Feed Spacer Research Articles

The role of feed spacers in membrane technology: 45 years of research

Feed spacers are crucial for enhancing the performance and efficiency of membrane-based technologies. Researchers have long focused on optimizing feed spacer designs and materials to improve fluid mixing and mass/heat transfer across membranes. However, these improvements often increase pressure drops, raising energy requirements. Therefore, innovative designs are sought to balance enhanced mass/heat transfer with reduced pressure drops and improved antifouling properties. This study analyzes patterns and trends in the feed spacer field using bibliometric methods, data analysis, and machine learning. The analysis includes 457 articles from the Scopus database, collected on March 5, 2024, covering publications from 1978 to 2023 across 45 journals. The analysis revealed that reverse osmosis technology emerges as the most studied membrane process, with 153 articles. Furthermore, experimental research in this field is preferred over theoretical evaluations, and the impact of feed spacers on mass transfer and pressure drops is the most explored topic, with 197 articles addressing one or more of these phenomena. Additionally, 204 articles focused on feed spacers’ role in fouling, scaling, and biofouling, with commercial feed spacers being the most frequently studied. The Journal of Membrane Science leads in publication volume with 152 articles, and Vrouwenvelder J.S. is the top author in 4 out of 6 metrics. Sentiment analysis of abstracts shows that authors generally express positive sentiments (385 articles) while maintaining an objective (453 articles) and emotion-free (446 articles) writing style.

Insights into iron-accelerated gypsum scaling mitigation strategies in nanofiltration membrane process

In this study, the impact of ferric ions on gypsum crystallization and NF membrane performance was investigated to mitigate iron-accelerated gypsum scaling. Gypsum scaling in the presence of ferric ions led to a significant decline in the water flux, but a relatively higher reversible fouling ratio was observed compared to that under individual gypsum and iron-oxide scaling. Ferric ions influenced the crystallization of gypsum on NF membranes by serving as additional nucleation sites, leading to accelerated gypsum scaling. Various mitigation methods (e.g., feed spacers and cleaning processes) were evaluated to effectively control iron-accelerated gypsum scaling. The introduction of spacers exhibited a high mitigation efficiency by enhancing the mass transfer of scalant ions due to changes in the water channel hydrodynamics, but the overall efficiency decreased over time. To enhance the mitigation efficiency, different cleaning methods (e.g., CO2 oversaturated solution, HCl, and NaCl flushing) were conducted with feed spacers. A CO2 saturated solution demonstrated high cleaning efficiency owing to the high turbulence induced by CO2 bubbles, whereas HCl flushing showed negligible efficiency. NaCl flushing exhibited the highest cleaning efficiency through mono/divalent ion-exchange effects on iron-gypsum scaling. This study provides comprehensive insights into iron-accelerated gypsum scaling mitigation strategies for nanofiltration membranes, highlighting the impact of coexisting ferric compounds on gypsum scaling.

Enhanced mass transfer and energy efficiency by a biomimetic feed spacer in reverse osmosis membrane modules

Inspired by the structure of seal whiskers, this study undertakes a biomimetic design of the spacer in Reverse osmosis (RO) desalination, the performance of biomimetic spacers based on parameters such as elliptical cross-sectional area ratio (SR), twist angle (φ) and Reynolds number (Re) are analysed. Spacer performance ratio on the water production per unit pressure drop (SPR) and energy loss factor (λ) are introduced to better elucidate the structural performance of the spacer. The experimental and simulation studies on the adopted commercial spacer and the improved biomimetic spacer are used to demonstrate the reliability of the simulation. The structure of commercial spacer is further obtained by using micro-CT scanning, then the performance of commercial spacer (S1), circular cross-section spacer (CS), and prototype biomimetic spacer (BS) are numerically compared, and an improved biomimetic spacer (IBS) is obtained. When Re = 50 (Re = 300), the pressure drop of IBS is reduced by approximately 38 % (35 %) compared to the CS, and 39 % (28 %) compared to the S1; SPR is increased by approximately 83 % (57.4 %) compared to the CS, and 60.8 % (37 %) compared to the S1. With a filament angle (γ) of 60°, the IBS exhibits optimal performance. Ultimately, through data and theoretical analysis, theoretical formulas are developed to reflect the energy loss factor (λ) based on the projected area of the spacer along the flow direction, Re, and pressure drop. Through optimization of design, the improved biomimetic spacer can not only significantly reduce the pressure drop, but also obtain the high water flux, which provides new insights and methods for the development of seawater desalination technology.

Hydrophilic modification of feed spacer and its impacts on antifouling performance of reverse osmosis membrane

AbstractFeed spacers improve mixing and mass transfer in membrane modules. However, they also lead to foulant deposition in the vicinity of the spacer surface. In this paper, two hydrophilic monomers, namely, acrylic acid (AA) and 2‐hydroxyethyl methacrylate (HEMA), are respectively coated on the surface of a commercial feed spacer via a plasma‐enhanced chemical vapor deposition (PECVD) method. The resulting modified spacers are then evaluated alongside with a reverse osmosis (RO) membrane for its solute rejection, water permeability, and antifouling properties. Results show that the surface hydrophilicity of feed spacers has been enhanced upon the AA and HEMA deposition. During filtration test, the HEMA‐modified spacer demonstrates higher flux recovery rate (94.17%) and salt rejection (95.78%) for the RO membrane. In contrast, the membrane with the unmodified spacer only shows 89.44% and 92.46%, respectively. Additionally, the membrane with the HEMA‐modified spacer has a thinner fouling layer (200 nm) compared to the unmodified spacer (700 nm). The HEMA‐coated spacer outperforms all the tested spacers, demonstrating that feed spacer modification with a hydrophilic monomer via the PECVD method can effectively reduce membrane fouling.

Inverse design of V-shape feed spacer for batch and semi-batch reverse osmosis

In recent years, batch and semi-batch reverse osmosis (RO) processes have received wide attention because of their internal staging feature. However their performance is severely compromised by salt retention induced by incomplete flushing, which leads to elevated salt concentration, uplifted peak pressure, and extra power consumption. Herein we adopt transient three-dimensional computational fluid dynamics to systematically analyze the effect of the V-shape feed spacer geometries on hydrodynamics and mass transfer characteristics. After a sensitivity analysis of all geometric parameters, a heuristic optimization framework is proposed for inverse design of the feed spacer. Using the optimized feed spacer, flushing efficacies after one displacement volume are 0.936, 0.962, 0.969 and 0.974 respectively for one, three, five and seven membrane elements connected in series (whereas 0.884, 0.926, 0.942 and 0.952 for commercial spacers), which help to mitigate membrane scaling and fouling. Moreover, the optimized spacer has a pressure drop per meter 73 % lower than that of the commercial spacer. If used in conjunction with high permeability membranes, batch RO and semi-batch RO could save 29.9 % and 24.1 % specific energy consumption relative to conventional one-stage seawater RO.

Automated image processing algorithm for 3D OCT images of fouling in spacer-filled membrane filtration channels

OCT imaging is an important technique to study fouling in spacer-filled channels of reverse osmosis systems for seawater desalination. However, OCT imaging of membrane filtration channels with feed spacers is challenging because the spacer material can be (partly) transparent, making it difficult to detect and possibly mistaken for fouling, and the longer optical pathway through the spacer material distorts the image below the spacer. This study presents an automated 3D OCT image processing method in MATLAB for visualization and quantification of biofouling in spacer-filled channels. First, a spacer template of arbitrary size and rotation was generated from a CT scan of the feed spacer. Second, background noise and file size were reduced by representing the OCT image with a list of discrete reflectors. Finally, the spacer template was overlayed with the feed spacer in the 3D OCT image, enabling automated visualization of the feed spacer and correction of the distortions. Moreover, the method allows the selection of datasets with the same location relative to the position of the spacer, enabling systematic comparison between datasets and quantitative analysis.•A spacer template of arbitrary size and rotation was generated from a CT scan.•The background noise was removed, and the file size was reduced by representing the OCT dataset with a list of discrete reflectors.•The spacer template was overlayed with the feed spacer in the 3D OCT image.

Optimizing spiral‐wound pervaporation membrane modules through simulation: Unraveling the permeate spacer structure

AbstractFor low‐pressure pervaporation, the performance of spiral wound pervaporation membrane (SWM‐PV) module is significantly influenced by permeate spacer structure. This study addresses mass transport challenges in SWM‐PV modules, focusing on increased gas flow resistance and vacuum attenuation due to membrane envelope deformation in the permeate side channel. Employing fluid and structural simulation models to evaluate phase change and membrane deformation, we successfully optimized SWM‐PV module configurations for improved ethanol recovery. Our strategies included a mass transfer‐enhanced feed spacer to mitigate concentration polarization, a high‐strength permeate spacer to alleviate membrane deformation, and tailored membrane envelopes to balance packing density and mass transfer efficiency. These synergistic optimizations led to a 22.1% improvement in ethanol mass transfer coefficient and a 78.5% reduction in module's specific energy consumption. Our work reveals the importance of permeate spacer structure in optimizing SWM‐PV modules, offering clear guidance for the development of mass transfer‐enhanced SWM‐PV modules.

Synergistically controlling biofouling and improving membrane module permeability by using simultaneously structurally optimized and surface modified feed spacers

This study developed a new protocol to prepare feed spacers in the membrane module, by combining the optimization of spacers' geometrical parameters with subsequent chemical modification of the spacers’ surface, to enhance filtration performance comprehensively. Geometrical parameters of columnar spacers were optimized using an object-oriented and automatic optimization method based on computational fluid dynamics (CFD) simulation coupled with response surface optimization. In chemical modification, polydopamine was firstly used to provide anti-adhesive properties, followed by the even integration of silver nanoparticles (AgNPs) to exhibit antimicrobial activity. Anti-biofouling experiments involving Gram-negative (E. coli) and Gram-positive (S. aureus) bacteria demonstrated that the combined structurally optimized and chemically modified spacers resulted in over 10 % improvement in permeate flux and a 27 % reduction in feed channel pressure (FCP) drop. Chemical modification enhanced the structural optimization resistance to flux attenuation and FCP drop increase by over 220 % and 200 %, respectively. Analysis of the anti-biofouling behavior indicated that the primary mechanism of the integrated, optimized spacers lies in the increased wall shear, bactericidal activity of AgNPs, and improved interfacial interaction energy between the spacers and foulants. This study not only developed a novel modification method for anti-biofouling spacers, but also provides in-depth understanding of the roles of modified spacers, all of which are important for their practical applications in improving membrane filtration performance.

Numerical study of energy consumption in spacer-filled feed channels through 3D inverse modeling and computational fluid dynamics

This project employs advanced Computational Fluid Dynamics (CFD) simulations to investigate the complex flow field dynamics within the channel of membrane module featuring a commercially available feed spacer. Utilizing Micro-CT scanning, the intricate three-dimensional (3D) structure of the spacer is accurately captured, enhancing the precision of the simulation models. The project focuses on the effects of varying Reynolds number (Re) and Aspect Ratio (AR) on the energy consumption within the feed channel of membrane module, analyzing streamline patterns, vorticity, and flow separation angles in detail. Findings indicate that the total enstrophy identification method effectively pinpoints areas of high energy consumption, especially at lower Re levels where flow separation significantly contributes to hydraulic losses. As Re increases, the separation vortex shifts rearward, resulting in a marked decrease in the energy consumption coefficient. Furthermore, the flow separation angle consistently declines with increasing Re, stabilizing at higher levels. Significantly, a reduction in AR from 1.015 to 0.725 more than doubles the decrease in flow separation angle, highlighting substantial potential energy savings through spacer design optimization. These insights are crucial for improving the design and efficiency of spiral wound membrane modules and for refining feed spacer configurations to enhance performance.

PSIII-6 Tail damage caused by tail biting in growing-finishing pigs housed in two group sizes

Abstract Tail biting can compromise the welfare of pigs and cause economic losses for pork producers, but little is known about the development of tail biting and its resulting impact on pigs. In this study, we investigated victimization by tail biting and the resulting impacts on the welfare and performance of pigs housed in two group sizes. Pigs (n = 432, initial body weight = 22.0 ± 3.7 kg) with intact tails were housed in large (LG = 18 pigs/pen, 12 pens) or small groups (SG = 9 pigs/pen, 24 pens) in a barn with fully slatted floors for 14 wk until market weight (120.7 ± 11.8 kg). Floor space (0.76 m2/pig) and feeder space (4 feeder spaces/9 pigs) allowance were identical between group sizes, and pigs were stratified by initial body weight and sex across treatment pens. Growth performance, pig removal, and tail damage were monitored throughout the study. Tail damage was assessed for each pig weekly and during tail biting outbreaks, using a subjective scoring system (0 = no damage; 1 = healed lesions with small scabs; 2 = puncture wounds with visible blood; 3 = wounds with signs of infection; 4 = partial or total loss of the tail). The maximal tail score (MTS) each pig received every four weeks and over the entire 14 weeks was summarized. Pigs that received MTS of ≥ 2 were considered victimized by a tail biter. Data were analyzed using Glimmix procedure with logit function and FREQ procedure with chi-square and CMH test of SAS software. Compared with SG, LG had greater MTS during the initial 4 wk (1.1 vs. 0.8, chi-square = 17.9, df = 1; P < 0.001) and reduced MTS during the last 2 wk (0.7 vs. 0.9, chi-square = 4.8, df = 1; P = 0.03), suggesting that tail damage declined as pigs grew in LG, but not in SG. The number of pigs removed for tail biting tended to be less and those removed for death and sickness tended to be greater in LG than in SG (chi-square = 7.4; df = 3; P = 0.06). Across group sizes, 68% of the removed pigs (n = 28) were victimized by tail biters (MTS ≥ 2). Between group sizes, there was no difference in time to first victimization or how often individual pigs were victimized throughout the study. Across group sizes, 45% of pigs were never victimized, but 22%, 16%, and 9% were victimized 1, 2, and 3 times, respectively. Eight percent of pigs were victimized more than three times, including 6% with MTS of 3 or 4. Pigs with MTS of 4 over the entire study period were three times more likely (odds ratios between 3.18 and 3.70; all P ≤ 0.03; Table 1) to have market weight lower than the average compared with other pigs. Based on these results, we suggest that management strategies should prevent multiple victimizations or tail loss to maintain pig welfare and performance.

What will it take to get to 250,000 ppm brine concentration via ultra-high pressure reverse osmosis? And is it worth it?

The possibility of ultra-high pressure reverse osmosis (UHPRO) to replace thermal brine concentration promises to reduce up to 50 % of both energy consumption and capital cost. However, commercially available reverse osmosis (RO) membranes lose up to 50 % of their water permeability when operated up to 200 bar. Higher temperature operations such as in Middle East seawater desalination and brine mining further exacerbate compaction due to softening of the polysulfone support membrane. Assuming that pressure and temperature-related compaction issues can be resolved through innovations in membrane materials and/or module designs, this study asks the questions, “What will it take to get to 250,000 ppm via ultra-high pressure reverse osmosis? And is it worth it?” Herein we comprehensively examine a three stage RO process beginning with seawater RO (SWRO) to high-pressure RO (HPRO) and ultra-high-pressure RO (UHPRO). We elucidate the influence of thermophysical properties, hydraulic pressure, permeate flux, water permeability, feed spacer design, concentration polarization (CP), salt rejection and stage design on recovery and specific energy consumption (SEC). Our analysis of high rejection (HR) and high flux (HF) RO membranes reveals that while HF RO membranes boast superior water permeability and lower trans-membrane (hydraulic) pressure (TMP), they require higher operating flux, which leads to severe CP and operating pressures of 300 to 400 bar to meet the targeted brine concentration of ~250 g/L TDS. In addition, membrane compaction drives up the TMP, SEC, and capital cost of UHPRO systems. To bring the applied pressure below 300 bar, compaction-resistant UHPRO membranes and mass-transfer enhancing feed spacers will be required. The findings herein show that it will take time, money and technological innovation to enable UHPRO at commercial scale, and it may or may not be worth it. Further, this work makes clear the technological refinements needed to enable UHPRO membrane brine concentration.

Optimizing Reverse Osmosis Feed Spacer Design for Enhanced Dimethylphenol Removal from Wastewater: A Study of Hydrodynamics and Performance Indicators

Due to its high pollutant rejection and low energy usage, the spiral wound module of reverse osmosis (RO) process is the most commonly used technology utilised in wastewater treatment. For a spiral wound module, the presence of a feed spacer is important as a key solution to mitigate the concentration polarisation phenomenon, due to disorderly fluid flow, and to improve the mass transfer coefficient. Undoubtedly, improvements in the spiral wound module design, mainly in the symmetrical shape of the feed spacer, can have a significant impact on the cost and probable use of these modules. Despite the wide interest in appraising the impact of feed spacer geometry and orientation on the performance of a spiral wound module for RO process-based water desalination, the hydrodynamics of feed spacers (pressure drop and mass transfer coefficient) and the associated influences of feed spacer design (the height of the feed spacer, the angle of the filaments, and the porosity) on the removal of pollutants from wastewater have not yet been addressed. The current investigation aims to fill this gap by studying the hydrodynamics and design parameters of the selected parallelogram feed spacer type ultrafiltration (UF−3) for the removal of dimethylphenol from wastewater. Using model-based simulation, the impacts of UF−3 feed spacer design parameters, including the height, angle between the filaments (orientation), and porosity on the pressure drop, friction factor, axial flow fluid velocity, mass transfer coefficient, water flux, dimethylphenol rejection, recovery rate, and specific energy consumption are detailed in this study. The study intends to demonstrate the optimum design features of UF−3 feed spacer that should be considered to assure the highest elimination of dimethylphenol from wastewater in addition to the lowest specific energy consumption.

A computational fluid dynamics study on TPMS-based spacers in direct contact membrane distillation modules

Feed spacers are incorporated in membrane modules to enhance fluid mixing, thereby enhancing membrane flux. Previous experimental work showed that triply periodic minimal surfaces (TPMS)-based spacers induce significant improvements in membrane distillation (MD) performance, which was attributed to the suppression of membrane boundary layer, reducing heat and mass transfer resistance. To corroborate those findings, in this study, we assess the performance of TPMS spacers in direct contact MD (DCMD) modules using computational fluid dynamics (CFD). Results showed that the Fischer-Koch S TPMS spacer topology achieved twice the flux of the empty channel case and exhibited a 13 % increment in flux compared to the net-type spacer, but this improvement was accompanied by a higher pressure drop in the feed channel. Therefore, a normalized power ratio (NPR) was used to evaluate the overall performance of spacers. For Reynold number (Re) ranging between 200 and 1200, Fischer-Koch S spacer had a 12 % improvement in NPR compared to the net-type spacer and resulted in higher shear stress near the membrane surface, indicating a promising mean for mitigating fouling in membrane distillation. This research highlights the importance of utilizing novel spacers in membrane distillation and showcases the power of CFD tools in optimizing the process.

A clear view of biofouling in spacer filled membrane filtration channels: Integrating OCT and CT for improved visualization and localization

Spiral wound membrane elements for reverse osmosis (RO) seawater desalination are increasingly important to produce clean water to cope with the rising global freshwater scarcity. Spiral wound elements are prone to biofouling development which can be monitored in-situ using optical coherence tomography (OCT). Although OCT has emerged as a dominant technology for nondestructive monitoring of membrane fouling, the application of OCT to study fouling on feed spacers has been limited because image processing of spacers is complex. In this study, an automated image processing algorithm was developed for visualization and quantification of fouling in spacer filled channels. The spacer shadow was used to estimate the location of the spacer in the OCT image. Subsequently, a computed tomography (CT) scan of the same spacer type was overlaid, providing a clear indicator of the spacer position. The spacer position was used to i) correct the distortion below the spacer, ii) visualize fouling in 3D with reference to the membrane and spacer, and iii) reproducibly and precisely locate images to make time series and compare parallel experiments. The results showed that the addition of a spacer geometry as a solid object in a 3D representation of an OCT-scan greatly improves visualization, because fouling and the spacer can be distinguished and the position of fouling relative to the spacer and membrane can be clearly seen. Moreover, the ability to select a dataset relative to the orientation of the spacer will enable objective and automated quantitative analysis in future work.

The ring-an optimized spaceship for the 21st century

With NASA's anticipated return to the Moon and ambitious lunar plans by major spacefaring nations, a new era of space development is on the horizon. This marks a significant progression from the pioneering activities initiated with Sputnik in 1957. The Moon, followed by Mars and selected asteroids, will serve as the new frontier for human civilization, facilitating the transformation into a multiplanetary society. The exploration and development of these celestial bodies will necessitate the creation of new equipment, spaceships, and vehicles that are not only efficient but also cost effective, enabling rapid progress in our expansion into space. In this context, the Ring a proposed vehicle consisting of a lander and a container emerges as a potential solution to meet these evolving requirements. This article outlines the concept of the Ring and its potential role as an ideal solution for a cruiser feeder space transportation system, addressing the needs of future space exploration endeavors.

Potentiality of PLA 3D printed macro-structured feed spacers with a rational and facile layout for improved MD desalination performance

Membrane performance, regarding water flux and water recovery during membrane distillation (MD), is crucial during desalination. In this study, the membrane performance was improved using 3D-printed macro-structured feed spacers. Typically, 3D-printed feed spacers offer maximum flexibility for designing favorable geometrical transformations. The role of 3D-printed spacers in enhancing the permeate flux and recovery in direct contact membrane distillation (DCMD) has been thoroughly investigated. A comparative assessment was performed for various designs of 3D printed feed spacers with varying hydraulic diameters and filament thicknesses. An economical, biocompatible, and highly robust 3D-printed membrane spacer was developed using polylactic acid (PLA), which has a high elastic modulus. PLA is a biodegradable and environmentally friendly material. The thermal stability of PLA materials is advantageous for temperature-driven MD processes. PLA filaments were subjected to thermogravimetric analysis (TGA) for evaluating thermal stability. It provides structural support for the membranes and enhances mass movement through the membrane surface. In addition, these 3D-printed membrane spacers employing PLA have proven superior to conventional layouts in performance. These 3D-printed feed spacers were rationally designed to create a high flow disruption, which can lead to increased turbulence, thereby increasing the permeate flux. The overall results suggest that the 3D printed spacers can be ranked like TR˃DI ≈ SQ ˃ CR in terms of water flux. Eventually, the presence of 3D-printed spacers may prevent the external foulant layer onto the surface of membrane. Thus, the 3D printed spacers were ranked as TR˃DI ≈ CR≈ SQ for fouling mitigation ability. Furthermore, the used PVDF membrane with 3D printed spacers indicates lower hydrophobicity reduction, 11–14%. Therefore, this paper illustrates a facile approach to designing 3D-printed feed spacers that exhibit increased membrane performance in MD operation.

Solar-driven surface-heating membrane distillation using Ti3C2Tx MXene-coated spacers

The emergence of two-dimensional (2D) MXenes as efficient light-to-heat conversion materials offers significant potential for solar-based desalination, particularly in photothermal interfacial evaporation, enabling cost-effective solar-powered membrane distillation (MD). This study investigates solar-powered MD afforded by a photothermally functionalized spacer, which is built by spray-coating Ti3C2Tx MXene sheets on metallic spacers. 2D Ti3C2Tx MXene gives an ultrahigh photothermal conversion efficiency; thereby, by Ti3C2Tx MXene-coated metallic spacer, this rationally designed spacer allows for a localized photothermal conversion and interfacial feed heating effect on the membrane surface, especially for MD operation. As a feed spacer and a photothermal element, Ti3C2Tx MXene-coated metallic spacer exhibited stable enhanced water flux of up to 0.36 kg·m−2h−1 under one sun illumination for a feed salinity of 35 g·L−1, corresponding energy conversion efficiency of 28.3 %. Overall, the developed photothermal Ti3C2Tx MXene-coated spacers displayed great potential in enhancing the performance, scalability, and feasibility of solar-driven MD process, paving the way for further development of photothermal elements that can be implemented in solar MD applications.

Разведение молочных коз в условиях промышленной технологии

The aim of the work is to adapt the industrial technology used on European industrial farms for Russian farms. The main elements of industrial/production technology of milk goat maintenance were defined and characteristics of the main industrial/production processes were specified while studying. The study was carried out with the usage of methods of comparison, correlation and analysis of the own materials and literature sources. Analysis of the main elements of industrial technology practices in milk goat keeping adapted to Russian experience was carried out. The analysis was carried out on the industrial/production farms where there were from 1000 to 4000 heads. The main technological processes - feeding, milking, watering, raising kid crop are mechanized and optimized on these farms. The minimum feeding front on industrial farms is 26 sm/head, optimal - 30-33 sm. Decreasing a feeding space from 26 to 14 sm/head increases the quality of conflicts between the animals in 3,5 times. Increasing the workload on 1 stock fount from 25 to 35 goat’s decreases water consumption for 10,2% and daily yield for 8,5%. When observing the main production processes this technology provides the average yield from one goat on its first lactation 700 kg and more. This surpass the minimum requirements of the Standard in 1,4 times when the time period of production usage of dam goats is 7-8 years. Intensive raise of kid crop provides live weight at the age of 2 months as 15-17 kg and inseminate young goats at the age of 8-14 months. High level of mechanization of the main production processes from 70 to 100% support the decrease of labourship in 2 times.

Analysis and prediction of SWM feed spacer performance based on CFD results with an emphasis on the effect of micro-scale lateral and longitudinal washing flows

In reverse osmosis applications, feed spacers are used in spiral wound membranes to separate the membrane surfaces and enhance mass transfer while incurring an acceptable pressure drop. In this study, an attempt has been made to understand the effect of spacer characteristics, such as arrangement and size, on mass transfer and pressure drop. Power-law equations were successfully developed to describe different spacer performance measures as a function of Reynolds number (Re), where both the multiplier of the Re term and the Re exponent vary for each spacer arrangement. Although at the macro level, it was not possible to adequately correlate the equation parameters with the spacers’ geometrical parameters (such as porosity), examining the post-processed CFD results at the micro level led to explanations for the observed concentration profiles, trends in spacer performance and changes in the equation parameters. A key observation was the importance of lateral flow recirculation, which was termed side-washing. Overall, based on the Spacer Configuration Efficacy performance measure and by assessing the trade-off between Sherwood number and pressure drop, the Woven configuration shows the best performance among the spacer arrangements and range of flowrates studied.

Oil-infused feed spacers for biofouling inhibition

A novel approach is investigated for preventing biofouling of spacer filaments, which are an essential part of spiral-wound modules used in membrane-based desalination. Biofouling, caused by the growth and multiplication of microorganisms on the membrane surface, can significantly impact the efficiency and cost-effectiveness of the desalination process. Herein, a method is proposed for fabricating modified feed spacers based on oil-infused slippery substrates made of polydimethylsiloxane (PDMS). These feed spacers, when infused with silicone oil, create a stable, extremely slippery interface that exhibits exceptionally low bacterial adhesion and prevents biofilm formation, especially under flow conditions. By examining the effect of the silicone oil's viscosity, we determined the optimal ratio of the curing agent for fabricating the oil-infused feed spacer. Results showed a substantial reduction of bacterial adhesion to the surface for all tested oil viscosities, particularly under dynamic conditions. Furthermore, even where bacterial adhesion occurred, primarily on samples infused with lower-viscosity oil, it could be easily removed by simple rinsing. Overall, the oil-infused feed spacer demonstrated exceptional biofilm inhibition, providing preliminary indication of the potential offered by this promising approach.