Two-stage Membrane Process Research Articles

A Compatible Membrane Process for Separation and Concentration of Pediocin PA-1 from Fermentation Broth

This work describes an effective combined ultrafiltration (UF)-nanofiltration (NF) membrane process for the separation and concentration of pediocin PA-1 from fermentation broth. Three polysulfone (PS) membranes with MWCOs of 5, 10, and 30 kDa were tested for ultrafiltration effectiveness. The 10 kDa membrane was selected because it displayed high permeability, good pediocin PA-1 recovery and reduced fouling. When the volume concentration factor (VCF) of UF reached 2.5, continuous diafiltration (DF) was carried out. The optimal diafiltration factor (DFF) was 1. The permeate obtained from UF was then concentrated by NF. When the VCF of NF reached 4.5, pediocin PA-1 recovery loss was only 10.5%. This two-stage membrane process improved the loading solutions by 4.5-fold, allowing up to 71.6% recovery of pediocin PA-1. After the membrane process, the NF retentate could be concentrated and subjected to preparative chromatography to obtain purified pediocin PA-1, or it could be dried to obtain a rich pediocin PA-1 preservative.

Techno-economic Performance of a Hybrid Membrane – Liquefaction Process for Post-combustion CO2 Capture

Gas separation membranes, considered among one of the promising emerging capture technologies for post-combustion capture, requires a two-stage process with significant compression work for CO2 capture from a coal fired power plant flue gas. A hybrid membrane–liquefaction process for post-combustion CO2 capture from the power plant flue gas is developed to mitigate the deficiencies of the two-stage membrane process. The energy efficiency of the process depends on the permeate CO2 composition from the membrane unit. The performance envelope of the hybrid process is evaluated and shows that the optimum CO2 concentration in the permeate is 65%– 67% depending on the targeted CCR. A techno-economic analysis for 85% CCR was performed and the cost of CO2 avoided is calculated to 48 €2008/tCO2,avoided, that is, 9% more cost-efficient than the baseline MEA absorption process.

A Novel Membrane Prepared from Sodium Alginate Cross-linked with Sodium Tartrate for CO2 Capture

The membrane-based CO2 separation process has an advantage compared to traditional CO2 separation technologies. The membrane is the key of the membrane separation process. In this paper, preparation, characterization and laboratory testing of the membrane, which was prepared from sodium alginate, hydrogen bond cross-linked with sodium tartrate and used for CO2/N2 separation, were reported. The resistance to SO2 of the membrane was also investigated. The experimental results demonstrate that the membrane possesses a high resistance to SO2. Finally, based on experimental results, the economic feasibility of the membrane used for CO2/N2 separation was evaluated, indicating the two-stage membrane process can compete with the traditional chemical absorption method.

Separation of galactose, 5-hydroxymethylfurfural and levulinic acid in acid hydrolysate of agarose by nanofiltration and electrodialysis

A two-stage membrane process for the separation of galactose, 5-hydroxymethylfurfural (5-HMF) and levulinic acid (LA) has been proposed. The first step of nanofiltration (NF) is to remove 5-HMF and LA from galactose solution obtained by the hydrolysis of agarose, the main component of red algal galactan for the reduction of its microbial toxicity. 5-HMF and LA are inhibitory to fermentation but at the same time useful compounds themselves with many applications. The second step of electrodialysis (ED) is to separate 5-HMF and LA in the permeate from NF. More than 91% of 5-HMF and up to 62% of LA could be removed from agarose hydrolysate, while galactose was almost completely retained by NF. Further removal of LA was expected to be possible with no loss of galactose by operating the NF process in a diafiltration mode. 5-HMF and LA could be effectively separated from each other by ED.

Post-combustion Carbon Capture with a Gas Separation Membrane: Parametric Study, Capture Cost, and Exergy Analysis

A systematic method that integrates process simulation, capture cost estimation, and exergy analysis is applied to evaluate a gas separation membrane process for post-combustion carbon capture in a coal power plant. The influences of membrane performance and process configuration on the energy consumption, required membrane area, and capture cost have been studied. The results indicate that the energy consumption decreases with the increase of CO2/N2 selectivity, but a larger membrane area is required, while for a high CO2 permeance, the membrane area can be significantly reduced. The carbon capture ratio influences the specific energy consumption as well, which should be a trade off. For a two-stage membrane process, the capture load distribution between the first and second stage affects the separation performance greatly, and the optimal range varies with the other parameters. Under the assumptions in this work, the profiles of capture cost related to membrane parameters show that the optimal CO2/N2 selectivity is 70–90. The exergy analysis indicates that the main energy bottleneck of a membrane technology is located in the membrane unit operation, which has relatively low exergy efficiency. On the other hand, CO2 compression has less potential for energy savings because it has already had very high exergy efficiency.

Simulation of membrane-based CO2 capture in a coal-fired power plant

A two-stage membrane process is designed for CO2 capture from coal-fired power plants. Vacuum operation on the permeate side of the membrane is the preferred option to reduce the power demand for compressing the huge feed volume. The energy recovered from the CO2-depleted emission stream and the energy consumed for post-capture CO2 liquefaction are considered in this simulation study. A numerical modeling of the membrane process and a brief description on assessing both the capital and operating costs of the process are provided. It is found that the membrane area requirement is dominated by recovery of the lower concentrations of CO2 in the tail portion of the flue gas stream. Process optimizations allowing the minimal CO2 capture cost or minimal power demand indicate that current membrane technology is promising for flue gas CO2 capture, assuming a permeance of 1000 GPU and CO2/N2 selectivity of 30. The potential of membrane technology for CO2 capture was also explored by using membranes with a CO2/N2 selectivity of 50 and 200.

Treatment of dairy wastewater by two-stage membrane operation with ultrafiltration and nanofiltration

Treatment of dairy wastewater by a two-stage membrane process with ultrafiltration (UF) and nanofiltration (NF) was investigated. The results showed that the flux of UF was higher at pH = 4.6 than that at pH = 8 because the resistance of the fouling membrane was lower at the isoelectric point of protein (pH = 4.6) in UF operation. Protein rejection exceeded 99% by UF + NF operation. Lactose rejections were 98.5 and 54% for UF + NF90 and UF + NF270 respectively. Experiments on membrane cleaning showed that the fouling layer of UF and NF was mainly protein and casein which could be removed by aqueous NaOH with pH = 10. The result of long-term experiments showed that the chemical oxygen demand (COD) of NF90 permeates was below 70 mg/L consistently and the wastewater could be concentrated to 24% by a two-stage membrane process.

Design and economics of a hybrid membrane–temperature swing adsorption process for upgrading biogas

Abstract Processing biogas from wastewater digesters allows recovery of valuable methane and reduction in green house gas emissions. A two-stage membrane process, coupled with a temperature-swing-adsorption (TSA) as pre-treatment, was designed to generate pipeline quality methane. To improve methane recovery and process energy efficiency, the non-product streams of the membrane process were recycled and the permeate of the first membrane stage was maintained at a given pressure as the driving force for second membrane stage. The membrane process design was optimized by minimizing the objective function; the overall processing cost. It was found the membrane approach excels the PSA for producing pipeline quality methane (97% purity) in terms of methane recovery, processing cost and lower emissions. A techno-economic analysis showed that the payback time for an operation processing 200 Nm3/h of biogas was 6.8 months.

Multi-objective Optimization of a Two-stage Membrane Process with Metaheuristics

Multi-objective Optimization of a Two-stage Membrane Process with Metaheuristics

Diafiltration and concentration of Reactive Brilliant Blue KN-R solution by two-stage ultrafiltration process at pilot scale: Technical and economic feasibility

In this study, a two-stage ultrafiltration (UF) membrane separation process on a pilot scale was introduced to resolve the shortcomings caused by the application of salt precipitation technique in the conventional process of Reactive Brilliant Blue KN-R production. The first stage was used for diafiltration and concentration of dye solution, and the second stage was applied to recover the dye from permeate of the first stage. Both the operating pressure and cross-flow velocity had significant and moderate effect on the permeate flux (24.9 to 129.7 L·m − 2 ·h − 1 ) and salt rejection (26.9%–55.7%), but insignificant effect on dye rejection since the rejections were always higher than 99.5%. The two-stage UF membrane process exhibited good performance as the dye and salt concentrations in concentrate of first stage were 203 and 5.4 g/L, and 67.1% of salt could be removed and the dye loss was negligible (0.1%) in the whole process. For a dye plant with a capacity of 1000 ton per year, the preliminary economic evaluation of an UF plant based on pilot scale showed that the cost of every ton of Reactive Brilliant Blue KN-R was US $154.

Potential of Two-Stage Membrane System with Recycle Stream for CO2Capture from Postcombustion Gas†

In order to restrict greenhouse gases emissions, CO2 should be captured from the postcombustion gas for further treatment, for example, geosequestration. In this work, the separation performance of the two-stage membrane system with a recycle stream was investigated using the cross-flow model. For larger CO2/N2 selectivities that can be achieved in the lab, for example, selectivity of 52, the separation target of CO2 purity >95% and CO2 recovery >90% can be fulfilled by the two-stage system. The process cost of the two-stage membrane process was investigated. There is an optimum pressure ratio with which the capital cost and the energy cost can be balanced to minimize the total cost. Using the optimum pressure ratios and efficient membranes, the total cost of the two-stage system can be reduced to a range that is competitive with the process cost of the traditional chemical absorption method. For example, with feed compression applied, the total cost of the two-stage membrane system using the membrane wit...

Anaerobic digestion of the organic fraction of municipal solid waste in a two-stage membrane process

A batch of the Organic Fraction of Municipal Solid Waste (OFMSW) was treated in a two-step process with effluent recirculation comprising a novel hydrolytic reactor (HR) followed by a Submerged Anaerobic Membrane Bioreactor (SAMBR) operating at a stable permeate flux of 5.6 L/m(2) hr (LMH). A soluble COD removal higher than 95% was obtained from the SAMBR. The soluble COD as well as the Total Suspended Solids (TSS) did not build up due to efficient hydrolysis inside the SAMBR, and no VFA accumulation occurred due to the complete retention of methanogens by the membrane as well as the formation of syntrophic associations. Because of the microfiltration membrane in the second reactor a stabilized leachate was obtained from the very first days of the treatment and the highly stable process enabled shorter treatment periods compared to traditional leach bed processes. This experiment showed that the recycle of the stabilised leachate does not lead to a build up of SCOD. Size exclusion chromatography analysis confirmed that high molecular weight compounds were completely degraded and did not appear in the SAMBR permeate, and that low molecular weight fulvic-like and medium MW material were present in the permeate of the SAMBR but their concentration remained stable with time.

Continuous treatment of the organic fraction of municipal solid waste in an anaerobic two-stage membrane process with liquid recycle

The stability and performance of a two-stage anaerobic membrane process was investigated at different organic loading rates (OLRs) and Hydraulic Retention Times (HRTs) over 200 days. The Hydrolytic Reactor (HR) was fed with the Organic Fraction of Municipal Solid Waste (OFMSW), while the leachate from the HR was fed continuously to two Submerged Anaerobic Membrane Bioreactors (SAMBR1 and 2). The Total COD (TCOD) of the leachate varied over a wide range, typically between 4000 and 26,000 mg/L while the Soluble COD (SCOD) in the permeate was in the range 400–600 mg/L, achieving a COD removal greater than 90% at a HRT of 1.6–2.3 days in SAMBR1. The operation was not sustainable below this HRT due to a membrane flux limitation at 0.5–0.8 L/m 2 h (LMH), which was linked to the increasing MLTSS. SCOD in the recycled permeate did not build up indicating a slow degradation of recalcitrants over time. SAMBR2 was run in parallel with SAMBR1 but its permeate was treated aerobically in an Aerobic Membrane Bioreactor (AMBR). The AMBR acted as a COD-polishing and ammonia removal step. About 26% of the recalcitrant SCOD from SAMBR2 could be aerobically degraded in the AMBR. In addition, 97.7 % of the ammonia–nitrogen was converted to nitrate in the AMBR at a maximum nitrogen-loading rate of 0.18 kg NH 4 +–N/m 3 day. GC–MS analysis was performed on the reactor effluents to determine their composition and what compounds were recalcitrant.

Optimization of membrane-based CO 2-removal from natural gas using simple models considering both pressure and temperature effects

Simple models for permeability and selectivity variations of the CO 2/CH 4 system in 6FDA-2,6-DAT membrane have been derived that include both temperature and pressure effects simultaneously in a single equation. The proposed models were used in MATLAB, for a membrane-based CO 2-removal process design for natural gas sweetening. The effects of the following factors on design parameters were examined: feed temperature, feed pressure and permeate pressure. The effect of permeate pressure was found to be very significant in the optimization process. In order to reduce hydrocarbon losses to below 2%, a two-stage membrane process was modeled and simulated in MATLAB, and the extent of desired hydrocarbon recovery was shown to be crucial in the optimization process. It has also been shown that there exist minima for the total required area of the two-stage membrane-based process, and as the CO 2 load increases in the feed, the position of these minima shift to higher values of methane loss.

Improving Specific Activity of Aspergillus carbonarius Polygalacturonase Using Polymeric Membranes

Microfiltration (MF) and ultrafiltration (UF) membranes were screened for improving the specific activity of polygalacturonases (PG) in the culture broth of Aspergillus carbonarius obtained after submerged fermentation. While 200 and 450 nm MF membranes eliminated some of the larger non-enzymatic proteins, 50 kDa UF membrane exhibited a marginal selectivity between the enzyme and other smaller proteins. The 450 nm MF and 50 kDa UF membranes selected were further evaluated under different process conditions for an integrated membrane process. The process efficacy of three different schemes was also studied for enzyme purification. A two-stage membrane process employing MF followed by UF improved the enzyme-specific activity (5,590 U/mg) by 4.69-fold eliminating the larger and smaller non-enzymatic proteins as well as non-protein impurities with a recovery of 76% enzymes, besides resulting in higher productivity. Thus, adoption of integrated membrane process with appropriate selection of membranes could result in high recovery of enzymes with improved specific activity.

Separation of hyaluronic acid from fermentation broth by tangential flow microfiltration and ultrafiltration

This work examined the use of a two-stage tangential flow filtration process for the separation of hyaluronic acid from fermentation broth. Microfiltration (MF) membranes (0.45, 0.20 μm in pore diameter) and ultrafiltration (UF) membranes (MWCO 300, 100 kDa), made from polyvinylidene fluoride, were used to achieve the separation in series. Operating conditions of each stage were firstly optimized to give the best separation. Then, the two-stage membrane process was undertaken with two separating schemes: the first using MF followed by UF with pure water as diafiltrate, the second similar to the first except permeate from previous UF stage as diafiltrate for MF stage. The optimal conditions were transmembrane pressure 0.1 MPa, crossflow velocity 1.25 m/s, solution pH 4.0 and enhanced ionic strength 0.25 mol/l NaCl for MF membranes, and 0.15 MPa, 1.25 m/s, pH 7.0 and 0.1–0.25 mol/l NaCl for UF membranes, respectively. The two schemes could effectively separate and purify HA with above 77% overall yield and about 1000 purification factor. The second scheme seemed to be more effective for its higher overall yield (89%) and saving water.

00/01776 Thermal analysis of alternative diesel fuels from vegetable oils

Membrane-based gas separation has been applied for carbon dioxide (CO2) removal from commercial city gas supply plants in Japan. This paper provides the relationship between methane reforming process, design of two-stage membrane process and their optimization.

CO 2 removal from synthetic natural gas for city gas use

Membrane-based gas separation has been applied for carbon dioxide (CO 2) removal from commercial city gas supply plants in Japan. This paper provides the relationship between methane reforming process, design of two-stage membrane process and their optimization.

Desalting of seawater using UF and RO — results of a pilot study

As part of the search for alternative water supplies during the current drought conditions in eastern England, Anglian Water have been investigating the use of desalination as a potential future water resource. Anglian Water and Norit have designed and constructed a mobile pilot plant and have carried out a series of trials to establish the performance of the combination of hollow fibre ultrafiltration membranes followed by reverse osmosis to produce potable water from the North Sea. A small mobile pilot plant has been manufactured and installed at a side adjacent to the beach at Felixstowe in Suffolk. A series of site trials has been carried out to determine the potential of this two-stage membrane process for producing potable water from the North Sea. The pilot trials were carried out in two phases: the first phase used seawater abstracted from a beach well; the second phase was carried out using water abstracted directly from the sea. The results obtained demonstrate the water quality that can be achieved, the cost of water production and the performance of the specially manufactured RO membranes.