kDa Polyethersulfone Membrane Research Articles

The Performance of Ultrafiltration Process to Further Refine Lactic Acid from the Pre-Microfiltered Broth of Kitchen Waste Fermentation

Lactic acid (LA) is an important chemical material facing rapid demand in recent years. The oriented fermentation of kitchen waste is a promising route for economic LA production. However, the refinement of LA from fermentation broth is a spiny issue. In this study, the performance of ultrafiltration (UF) process for the refinement of LA from the pre-microfiltered broth of kitchen waste fermentation was first investigated. The results showed that with 50 KDa polyethersulfone membrane, under the optimum pressure of 120 KPa, the pH of 6.0, and the backflushing mode with the deionized water for 3 min, the best performance was achieved with the chroma removal efficiency, turbidity removal efficiency, protein removal efficiency and total sugar removal efficiency of 54.3%, 89.8%, 71.7% and 58.5%, respectively, and LA recovery efficiency was 93.6%. The results indicated that the UF process could further effectively refine the pre-microfiltered broth of kitchen waste fermentation, and the combination of microfiltration and UF process is ideal for achieving desirable LA refinement performance. This study verified the feasibility of UF process in LA refinement from pre-microfiltered broth of kitchen waste fermentation, and based on the results, the further exploration of proper post-process to treat UF filtrate for obtaining LA product with higher quality should be explored in the future.

Membrane Technology as a Strategy for Improving β-Galactosidase Concentration Processes: The Influence of the pH, Membrane Molecular Weight, Pressure, and Ionic Strength in the Process

The enzyme β-galactosidase catalyzes the hydrolysis of lactose into glucose and galactose, although for its effective application it is necessary to establish techniques for purification, concentration, or polishing, such as membrane separation processes, in particular ultrafiltration. The present study aimed to investigate ultrafiltration and diafiltration applied as initial steps for concentration and salt removal, respectively, in the β-galactosidase purification processes. Additionally, the influence levels of the pH (6.5, 7.7, or 7.5), membrane molecular weight cut-off (30, 50, 60, or 100 kDa), operating pressure (1.5, 2.0, or 2.5 kgf/cm2), and ionic strength of the ultrafiltration using NaCL or KCl (0.01–0.1 M) were evaluated considering the enzyme recovery, purification, retention, and concentration factors in relation to the proteins, volume, activity, and protein flux and yield of the processes. The ultrafiltration of the crude enzyme extract at pH 7.5 and 1.5 kgf/cm2 with a 50 kDa polyethersulfone membrane resulted in a volume concentration of the β-galactosidase extract up to 7.1-fold greater, a purification factor 1.2-fold greater, and an enzyme recovery rate of 108.9% by eliminating metabolites during the purification process. In addition, the lowest flux variation range (16.0 to 13.1 L/m2·h) was observed under these same conditions, thereby representing a decrease of 18.0%. An increase in the operating pressure and the addition of salts results in reduced enzyme recovery (up to 38% of the process yield (734.1 to 453.7 U/h) and up to 40% of the enzyme recovery rate (108.9 to 60.6%) during the ultrafiltration using NaCl, respectively). The operation in the diafiltration mode allowed salt removal after the purification of β-galactosidase (enzymatic recovery rates above 93.4%) via precipitation and ion-exchange chromatography elution and as part of an aqueous two-phase system using 6 diafiltration cycles, thereby revealing its application potential.

Ultrafiltration of Fucus vesiculosus Extracts Under Different Operating Conditions

The interest in separating and concentrating bioactives and minerals from seaweeds extracts is growing due to large health benefits of these substances. The aim of this study was to investigate the separation of components of Fucus vesiculosus seaweed extracts by tangential ultrafiltration and apply Hermia’s models adapted to crossflow ultrafiltration to understand the fouling mechanism. The influence of membrane cut-off varying from 5 to 150 kDa, crossflow velocity from 0.081 to 0.095 m/s and transmembrane pressure between 2 and 8 bar was studied. The present study revealed that the ultrafiltration membranes process was successful in clarifying and still delivering permeates with a high content in iodine. Clarification was almost completely achieved with 5 kDa polyethersulfone membrane, while the hydrophilic polyethersulfone membrane was not adequate to due to the high retention in iodine. Cake layer formation mathematical model was successfully used to predict the permeate flux over time. There was evidence that cake layer is the fouling mechanism in the filtration of Fucus vesiculosus extracts, whatever the membrane crossflow velocity or transmembrane pressure, probably due to the high content of these extracts in alginates.Graphical Abstract

Microfiltration and Ultrafiltration Process to Produce Micellar Casein and Milk Protein Concentrates with 80% Crude Protein Content: Partitioning of Various Protein Fractions and Constituents

The objective of the study reported in this research paper was to produce micellar casein concentrate (MCC) and milk protein concentrate (MPC) with 80% crude protein relative to total solids (TS) using MF and UF processes respectively. Additionally, capillary gel electrophoresis (CGE) was used to study the protein fractions in retentate and permeate. For MCC production, 227 L of pasteurized SM was subjected to MF using 0.5-micron spiral wound polyvinylidene fluoride membrane. During the process, diafiltration (DF) water was added at six intervals, totaling 100% of the feed volume. For MPC production, 227 L of pasteurized SM from the same lot was subjected to UF using 10 kDa Polyethersulfone membranes. During the process, DF water was added at four different intervals, with a final total addition of 40% of the feed volume. Both processes used a volume reduction of five. There were significant (p < 0.05) differences in all of the compositional parameters, except fat and casein for the MF retentate (MFR) and UF retentate (UFR). UFR had a higher crude protein (CP), TS, lactose, ash and calcium content as compared to MFR and this affected the CP/TS ratio found in both the retentates. The differences in membrane pore sizes, operating pressures and level of DF used all contributed to the differences in final CP/TS ratio obtained. The CGE analysis of individual protein fractions present in the UFR and MFR showed that UFR has a β-lactaglobulin to α-lactalbumin (α-LA) ratio similar to SM, whereas the MFR has a higher ratio, indicating preferential transmission for α-LA by the MF membrane. The results from this study show that MF and UF processes could be used for production of MCC and MPC with similar CP/TS ratio with careful selection of operating parameters, and that CGE can be used for detailed analysis of various protein fractions.

Comparison of different ultrafiltration membranes as first step for the recovery of phenolic compounds from olive-oil washing wastewater

The production of olive oil generates wastewater with a high organic load and toxicity due to the high concentration of phenolic compounds. In recent years, the study on the treatments of these waters has been intensified together with the search for a process to recover these phenolic compounds due to their great antioxidant potential. All this with the aim of implementing the concept of circular economy. In this study, four different organic ultrafiltration membranes were evaluated in order to recover the phenolic compounds present in olive oil washing wastewater (OOWW) from an oil mill in the Valencian Community (Spain). The tested membranes differ in materials and molecular weight cut-off (MWCO): two permanently hydrophilic polyethersulfone (PESH) membranes with MWCO of 4 and 50 kDa, respectively, one polyethersulfone (PES) membrane with a MWCO of 5 kDa and a regenerated cellulose acetate (RCA) membrane with a MWCO of 10 kDa. Transmembrane pressure (TMP) and crossflow velocity (CFV) were varied from 1 to 3 bar and from 1.5 to 3.4 m·s−1, respectively. The effectiveness of the different membranes and operating conditions were evaluated comparing the permeate flux and the rejection of chemical oxygen demand (COD) and total phenolic compounds (TPhs). The membranes with lower MWCO showed stable permeate fluxes without significant changes over time, while the 50 kDa membrane showed a gradual decrease, without achieving a stable flux. Low rejection of phenolic compounds was observed in all cases, while the rejection of COD varied between 19.5 % and 62.9 % depending on the membrane and operating conditions tested. Except for the 50 kDa PESH membrane, initial permeability recovery greater than 95 % was achieved with a 35 °C water rinse, indicating that membrane fouling was not severe. Since the aim was to recover the TPhs in the permeate stream and separate them from the organic matter, the 5 kDa PES membrane at 2 bar and 2.5 m·s−1 was considered to be the best option. At those conditions a stable permeate flux of 40 L·h−1·m−2 was obtained, while the lowest TPhs rejection was observed (8.01 %) with a high COD rejection (61.18 %).

Effect of Polysaccharide Conformation on Ultrafiltration Separation Performance

The manifold array of saccharide linkages leads to a great variety of polysaccharide architectures, comprising three conformations in aqueous solution: compact sphere, random coil, and rigid rod. This conformational variation limits the suitability of the commonly applied molecular weight cut-off (MWCO) as selection criteria for polysaccharide ultrafiltration membranes, as it is based on globular marker proteins with narrow Mw and hydrodynamic volume relation. Here we show the effect of conformation on ultrafiltration performance using randomly coiled pullulan and rigid rod-like scleroglucan as model polysaccharides for membrane rejection and molecular weight distribution. Ultrafiltration with a 10 kDa polyethersulfone membrane yielded significant different recoveries for pullulan and scleroglucan showing 1% and 71%, respectively. We found deviations greater than 77-fold between nominal MWCO and apparent Mw of pullulan and scleroglucan, while recovering over 90% polysaccharide with unchanged Mw. We anticipate our work as starting point towards an optimized membrane selection for polysaccharide applications.

Ultrafiltration for the recovery of proteins from surimi washing water

The aim of this study was to evaluate the efficiency of the ultrafiltration process (UF) in the cleansing treatment of the tilapia surimi washing water and in the recovery of components. After producing surimi, the water generated in the washing operations was subjected to UF in a 30 kDa polyethersulfone membrane. Unfiltered washing waters and UF permeate and concentrate were analyzed for pH, total solids (TS) and fixed solids (FS), total proteins, and lipids. The chemical oxygen demand (COD) was determined in the original water and in the permeate. The concentrate was dehydrated in a spray dryer and analyzed for amino acids and carotenoids. The permeate showed a significant decrease in TS, proteins and COD, indicating that UF was efficient in removing the organic load from the waters. The percentage of protein recovery by UF was 93.12% and the dehydrated concentrate had all the essential amino acids, being leucine (5.47%), lysine (6.49%), valine (3.59%), and phenylalanine (3.68%) those with the highest concentrations, and also 0.67 mg/100 g of carotenoids. The application of UF has proved to be viable both in the recovery of valuable compounds and in the decontamination of water, contributing to the sustainability of the fish productive sector.

Purification of Cas9-RNA complexes by ultrafiltration.

The discovery of CRISPR-Cas9 has revolutionized molecular biology, greatly accelerating the introduction of genetic modifications into organisms and facilitating the development of novel therapeutics and diagnostics. For many applications, guide RNA and Cas9 protein are expressed, combined, and purified to produce a ribonucleic enzyme complex that is then added into a diagnostic device or delivered into cells. The objective of this work was to develop an ultrafiltration process for the selective purification of Cas9 ribonucleoprotein by removal of excess guide RNA. A His-tagged Streptococcus pyogenes Cas9 protein was produced in Escherichia coli, purified by metal affinity chromatography, and complexed with a 40 kDa (124 nucleotide) single guide RNA. Ultrafiltration experiments were first performed on solutions containing either guide RNA or Cas9 protein to identify the effect of filtration conditions and membrane pore size on the selectivity. Shear-induced aggregation of the Cas9 led to significant fouling under some conditions. A diafiltration process was then developed using a Biomax® 300 kDa polyethersulfone membrane to selectively remove excess guide RNA from a solution containing Cas9-bound guide RNA and free guide RNA. These results demonstrate the potential of using ultrafiltration for the removal of excess RNA during the production of functional ribonucleoprotein complexes.

Enrichment of fishburgers with proteins from surimi washing water

The proteins recovered by ultrafiltration (UF) represent a co-product of fish industrialization and can be used as a protein ingredient in the fortification of food formulations. The objective of this study was to evaluate the quality of surimi fishburger elaborated with the proteins recovered by UF from the wastewater generated in the production of surimi. The water generated in the washing operations of trims of farmed tilapia (Oreochromis niloticus) were filtered in a 30 kDa polyethersulfone membrane. The recovered proteins were dehydrated in spray dryer and added at 5 and 10% into fishburgers made with tilapia surimi. The fishburgers were evaluated for proximal composition, cooking yield, sensory parameters and acceptability. The incorporation of proteins into the fishburgers improved the sensory aspects of the final product and provided greater acceptability while maintaining the same manufacturing yield. The addition of 10% of the recovered proteins increased the nutritional value of surimi fishburgers.

Tangential streaming potential, transmembrane flux, and chemical cleaning of ultrafiltration membranes

Transmembrane flux measurements are the only practical tools used to evaluate the degree of organic fouling and the efficiency of chemical cleaning of ultrafiltration membranes in situ. Tangential pH-streaming potential profiles may become a comprehensive in situ method to analyse cleaning efficiency versus potential membrane damage. A parallel implementation of the two methods was used to assist in tuning an efficient cleaning protocol for 300 kDa polyethersulfone membranes. The membranes were fouled with a mixture of organics and cleaned with nitric acid, acetic acid, caustic soda or liquid bleach, each at concentrations of 1, 5, or 10 mg/L. A modified Kolmogorov-Smirnov test for divergence in datasets clearly indicated cleaning with 5 mg/L NaOH or NaOCl. These findings were confirmed by atomic force microscopy surface contouring and infrared spectra recording.Tangential pH-streaming potential profiling is easy in terms of operation and maintenance, inexpensive, and may be conducted in situ. Implementation of two independent tests is instrumental in the validation of the cleaning agent efficiency, optimisation of the cleaning dose and pH, and assessment of membrane fouling potential by complex organic mixtures. A combination of transmembrane flux and tangential streaming potential tests may reduce the cost of chemical cleaning and suspend membrane ageing.

Watermelon juice concentration using ultrafiltration: Analysis of sugar and ascorbic acid.

Raw watermelon juice was concentrated in a laboratory-scale flat-plate ultrafiltration system incorporating polyethersulfone membranes with a molecular weight cutoff of 5 kDa. The experiments have been carried out over a wide range of transmembrane pressures (100-300 kPa). The effect of ultrafiltration with molecular weight cutoff of 5 kDa polyethersulfone membrane on concentrate properties is reported. The total soluble solid content of the permeate was found to be very good, while the ascorbic acid content was on the lower side as compared to feed. The analyses of flux decay according to fouling models reported in the literature revealed that the formation of a cake layer covering the entire surface of the membrane is the main cause of the membrane fouling.

Single stage ultrafiltration for enhanced reverse selectivity in a binary protein system

ABSTRACTIn single stage operation, high quality separation of similar size proteins was performed via batch ultrafiltration. Two permeable proteins, hemoglobin and ovalbumin, were separated using a 100 kDa polyethersulfone membrane for a volume concentration factor of 3.5. At low ionic strength, hemoglobin and ovalbumin showed their enhanced reverse selectivity of 11 and selectivity of 14 at pH 9 and 3.5, respectively. Protein adsorption on the membrane during ultrafiltration was carefully controlled by fine adjustment of pH and ionic strength of feed. The high separation factor was achieved as a result of pore constriction by protein adsorption and the electrostatic interaction between proteins and the membrane.

Determination of fouling mechanisms in polymeric ultrafiltration membranes using residual brines from table olive storage wastewaters as feed

In this work, the fouling mechanisms that dominate the ultrafiltration of residual brines from table olive packing plant wastewaters were investigated. For that purpose, Hermia's models adapted to crossflow filtration, resistance-in-series model and a model combining intermediate blocking and cake formation mechanisms were fitted to the experimental data. Tests were performed with a 5 kDa polyethersulfone membrane at transmembrane pressures between 1 and 3 bar and crossflow velocities between 2.2 and 3.7 m s−1. Results demonstrated that the resistance-in-series model was the most accurate to predict permeate flux evolution with time. The predominant fouling mechanism was cake formation followed by intermediate blocking/adsorption. The fouling resistances that were determined by means of the resistance in series model were tested using a well-established mathematical model proposed by Mondal and De that also combines both fouling phenomena (intermediate pore blocking and cake formation). Results demonstrated that the predicted resistances are consistent with those determined by Mondal and De's model.

Effect of Ultrafiltration on Anthocyanin and Flavonol Content of Black Currant Juice (Ribes nigrum L.)

This paper evaluates the efficiency of ultrafiltration and the effects of processing on the total anthocyanin and flavonol contents of black currant juice at chosen operational conditions. Ultrafiltration of black currant juices was carried out using Biomax 100 kDa polyethersulfone membrane. Ultrafiltration was used to process the juice prior concentration by reverse osmosis; with the aim to enhance the efficiency of the concentration process in terms of permeate flux. To avoid the fouling of the membrane, the juices were depectinized with Panzym Super E liquid enzyme preparation. The ultrafiltration was carried out at a transmembrane pressure of 2 bars and the operating temperature of 25 °C. The effect of processing on the valuable anthocyanin and flavonol content of the juices was evaluated based on the results of high-performance liquid chromatography analyses. The article includes detailed analyses of anthocyanin and flavonol compounds of the enzyme treated and ultrafiltered juice as compared with the original juice. The results indicate that, due to the enzymatic treatment, the valuable compound content of the juice increases. However, the ultrafiltration process resulted in a significant loss of a valuable content; 54% of total flavonol and 50% of total anthocyanins maintained in ultrafiltered juice when compared to the feed samples.

Effects of the operational parameters on carbon recovery and water flux in ultrafiltration using fractional factorial design

The distribution of molecular weight of natural organic matter on the effect of operational efficiency for water treatment units is very important, like coagulation, the biological activated carbon, and chlorination. This work discusses the following three topics: (1) The properties of humic acid were compared using fluorescent spectrometry and optical spectrometry; (2) the variations of carbon recovery and the water flux in the membrane filter after repeated rinsing with a 0.1 M sodium hydroxide and 10 ppm NaOCl mixed cleaner and reuse; and (3) the effect of operational parameters, such as the concentration of humic acid, the operating pressure, the mixer speed, and the fractional reduction in retentate volume, on the membrane filter during the fractionating of organic matter in a stirred cell using Statistica 7 software with fractional factorial design. Humic acid yields both fluorescent peaks of both 240/440 nm and 450/510 nm. Fluorescent organic matter with an emission wavelength of 510 nm can be removed using a 5 kDa polyethersulfone membrane filter with rinsing for 90 min. Rinsing with a mixed cleaner reduced both carbon recovery and water flux, but especially the latter. NaOCl solution included in the mixer cleaner should be considered not only because of its ability to destroy organic matter but also because it might transform the properties of the cleaning membrane surface. With respect to the absolute magnitude of the effect of the four factors on the water flux ratio, the humic acid concentration affected the carbon recovery more than the other three factors. The humic acid concentration is negatively correlated with carbon recovery. The operating pressure more strongly affects the water flux than do any of the other parameters. Furthermore, the operational pressure was positively correlated with the water flux.

Production and Purification of Xylanase From Indonesian Isolate Bacillus sp. AQ-1 Grown on Bunch Palm Oil

Xylanase (endoxylanase, EC 3.2.1.8) is a commercial enzyme that has been applied in the industrial production of fuel, food, textiles and paper. Xylanase was isolated from the culture supernatant of Bacillus sp. AQ-1 grown on Nakamura medium containing 0.5% powder bunch palm oil. The optimum pH and temperature of xylanase activity were pH 7.0 and 60 °C, respectively. The enzyme was purified by anion exchange chromatography using DEAE-Sepharose-Fast-Flow column and gel filtration chromatography using Sephacryl S-300 column. The results showed that purification of xylanase produced two forms of xylanase, which were identified as xylanase A and xylanase B. Xylanase A can be separated from xylanase B by ultrafiltration using a 30 kDa polyethersulfone membrane. The molecular weight of xylanase A and B were 15.7 and 57.7 kDa, respectively.

Effects of operating parameters and nature of fouling behavior in ultrafiltration of sesame protein hydrolysate

Sesame seeds contain important proteins like globulin, albumin, prolamine and glutelin. Sesame protein hydrolysate is also thought to be an important source of nutritional supplement. The work in this study was carried out to assess the feasibility of concentrating sesame protein hydrolysate by ultrafiltration (UF) and to obtain the effects of different operating parameters like transmembrane pressure (TMP), feed concentration and solution pH on UF flux and rejection. No studies regarding the application of UF in treating sesame protein hydrolysate have been reported in the literature elsewhere. A polyether sulfone (PES) membrane of 5 kDa molecular weight cut-off was used for this study. Results of investigation show the membrane fouling to be quite dominant, though in most of the cases, water flux could be recovered by following the suggested cleaning methodology. Capillary electrophoresis was carried out for feed characterization with an objective to obtain molecular weight distribution. Solute rejection with a 5 kDa PES membrane was found to lie within the range of 50–70% depending upon the operating condition—an observation which is commensurate with the molecular weight distribution results obtained through capillary electrophoresis. Minimum flux and maximum permeate concentration (i.e. minimum rejection) were obtained at the isoelectric point of the sesame protein hydrolysate. Adequate explanations for all the observations reported in this study were cited in appropriate places. The investigation clearly proved that UF could be used as an effective tool for concentration of sesame protein hydrolysate after proper choice of operating conditions.

Recovery of α-Phenylglycine by Micellar Extractive Ultrafiltration

The recovery of α -phenylglycine from diluted aqueous solutions by micellar extractive ultrafiltration (MEUF) was investigated using several surfactants as extraction agents: cetyl trimethyl ammonium bromide (CTAB, cationic), sodium dodecyl benzene sulfonate (SDBS, anionic), polyoxyethylene-sorbitan mono-oleate (Tween 80, non-ionic) and lauryl sulfobetaine (SB3-12, amphoteric). Preliminary centrifugal ultrafiltration experiments were carried out at different pH conditions, and at various amino acid and surfactant concentrations, using Millipore Ultrafree-4 units of 5, 10 and 30 kDa polyethersulfone membranes. Experimental results show that similar amino acid extraction yields were obtained with the ionic surfactants, and the extraction was negligible when non-ionic and amphoteric surfactants were used. Best results were obtained using the 5 kDa membrane for an aqueous system with 1000 mg L –1 of α -phenylglycine at pH = 11.2 and at CTAB concentrations higher than 50 mM. Crossflow ultrafiltration experiments were carried out using a tubular ceramic zirconia membrane of 20 nm pore size, under different process conditions and operation modes. More than 90% of CTAB rejection and 85% of α -phenylglycine extraction were achieved for the MEUF of a CTAB (80 mM)–water– α -phenylglycine (1000 mg L –1 ) system, with permeate fluxes higher than 70 kg m –2 h –1 after 8 h of operation time.

Concentration of total milk proteins by high shear ultrafiltration in a vibrating membrane module

This paper investigates the concentration of total milk proteins from a reconstituted low heat skim milk with a composition close to that of fresh milk using a vibratory shear-enhanced process (VSEP) pilot. This pilot was equipped with a 500 cm 210 kDa polyethersulfone membrane ensuring satisfactory whey protein rejection. Due to concentration polarization reduction by very high shear rates, the permeate flux keeps increasing with transmembrane pressure until at least 1500 kPa and exceeds 80 L h −1 m −2 at initial concentration, resonant frequency and 45 °C. In concentration tests, the theoretical maximum volume reduction ratio (VRR) corresponding to zero flux was found to be 17.6 for reconstituted milk versus 9 for UHT (sterilized at ultra high temperature) skim milk in same conditions. This difference can be explained by the higher viscosity of UHT milk at VRRs above 5 due to a faster increase in dry matter with VRR. However, when permeate fluxes from both milks are plotted versus the percentage of dry matter they follow the same pattern with a theoretical maximum percentage of 38%. Energetic calculations based on these results show that large VSEP units, which are available up to 151 m 2 of membrane area will consume significantly less energy per m 3 of permeate than cross-flow filtration.

Separation of human serum albumin and human immunoglobulins using carrier phase ultrafiltration.

The fractionation of the plasma proteins human serum albumin (HSA) and human immunoglobulins (HIgG) using the combination of two newly developed techniques, pulsed sample injection technique and carrier phase ultrafiltration (CPUF), is discussed in this paper. The effects of pH and ionic strength on the transmission of a single protein (i.e., either HSA or HIgG) through 100 and 300 kDa MWCO polyethersulfone (PES) membranes were quantified using the pulsed sample injection technique. The experimental results thus obtained suggested that it would be possible to fractionate these proteins by optimizing the solution pH and ionic strength. With 100 and 300 kDa PES membranes, effective separation of HSA and HIgG was achieved by CPUF using suitable conditions, i.e., pH 4.7 and low salt concentration. The fractionation of HSA and HIgG by "reverse selectivity" using 300 kDa membranes was also examined.