Filtration Of Suspensions Research Articles

Electroless Ni–Sn–P plating to fabricate nickel alloy coated polypropylene membrane with enhanced performance

Surface metallization of membrane via electroless plating for improvement of permeation flux and anti-fouling performance has attracted extensive attentions in recent years. However, high activation cost and poor stability have always been the obstacles to its practical application. It is urgently desired to explore economical and stable membrane modification methods. Herein, a novel strategy for fabrication of a hydrophilic and conductive separation membrane with low cost, excellent filtration performance, and high chemical stability was ingeniously proposed. A nickel-tin/cobalt-polypyrrole (NiSn/Co-PPy) coating was deposited onto the PP membrane through successive three-step route including in-situ vapor-phase polymerization, cobalt activation and electroless plating. The successful formation of NiSn/Co-PPy coating on membrane surface was confirmed by a series of characterizations. Driven by self-gravity, the optimum modified membrane (NiSn4-15/Co-PPy) applied with an external electric field (9.0 V) had prominent permeation flux (189 L m-2 h-1), impressive separation efficiency (100%) and outstanding cycle stability for separation of n-hexane/water emulsion. Under the micro-electric field (2.0 V), the average flux of the NiSn4-15/Co-PPy membrane for yeast suspension filtration reached 22.3 L m-2 h-1, which is approximately 3 and 9 times higher than that of the modified membrane without electric field and the original membrane, respectively. Meanwhile, the external electric field also endowed the NiSn4-15/Co-PPy membrane with a maximum flux recovery rate of 82.7%. In addition, the modified membrane was confirmed to have brilliant stability and acid resistance. This study provided a new strategy and novel insights into fabrication of composite hydrophilic conductive membrane for water treatment.

Hydraulic clamp drive of frame filter press for AGMK cadmium workshop, Uzbekistan

Almalyk Mining and Smelting Plant (AGMK), which is the largest producer and supplier of copper and zinc, about 20% of gold and 90% of silver in the Republic of Uzbekistan, is briefly presented. The end products of the plant include refined copper, affined precious metals, metal zinc, cadmium, copper wire, copper enameled wire and many other things. AGMK cadmium workshop uses frame filter presses for the filtration of suspensions of copper–cadmium cake. The current filter presses have electromechanical clamping drives with f a screw couple set in motion by the electric motor through a reducer by means of a gear wheel and a cogwheel with the screw couple nut pressed in the spider. The operation of these filter presses reveals three key disadvantages of the existing design: low durability of sliding bearings; increased wear of the nut of the screw couple; highly laborious maintenance and repair of the drive. For the solution of these problems, the new design is offered for the clamping system of the frame filter press with the hydraulic drive. The purpose of the filter press updating is to increase its operational reliability in order to extend the life duration of the machine, to reduce the downtimes for repairs and to cut down power and labor consumption. During the studies, the hydraulic circuit is designed, the standard sizes of hydraulic devices are selected as gear pump GP-16-G-3, bilateral hydraulic cylinder HS2 200.90×1000, the volume of a hydraulic tank is determined, etc. Rejection of the mechanical drive provides an increase in the overhaul life due to the higher reliability of the hydraulic drive components and owing to more efficient control of the clamping force. The calculations show that implementation of the design requires no heavy capital expenditure. In the meanwhile, as a result of introduction of the design, the product cost will decrease by 0.05% at the payback period of the investment not longer than 3 months.

Dynamic linear adsorption with solid adsorbent material

A mathematical problem of linear physical adsorption of a dissolved impurity is formulated, by consider-ing its diffusion transfer during the filtration of an aqueous suspension through a uniform adsorbent bed at a constant rate. By averaging the impurity concentrations in the free and bound states over an arbi-trary time period, an approximate solution of the problem is obtained, which is only expressed in terms of the elementary functions. On its basis, it is proposed to calculate the rational duration of the filter run. The solution is discussed and illustrated with a number of examples with typical input data.

Biological control of Ralstonia solanacearum (Smith), the causal pathogen of bacterial wilt disease by using Pantoea spp

BackgroundBacterial wilt of tomato (BWP) caused by Ralstonia solanacearum (Smith) is a very important disease. Biological control of this disease is a very important tool to protect the plant and environment from pollution of chemical control.ResultsTwenty isolates of genus, Pantoea were isolated from healthy tomato root. Out of 20 isolates, 2 strains, PHYTPO1 and PHYTPO2, showed highly antagonistic property to control the growth of R. solanacearum in vitro conditions. They were identified as P. agglomerans by using 16S rRNA nucleotide sequence analysis. The 2 isolates were selected to study their effect (as cell suspension or culture filtrate) on the bacterial wilt under greenhouse conditions. PHYTPO1 inhibited maximum growth reduction of R. solanacearum and formed 2.5 cm2 of inhibition zone, followed by 1.2 cm2 in PHYTOPO2 under in vitro conditions. Treating with both isolates of P. agglomerans was significantly reduced disease severity of tomato wilt disease. The disease severity was reduced to 74.1 when treated as cell suspension, while when treated as culture filtrate, it reduced the disease severity up to 69.4 than infected control.ConclusionThe strains of Pantoea can be used as an ecofriendly method to control of the most economic pathogen of tomato under greenhouse conditions. Further study is needed to find an appropriate formulation and approving application of these bacteria under field conditions.

A Theoretical Analysis of Profile Conformance Improvement Due to Suspension Injection

This study is focused on a solution for the problem of suspension penetration in a porous formation. Such a solution forms the basis of injection profile diversion technology for oil reservoir sweep improvement. A conventional model of deep-bed suspension flow was used to describe the suspension injection process. The suspension slug was followed by water injection, and the inflow injection profile before and after treatment was investigated. For the first time, the criteria that determine the effectiveness of the inflow profile improvement process are introduced. The effect of the suspension filtration coefficient on the particle penetration depth was studied. A specific filtration coefficient value for the maximum penetration depth was achieved. The obtained analytical solution was generalized on multi-reservoir strata with poor interlayer crosslinking. The efficiency of profile conformance improvement was described by the differences in the root-mean-square deviations of the inflow velocities in interlayers from mean values before and after the treatment. It was shown that the complex criterion of suspension treatment efficiency should include a reduction in total injectivity. An increase in suspension slug volume improves the injectivity profile but decreases the total injectivity of an injector.

Modification of GO-based pervaporation membranes to improve stability in oscillating temperature operation

Graphene oxide (GO)-based pervaporation membranes have great potential for desalination and lithium containing brine enrichment. However, they experienced critical challenges when used in aqueous solution and exposed to oscillating temperatures due to swelling and microdefects. In this work, the GO-based membranes were fabricated by the filtration of GO suspension with sulfonate-containing diamine molecules on porous substrates, then dip-coated with chitosan and polyvinyl alcohol (PVA). The resultant GO-based membranes demonstrated 99.99% salt rejection during pervaporation using NaCl or lithium-containing concentrated inland brine with humic acid as the feed solution under oscillating temperature. The intercalation of diamine molecules inside the GO nanochannels was able to increase water flux by 20% while the coated chitosan/PVA layer reduced structural defects and undesired scaling/fouling on the membrane surface resulting in minimal reduction of water flux (16%) over 72 h of oscillating temperature pervaporation. Moreover, the membrane exhibited good stability after chemical cleaning. The proposed GO-based membranes provided significant performance sustainability in concentrated inland brine and oscillating feed temperature condition.

Mathematical modeling of filtering suspensions of non – newtonian behavior in alluvial filters

Clarification of liquids and preparation of industrial water plays an important role in various industries, in particular, in the development of oil fields, in the fuel oil industry. In this article, the filtration of a fine suspension of non-Newtonian behavior in a batch alluvial filter is considered. The power-law fluid model is used to describe the rheological state of the medium. A mathematical model is constructed for a filter element of the tubular type. To calculate the thickness of the formed sediment layer, differential equations are constructed. The results of numerical calculations are presented. The influence of the degree of nonlinearity of the medium on the duration of the filter cycle is shown.

Filtration of 2-particles suspension in a porous medium

During the construction of underground storage of hazardous waste, it is necessary to create waterproof walls in the ground. The grout is filtered in the rock, fills the pores and, when hardened, creates a reliable barrier to groundwater. A one-dimensional model of the flow of inhomogeneous particles in a porous medium is considered. The retained particles profiles formed during deep bed filtration are studied. It is shown that when filtering a 2-particle suspension, the deposit is distributed unevenly. The profile of large retained particles is always monotonous, and the profile of small retained particles is nonmonotonic. The monotonicity of the total deposit profile depends on the model parameters. The shape of non-monotonic profiles is time-dependent. At short times, the profile decreases monotonously. At some point, a maximum appears on the profile graph, which shifts from the inlet to the output with increasing time. When the maximum point reaches the outlet, the profile becomes monotonically increasing. With a further increase in time, the retention profiles remain monotonically increasing. Analytical solutions for a filtration model with particles of three or more different types are unknown. Analysis of the retention profiles of the polydisperse suspension requires further study.

Reducing the membrane fouling in cross-flow filtration using a facile fluidic oscillator

Membrane fouling is a main factor that hinders the wide spread adoption of membrane filtration process. In this study, we demonstrate that a passive fluidic oscillator can effectively reduce the fouling and enhance the permeate flux in cross-flow microfiltration. The oscillator produces a pulsating flow of frequency 56–115 Hz and pressure amplitude 500–700 kPa, which leads to transient high shear rates, surface scouring and back-flushing effects. As a result, it mitigates the concentration polarization, prevents micropores clogging, and inhibits the formation of fouling layer. Its applications for filtration of an inorganic particulate suspension and an organic macromolecular solution, as well as the effect of the operating pressure of the oscillator and the membrane material were investigated. In comparison with the static filtration, the membrane fouling was significantly reduced for both the feed solutions using the oscillator. The current method was further tested for recovery of bacterial capsular polysaccharide from 100 L of pneumococcus fermentation broth. The recovery ratio was improved from 2.0% to 39.3% using the conventional method to around 100% with the oscillator. The process time was also greatly reduced by 30%. Furthermore, though the oscillator provides dynamic filtration, it works under constant pressure without the need of additional motors and stirrers. Potentially, it could be applied to some currently existing filtration systems, to improve the flux performance but without increasing too much the system complexity.

Dewatering of microalgae suspensions by cake filtration with filter cloths

Microalgae are a promising bioresource because they produce various materials that can be used as fuels, nutraceuticals, cosmetics, and pharmaceuticals. Additionally, microalgae production is not highly competitive with food production. However, it is quite expensive to harvest microalgae because they are small and suspended in culture broth at dilute concentrations during cultivation. Many studies have been conducted to develop a cost-effective and energy-efficient system for the harvest of microalgae. In this study, cake filtration of a microalgae suspension with a filter cloth was investigated, which is an inexpensive method compared with using conventional microfiltration and ultrafiltration membranes. Because particles deposited on the membrane serve as a secondary membrane during cake filtration, no expensive membrane is needed. To perform cake filtration under optimum conditions, the effects of filter cloths with different pore sizes (0.8–14 μm) on the filtration performance were examined using a constant pressure filtration apparatus. Moreover, filtration behavior was analyzed using existing filtration models. The results showed transition of filtration modes from blocking filtration to cake filtration as the process progressed. Based on these results, we proposed filtration of a preconcentrated suspension using a rough filter cloth having a pore size larger than the algal cell size and then verified the system. Using this system a high solid concentration of cake (18.4 wt%), which was desirable for subsequent processing, was achieved. Furthermore, both relatively high permeate flux and low solid contents in the filtrate were achieved by cake filtration.

Numerical algorithm for the problem of the technological process of filtering low-concentrated suspensions

The paper presents a mathematical model in the form of a second-order nonlinear differential equation with initial and boundary conditions and a numerical method for solving the problem based on the finite-difference method of the technological process of filtration of low-concentration suspensions to determine the ranges of variation of the ion-exchange filter parameters, as well as the results of computational experiments. When developing a mathematical model, the following main filter parameters and physico-mechanical properties of solutions (liquids) were taken into account: filtration rate, rate of sedimentation of gel particles on the pores of the filter, filter porosity, filter layer thickness, kinetic coefficient, dynamic viscosity coefficient and outlet concentration of the suspension. The developed mathematical model and a numerical solution method allow determining the deposition rate of gel particles in the pores of the filter, the outlet concentration of the solution and changes in the concentration of the driving solution of the ion-exchange filter.

Numerical study to control the filler distribution in fibrous media during the particle-filled resin transfer molding process

A numerical model is developed for analyzing the filtration of suspension through fibrous media, during the particle-filled resin transfer molding process. The modeling approach is based on a coupling between flow and filtration models, and it is validated by comparison to various experimental results. The effect of process parameters on the distribution of the concentration and retention of particles within the preform was studied. Four parameters were considered: (i) the injection velocity, (ii) the injection pressure, (iii) the initial filler concentration, and (iv) the overflow time and the lost suspension. The obtained results reveal that the particle distribution and retention depend strongly on the initial concentration and the injection pressure, but very weakly on the injection velocity. A comparison between the distributions of the concentration and retention obtained was established with the two injection modes (imposed velocity and imposed pressure). A quasi-uniform distribution is obtained with the injection at imposed pressure, while a significant non-homogeneity in the distribution is observed in the case of injection at imposed velocity. In the latter case, a marked improvement in the distribution of the concentration and the retention of the particles is obtained by modifying the injection strategy. This operation consists of continuing the suspension injection after filling the mold and evacuating the suspension overflow through the vent. It was found that a small volume of lost suspension is enough to significantly improve particle distribution.

Pulsatile crossflow improves microfiltration fractionation of cells and proteins

The application of pulsatile crossflow is known to mitigate fouling and enhance permeate flux during filtration of simple one-component suspensions. However, previous studies lack a systematic investigation of the effect on pulsation frequency and amplitude on permeate flux, but also on solute transmission during fractionation processes, which hinders industrial application. We used a model feed containing yeast cells as deposit forming material and bovine serum albumin as permeating solute to investigate the influence of pulsatile crossflow with a rather low frequency of 0.1–0.5 Hz on permeate flux and protein transmission in comparison to conventional steady crossflow microfiltration. We found that pulsatile crossflow microfiltration has the highest effect, when it is applied at high transmembrane pressure, high pulsation amplitude, and a frequency above 0.2 Hz. Then, besides enhancing the permeate flux up to 25% (from approximately 200 to 250 L m−2 h−1), pulsatile crossflow is able to double the protein transmission (from approximately 30 to 60%), which has a strong beneficial effect on fractionation efficiency. Further to that, this work contributes to enhance the implementation of pulsatile crossflow filtration by suggesting an easy to implement and scalable pulsatile filtration plant as well as suitable process conditions.

On the reversibility of membrane fouling by deposits produced during crossflow ultrafiltration of casein micelle suspensions

The formation of a deposit layer on membrane surfaces is an important problem, particularly in milk filtration. Properties of the deposit and efficiency of deposit removal can be studied using various indirect methods based mainly on average membrane resistance in deposit formation–deposit removal cycles, but their conclusions on deposit reversibility depend on conditions surrounding deposit analysis.Here we present a method for direct characterization of the reversibility of deposit compression via analysis of local solid concentration distribution during deposit formation at constant pressure and cross-flow velocity and deposit removal after pressure relaxation. Two models are proposed for deposit characterization: a model of crossflow filtration with deposit formation to characterize deposit compressibility-permeability from the data on concentration distribution at steady-state of deposit formation, and a model for evaluating deposit swelling kinetics from the data on steady-state compressibility-permeability.The method was applied here for analysis of the deposit formed on the surface of a polymeric ultrafiltration membrane during crossflow filtration of casein micelle suspensions at 25°C. Local solid concentration distribution in the deposit and concentration polarization layer was probed in situ using small-angle X-ray scattering (SAXS). Experiments were performed in a special-purpose SAXS–filtration cell. It was demonstrated that casein micelle deposits obtained at 1.1 bar transmembrane pressure swell after pressure relaxation. However, swelling rate was significantly lower than that obtained by modeling using deposit compressibility–permeability obtained from the analysis of steady-state concentration distribution. We thus find evidence that casein micelle deposits produced during crossflow membrane filtration undergo compression that is partially irreversible.

Bentonite Suspension Filtration and its Electro-Kinetics in the Presence of Additives

Abstract Invasion of fluids into porous media during drilling can lead to irreparable damage and reduced well productivity. Hence, minimizing the filtration loss of the drilling fluid into the formation is very important. The stability of colloidal suspensions plays a crucial role in controlling the interfacial forces and consequently on minimizing the filtration. The zeta potential is an indicator of the stability of colloids with respect to their electrostatic interactions. In this study, the rheological properties of bentonite suspensions are investigated with and without additives. The starch and CMC were used as additives to enhance the rheological properties of bentonite. The effects of these additives on the drilling fluid filtration were examined. Zeta-potential, viscosity, gel strength and yield point were measured to characterize the extent to which control of the filtration loss of the drilling fluids can be achieved. The zeta-potential and the amount of filtration loss of water-bentonite suspensions were correlated. Finally, the results showed that the addition of either starch or carboxymethyl cellulose (CMC) enhances the filtration properties of water-bentonite suspensions.

Effects of salinity and rock clogging on injectivity dynamics of flooding wells: Experiments, modeling and validation on field data

Injection of water into a rock formation is a common oilfield services technology to maintain high reservoir pressure and increase ultimate recovery of hydrocarbons. While flowing through the well from surface to the rock formation, injected water typically transports fine particles, for example, fine sand grains and calcite precipitated at surface pipeline conditions while mixing water from different sources (e.g., fresh, Cenomanian and formation brine). In the framework of the two-fluid approach to suspension flow modelling, we formulate mathematical model for linear filtration of a particle-laden suspension in the vicinity of a fractured flooding well and transport of ion concentration (salinity). Two major factors of well injectivity decline are described, namely, particle trapping with associated reduction in permeability and porosity of the rock as well as the effect of salinity of injecting water leading to clay swelling, calcite precipitation and change of relative permeabilities of the rock with respect to water and oil. We calibrate suspension filtration model against in-house experiments on clogging of artificial and natural rock cores, in which the profiles of fines concentration along the cores are obtained using X-Ray computed tomography and analysis of 3D rock reconstruction images. The water injection model is adopted to conditions of Priobskoye oilfield of Western Siberia by using the results of standard laboratory experiments on fluid-fluid (calcite precipitation) and fluid-rock (clay swelling, migration of internal fines) compatibility, as well as the effect of salinity on oil displacement and analysis of solid fraction in the injecting water. The calibrated model is then used to describe field data on dynamics of injection rate of three flooding wells. It is obtained that the simulations predict the long-term injectivity dynamics of the wells very well, while at early times (up to 5 months from the start of injection) the model underestimates the injection rate. While fitting the model to field data, we varied only two parameters, namely, solids concentration in the injecting water (in the range provided by lab experiments) and trapping coefficient (the range is limited to result of experiments made with target rock cores). It is demonstrated that only a combination of injectivity decline factors allows to describe the long-term flooding rate of the wells. Ignoring either particle trapping or salinity effects lead to significant overestimation (up to 50%) of the long-term injection rate. Parametric study of water injection showed that two-fold increase in solids concentration in the injecting water as well as oil compressibility lead to similar decrease in long-term injection rate of a well.

Improvement of Microbial Cell Concentration Technology in the Production of Live Plague Vaccine in the Form of Orodispersible Tablets

The aim of the study was to improve the procedure for the Yersinia pestis EV strain cell concentration using the system for tangential flow microfiltration with the ASF-020 filter support unit.Materials and methods. The study used the vaccine Y. pestis EV strain derived from NIIEG cell line. Submerged cultivation of the native culture was performed using BIOR-0.25 reactor with automated control system. Microbial suspension concentrate was produced through microfiltration applying (Adaptive filtration system) AFS-009 and AFS-020 installations. The content of live microbial cells was determined by cytorefractometry. Assessment of the resistance of Y. pestis EV strain cells to technological factors was performed by photometric registration of changes in the optical density of bacterial suspension during the lytic response of cells to sodium dodecyl sulfate. Physical-chemical and immunobiological properties of the dry live plague vaccine were determined in accordance with the pharmacopoeial item.3.3.1.0021.15 of the State Pharmacopoeia of the Russian Federation, 14th edition.Results and discussion. The design features of the equipment introduced made it possible to carry out membrane filtration of microbial suspension, using BIOR-0.25 reactor as an intermediate storage unit, thereby excluding three technological stages. The total concentration of microbes in the suspension obtained by routine and improved methods was more than 150 billion microbial cells per ml. A comparative study of the effect of various hydrodynamic regimes in the working cavities of AFS-009 and AFS-020 filter units did not significantly affect the morphometric properties and resistance of microbial cultures to extreme (technological) factors. Based on the experimental data, the mass balance of the membrane filtration process has been determined. The optimized technology gave 0.13 liter yield of concentrate from 1 liter of native culture, and the process duration was reduced to 5 hours, the yield of the finished product in one production cycle was increased by 3 times. Thus, the process of concentrating Y. pestis EV strain cells during the production of the tablet form of live plague vaccine has been enhanced. A comparative study of the morphometric properties and resistance of plague microbe cultures to technological factors in the process of their concentration using optimized technology did not reveal any significant differences as compared to the routine one. Technological stage of concentrating has been reduced to 5 h term with a three-fold increase in the yield of finished product.

ПОЛУЧЕНИЕ КУЛЬТУР АЛЬВЕОЛОЦИТОВ I И II ТИПА ДЛЯ МЕДИКО-ЭКОЛОГИЧЕСКИХ ИССЛЕДОВАНИЙ

The alveolar epithelium is a dynamic tissue, consisting of cells of types I and II, covering more than 99 % of the lung inner surface and actively responding to various endogenous and exogenous stimuli. The technology of alveolocyte isolation is presented, which consists in mechanical disaggregation of tissue with subsequent processing of the resulting explants with 0.25 % trypsin solution in combination with filtration of the cell suspension through pores with a diameter of 100 µm and 50 µm. In two-dimensional static culture viable actively dividing rounded cells and large alveolar epithelial cells with cuboid or polygonal morphology, producing surfactant proteins, were visualized.

DETERMINING THE LENGMUR COEFFICIENT OF THE FILTRATION PROBLEM

Filtration of suspension in a porous medium is actual in the construction of tunnels and underground structures. A model of deep bed filtration with size-exclusion mechanism of particle capture is considered. The inverse filtration problem - finding the Langmuir coefficient from a given concentration of suspended particles at the porous medium outlet is solved using the asymptotic solution near the concentrations front. The Langmuir coefficient constants are obtained by the least squares method from the condition of best approximation of the asymptotics to exact solution. It is shown that the calculated parameters are close to the coefficients of the model, and the asymptotics well approximates the exact solution

Filtration of kaolinite and coal mixture suspension: Settling behavior and filter cake structure analysis

The filtration of kaolinite-coal mixture suspension was investigated by settling behavior observation and filter cake structure analysis. Three-dimensional X-ray microanalysis was used to analyze filter cake structure. The settling rate and specific filter cake resistance of kaolinite-coal mixture gradually increased with the increasing content of kaolinite in suspension. A high settling rate made filter cake form quickly during filtration, which prevented water to pass through, increasing the specific filter cake resistance. Filter cake structure analysis showed kaolinite trapped fine coal particles into the gap between kaolinite flocs during filtration. The size and number of pores in the filter cake formed by a high kaolinite content mixture were smaller and fewer than that formed by a low kaolinite content mixture. A high specific cake resistance was created by a high kaolinite content mixture. This study provides a novel insight into the filtration of coal slurry in coal mining and cleaning processes.