Cake Filtration Model Research Articles

The effects of buffer condition on the fouling behavior of MVM virus filtration of an Fc-fusion protein.

A combined pore blockage and cake filtration model was applied to the virus filtration of an Fc-fusion protein using the three commercially available filters, F-1, F-2, and F-3 in a range of buffer conditions including sodium-phosphate and tris-acetate buffers with and without 200 mM NaCl at pH 7.5. The fouling behaviors of the three filters for the feed solutions spiked with minute virus of mice were described well by this combined model for all the solution conditions. This suggests that fouling of the virus filters is dominated by the pore blockage mechanism during the initial stage of the filtration and transformed to the cake filtration mechanism during the later stage of the filtration. Both flux and transmembrane resistance can be described well by this model. The pore blockage rate and the rate of increase of protein layer resistance over blocked pores are found to be affected by membrane properties as well as the solution conditions resulting from the modulation of interactions between virus, protein, and membrane by the solution conditions.

Treatment of tea industry wastewater using coagulation-spinning basket membrane ultrafiltration hybrid system

The present study delivers the significant effects of the coagulation-spinning basket membrane ultrafiltration on the treatment of tea industry generated effluent. Response surface methodology (RSM) was applied to optimize the process parameters, namely, alum dosage (50–300 mg L−1), pH (4–10), stirring speed (10.47–62.83 rad s−1), and stirring time (30–180 min) during the pretreatment of effluent. Prior to final treatment, the spinning basket membrane filtration was performed to explore the permeate flux decline behavior at different parametric conditions such as, applied transmembrane pressure drop (TMP drop: 207–414 kPa), rotational speed (10.47, 31.41, 52.36 and 73.30 rad s−1) and membrane MWCOs (5–50 kDa). Artificial neural network (ANN) analysis helps to compare the theoretical flux decline behavior with the experimental data. Modified Hermia's models were used to identify the reversible and irreversible fouling as well as cake layer formation. The decrease of cake filtration model constant from 1.31 × 107 to 0.56 × 107 m−2 s indicates the minimization of concentration polarization by virtue of membrane basket rotational speed. The effects of various parameters on the permeate quality have also been verified. The maximum improvement of permeate clarity of 94.46% was observed when the membrane basket rotation was 52.36 rad s−1. With changing MWCO of 50 to 5 kDa, the removal of chemical oxygen demand has been increased from 87% to 96.70% at a rotation of 52.36 rad s−1.

Preparation, characterization and fouling analysis of in-air hydrophilic/underwater oleophobic bio-inspired polydopamine coated PES membranes for oily wastewater treatment

The core of this study is utilization of the facile one-side self-polymerization of dopamine (DA) on surface of the non-recoverable polyethersulfone (PES) membrane and its antifouling ability assessment during oil-in-water (O/W) emulsion separation. The pristine PES membrane was coated by DA solution for 2 and 4 h. The membranes were characterized using FESEM, AFM, FTIR, water contact angle (WCA) and underwater oil contact angle (UOCA) analysis. The results showed that hydrophilicity and underwater oleophobicity can be achieved successfully. Antifouling properties of the modified membranes were improved so that water flux of the 4 h polydopamine (PDA) coated membrane increased about 793% in comparison to the pristine PES membrane. Also, implementation of classical models showed that PDA coating changes the membrane fouling mechanism from standard blockage model to cake filtration model. The 4 h PDA modified membrane shows antifouling property and easy recovery capability during 30 h of operation. Also, the dependences of steady-state water flux were investigated via changing initial oil concentration, feed salinity, trans-membrane pressure and self-polymerization time of DA. Self-polymerization time of DA was found as the most influential factor on water flux. Also, during O/W emulsion separation, all the membranes exhibited high removal efficiency (above 98%) introducing a promising candidate for practical applications.

Treatment of aqueous bacterial solution using ceramic membrane prepared from cheaper clays: A detailed investigation of fouling and cleaning

This article reports the preparation of ceramic membranes using inexpensive precursors for microfiltration of bacteria. The membranes were prepared via uniaxial compaction method and sintered at different temperatures in the ranges of 900–1100 °C. The membranes were characterized by x-ray diffraction (XRD), thermo-gravimetric (TG) and scanning electron microscopic (SEM) analysis. The porosity, water permeability, average pore size, pH and chlorine tolerance of membranes were also evaluated. It was found that the porosity decreased from 42 to 34% with increasing temperature. On the other hand, the pore size and water permeability increased from 180 to 650 nm and 3.24 × 10−4 to 3.60 × 10-3 L/m2hPa, respectively, with increasing temperature. The membranes showed excellent pH and chlorine tolerance. Based on the results, the membrane fired at 900 °C was selected as an optimum membrane and subjected to the microfiltration of bacteria. The membrane provided bacterial rejection of 90.24% with good permeate flux of 50.65 L/m2h. In addition, the fouling test was conducted by microfiltration of synthetic polyethylene glycol (PEG) solutions. It was analysed that the cake filtration model offered good fit with the measured experimental values of both bacteria and PEG. Membrane cleaning experiment was conducted using water, surfactant (sodium dodecyl sulphate), alkali (NaOH) and ultrasonication. It was found that the ultrasonication method provide maximum flux recovery during bacterial cleaning, whereas alkali treatment was sufficient to clean the PEG. Henceforth, the low cost membranes with better properties can be utilized for bacteria removal application in biotechnology field.

Phenolic compounds from Syzygium cumini (L.) Skeels leaves: Extraction and membrane purification

A hybrid process consisting of extraction and microfiltration was proposed in this study for producing purified, clear and stable aqueous phenolic extract from jamun (Syzygium cumini (L.) Skeels) leaf. Response surface methodology was successfully used for optimization of extraction conditions. Pseudo-first order kinetic model successfully described the extraction of total polyphenols from jamun leaves, with the activation energy determined as 9.5 kJ/mol based on the Arrhenius model. The kinetic constants were used to study the kinetic and thermodynamic compensations of extraction of TPC from jamun leaves. Applying the statistical criterion, the kinetic and thermodynamic compensations were concluded to be real and the extraction process was controlled by entropy. A total of ten phenolic compounds including six phenolic acids (tannic acid, gallic acid, ellagic acid, caffeic acid, ferulic acid and p-coumaric acid) and four flavonoids (catechin, epicatechin, quercetin and myricetin 3-O-rhamnoside) were identified and quantified in jamun leaf extract obtained under optimum extraction conditions. The selection of appropriate membrane in the microfiltration step was a critical aspect. To observe the effect of membrane pore size on the permeate flux and permeate quality, leaf extracts were then microfiltered using four different microfiltration membranes (0.1, 0.22, 0.45, and 0.8 μm) under batch concentration mode. The flux decline was successfully described by the Hermia’s cake filtration model. The stability of clarified extract was investigated at 4 °C for 45 days. The 0.45 μm microfiltration membrane was suggested for the clarification of jamun leaf extract in order to achieve high flux, polyphenol recovery, extract purity and improved storage stability.

Permeate flux increase by colloidal fouling control in a vibration enhanced reverse osmosis membrane desalination system

Experiments and Computational Fluid Dynamics (CFD) simulations were performed to investigate the colloidal fouling control of a vibration enhanced reverse osmosis (VERO) membrane system for up to 12 h of operation time. A porous cake mass transfer model for the reverse osmosis (RO) colloidal fouling analysis was derived by combining the cake filtration model, cake enhanced osmotic pressure (CEOP) effect, the critical flux theory, and the solute convection-diffusion model. The process of colloidal particle deposition and fouling formation on the membrane surface were visualized using this model. The permeate flux variation and cake layer distribution along the membrane were depicted. Systematic studies including different initial permeate fluxes, Reynolds numbers, particle concentrations, and vibration frequencies were carried out to investigate the system performance under different operation conditions. The results suggest that colloidal fouling induced permeate flux decline could be improved by the high-frequency vibration in the VERO module. Both simulations and experiments demonstrated that, with a fixed vibration amplitude, membrane module with higher vibration frequencies will have less NaCl accumulation and higher permeate flux under the influence of colloidal fouling.

A lab-scale spinning basket membrane module for the assessment of humic acids ultrafiltration with effect of sonication on membrane fouling

ABSTRACTIn the current study, humic acids ultrafiltration was explored using spinning basket membrane module at different transmembrane pressure drops (207, 276, 345, and 414 kPa), rotational speeds (10.47, 20.99, 31.41, 52.36, and 73.30 rad s−1) and different concentration of HAs (50, 150, and 250 mg L−1). The internal pore blocking characteristics was investigated using modified Hermia’s pore clogging models like complete, standard, intermediate pore blocking, and the cake filtration model. After ultrafiltration of 50 mg L−1 solution, the cleaning process of fouled membrane was carried out using a system inbuilt back rotation of the membrane basket (10.47–52.36 rad s−1) and compared with the effect of ultrasonication (ultrasound power: 120 W, frequency: 50 kHz) for the same fouled membrane at the different sonication time interval (5–25 min). The maximum cleaning efficiency of 88% was observed at 25 min of ultrasonication of fouled membrane.

Evaluation of variable pressure dead-end ultrafiltration behaviors of nanocolloids based on filter cake properties

Variable pressure dead-end ultrafiltration experiments including constant rate filtration experiments were performed for nanocolloids such as protein solutions of bovine serum albumin (BSA), lysozyme and myoglobin, and nano-silica sol. The relationships for representing the dependences of average specific cake resistance and average cake porosity on the pressure drop across the filter cake necessary for the evaluation of these filtration behaviors were determined from the temporal flux decline data obtained in a step-up pressure dead-end ultrafiltration experiment using a filter with an abrupt reduction in the effective filtration area. In case of a relatively high colloid concentration, it was necessary to acquire the porosity data for evaluation of ultrafiltration behaviors based on the compressible cake filtration model. The filtration behaviors were successfully evaluated even in a relatively high pressure rising rate. Moreover, the pressure variation calculated based on the constant rate filtration equation enabled us to maintain a constant filtration rate in dead-end ultrafiltration.

Superoleophilic and superhydrophobic carbon membranes for high quantity and quality separation of trace water-in-oil emulsions

Oil purification is an important issue, with its growing commercial demand. In this work, a superoleophilic and superhydrophobic carbon membrane was prepared, and its potential for trace water-in-oil (w/o) separation was evaluated. The carbon membrane was prepared by a spin coating method, with optimization of variables such as spin speed and coating times, and then pyrolyzed at a high temperature under vacuum. Using a capillary flow porometer, the dominated pore-throat size distribution of the carbon membrane was shown to be ranged from 0.5 to 2.5 µm. Furthermore, the separation performance and fouling mechanism were analyzed using several cake filtration models. In the case of low TMP (0.110 bar), steady flux rates with clean membranes were 1203 L/m2/h, which is much higher than in microfiltration systems, and the water content of the permeate flux could be reduced to 0.0306%. The model correlations also indicated that the specific cake resistance obtained in this case was considerably lower than 4.8 min/L2.

Synthesis and characterization of low-cost ceramic membranes from fly ash and kaolin for humic acid separation

Ceramic microfiltration membranes were prepared using five different compositions formulated with different amounts of fly ash and kaolin and sintered at 900 °C. The SEM analysis evidenced a large number of small pores on the surface of kaolin-rich membranes. The M4 membrane prepared using 25% fly ash and 50% kaolin was found to be optimum as it had a good combination of pore size (0.885 μm), porosity (42.7%), mechanical strength (43.6MPa), and chemical stability (<3% weight loss in acid and 0.02% in base), and this membrane was successfully applied in separation of humic acid from water. The permeate flux data fitted very closely with cake-filtration model, indicating the formation of a cake layer on membrane surface. Membrane fouling was found to be reversible and easily negated by cleaning and backflushing. The regenerated membrane showed better rejection of humic acid than fresh membrane with a flux recovery of above 80%.

&lt;b&gt;Cake formation and the decreased performance of whey ultrafiltration

Fouling in whey ultrafiltration is still a problem to be solved and modelling the permeate flux is still a challenge. A set of experiments of whey ultrafiltration was performed and it was demonstrated that the cake filtration model accurately represents the permeate flux over time despite exist more complex models to describe the phenomenon. In less than 10 s an irreversible resistance is established, and the cake starts to build up. It was observed changes in protein rejection in a range of 98 and 94% when a higher cake layer was set up, but it was not noticed strong evidences that the layer deposited on the membrane surface drives this change.

Combined Depth and Cake Filtration Model Coupled with Flow Simulation for Flat and Pleated Filters

AbstractFiltration processes characterized by initial depth filtration, followed by a stage during which the cake acts as both a depth and surface filtering medium are studied. Such phenomena can occur especially for polydisperse dust. Based on one‐dimensional depth filtration modeling, a combined depth and cake filtration model is formulated and coupled with the fluid flow. The evolution of flow resistivity and filtration efficiencies is investigated in the case of relatively dilute suspensions and constant flow rates. Numerical simulations of single‐pass experiments are performed for both flat and pleated filter media. The model presented here is able to predict a nonlinear pressure drop for incompressible filter cakes due to the reduction of pore volume by particle deposition in the cake region.

Investigation of the fouling effect on a commercial semi-permeable membrane in the pressure retarded osmosis (PRO) process

Abstract One of the main challenges for generating osmotic power by using PRO technology is the membrane fouling which reduces the permeate flux and consequently increases the cost and decreases the osmotic power generation. In this research, different feed waters with various qualities were used to investigate the effect of fouling on a commercial membrane in PRO mode in continuous conditions. Also, the fouling mechanisms were investigated in order to study the cleaning of the membrane in PRO mode in the future research. In addition, four classic fouling models such as complete blocking model (CBM), intermediate blocking model (IBM), standard blocking model (SBM) and cake filtration model (CFM) were used. Cake enhanced osmotic pressure as a new mechanism for osmotically driven membranes was studied as well. According to the results, the fouling rate when the draw solution was synthetic salt water followed the order of: untreated river water > multimedia sand filter > microfiltration > ultrafiltration effluents. The fouling rate in ultrafiltration and microfiltration effluents using sea water occurred faster compared to the results for untreated synthetic salt water. Complete fouling (permeate flux was negligible) occurred after 580 h using feed water from ultrafiltration unit. It was observed that cake filtration and cake enhanced osmotic pressure were the main fouling mechanisms that governed the membrane fouling. These models could describe the membrane fouling in PRO processes.

Filtration behaviors of suspension of dual-sized submicron particles through semi-permeable microfiltration membrane

Abstract Particulate filtration behaviors such as the flux decline and particle retention by the membrane during the course of filtration were examined for dead-end constant pressure microfiltration of dilute suspension of dual-sized submicron polystyrene latex (PSL) particles through a semi-permeable membrane with a pore size larger than both particle sizes. The variation of rejection of both larger and smaller particles with the progress of filtration was approximated by the logistic equation. Our analysis was based on the cake filtration model accompanied by partial permeation of particles through the membrane. The model enabled us to evaluate the variation of the reciprocal filtration rate with the filtrate volume per unit effective membrane area, the relation between the filtrate volume and the filtration time, and the characteristic filtration curve frequently employed in the analysis of the blocking filtration law, on the basis of the data of temporal variation of particle retention. It was found that the retention of smaller particles was particularly promoted by the increase in the relative concentration of larger to smaller particles. It was also found that lower applied filtration pressure promoted the retention of both larger and smaller particles, resulting in the profound flux decline.

A precise combined complete blocking and cake filtration model for describing the flux variation in membrane filtration process with BSA solution

It is difficult but significant to describe the flux variation for the membrane filtration process with complex combined filtration mechanisms. In this paper, the steady membrane frontal area (K) was proposed to improve the predictive accuracy of cake-complete model for combined fouling mechanisms of complete blocking and cake filtration. Meanwhile, the transition point when the fouling mechanisms changed from combined complete blocking and cake filtration into individual cake filtration could also be analyzed under different conditions. The results showed that the predictions of the proposed model had good agreements with experimental data under different conditions for bovine serum albumin (BSA) solution. Meanwhile, the proposed combined model possess higher accuracy (relative error σ¯=1.83%) than cake filtration (σ¯=7.36%), complete blocking (σ¯=15.90%) and pore blockage-cake (σ¯=5.54%) model. Moreover, the transition point appeared earlier at higher pressure and concentration. And larger K was obtained at higher concentration and lower pressure which represented less fouling caused by complete blocking. In addition, the application of the proposed model was validated not only by different suspensions but also by different membranes.

Separation of oil from oily wastewater using low cost ceramic membrane

Safe disposal of oily wastewater is a global issue across the industrial world. Stable oil-in-water emulsion has been separated by dead end filtration using low cost ceramic membrane. The efficiency of separation at different oil-water emulsion concentrations was evaluated at different trans-membrane pressures. Maximum rejection of oil 95.4% was observed for membrane sintered at 850 °C for oil concentration of 250 mg/L at 137.89 kPa. The permeate oil concentration was within the permissible range of environmental tolerance (<12 mg/L). The flux decline data was compared with various pore blocking models and it was appraised that cake filtration model best represents the fouling mechanism within the experimental range of pressure and oil-in-water concentration. Solvent permeation studies revealed that nonpolar solvents were more permeable than the polar solvents. The selection parameter of 14.78×10−6m3/m2·s indicates a good combination of flux permeation, declination and rejection for the membrane sintered at 900 °C.

Treatment of Simulated Oily Wastewater by Ultrafiltration and Nanofiltration Processes

A study in the treatment and reuse of oily wastewater generated from the process of fuel oil treatment of gas turbine power plant was performed. The feasibility of using hollow fiber ultrafiltration (UF) membrane and nanofiltration (NF) membrane type polyamide thin-film composite in a pilot plant was investigated. Three different variables: pressure (0.5, 1, 1.5 and 2 bars), oil content (10, 20, 30 and 40 ppm), and temperature (15, 20, 30 and 40 ᵒC) were employed in the UF process while TDS was kept constant at 150 ppm. Four different variables: pressure (2, 3, 4 and 5 bar), oil content (2.5, 5, 7.5 and 10 ppm), total dissolved solids (TDS) (100, 200,300 and 400 ppm), and temperature (15, 20, 30 and 40 ᵒC) were manipulated with the help of statistical method of Taguchi in the RO process. Analysis of variable (ANOVA) and optimum condition was investigated. The study shows that pressure has the greatest impact on the flux of UF process, while temperature and pressure have similar contribution on flux of NF process. The temperature seems to have the greatest effect on TDS rejection. It was noticed that more than 96% oil removal can be achieved with flux of 624 L/m2.hr by UF process and that the fouling mechanism of UF process follows the cake/gel layer filtration model. It was observed that 100% removal of oil content can be achieved along with 79% for the TDS rejection and flux of 65 L/m2.hr by NF process. The result shows fouling in NF process follows the cake filtration model. It was concluded that the observed values are within ±5% of that the predicted which reflects a strong representative model. The treated wastewater has the characteristics that it can be reused in the process to reduce the operating cost.

On the fouling mechanism of polysulfone ultrafiltration membrane in the treatment of coal gasification wastewater

Membrane fouling has been investigated by using a polysulfone ultrafiltration membrane with the molecular weight cutoff of 20 kDa to treat crushed coal pressurized gasification wastewater. Under the conditions of different feed pressures, the permeate flux declines and rejection coefficients of pollutants referring to three parameters (total organic carbon (TOC), chroma and turbidity) were studied. The membrane fouling mechanism was simulated with three classical membrane fouling models. The membrane image and pollutants were analyzed by scanning electron microscopy and gas chromatography-mass spectrography (GC-MS). The results indicate that the permeate flux decreases with volume reduction factor before reaching a constant value. The rejection coefficients were also measured: fTOC = 70.5%, fC = 84.9% and fT = 91%. Further analysis shows that the higher the feed pressure is, the sooner the permeate flux reaches constant value and the more sharply the permeate flux declines. Constant flux indicates a nonlinear growth with feed pressure (PF): when PF equals 1.2 bar, the mark for the critical flux, slight membrane fouling occurs; when PF exceeds 1.2 bar, cake layer pollution aggravates. Also the rejection coefficients of global pollutant increases slightly with PF, suggesting the possibility of cake compression when PF exceeds 1.2 bar. Through regression analysis, the fouling of polysulfone ultrafiltration membrane could be fitted very well by cake filtration model. The membrane pollutants were identified as phthalate esters and long-chain alkenes by GC-MS, and a certain amount of inorganic pollutants by X-ray photoelectron spectroscopy. Open image in new window

Analysis of fouling development under dynamic membrane filtration operation

This research is a contribution towards evaluating the appropriate fouling mechanism responsible for the flux decline under dynamic membrane (DM) filtration and its formation mechanism by using gravity-driven filtration in a specifically designed experimental setup. Series of extended short term filtration experiments were performed at varying operating conditions of mixed liquor suspended solids (MLSS) concentrations, trans-membrane pressures (TMP) and mesh pore sizes. Blocking models were applied to identify the fouling mechanisms occurring in DM development. The results demonstrated that cake filtration model can adequately describe fouling mechanisms during DM filtration. According to the analysis of variance, DM development, as described by flux (J) trends during filtration, was significantly affected only by MLSS concentration while effluent turbidity was significantly affected by MLSS concentration and TMP. On the contrary, J and effluent turbidity trends during filtration were not significantly influenced by mesh pore size, at least in the range used in this study (10–200μm).

Dairy wastewater treatment using a novel low cost tubular ceramic membrane and membrane fouling mechanism using pore blocking models

This study investigated the potential application of a novel low cost tubular ceramic membrane in treating wastewater generated by a local dairy industry. The low cost tubular membrane ($0.5) with 0.309μm pore size, 53% porosity and 5.93×10−7m3/m2skPa water permeability was fabricated from natural clay materials by extrusion technique. The capability of the membrane for treating real dairy industry wastewater was tested in tangential mode of microfiltration operation at different applied pressure (207–414kPa) and cross flow rate (5.55×10−7–2.22×10−6m3/s). An increase in applied pressure and cross flow rate on the microfiltration process resulted in a decrease in percentage removal of chemical oxygen demand (COD). The novel membrane achieved a maximum reduction in COD up to 91% (135mg/L) in the permeate stream with a flux of 2.59×10−6m3/m2s, which is well within the permissible limit for wastewater discharge into the environment. These investigations affirmed the potential suitability of the membrane in dairy wastewater treatment to attain acceptable limit (<200mg/L) of the permeate stream. Consequently, the membrane fouling mechanism was examined using conventional pore blocking models, viz. complete, standard, intermediate pore blocking and cake filtration model. The experimental results were well described by the cake filtration model. Additionally, the potential of the novel membrane was compared with other membranes reported in the literature for dairy wastewater treatment application.