Filtration Rate Flow Research Articles

Edoxaban pharmacokinetics during in vitro continuous renal replacement therapy

BackgroundTo evaluate the clearance of edoxaban during modeled in vitro continuous renal replacement therapy (CRRT), assess protein binding and circuit adsorption, and provide initial dosing recommendations.MethodsEdoxaban was added to the CRRT circuit and serial pre-filter bovine blood samples were collected along with post-filter blood and effluent samples. All experiments were performed in duplicate using continuous veno-venous hemofiltration (CVVH) and hemodialysis (CVVHD) modes, with varying filter types, flow rates, and point of CVVH replacement fluid dilution. Concentrations of edoxaban and urea were quantified via liquid chromatography-tandem mass spectrometry. Plasma pharmacokinetic parameters for edoxaban were estimated via noncompartmental analysis. Two and three-way analysis of variance (ANOVA) models were built to assess the effects of mode, filter type, flow rate, and point of dilution on CLCRRT. Linear regression was utilized to provide dosing estimations across CRRT effluent flow rates from 0.5 to 5 L/h. Optimal edoxaban doses were suggested using CLCRRT and population non-renal clearance (CLNR) to estimate total clearance and match the systemic AUC associated with efficacy in the treatment of venous thromboembolism.ResultsEdoxaban clearance from the CRRT circuit occurred primarily via hemofilter adsorption to the HF1400 and M150 filters at 74% and 65%, respectively, while mean percent protein binding was 41%. Multivariate analyses confirmed the lack of influence of CRRT mode, filter type, and point of dilution on the CLCRRT of edoxaban allowing dosing recommendations to be made based on effluent flow rate. Edoxaban doses of 30-45 mg once daily were estimated to achieve target the AUC threshold for flow rates from 0.5 to 5 L/h.ConclusionFor CRRT flow rates most employed in clinical practice, an edoxaban dose of 45 mg once daily is predicted to achieve target systemic exposure thresholds for venous thromboembolism treatment. The safety and efficacy of this proposed dosing warrants further investigation in clinical studies.

Chromium adsorption efficiency by functional polymeric nanocomposite membrane: A case study for environmental sustainability

AbstractWe have designed and developed nonwoven fabric supported electrospun polymeric nanofibrous‐based membrane for robust filtration system for ecological sustainability of clean water. The fabricated nanocomposites filters were tested for the removal of chromium (VI) toxic heavy metal ions from contaminated feedstock water. The interpenetrating network like morphological structure obtained from pure and composite nanofibers‐based membranes have been thoroughly investigated to understand the structure–properties of highly entangled system. It has been found that incorporating functional moieties onto nanocomposite membranes significantly impacts the absorption efficiency of toxic metals. The pore sizes of the hierarchical geometries have been varied to insight into its impact on flow rate and efficiency of filtration. The strategy of interfacing the multifunctional composite polyethylene terephthalate nanofiber membrane supported on nonwoven fabric to generate heterostructures has found to provide mechanically stable platform for efficient metal ion removal. It has been found by BET surface area analysis that the nanofibers reinforced with functional nanomaterials has controlled pore geometry compared to pristine PET electrospun nanofibers which lead to higher absorption of metal ions. We have highlighted the importance of mechanically stable electrospun polymeric nanofibers membrane‐based mitigation strategies to meet the huge demand of potable water for long‐term environmental sustainability.Highlights Mechanically toughened freestanding nanofibers mat supported on nonwoven fabric. Functionally upgrade nanofibers by incorporation of carbon based nanofillers. Controlled porosity by morphological optimization for removal of contaminates.

Loss of micropollutants on syringe filters during sample filtration: Machine learning approach for selecting appropriate filters

Prefiltration before chromatographic analysis is critical in the monitoring of environmental micropollutants (MPs). However, in an aqueous matrix, such monitoring often leads to out-of-specification results owing to the loss of MPs on syringe filters. Therefore, this study investigated the loss of seventy MPs on eight different syringe filters by employing Random Forest, a machine learning algorithm. The results indicate that the loss of MPs during filtration is filter specific, with glass microfiber and polytetrafluoroethylene filters being the most effective (<20%) compared with nylon (>90%) and others (regenerated-cellulose, polyethersulfone, polyvinylidene difluoride, cellulose acetate, and polypropylene). The Random Forest classifier showed outstanding performance (accuracy range 0.81–0.95) for determining whether the loss of MPs on filters exceeded 20%. Important factors in this classification were analyzed using the SHapley Additive exPlanation value and Kruskal–Wallis test. The results show that the physicochemical properties (LogKow/LogD, pKa, functional groups, and charges) of MPs are more important than the operational parameters (sample volume, filter pore size, diameter, and flow rate) in determining the loss of most MPs on syringe filters. However, other important factors such as the implications of the roles of pH for nylon and pre-rinsing for PTFE syringe filters should not be ignored. Overall, this study provides a systematic framework for understanding the behavior of various MP classes and their potential losses on syringe filters.

Membrane fouling during the harvesting of microalgae using static microfiltration

A challenge in the filtration of algal suspensions is the reduction in filtrate flow rate with time, associated with membrane fouling and filtercake formation. These two fouling mechanisms may occur simultaneously and have different effects on the scaling relationship of filtration rate with time, making quantitative predictions of the filtration behaviour complex. The foulants include suspended microalgal cells and their presumed Extracellular Polymeric Substances (EPS). To investigate this problem, we perform static microfiltration experiments to harvest oil-rich marine microalgae Nannochloropsis oculata. Batch filtration experiments of microalgal suspensions using glass-fibre membranes are conducted under filtration pressures varying between 0.5 and 200 kPa. Here we investigate the relative importance of potential fouling mechanisms, including pore plugging, entrance blocking, and filtercake formation. We examine variations in filtrate flux, using a novel approach involving numerical differentiation of the filtrate volume to identify how its scaling relationship with time and compare with the traditional root-time behaviour. These results are analysed with reference to the blocking filtration laws to determine the potential fouling mechanism. Rheology tests of both filtration feeds and filtrate are performed, and both optical and scanning electron microscopy are used to observe the filtercake. Our results show a significant drop in the filtrate flux after a spurt loss phase under pressure. The scaling analysis demonstrates a power law relationship between cumulative filtrate volume and time in the post-spurt phase. We show here, for the first time, that the scaling exponent varies with time, approaching a value close to 0.5 (i.e. the root-time behaviour) after a long period of time. Using the analysis, we conclude that the filtration process can be divided into various stages; a spurt loss phase when the pressure is initially applied, followed by a stage in which both internal and external filtercake formation occurs, and a final stage which is dominated by external filtercake formation (at which point root-time behaviour is observed). Furthermore, our findings suggest that fresh microalgal suspensions experienced a larger spurt loss compared to aged suspensions in microfiltration. This difference may be attributed to the limited production of EPS and microalgal debris during shorter cultivation periods. The microscopic observations reveal the invasion of microalgal cells into the membrane, which verifies the formation of an internal filtercake suggested by our scaling analysis. The contamination of the membrane increases with higher filtration pressures. Finally, we demonstrate that Fe3+ coagulant can be used to increase the microalgal particulate size before filtration, resulting in a much higher filtrate flux compared to uncoagulated suspensions. This result provides opportunities to reduce membrane contamination to a negligible level.

Treatment of oil sands process-affected water using a semi pilot-scale coalescing filter: Effect of fundamental conditions and water characteristics on filtration performance

The reuse of oil sands process-affected water (OSPW) generated during oil extraction is becoming essential due to oil extraction efficiency and stringent environmental regulations. This study investigates the efficacy of a coalescing filter (CF) in removing oil components from OSPW by exploiting coalescence, which involves merging small oil droplets into larger ones using fibers. Real-time, precise oil measurement systems were employed to evaluate the oil removal efficiency of the CF across synthetic OSPW samples with varying properties. Fundamental conditions and water quality components were systematically adjusted to elucidate the influencing factors on oil removal by the CF. Results showed that despite the diesel having significantly lower viscosity than the oil contents in OSPW, CF achieved a removal efficiency of over 60% within the first 10 min of operation time, regardless of oil concentration. Total suspended solids/turbidity exhibited a decreasing trend as it passed through the filter, indicating fouling occurring within the filter. On the other hands, its increase improved CF performance by 6% compared to baseline conditions, while an increase of alkalinity decreased performance by 10%. When each water quality component exists independently, they do not significantly impact the oil removal efficiency. However, when present together, there is a more decrease in removal efficiency due to the reduced interaction between oil and filter. CF was resistant to changes in water quality. Rather, changes in fundamental factors are more sensitive to CF performance. Filter characteristics and mechanisms make residence time the primary factor affecting oil removal by the CF, with variations exceeding 30% depending on conditions. Therefore, optimizing filter number and flow rate is essential to maximize the filtration performance.

The role of natural sorbents and piping production waste in the treatment of acid iron-containing waste water

In this article, we consider the sorption purification of production wastewater from pipe industry enterprises. We have presented and studied the potential sorbents from among natural materials and from piping production waste. The authors of this paper have studied the sorption capacity of the materials under consideration with regard to heavy metals from highly acidic iron-containing wastewater both in static and dynamic modes. The static-mode research has been conducted for various temperatures: 10°С, 20°С and 30°С. In the dynamic conditions, the filtrate flow rate equaled 0.3, 0.6 and 1.2 l/h. The authors have proven that a number of the examined materials can be used as sorbents or constituting elements of composite sorbents for the technology of wastewater treatment at pipe industry enterprises.

Experimental investigation of filter cake deposition under cross-flow and static filtration conditions

Effects of cross-flow velocity, filtration pressure, and solid concentration on filter cake properties are studied by using a new filtration setup that allows performing filtration tests under a wide range of operating conditions. The main feature of this setup is that pressure and cross-flow velocity are decoupled, so it was possible to independently investigate the effect of these variables on filter cake properties. Filtration tests have demonstrated that particle invasion into filter media pores occurs initially, leading to the formation of an external filter cake. The increased cross-flow velocity creates an erosive shear stress at the surface of the external cake, which limits cake growth, indirectly maintaining a high filtrate flow rate. This high filtrate rate imparts a considerable drag force onto suspended particles, driving a high count into the porous substrate where these particles could deposit. Increasing pressure amplifies this internal particle deposition, particularly where there is no or limited external filter cake to limit filtrate drag and screen particles at the cake surface. The effect of cross-flow velocity on pore blocking and filter cake structure is observed and demonstrated by CT scanning and scanning electronic microscopy.

Effect of sludge conditioning by microbial fuel cell on electro-dewatering performance

Electro-dewatering (EDW) is an efficient and energy-saving technology for deep dewatering of sludge. It is significantly influenced by the physicochemical properties (e.g., conductivity, pH and zeta potential) of sludge, which can be altered by conditioning. In this study, sludge conditioning by microbial fuel cell (MFC) was innovatively coupled with EDW. In a single-chamber MFC filled with municipal sludge, a maximum power density of 436 mW/m3 was achieved after a 5-day operation. Substantial changes in the physicochemical properties of the sludge were observed. Compared with raw sludge, the sludge subjected to 7-day MFC conditioning had higher liquid-phase conductivity (425 μS/cm vs. 301 μS/cm), higher pH (6.8 vs. 6.3) and a more negative zeta potential (−16.0 mV vs. −12.8 mV). These changes facilitated EDW. Generally, longer MFC conditioning time led to higher electric current, higher filtrate flow rate and less final moisture content during a 12-min constant-voltage (25 V) EDW process. The final sludge moisture content after EDW was 64.0 % without conditioning and 54.8 % with 7-day MFC conditioning. Although sludge EDW with longer MFC conditioning time required more energy, the dewatering efficiency was noticeably higher, making the process more economically beneficial. Seven days of MFC conditioning is the recommended scheme in this study due to its low Ksi (1.6 kWh·h/kgDS2) and the potential to generate ~0.0336 USD/ton dry solids as green energy revenue. The study has newly developed an MFC-EDW coupled process that recovers bioresources through electricity generation while MFC conditions the sludge to facilitate EDW simultaneously.

A practical design equation for accurate quantification of CRRT filter design factors and convection effects.

Considering the increasing clinical need for continuous renal replacement therapy (CRRT), further improvement in therapeutic efficacy has become an important focus for researchers. Here, we designed nine CRRT filters with various combinations of hollow fiber packing density (PD) and housing shape (effective hollow fiber length (L) and inner housing diameter (D) ratio (L/D ratio)) to evaluate the clearance of middle molecular uremic toxins (MMs) via simulation of an in vitro continuous veno-venous hemodialysis treatment model. We also used Doppler ultrasonography to measure the maximum internal filtration flow rate (QIF-Max) as an aid; this approach facilitated an exploration of the impacts of various design factors on convection effects, while revealing the mechanisms influencing MM removal performance. Furthermore, we constructed a multiple linear regression model of design factors and QIF-Max, then conducted experimental verification. Finally, we proposed an accurate and practical design equation to quantify the design factors influencing CRRT filters and convection effects: , where N/D2 and L/D affect QIF-Max by 15.0% and 85.0%, respectively. This design equation was able to effectively quantify the convection effects of CRRT filters with different design factors, thereby predicting MM removal performance; this convenient design equation can support the development of CRRT-related products.

Исследование фильтрации из оросительного канала методом электрогидродинамических аналогий

Purpose: simulation of the filtration process from an irrigation canal made in an earthen channel. Materials and methods. One of the most common methods in the waterworks construction and operation is the filtration process modeling. In practice, the use of mathematical modeling based on the use of mathematical analogies of various physical processes, which are described by the same differential equations, is widespread. The electric analogy method (EGDA) is based on the analogy between the groundwater velocity and the electrical current flow and allows solving various filtration problems on models of electrically conductive materials. The purpose of modeling the groundwater velocity using the EGDA method is to develop a model similar to a full-scale object, for studying the ongoing filtration processes with its help. Results. A flow net and a filtration velocity profile which were used to study free filtration from a canal in an earthen channel were constructed. As a result of the study, the specific filtration flow rate, filtration rate were determined and a comparison with the values obtained by calculation was made. Comparison of the results obtained from the flow net with the calculation formula showed that their values coincide with an error of 1.26 %. The specific flow rate determined by the calculation method coincides with the flow net value for the selected belt of equal pressure with an error of 2.8 %. Conclusions: the EGDA method allows determine effectively the seepage water losses from the canal, however, when quantifying the seepage flow, it gives more significant errors due to the complexity of complete recording when modeling the real conditions of the object under consideration.

Investigation of the interaction of hydraulic parameters of the channel in the filtration process

One of the most important and complex issues in the design of soil drainage channels is the issue of correct accounting of the filtration process. It is necessary to take into account hydraulic parameters and soil composition of existing channels in order to reduce filtration flow rate in ditches with uncoated soil. The article shows how to choose its theoretical basis for reducing the filtration flow rate correctly. Hydraulically convenient design is one of the current problems in the design of canals. This can be achieved by reducing the wet perimeter of the channel to reduce the filtration process in the channel. The article recommends that measures to reduce the filtration process be implemented during the construction or reconstruction of canals, without dismantling and rehabilitating existing canals. Field research was conducted on the North Fergana main canal. In order to study the filtration processes, measurement works were carried out on the PK 396+00, PK 497+01, PK 688+7, PK 692+6, PK 694+6, PK 697+00 pickets crossing the 2-section of the channel in the city of Namangan. In addition, the article developed recommendations on the methods and procedures for the application of bentonite clay from the Lagon betonet clay deposit of the Fergana region to the bottom of the channel in order to reduce the filtration process that occurs in the canal area. According to the results of the study, in the range from PK 411 + 00 to PK 426 + 74, filtration consumption was higher than other pickets.

Desain Media Filter Bioring dan Karbon Blok untuk mengurangi Kesadahan Zat Kapur Air Sumur Gali

Clean water is needed in fulfilling human needs to carry out all activities so it is necessary to know how water is said to be clean in terms of quality and can be used in adequate quantities in human daily activities. In terms of quality, there are several requirements that must be met, including physical quality consisting of odor, color, and taste, chemical quality consisting of pH, hardness, and so on as well as biological quality where the water is free from disease-causing microorganisms. One of the water sources that are still widely used by the people of Pulau Tenga Village, Kec. Menui Central Sulawesi Islands is dug well water. The high hardness value in the dug well water is 518 mg/L. It can be identified that the water contains lime so it is necessary to treat water in order to meet clean water quality standards. One of the efforts that must be done is to make water treatment by filtration. The design of the filter device is made of pipe measuring 3 inches. The filter material used for the bioring, water filter, zeolite, and activated carbon which is applied in a water filtration filter device with a filtration flow rate of 0.006 L/s.

Removal of zinc from surface runoff by using recycled mussel shell waste as treatment media, with and without heat treatment

Stormwater control measures (SCMs) are essential to manage runoff in urban areas. Mussel shell waste has been recently proposed as sustainable treatment media in SCM to remove metals from runoff. In this study, a group of laboratory-scale column experiments were conducted to investigate the use of crushed mussel shell waste to remove dissolved zinc from actual roof runoff during different filtration flow rates (1, 3, 5, 10 L/min). Heat-treated mussel shells (TMS) and untreated mussel shells (UTMS) were utilized as treatment media with two column depths (1.0 m and 0.8 m). The microstructures and chemical characteristics of TMS and UTMS were examined by using a group of Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Spectroscopy (EDS) tests before and after the filtration process, and water samples were analyzed by using an Inductively Coupled Plasma Mass Spectrometry (ICP-MS) instrument. TMS and UTMS showed consistent high removal efficiency for dissolved zinc with (>98%) efficiency during 1 L/min filtration rate. The average removal performance was estimated at >94% and >82% for the 1.0 m and 0.8 m column depths of TMS media, and >92% and >72% for the 1.0 m and 0.8 m depths of UTMS media, respectively. The heat treatment improved the removal of zinc with significant statistical difference (i.e. p < 0.05) during short contact times (0.8 m depth, and high filtration rates). Mussel shell waste showed practical removal performance of zinc even during high filtration rates (>5 L/min). Mussel shell waste showed potential benefits as a sustainable and cost-effective filtration media for removal of dissolved zinc in future stormwater systems. • Mussel shell waste showed high removal efficiency for zinc in runoff (>92%). • Heat treatment improved the ability of shells to remove zinc. • Organic matters attached to mussel shells slowed the removal of zinc. • Coarse crushed shells (>4.75 mm) support higher filtration rates through filtration media. • Mussel shell provided practical removal performance (>72%) during high filtration rates.

Clarification of large-volume bacterial cultures using a centrifuge-free protocol.

AimsTo provide a reliable, reproducible and centrifuge‐free filtration protocol for clarification of large volumes of bacterial cultures.Methods and ResultsFour experiments were designed to compare different techniques enabling clarification of Escherichia coli cultures using as a benchmark the concentration and quality of bacterial outer membrane vesicles (OMVs). The experiments were designed to examine the performance of different extraction methods on large volume (≥1 L) filtrations of bacterial culture media. Performance parameters included filtration flow rates, sterility testing and characterization of the filtrates by: (i) SDS‐PAGE, (ii) cryogenic transmission electron microscopy, (iii) nanoparticle tracking analysis and (iv) Qubit protein quantification. The experiments revealed that: (i) addition of the filter aid Diatomaceous Earth to the bacterial cultures improved filtration flow rates significantly and eliminated the need for centrifugation prior to filtration; (ii) sterile filtration was successful as no bacterial passage was identified through the membrane filter; (iii) centrifuge‐free filtrates contained an increased amount of OMVs compared to centrifuged filtrates.ConclusionsIn comparison to conventional centrifuge‐based protocols, the clarification method presented has universal applicability for a broad range of microbial extraction procedures, regardless of the volume of culture harvested. Moreover, the decreased amount of OMVs presented in the filtrates following centrifugation step provides an additional argument in favour of a centrifuge‐free approach.Significance and Impact of the StudySterile filtration is a universal method for the clarification of bacterial cultures. Common challenges related to filtration include filter clogging and long processing times, due to limited centrifugation capacity, which can affect product quality. The proposed protocol is likely to ensure a highly effective filtration process and could be a novel approach in improving the filtrate products without the need of centrifugation.

Dust collection efficiency of commercial gas collection tubes

Gas sampling tubes are essential tools for the evaluation of air quality in work environments. It adsorbs toxic gaseous matters onto the surface of various granular adsorbents, such as silica gel or activated carbon packed in a thin glass tube, for quantitative analysis by gas chromatography. Currently, most of the semi-volatile matters are evaluated via aerosol filtration or solid-phase gas adsorption depending on the main phase of the substances; however, only a few substances have a sampling protocol regarding both solid and gaseous phases. Therefore, semi-volatile components evaluated by the solid-phase adsorption may result in the underestimation of the component concentrations due to particulate components passing through and remaining in the adsorbent. To highlight issues on sampling of semi-volatile matters by the solid-phase adsorption method, the collection efficiency of aerosol particles by 17 commercial gas sampling tubes were measured via pressure drop. To measure the particle collection efficiency of the gas collection tubes, precise control and dilution of the aerosol particle monitors are essential. However, we cannot apply typical filter test methods at a lower filtration flow rate than that of the aerosol particles monitors. Therefore, we developed a new experimental method that considers flow adjustment between the aerosol monitors. By assuming two specific particle size distributions and five inlet conditions, the collection efficiencies of total mass particles are estimated. From the gas-particle partitioning ratio of 16 polycyclic aromatic hydrocarbons (PAHs) in a coal tar pitch manufacturing industry, the underestimation of the concentration of semi-volatile matters using the gas collection tubes has been discussed. The aerosol particles were collected in all kinds of layers in the gas sampling tubes, such as in the glass wool cap, gas adsorbent granular bed, and polyurethane foam. Furthermore, the collection efficiency curve of all 17 gas sampling tubes tested showed similar trends; a valley around particle sizes ranging from 0.2-0.3 μm between high collection zones below 0.1 μm and above 1 μm was observed. The observations suggested granular bed filters collection mechanisms such as inertial impaction, Brownian diffusion, gravity, and interception as same as air filters. Solid-phase collection can underestimate the concentrations of multi-phase matters. Thus, we wish to highlight the importance of solid-phase collection methods along with filtration collection methods to collect all phases of semi-volatile matters.

MO650: In Vitro Performance Evaluation of a Filter Used for Hemodiafiltration by Using Β-Lactoglobulin

Abstract BACKGROUND AND AIMS Filters currently used for hemodiafiltration (HF) can remove sufficiently low to middle molecular weight solutes, like urea to β2 microglobulin (molecular weight: 11.800). Therefore, the removal rate of α1 microglobulin (α1-MG; molecular weight: 33.000) and albumin leakage are used as a guide to select a filter and to set appropriate operating conditions. Since α1-MG is very expensive, in vitro performance evaluation of the filters using α1-MG is not practical. In the present study, we aimed to investigate whether β-lactoglobulin (β-LG), which has a molecular weight of 18.400 and forms dimer (molecular weight: 36.800) under physiological conditions, can be used as a marker solute in the 30.000 molecular weight region. METHOD HF experiments were performed using 1.8 L of porcine whole blood (hematocrit: 30 ± 3%, total protein concentration: 6.5 ± 0.5 g/dL). The sieving coefficients of β-LG, separated from milk by membrane separation (untreated), made whey containing β-LG by acid treatment of milk and pH adjusted (acid-treated) and powdered reagent, were measured in porcine blood. In addition, HF experiments with permeate recycle were performed using three filters with different pore sizes (MFX-S, MFX-E and MFX-M; Nipro) at a blood flow rate of 250 mL/min and filtration flow rate of 42 mL/min for 240 min. The concentration of β-LG was measured by an enzyme-linked immunosorbent assay. RESULTS The sieving coefficient of acid-treated or powdered reagent β-LG added to the blood was almost equal to that of untreated β-LG. When the powdered reagent β-LG was treated with mercaptoethanol, the sieving coefficient became larger, meaning that the β-LG is tightly bound by disulfide bonds to form a stable dimer. In HF experiments using three filters with different pore sizes, the filter with a larger pore size resulted in lower transmembrane pressure. The sieving coefficients of β-LG decreased with time and were 0.15 ± 0.024, 0.39 ± 0.023, 0.75 ± 0.064 (mean ± SD, n = 3) at 60 min for MFX-M, MFX-E and MFX-S, respectively, indicating that the difference in filter performance was able to classify in the sieving coefficient of β-LG. CONCLUSION β-lactoglobulin existed stably as a dimer and was able to classify the performance of filters used for hemodiafiltration as a marker solute in the 30.000 molecular weight region.

The Separation Power of Highly Porous 3D Nanofiber Sponges

Sponges formed by the self-assembly of nanofiber building blocks are versatile materials used in various fields such as filtration, thermal insulation, scaffolding or sound absorption. Their potential seems to be constantly expanding given the variety of possible fiber materials, from bio-based to fossil polymers to inorganic nanofibers. In general, nanofiber sponges – also called nanofiber aerogels – are flexible, have low density, and a large specific surface area thanks to their tunable open-porous nanofiber based architecture. The latter property makes nanofiber sponges an interesting material for separation problems, as recently demonstrated for a variety of mixtures such as aerosols, emulsions, dispersions, solutions or two-phase systems. Due to their highly porous structure, they generally exhibit high filtration efficiency, flow rate and capacity. This article reviews the state of the art in the application of 3D nanofiber sponges for the different classes of mixtures. We will discuss on a mechanistic basis why nanofiber sponges are particularly well suited for separation applications. Finally, their performance in terms of efficiency, flow rate, capacity and regeneration will be compared to other fiber-based filter media.

Design-oriented evaluation of the hydrodynamics in a full-scale combined filter-lamella separator for urban stormwater treatment.

The development of compact treatment devices with high removal efficiencies and low space requirements is a key objective of urban stormwater treatment. Thus, many devices utilize a combination of sedimentation and upward flow filtration in a single system. This study, for the first time, evaluates the flow field inside a combined filter-lamella separator via computational fluid dynamics. Herein, three objectives are investigated: (i) the flow field for different structural configurations, (ii) the distribution of particulate matter along the filter bed and (iii) the dynamic clogging in discrete filter zones, which is addressed by a clogging model derived from literature data. The results indicate that a direct combination of a filtration stage with a lamella separator promotes a uniform flow distribution. The distribution of particulate matter along the filter bed varies with configuration and particle size. Clogging, induced by particles in the spectrum <63 μm, creates gradients of hydraulic conductivity along the filter bed. After treating about half of Germany's annual runoff-efficient precipitation at a rainfall intensity of 5 L/(s·ha), the filtration rates increase in the front of the filter bed by +10%. Thus, long-term operating behavior is sensitive to efficient filter utilization in compact treatment devices.

ГИДРАВЛИЧЕСКИЙ РАСЧЕТ РЕЗЕРВНОГО ВОДОСБРОСА (ВОДОСЛИВА С ШИРОКИМ ПОРОГОМ)

Purpose: to carry out hydraulic studies and calculations of a reserve spillway structure (broad-crested weir) of a rockfill dam. Materials and methods. Current studies show that in open channels the regime of fluid movement can be different, and the boundary surfaces of the channel in some cases should be considered as hydraulically smooth, in others – as hydraulically rough. The broad-crested weir of rectangular and trapezoidal section is considered. To determine the experimental discharge coefficient of the reserve spillway of an earth rockfill dam, the known dependences for unflooded broad-crested obtained by A. R. Berezinsky and D. I. Kumin were used. Results. Based on the results of comparing the calculated flow coefficients with the experimental data of other authors, close values with the data of A. R. Berezinsky and D. N. Kumin were obtained. At the same time, the values of the discharge coefficients of the water discharge according to Berezinsky and Kumin are in the range of 0.339 and 0.324, which confirms their compliance and high accuracy. The results of the calculation of the filtration flow rate through the rockfill of the dam with a reserve spillway are the filtration flow rates in the range of 726.81–2260.76 m³/s. Conclusions. The performed calculations showed that the values of the discharge coefficients of the weir of a trapezoidal section correspond to the data obtained by A. R. Berezinsky and D. I. Kumin. At the same time, the values of the spillway discharge coefficients by Berezinsky and Kumin are within acceptable limits, which confirms their compliance. The average flow velocities passing through the broad-crested weir were: for profile 1 – 3.76 m/s, for profile 2 – 0.612 m/s, for profile 3 – 2.13 m/s.

Characteristics of Viscoelastic-Surfactant-Induced Wettability Alteration in Porous Media

Wettability alteration is one of the most important mechanisms of surfactant flooding. In this work, the combined Amott/USBM (United States Bureau of Mines) method was applied to study the average wettability alteration of initially neutral cores after viscoelastic-surfactant (VES) filtration. The effects of static aging, dynamic aging, VES concentration, filtration flow rate, and pore radius on the alteration of a core’s average wettability were studied. The wettability-alteration trends measured by Amott and USBM were consistent, demonstrating that the overall hydrophilicity of the core was enhanced after VES filtration. The wettability alterations of the core brought about by dynamic aging were more significant than by static aging. The viscoelastic properties of the VES played an important role in altering the wettability. In addition, the ability of the VES to affect the core’s wettability was significantly enhanced when the VES concentration was increased, which was beneficial in increasing VES adsorption on the pore-wall surface, thus altering the overall wettability of the core. Increasing filtration flow rates can destroy those high-viscosity VES aggregates via the higher shear rate. A higher retention of VES makes the core more hydrophilic. The difference in the wettability of cores with different pore radius after VES filtration was not significant. The alteration of average wettability caused by VES in porous media provides a new vision for studying the EOR mechanism of VES.