared the results with experimental data obtained in an SWM pilot plant. The model consists of the classical mass and momentum balance equations for an incompressible viscous mixture coupled with an advection-diffusion equation for the milk concentration. The power-law model was utilized to describe the shear-thinning viscosity of the milk protein concentrates. The shear-thinning behavior was further assumed to depend on the milk protein content. The calculations confirmed significantly shorter rinsing times and lower mixed-phase volumes for lower milk protein concentrations. The rinsing time can further be lowered by increasing the volumetric flow rate. Through the numerical simulations, we identified nearly inaccessible zones behind the filament crossings that prolong the rinsing process.

Selective removal of boron from industrial wastewater containing high concentration of ammonia by radiation grafted fibrous adsorbent in fixed bed column

Removal of boron from real industrial wastewater containing high concentration of ammonia was investigated using a fibrous adsorbent bearing glucamine groups obtained by green method. The adsorbent was prepared by radiation induced emulsion grafting (RIEG) of glycidyl methacrylate (GMA) onto nylon-6 fibres and subsequent treatment with N-methyl-D-glucamine (NMDG) under controlled conditions. The performance of the obtained adsorbent was tested for adsorption of boron from a real industrial wastewater containing high concentration of ammonia in comparison with a synthetic aqueous solution using in a fixed bed-column under different feed space velocities (SV). The dynamic adsorption data of the fixed column was tested against three most common mathematical adsorption models: Yoon–Nelson, Thomas and Modified Dose-Response (MDR) models to predict breakthrough curves and determine the column design parameters. The results showed that the experimental breakthrough curves were best fitted by MDR model. The adsorbed boron was eluted with 1 M HCl solution and the adsorbent was regenerated for stability evaluation using 5 adsorption/desorption cycles. The results suggest that the obtained adsorbent has a strong potential for industrial pilot scale boron removal applications.

Socio-cultural practices of deciduous canine tooth bud removal among Maasai children

The removal of teeth amongst the Maasai is a traditional practice as part of an initiation or to make space for feeding in an event of diseases locking the jaw. Removal of deciduous canine tooth buds (DCB) among infants below 2 years has been reported in several studies to be common mainly amongst communities in East Africa, Ethiopia and Sudan. The main reason for the practice revolves around the belief that tooth buds or 'maggots' are false teeth, nylon or worms and are responsible for diarrhoea, vomiting, fever and growth retardation in children, amongst other illnesses. The main objective of this study was to assess the socio-cultural factors which contribute to this practice. The main methods of data collected included Focus Group Discussions (FGD) with mothers of children in that age group and Traditional Birth Attendants (TBA). In-depth interviews (IDI)were conducted with key informants versed with Maasai traditions whereas observations were done within the manyattas where participants live. Proceedings at both the FGD and the IDI were recorded on paper and were analysed thematically. The study showed that the removal of canine tooth buds amongst children that started initially with calves--that diseases that cause diarrhoea in calves were brought about by the canine tooth buds that were turning reddish in colour--is deeply rooted and practised in the community despite sensitisation interventions mounted jointly by the University of Nairobi, Kenya Medical Research Institute and the Kenya Medical Training College, among others. This study discovered that canine tooth buds are associated with bad spirits that cause diarrhoea and vomiting and the belief that removing them is a sure way of providing a cure for all children's ailments.

PSXI-17 Increasing the number of water troughs do not increase water intake or improve calf performance

Abstract Provision of adequate quantity of water is essential for cattle as it can affect their health and growth. In addition, during summer months, the amount of water that calves can drink may double, limiting water access. One hundred and eight Holstein male calves (241 ± 3.1 Kg and 184 ± 0.9 d of age) were used in a randomized design to evaluate the effect of increasing from one to two water troughs per pen on water intake, performance and calf behavior over time. Calves were allocated in 6 pens (3 pens per treatment; 18 calves per pen) with one computerized concentrate feeder and one straw feeder with 5 feeding spaces. Pens were assigned to one of the two treatments according to the number of water troughs, a singles water trough (SWT) or a double water trough (DWT). Concentrate and water intake was recorded daily, and body weight (BW) and behavior fortnightly. Data were analyzed using a mixed-effects model with repeated measures including treatment, period and their interaction as main effect and pen per treatment as random effect. Final BW, average daily gain, water and concentrate intake were not affected by the number of water trough in the pen, as well as carcass weight and dressing percentage. However, water intake increased (P < 0.001) by period with an average water intake per calf of 21 L/day in calves with 241 d of age in February, to 51 L/day in calves with 409 d of age in August. Sexual and agonistic behaviors such as grooming, oral non-nutritive behaviors, fighting and mounting did not differ between treatments. The provision of an extra water trough per pen did not improve calf performance nor increase water intake even in summer month.

150 The effect of competition for an automated supplement feeder on supplement intake behavior of stocker steers

Abstract The objective of this research was to determine the effect of competition for a feeding space at an automated supplement feeder on supplement intake behavior. A 2 yr study was conducted; each yr, 128 mixed-breed beef steers (n = 256, initial BW = 245 ± 27.5 kg) were randomly assigned to 8 paddocks. One paddock each yr (n = 16 steers) was selected to have continuous access to the feeder for the duration of the 16 wk trial; this paddock was designated the “tester” paddock. The automated feeder had 4 feeding stations that dispensed supplement after eligible animal’s RFID tags were read by the electronics of the feeder. Steers were limited to 0.50 kg supplement/d. Weekly, additional paddocks were commingled with the tester paddock to increase competition for the feeder. This resulted in a stocking density from 4 to 32 steers per feeding station. For yr 2, one feeding station was disabled, resulting in a stocking density of 5.3 to 42.7 steers per feeding station. Approximately 31% of the steers did not voluntarily use the feeder; therefore, effective competition was less than the study design. Mean weekly supplement intake and GPS location were recorded for steers in the tester paddock. Additionally, pedometer data were collected in yr 2. Weekly mean supplement intake and time spent near the feeder were regressed on actual feeder stocking density with yr as a random variable; wk was the experimental unit (n = 16 wk). Tester steers consumed an average of 0.27 kg supplement/d. Competition for a feeding station numerically reduced (P = 0.01) supplement intake by 5 g/d per steer of additional competition. Steers spent 4.4% of the time within 15 m of the feeder regardless of competition (P = 0.54). As competition increased, steers took more steps (P < 0.01). These data illustrate that in environments similar to this experiment, the feeder can be stocked with at least 20 animals per feeding station with minimal effects on supplement intake.

Welfare Aspects of Raising Entire Male Pigs and Immunocastrates.

Simple SummarySurgical castration of male piglets without pain treatment and anaesthesia is not only a welfare problem but also violates the integrity of the animals. The favoured alternatives of raising entire male pigs (EM) with or without immunocastration (vaccination against boar taint) may, however, impose additional welfare problems under the current housing and management conditions. This focused review is intended to summarise the current state of scientific knowledge and practical reports on critical welfare issues and risk factors. Raising EM with or without subsequent immunocastration could be a welfare conform, future-oriented alternative to conventional surgical castration of pigs, provided that they are kept in a healthy and socially stable environment with sufficient physical resources, as safeguarded by measures of enhanced animal care and management control.For a long time, scientists assumed that newborns have a severely limited sense of pain (if any). However, this assumption is wrong and led to a “start of the exit” from piglet surgical castration. Some of the currently discussed or already implemented alternatives such as general or local anaesthesia during surgical castration raise additional welfare concerns as well as legal problems and/or are hardly applicable. The favoured long-term, welfare-friendly “gold standard” is to raise entire male pigs (EM). However, this may also impose certain welfare problems under the current conventional housing and management conditions. The specific types of behaviour displayed by EM such as mounting and aggressive behaviours but also increased exploration, which are partially linked to sexual maturation, increase the risk for injuries. The current status of knowledge (scientific literature and farmer experiences) on housing of EM suggests that environmental enrichment, space, group-stability, social constellation, feeding (diet and feeder space), health and climate control are critical factors to be considered for future housing systems. From an animal welfare point of view, an intermediate variant to be favoured to reduce problematic behaviour could be to slaughter EM before reaching puberty or to immunize boars early on to suppress testicular function. Immunization against endogenous GnRH can reduce EM-specific problems after the 2nd vaccination.

Antiscaling 3D printed feed spacers via facile nanoparticle coating for membrane distillation

Surface modification of feed spacers rather than membranes may hold more merit as an antiscaling strategy in membrane distillation (MD), as it avoids compromising the functionality of MD membrane. In this work, an antiscaling polyamide 3D printed spacer was developed for MD. The surface of the printed spacer was coated with fluorinated silica (FS) nanoparticles synthesized via a sol-gel process. The sol-gel approach used to synthesize the FS nanoparticles is considered a convenient and easy approach for engineering the spacer's surface structure and roughness. The performance of the FS coated printed surface was evaluated against other coating materials of different chemical properties. The coated surfaces were characterized using water contact angle measurements, ATR-FTIR, Raman, FESEM-EDX, atomic force and 3D microscopes. The 3D printed surface's microscale roughness and hydrophobicity increased, while its surface-free energy decreased with FS nanoparticles coating. The antiscaling performance of uncoated and FS coated spacers was then assessed in a direct contact MD process, using a scale-inducing aqueous solution of calcium sulfate as its feed. The scalant (Ca2+) attachment on the FS coated spacer was 0.24 mg cm−2, 74% lower than on the uncoated 3D spacer (0.95 mg cm−2). Also, by using the antiscaling FS coated spacer, scaling on the membrane surface dropped by 60%. The predominant factors that helped minimize scaling with FS coating were microscale roughness-induced hydrophobicity and reduced surface-free energy that weakened the scalant 's interaction with the spacer surface.

Steam Conversion of Propane in a Membrane Reactor with a Commercial Nickel Catalyst

The propane conversion in a membrane reactor with NIAP–03-01 commercial Ni catalyst at temperatures of 673, 723, 773, and 823 K, feed space velocities of 1800 and 3600 h–1, and steam/propane ratios of 5 and 7 was studied. The Н2 removal through the membrane leads to an increase in the conversion of the feed to Н2 and СО2 formed by the water-gas shift reaction. The conversion in this reaction increases when the rate of the Н2 recovery through the membrane is increased by the permeate evacuation. In the temperature interval 773–823 K, the feed conversion is 100%, and about 90% of high-purity Н2 is recovered from the reaction mixture. An increase in the feed/catalyst contact time leads to a decrease in the feed conversion to the target products and to an increase in the rate of carbon deposit formation. The regularities of the steam conversion of propane in a membrane reactor are similar to those found previously for n-butane with the same catalyst and under the same conditions.

Conceptual design of a dynamic turbospacer for efficient low pressure membrane filtration

This study presented a conceptual design of a novel dynamic turbospacer to enhance the performance of a low pressure membrane filtration process. It consists of ladder type filaments and a series of microturbine networks within the filament cells. The rotation of the turbines leads to the formation of turbulence in the feed channel that prevents foulants accumulation. Direct numerical simulation (DNS) was conducted to characterize the fluid flow behaviors of the feed channel for the proposed turbospacer and compared with a standard symmetric non-woven feed spacer. Further, their performances were investigated for a low pressure ultrafiltration (UF) process in a lab-scale experimental setup using 2.8 mm thick 3D printed prototypes of the turbospacer and the standard spacer. Experiments for the proof of this concept were conducted at 173 mL/min and 250 mL/min feed solution inlet velocity when Reynolds number of the flow is 160 and 230 respectively. Substantial reductions in fouling effects using the turbospacer was confirmed by the in-situ Optical Coherence Tomography (OCT) scans of the fouling cake layer accumulated over the membrane during the filtration of seawater with high fouling potential. The proposed turbospacer also lowered the average pressure drop by 4 times and enhanced the specific permeate flux by more than 3 times at 173 mL/min inlet flowratre. At the same operating condition, the specific energy consumption for the turbospacer was found about 2.5 folds lower than the standard spacer.

Modeling of Complex Reforming Reaction of Methane by Response Surface Methodology.

The objective of this study was to investigate the effect of feed composition, space velocity, and reaction temperature on methane/carbon dioxide conversion and H₂/CO ratio. Independent variables were feed ratio, flow rate, and reaction temperature while CH₄ conversion, CO₂ conversion, and H₂/CO ratio were set as dependent variables in the complex reaction of methane. As a result of mixed reforming reaction of methane through RSM modeling method, the reaction temperature was found to have the greatest influence. This is because the reaction temperature has the greatest influence on the reaction rate and equilibrium state as a factor directly affecting the thermodynamic value of the catalyst.

Synthesis of Modified Catalyst for Liquid Phase Alkylation of Benzene with Ethylene

Highly efficient binder-free catalysts, based on zeolite Y, for the liquid-phase alkylation of benzene with ethylene have been synthesized. The catalysts have been modified by treating with aqueous solutions of hydrochloric and citric acids to remove extra-framework aluminum formed during the partial dealumination of zeolite Y. The synthesized catalysts have been tested in the alkylation of benzene with ethylene at a temperature of 200°C, a pressure of 2.5 MPa, a benzene : ethylene molar ratio of 5 : 1, and a benzene feed space velocity of 5 h−1. Over the modified catalyst, the ethylbenzene (EB) content in the alkylate increases by 27% and the EB selectivity increases by 5% compared to the initial Y zeolite.

Impacts of feed spacer design on UF membrane cleaning efficiency

In this study, the impacts of three feed spacer design parameters; thickness, porosity and architecture, on the cleaning efficiency of ultrafiltration (UF) membranes were studied, both in backwash and relaxation cleaning modes, using sodium alginate solution dosed with CaCl2 as the process feed. Both commercial, net-type spacers and 3D-printed spacers based on triply periodic minimal surfaces (TPMS) architectures were utilized in the study. Increased spacer thickness and porosity were found to increase the cleaning resistance of the membrane, while TPMS spacers were found to yield a lower cleaning resistance than net-type spacers, even with the latter being thicker. The root causes of these observations were analyzed based on resistance analysis of the fouling layer on the membranes. To do that, overall, residual, reversible and irreversible fouling resistances were quantified at the end of a 20-cleaning cycle test. Statistical correlations were then established between these resistances and spacer properties.The results showed that the consequential impacts of spacer design on the shear stresses, created by the feed flow on the fouling layer, underscore the observed fouling mechanism and the consequent cleaning efficiency. The spacer design can impact these shear stresses through its hydraulic diameter and spacer-membrane contact area. When the spacer design leads to lower shear stresses, a cake filtration mechanism prevails, a more irreversible fouling occurs and more challenging cleaning becomes. A recently published work on combined intermediate pore blockage and cake filtration model for fouling was used to construe these observations.

Assessment of anti-bacterial adhesion and anti-biofouling potential of plasma-mediated poly(sulfobetaine methacrylate) coatings of feed spacer

In this work, an easy to up-scale method combining atmospheric plasma treatment and wet chemical coating with zwitterionic poly(sulfobetaine methacrylate) (pSBMA) was employed to modify the feed spacer surface aiming at reducing its susceptibility to biofouling. The goals of the study were: 1) to verify whether the proposed modification method is suitable for preparation of homogenous feed spacer coatings and 2) to compare the biofouling propensity of pSBMA modified and unmodified spacers. The effect of the plasma intensity and monomer concentration on the feed spacer surface composition, morphology and roughness were studied. The most favorable modification was compared with the reference material in a batch experiment and a continuously operated fouling simulator. The zwitterionic coating showed reduced adhesion of Pseudomonas fluorescens by 70% and postponed the EPS production in the short-term batch testing. However, the long-term studies performed under continuous flow conditions with nutrient dosage did not demonstrate any significant biofouling mitigation of the surface-conditioned spacers.

Effect of mechanical strain on the transport properties of thin-film composite membranes used in osmotic processes

In this work, we studied the mechanical behavior of commercial thin-film composite membranes and measured water and salt transport through membranes that were subjected to known degrees of strain. Our aim was to correlate linear strain with transport properties. Firstly, we showed that the global transport properties of the membranes did not change significantly after being subjected to linear strain values that are typical of pressure-retarded osmosis (PRO) operations. Secondly, using a newly developed osmotically-driven burst pressure test for flat sheet membranes, we theorized that the increased salt passage through the membranes was attributable to local deformation and defect formation in the membrane region along the border of the feed spacer opening. Using laser microscopy, we were able to pinpoint the area on the membrane with increased deformation, and to measure the deformation profile. We defined a deformability coefficient to estimate the membrane strain at a known pressure in terms of easily attainable characteristics like opening size, membrane thickness and secant modulus and used it to postulate a solution-diffusion model that accounts for defects by considering the deformability of the membrane in the experimental setup. By incorporating membrane deformation into the boundary layer equations used to describe water and salt flux in osmotic processes (OP), the model can describe the observed dependence of salt flux with applied pressure. The model was used to fit our PRO experimental data and numerous data reported in the literature, which revealed that salt passage increases as membrane deformation increases. Along with this effect, there is a lowered mass-transfer resistance, which constitutes the trade-off between mechanical deformation and mass-transfer resistance observed in pressurized OP. Our findings show that the deformability coefficient and our solution-diffusion model with defects can serve as guidelines for the design of membranes and modules for pressurized OP such as PRO.

Impacts of non-uniform filament feed spacers characteristics on the hydraulic and anti-fouling performances in the spacer-filled membrane channels: Experiment and numerical simulation

Feed spacer is universally used in spiral-wound nanofiltration (NF) and reverse osmosis (RO) membrane modules. It can separate membrane sheets, create flow channels, promote turbulence and enhance mass transfer. However, it also induces increased pressure drop across the flow channel, and generates dead zones for biofilm growth at specific locations. Optimization of feed spacer geometries is highly desirable for energy saving and biofouling control. In this study, four kinds of commercial feed spacers featured with non-uniform filaments were compared in terms of hydraulic and anti-fouling performances. Computational fluid dynamics (CFD) simulations were launched to give insights into the impacts of feed spacer characteristics on the flow field. Results show that the hydraulic performance was substantially affected by the number of filament layers (single or dual layer), the non-uniformity of filament diameter and the width of thinning zones. The design of single layer feed spacer of non-uniform filaments was not recommended due to high flow resistance and poor anti-fouling performance. The feed spacer structure of alternating filament diameter contributed to reducing dead zones and alleviating membrane fouling. The thinning zones located adjacent to the filament junctions achieved better anti-fouling performance, as it disturbed the dead zones and partially washed away the deposited foulants. This study demonstrates for the first time that the characteristics of non-uniform filament feed spacer had a crucial impact on the hydraulic and anti-fouling performances, and suggests that more emphasis should be laid on number of filament layers, variation of filament diameter and width and positioning of thinning zones for the optimization of feed spacer geometries in the future.

Acrylic Acid Production by Gas-Phase Dehydration of Lactic Acid over K+-Exchanged ZSM-5: Reaction Variable Effects, Kinetics, and New Evidence for Cooperative Acid–Base Bifunctional Catalysis

This study investigates the effects of reaction variables (including space velocity, temperature, and partial pressures of LA and H2O) and acidic and basic additives on the gas-phase dehydration of lactic acid (LA) for acrylic acid (AA) production, using an aluminum-rich K+-exchanged ZSM-5 zeolite (molar SiO2/Al2O3 = 27, K/Al = 1.0, K/Na = 8) identified among many high-silica zeolites as the most efficient catalyst in our prior work (Yan et al. ACS Catal. 2017, 7, 538−550). Under widely varied reaction conditions (340–380 °C, feed GHSV: 9,500–38,000 h–1, 1.8–11.7 kPa LA, 52.0–73.0 kPa H2O), the catalyst offers not only high selectivity for AA (>75 mol %) but also long-term catalytic stability. Rate equations and their associated kinetic parameters for LA consumption and AA production are obtained by measuring the kinetically relevant catalytic rates under high feed space velocity (GHSV ≥ 57,000 h–1). Acidic (CO2, acetic acid, and trifluoroacetic acid) and basic (NH3) additives are added, respectively, to the reaction feed to investigate their effects on performance of the working catalyst. While addition of either CO2 or acetic acid shows no effect on the catalyst performance, the addition of either NH3 or trifluoroacetic acid causes significant decline in both the catalyst activity and selectivity for AA production, due to poisoning of the surface acidic sites by NH3 or basic sites by trifluoroacetic acid. These data well highlight the excellent catalytic performance of the investigated catalyst and offer a new piece of evidence in support of the cooperative acid–base bifunctional catalysis for the LTA reaction.

Detection of Steady State Multiplicity during Dimethyl Ether Conversion Catalyzed by ZnO/γ-Al2O3 Composite: Effect of Coke and Hydrogen Peroxide

The heterogeneous catalytic conversion of dimethyl ether (DME) to 1,3-butadiene and butylenes in the presence of a ZnO/γ-Al2O3 catalyst in a wide range of temperatures, feed space velocities, and reactant concentrations has been studied. It has been found that temperature regions of 380–420 and 440–480°C, which are conventionally designated as low-temperature and high-temperature regions, differ in the laws governing the occurrence of the process associated with the specificity of coking of the catalyst surface and a redistribution of the surface concentration of Bronsted and Lewis acid sites. A hypothesis of a change of the catalytic process mechanism upon the transition of the reaction into the high-temperature region has been put forward and confirmed by the occurrence of a hysteresis detected in this temperature range. The effect of hydrogen peroxide on the hysteresis parameters and the steady state stability during DME conversion has been shown.

Enhanced performance of membrane distillation using radio-frequency induction heated thermally conducting feed spacers

In the last decade, there is a growing interest in membrane distillation (MD) technology for treating hypersaline water and wastewater. However, MD commercialization is still limited by technical challenges such as temperature polarization, high energy required for heating the bulk feed solution, and heat losses. We demonstrate a proof-of-concept approach to overcome these limitations using stainless steel thermally conducting feed spacers. Feed spacers were directly heated by induction heating, a contactless and instant heating method, using radio frequency (RF) altering electromagnetic fields. Results show that heat was efficiently transferred to the water-membrane interface by conduction and advection, thus, eliminating the need to continuously heat the bulk feed solution. Furthermore, the RF heated spacers were shown (experimentally and by numerical simulations) to reduce temperature polarization. The influence of operating conditions (i.e., flow velocity, vacuum pressure, and power) and the spacer’s material and geometry were evaluated and results were compared to a conventional MD process using a polymeric spacer. Overall, results show that higher spacer mass and larger porosity led to an increase in distillate flux and that the use of thermally conducting spacers heated by RF significantly enhance the distillate flux while reducing the specific heating energy.