Use Of Membrane Filtration Research Articles

Assessment and Upgrading of Preparation Protocols for Emulsified Crude Oils Mimicking Real Produced Water Characteristics

AbstractProduced water (PW) presents a significant challenge as a complex wastewater stream, necessitating thorough treatment prior to disposal or further reuse. This study is dedicated to the assessment, reproduction and upgrading of literature‐based preparation protocols for synthetic PW at the tertiary treatment stage; more specifically those methods utilizing high‐pressure homogenizers and ultrasonication. The objective was to produce synthetic model water that can be employed as a standardized controllable medium for optimization experiments of PW treatment techniques. This synthetic medium should facilitate the investigation of specific challenges associated with PW tertiary treatment, independent of the different and often unpredictable composition of real PW. The refined methods were modified for the application in lab‐scale research investigating the use of membrane filtration as tertiary treatment step.

Bio-inspired PDA@WS2 polyacrylonitrile ultrafiltration membrane for the effective separation of saline oily wastewater and the removal of soluble dye

The use of membrane filtration for saline oily wastewater separation remains challenging for industry application despite the progress in membrane technology. The use of two-dimensional (2D) nanoparticles is well known for improving membrane properties, yet they are still vulnerable to fouling and operational inconsistencies. In providing solutions, bio-inspired PDA@WS2 PAN UF membrane was fabricated with tailored molecular weight cutoff (MWCO) and excellent selectivity for effective removal of oil and dye in a saline environment. At high salinity, the modified membrane with the lowest MWCO of 5308.53 Da and Stokes diameter of 2.17 nm showed sufficient separation of oil and dye of about 99.53% and 98.23% respectively. Concurrently sustaining high water permeability of 58.57 L m−2h−1 with free transport of monovalent and divalent salts. Moreover, due to the synergistic effect of the adhesive PDA with WS2 nanosheet and PAN, the modified membrane displayed outstanding oil repellency and antifouling properties of about 98.6%. Furthermore, excellent thermal stability between the temperature of 100–900 °C, and pressure stability ranging from 1 bar to 6 bar of the modified membranes was reported. Overall, the operational stability of the modified membrane was sustained with high removal of oil and dye, and permeation of salt over a 90 h long-term operation. Consequently, this study demonstrates the potential application of bio-inspired PDA@WS2 PAN membrane for the treatment of saline oily wastewater.

Kenics Static Mixer Combined with Gas Sparging for the Improvement of Cross-Flow Microfiltration: Modeling and Optimization.

The use of membrane filtration as a downstream process for microbial biomass harvesting is hampered due to the low permeate flux values achieved during the microfiltration of fermentation broths. Several hydrodynamic methods for increasing permeate flux by creating turbulent flow patterns inside the membrane module are used to overcome this problem. The main goal of this study was to investigate the combined use of a Kenics static mixer and gas sparging during cross-flow microfiltration of Bacillus velezensis IP22 cultivation broth. Optimization of the microfiltration process was performed by using the response surface methodology. It was found that the combined use of a static mixer and gas sparging leads to a considerable increase in the permeate flux, up to the optimum steady-state permeate flux value of 183.42 L·m−2·h−1 and specific energy consumption of 0.844 kW·h·m−3. The optimum steady-state permeate flux is almost four times higher, whilst, at the same time, the specific energy consumption is almost three times lower compared to the optimum results achieved using gas sparging alone. The combination of Kenics static mixer and gas sparging during cross-flow microfiltration is a promising technique for the enhancement of steady-state permeate flux with simultaneously decreasing specific energy consumption.

Qualification of Membrane Filtration for Planetary Protection Flight Implementation.

Planetary protection is the practice of preventing forward and backward contamination of solar system bodies. Spacecraft and associated surfaces are sampled to ensure compliance with bioburden requirements. Current planetary protection sampling and processing methodologies consist of extracting microbial cells from wipe or swab samples through a procedure (NASA Standard Assay) that includes sonication, heat shock, and pour-plate steps. The pour-plate steps are laborious and prolonged. Moreover, results can be imprecise because only a fraction of the sample fluid is plated for CFU enumeration (80% for swabs and 25% for wipes). Thus, analysis requires that a pour fraction extrapolation factor be applied to CFU counts to account for bioburden in the remaining sample volume that is not plated. This extrapolation results in large variances for data, decreasing the accuracy of spore bioburden estimation of spacecraft hardware. In this study, we investigated the use of membrane filtration as an alternative method to pour-plate processing. Membrane filtration is an appealing methodology for planetary protection because it can process greater sample volumes and reduces the data variance for bioburden enumeration. A pour fraction extrapolation factor is still applied for both swabs and wipes (92%), however, it is a greater pour fraction than the pour-plate method. Here we present data collected by the Jet Propulsion Laboratory and the Applied Physics Laboratory to experimentally determine the equivalency of membrane filtration to pour-plate methodology for implementation during the NASA Standard Assay. Additionally, we outline the planned procedures for two membrane filtration systems: Pall® Laboratory Manifold system and Milliflex® Plus Vacuum Pump System. Both systems demonstrated equivalence of the membrane filtration method to the pour-plate method.

The Use of Membrane Filtration to Increase Native Whey Proteins in Infant Formula

The introduction of membrane filtration during infant milk formula (IMF) processing represents an innovative approach to increasing native protein content compared to standard IMF. The objective of this study was to compare IMF powder produced using a standard process and IMF produced from raw bovine skim milk with added whey protein isolate using a split-stream process incorporating a ceramic 1.4 μm filter followed by a polyvinylidene difluoride polymeric 0.2 μm filter. Retentates from 0.2 μm microfiltration (MF) were blended with fat, lactose, and minerals and subsequently high-temperature treated (125 °C × 5 s). The heat-treated retentate was merged with the permeate from the 0.2 μm MF, homogenised, and spray-dried (referred to as membrane-filtered IMF or MEM-IMF). A control IMF was also produced using standard treatment (referred to as high-temperature IMF or HT-IMF) without membrane filtration. Both IMF products were characterised by high-performance liquid chromatography, particle size, and enzyme activity assays. MEM-IMF powder had significantly higher amounts of native (1.1 g per 100 g powder) and monomeric (1.48 g per 100 g powder) whey proteins when compared to 0.18 and 0.46 g per 100 g powder in HT-IMF, respectively. MEM-IMF also exhibited a lower degree of protein aggregation compared to HT-IMF. Comparison of microbial and Maillard by-products markers demonstrated that a safe IMF product could be produced at scale, although levels of the Maillard by-product marker, carboxymethyl-lysine, were not significantly reduced in MEM-IMF. This study demonstrates how membrane filtration can be used to retain native proteins during IMF manufacture.

Reduction in flavor-intense components in fish protein hydrolysates by membrane filtration.

Enzymatic protein hydrolysates based on side stream materials from the fish-filleting industry are increasingly explored as food ingredients. However, intense sensory properties, and high salt contents, are often a limiting factor. Most of the sensory attributes, such as fish flavor and salty taste, can be ascribed to low-molecular-weight, water-soluble components, whereas bitterness is associated with small hydrophobic peptides. In this study, protein hydrolysates based on head and backbone residuals from Atlantic salmon (Salmo salar) and Atlantic cod (Gadus morhua) were produced using two different enzymes. The effects of micro- and nanofiltration on the chemical composition, protein recovery, and sensory properties of the final products were investigated. The choice of raw material and enzyme had negligible effects, whereas nanofiltration caused a considerable reduction in metabolites, ash, and the intensity of several sensory attributes. The intensity of bitterness increased after nanofiltration, indicating that small peptides associated with bitter taste were retained by the membrane. Total protein yield after microfiltration was 24%-29%, whereas 19%-24% were recovered in the nanofiltration retentate. PRACTICAL APPLICATION: Enzymatic protein hydrolysates can be included in food products to increase the protein content, and as a nutritional supplement and/or functional ingredient; however, unpalatable and intense flavors limit applications. This study investigated the use of membrane filtration to improve flavor quality and reduce salt content in fish protein hydrolysates. Although some protein loss is unavoidable in micro- and nanofiltration, this study demonstrates the production of fish protein hydrolysates with>90% protein and peptide content, which is suitable for inclusion in foods.

The use of membrane filtration for removal of aluminum from drinking water sources

The use of membrane filtration for removal of aluminum from drinking water sources

Nutrient recovery and fractionation of anaerobic digester effluents employing pilot scale membrane technology

Anaerobic Digester (AD) waste, known as digestate (spent anaerobically digested effluents) of agricultural origin, was collected for a feasibility study on the use of membrane filtration to fractionate phosphate and ammonia from digestate into nutrient streams. The digestate was pre-treated to remove bulk solids and then filtered using diafiltration (DF) with ultrafiltration (UF) (5.65 psi TMP) and then nanofiltration (NF) (operating pressure 253.82 psi). Having set the pre-treated effluents at pH 4.0, retention of phosphate reached 6.78 mmols L−1 during UF with lower values being achieved with repeated DF steps. In contrast, nitrogen retention was lower at 8.21 mmols L-1 and was continuously dropping at each DF step. During NF phosphorus was shown to be strongly retained by the membrane at 31.8 mmols L−1, while retention of ammonium was low at 13.4 mmols L-1 demonstrating the potential for this combination of membrane types for fractionating high value components from AD waste.

Effect of flocculation pre-treatment on membrane nutrient recovery of digested chicken slurry: Mitigating suspended solids and retaining nutrients

Use of membrane filtration is attracting increasing attention for nutrient recovery from anaerobically digested slurry. However, the challenge is to reduce membrane fouling by effective solids mitigation, while maintaining valuable nutrients. In this study, the effects of several flocculation pre-treatments using polyaluminium chloride, iron chloride, and flocculant aid at various dosages were investigated. The results showed significant improvement in membrane flux from 0.8 to 27.6 mL/m2/s due to solid migration (up to 75% removal). Significant loss of PO43−-P (99%) and humic acids (40–80%) was observed. However, the content of NH4+-N and indoleacetic acids was largely maintained in the treated slurry. Moreover, toxic metals were significantly removed through flocculation, making the final product risk-free of heavy metals for agricultural application.

Recovery of Campylobacter spp. from Food and Environmental Sources.

The recovery of Campylobacter species from food and environmental sources is challenging due to the slow growth of these bacteria and the need to suppress competing organisms during the isolation procedures. The addition of multiple selective antimicrobials to growth media can negatively impact recovery of some Campylobacter spp. Here, we describe our current method for the isolation of thermotolerant Campylobacter species, mainly C. jejuni and C. coli, from food and environmental samples. We emphasize the use of membrane filtration during plating for the specific isolation of Campylobacter spp. and a reduced use of antimicrobial supplements throughout the whole isolation process.

English

Some Salmonella spp. are important pathogenic bacteria that can be transmitted to people via food and water and that can cause disease characterized by mild to severe enteric and systemic illness. In developing countries, infections caused by pathogenic antibiotic resistant Salmonella spp. are a major health challenge, particularly in children. Through the use of membrane filtration and Environmental Protection Agency (EPA) 1200 methods, the presence of fecal coliforms and antibiotic resistant Salmonella spp. in surface water sources was investigated, some of which had shared access for animals and people. Out of 100 water samples, 76 were positive for fecal coliforms and 63% of the positive samples contained >100 CFU / 100 ml of water. We observed a significant positive correlation between the number of fecal coliforms and the presence of Salmonella spp. (r=0.46, n=100, P=0.01). Importantly, >26% of the samples were positive for Salmonella spp. and 88% of these samples harbored isolates resistant to ≥1 antibiotic. Moreover, we found that 26% of antibiotic resistant Salmonella spp. isolates were able to transfer their resistance traits to a recipient strain of Escherichia coli at the rate of 1-7 x 10-3 per donor cells. Microbiological contamination of water was clearly evident in open water sources from northern Tanzania, and the presence of Salmonella spp. poses an immediate risk to anyone who consumes these waters if untreated. Key words: Fecal bacteria, Salmonella, invA gene, polymerase chain reaction (PCR), water.

ABO Antibody and Complement Depletion By Immunoadsorption Combined With Membrane Filtration - A Randomized Controlled Crossover Trial.

Potent antibody depletion techniques have paved the way to successful ABO-incompatible transplantation. Considering its efficiency regarding IgG removal, the use of non-antigen-specific semiselective immunoadsorption (IA) has been advocated. One attractive strategy to overcome the caveat of incomplete IgM depletion and to interfere with complement activation could be the adjunctive use of membrane filtration (MF) to enhance the removal of macromolecules. To investigate the depletion efficiency of semiselective IA plus MF, we conducted a randomized crossover trial including 14 patients treated for autoimmune disease. Two treatment sequences, a single session of IA plus MF followed by IA alone after ≥7 days (and vice versa), were analyzed. IA plus MF markedly enhanced the median percent reduction of ABO-specific IgM as determined by flow cytometry (59% versus 23%, P<0.001) and hemagglutination (2 versus 1 titer steps, P<0.001). Combined treatment also substantially lowered C1q concentrations (86% versus 58% reduction, P<0.001) and the functionality of classical complement as reflected by impaired in vitro C3 activation capability. IgG was strongly reduced without any additional effect of MF. In conclusion, we demonstrate enhanced antibody elimination by adding MF to IA. This and the observed impact on classical complement could markedly enhance the efficiency of apheresis in ABO- and/or HLA-incompatible transplantation. DISCLOSURES:Boehmig, G.: Grant/Research Support, Unrestricted grant.

A size amplified immune magnetic microbeads strategy in the rapid detection of circulating tumor cells.

Using anti-EpCAM antibody modified magnetic microbeads allowed us to simultaneously apply size-amplification and magnetic labelling of CTCs to the capture and purification of CTCs by membrane filtration and immune-magnetic separation. High purity capture (>98%), rapid (<2 hours) and simple detection of CTCs were realized.

ABO antibody and complement depletion by immunoadsorption combined with membrane filtration--a randomized, controlled, cross-over trial

Potent antibody depletion techniques have paved the way to successful ABO-incompatible transplantation. Considering its efficiency regarding IgG removal, the use of non-antigen-specific semi-selective immunoadsorption (IA) has been advocated. One attractive strategy to overcome the caveat of incomplete IgM depletion and to interfere with complement activation could be the adjunctive use of membrane filtration (MF) to enhance the removal of macromolecules. To investigate the depletion efficiency of semi-selective IA plus MF, we conducted a randomized, controlled, cross-over trial including patients on regular IA treatment for indications outside recipient desensitization. According to the results of sample size calculation, 14 subjects were enrolled. Two treatment sequences, a single session of IA plus MF followed by IA alone after ≥7 days (and vice versa), were analysed. IA plus MF markedly enhanced the median per cent reduction of ABO-specific IgM determined by flow cytometry (primary end point; 59 versus 23%, P < 0.001) and haemagglutination (2 versus 1 titre steps, P < 0.001), respectively. Combined treatment also substantially lowered C1q concentrations (86 versus 58% reduction, P < 0.001) and the functionality of classical complement as reflected by impaired in vitro C3 activation capability. IgG was strongly reduced without any additional effect of MF. We demonstrate that the innovative strategy of combining MF with semi-selective IA may substantially increase IgM elimination and affect classical complement activation. Our findings suggest that this new treatment concept could be an efficient strategy for recipient desensitization in ABO- and HLA-incompatible transplantation.

Challenge tests with virus surrogates: an accurate membrane integrity evaluation system?

The use of membrane filtration in drinking water treatment has significantly increased in the last decades due to its advantages, including its capacity to produce water of high quality with a high level of pathogens rejection. However, if membrane integrity is compromised, this feature cannot be guaranteed, increasing the associated microbial risk of the treated water. This study has focused on the development and application of a protocol based on virus surrogates challenge tests applicable to the three existing ultrafiltration (UF) configurations. The operational conditions have been defined, and the tests have been conducted successfully. The selected micro-organisms, PDR-1, MS-2, GA and Bacillus spores, present different characteristics providing complementary information of membrane integrity and its status. In particular, PDR-1 and Bacillus spores, due to their larger size, are mainly removed by size exclusion and low removal rates may indicate membrane impairment. MS-2 and GA, 25nm in size approximately, may not be rejected by size exclusion but by adsorption and electrostatic interactions, so that their removal values may not necessarily be indicative of membrane integrity failures. Since they may be influenced by further factors, such as membrane characteristics, feed water quality, non-chemically removable fouling, etc., the results obtained can be used to better understand membranes performance.

Isolation of Alicyclobacillus and the influence of different growth parameters

Alicyclobacillus species are thermo-acidophilic, endospore-forming bacteria that are able to survive pasteurisation and have been implicated in a number of spoilage incidents involving acidic foods and beverages. The aim of this study was to compare three isolation methods used for the detection of Alicyclobacillus acidoterrestris and to investigate the influence of incubation temperature on the growth of A. acidoterrestris and A. acidocaldarius. Peach juice samples inoculated with A. acidoterrestris K47 were analysed using either the International Federation of Fruit Juice Producers (IFU) Method No. 12 (Method A), which involved spread plating onto Bacillus acidoterrestris (BAT) agar at pH 4.0; Method B, which involved pour plating using potato dextrose agar (PDA) at pH 3.7; or Method C, which made use of membrane filtration followed by incubation on K agar at pH 3.7. The performance of the three methods differed significantly, with the IFU Method No. 12 recovering the highest percentage of cells at 75.97%, followed by Method B at 66.79% and Method C at 3.43%. These findings strengthen the proposal of the IFU for the use of the IFU Method No. 12 as a standard international method for the detection of Alicyclobacillus. To investigate the effect on growth of different incubation temperatures A. acidoterrestris (three strains) and A. acidocaldarius (two strains) were incubated at either 45 °C or 25 °C. Growth at 25°C was slower and maximum cell concentrations were lower (1 x 10⁵-10⁶ cfu/mL compared to 1 x 10⁷-10⁸ cfu/mL) than at 45 °C for A. acidoterrestris. A. acidocaldarius was unable to grow at 25°C and cell concentrations decreased by 1-2 logs. Since a growth temperature of 25 °C could not inhibit growth of A. acidoterrestris, cooling to room temperature (20°-25 °C) is not an effective control measure for A. acidoterrestris inhibition.

Assessment of the presence and dynamics of fungi in drinking water sources using cultural and molecular methods

A comparison of different isolation techniques and culture media for detection of filamentous fungi and yeasts in the aquatic environment revealed that the use of membrane filtration with the media dichloran rose bengal chloramphenicol (DRBC) optimized fungi detection in terms of abundance and variety in three untreated water sources with very different characteristics (surface water, spring water, and groundwater). The diversity of the fungi population captured by direct DNA extraction of fungi collected by membrane filtration was compared with the isolates obtained after selective growth using different culture media through amplification of the internal transcribed spacer gene and denaturing gradient gel electrophoresis (DGGE). The Czapek-Dox agar, Sabouraud dextrose agar, and DRBC media showed closer similarities to those obtained by the uncultured biomass for the different water sources. Based on these data and the best enumeration results, DRBC is recommended for the assessment of fungi in water sources using culture-based methods. DGGE was also used to monitor temporal variations in the fungal population structure and showed that each water matrix possessed a distinct population profile as well as that changes in the fungal community can be expected in the different matrices throughout the year.

Observations on the use of membrane filtration and liquid impingement to collect airborne microorganisms in various atmospheric environments

The influence of sample-collection-time on the recovery of culturable airborne microorganisms using a low-flow-rate membrane-filtration unit and a high-flow-rate liquid impinger were investigated. Differences in recoveries were investigated in four different atmospheric environments, one mid-oceanic at an altitude of ~10.0 m, one on a mountain top at an altitude of ~3,000.0 m, one at ~1.0 m altitude in Tallahassee, Florida, and one at ~1.0 m above ground in a subterranean-cave. Regarding use of membrane filtration, a common trend was observed: the shorter the collection period, the higher the recovery of culturable bacteria and fungi. These data also demonstrated that lower culturable counts were common in the more remote mid-oceanic and mountain-top atmospheric environments with bacteria, fungi, and total numbers averaging (by sample time or method categories) <3.0 colony-forming units (CFU) m−3. At the Florida and subterranean sites, the lowest average count noted was 3.5 bacteria CFU m−3, and the highest averaged 140.4 total CFU m−3. When atmospheric temperature allowed use, the high-volume liquid impinger utilized in this study resulted in much higher recoveries, as much as 10× greater in a number of the categories (bacterial, fungal, and total CFU). Together, these data illustrated that (1) the high-volume liquid impinger is clearly superior to membrane filtration for aeromicrobiology studies if start-up costs are not an issue and temperature permits use; (2) although membrane filtration is more cost friendly and has a ‘typically’ wider operational range, its limits include loss of cell viability with increased sample time and issues with effectively extracting nucleic acids for community-based analyses; (3) the ability to recover culturable microorganisms is limited in ‘extreme’ atmospheric environments and thus the use of a ‘limited’ methodology in these environments must be taken into account; and (4) the atmosphere culls, i.e., everything is not everywhere.

Sterilization of glycerin

The sterilization of glycerin is described. Glycerin is used in a wide variety of pharmaceutical formulations, including oral, otic, ophthalmic, topical, and parenteral preparations. Of the myriad uses for glycerin, some require a sterile solution. Due to the nature of dry heat sterilization with resulting equipment and validation needs, sterile filtration is the preferred sterilization method for glycerin at the Mayo Clinic Pharmacy Services Production Laboratory in Rochester, Minnesota. A practical procedure was attained with the use of a chemically compatible 0.22-microm capsule filter, peristaltic pump, and sterile tubing. The sterile tubing is attached firmly, with a twisting motion, to the hose barb ends of the filter. The peristaltic pump is set at minimum speed, and a sterile syringe is used to capture the sterile glycerin filtrate. After filtration, filter integrity testing using the bubble point test is performed on the filter used to sterilize the solution. Packaging was then completed by placing glycerin aliquots into unit-of-use sterile syringes, placing a sterile tip cap on each syringe, and labeling the syringe. End testing is needed for preparations, such as sterile glycerin, that are made from nonsterile components, regardless of sterilization technique. This quality-control testing includes but is not limited to visual checks, pH checks, and tests for bacterial endotoxins, particulate matter, and sterility. Beyond-use dating is then assigned based on chemical, physical, microbiological, and packaging considerations. A practical method for sterilization of glycerin by compounding pharmacists is attainable through the use of membrane filtration. Sterility assurance is achieved through appropriate validation, and quality-control checks must be completed before release of the injectable preparation.

Membrane filtration method for enumeration and isolation of Alicyclobacillus spp. from apple juice

To evaluate the applicability of filtration membranes for detecting Alicyclobacillus spp. spores in apple juice. Ten types of nitrocellulose membrane filters from five manufacturers were used to collect and enumerate five Alicyclobacillus spore isolates and results were compared to conventional K agar plating. Spore recovery differed among filters with an average recovery rate of 126.2%. Recovery levels also differed among spore isolates. Although significant difference (P < 0.05) in spore sizes existed, no correlation could be determined between spore size and membrane filter recovery rate. Recovery of spores using membrane filtration is dependent on the manufacturer and filter pore size. Correlations between spore recovery rate and spore size could not be determined. Low numbers of Alicyclobacillus spores in juice can be effectively detected using membrane filtration although recovery rate differences exist among different manufacturers. Use of membrane filtration is a simple, fast alternative to the week-long enrichment procedures currently employed in most quality assurance tests.