Commercial Flat-sheet Membranes Research Articles

Tannic acid −3-aminopropyltriethoxysilane (TA-APTES) coated UHMWPE membrane for DCMD

Commercial flat sheet membranes have relatively low flux in membrane distillation. Here, a ultra-high molecular weight polyethylene (UHMWPE) composite membrane with high flux was prepared via thermally induced phase separation (TIPS) method for direct contact membrane distillation (DCMD). The UHMWPE membrane has low tortuosity (spherical structure) and low thickness to decrease the vapor mass transfer resistance. In addition, UHMWPE/decalin gel membrane washed in hot decalin (85℃) in order to increase the permeate flux, and the optimum membrane has the highest flux of 43.51 kg/(m2·h). In order to increase the anti-wetting properties of UHMWPE membranes, Tannic acid (TA) − 3-aminopropyltriethoxysilane (APTES) coating composed of abundant nanospheres is co-deposited on the surface of UHMWPE membrane to increase surface roughness. The subsequent fluorination process can decrease the surface energy and improve the anti-surfactant property. The optimum modified membrane has a water contact angle of 152.5°, and the permeate flux is 31.04 kg/(m2·h). Moreover, the membrane has high rejection (99.98 %) and high water recovery (82.87 %) over 60 h testing for high salinity anionic dyeing wastewater.

Role of Microfiltration Membrane Morphology on Nanoparticle Purification to Enhance Downstream Purification of Viral Vectors.

In the rapidly advancing realms of gene therapy and biotechnology, the efficient purification of viral vectors is pivotal for ensuring the safety and efficacy of gene therapies. This study focuses on optimizing membrane selection for viral vector purification by evaluating key properties, including porosity, thickness, pore structure, and hydrophilicity. Notably, we employed adeno-associated virus (AAV)-sized nanoparticles (20 nm), 200 nm particles, and bovine serum albumin (BSA) to model viral vector harvesting. Experimental data from constant pressure normal flow filtration (NFF) at 1 and 2 bar using four commercial flat sheet membranes revealed distinct fouling behaviors. Symmetric membranes predominantly showed internal and external pore blockage, while asymmetric membranes formed a cake layer on the surface. Hydrophilicity exhibited a positive correlation with recovery, demonstrating an enhanced recovery with increased hydrophilicity. Membranes with higher porosity and interpore connectivity showcased superior throughput, reduced operating time, and increased recovery. Asymmetric polyether sulfone (PES) membranes emerged as the optimal choice, achieving ∼100% recovery of AAV-sized particles, an ∼44% reduction in model cell debris (200 nm particles), an ∼35% decrease in BSA, and the fastest operating time of all membranes tested. This systematic investigation into fouling behaviors and membrane properties not only informs optimal conditions for viral vector recovery but also lays the groundwork for advancing membrane-based strategies in bioprocessing.

Integration of solvent extraction and membrane processes to produce an oleuropein extract from olive leaves

The integration of solvent extraction and membrane separation technology was used to recover and concentrate oleuropein from olive leaves. In this study, the effect of extraction solvent (type, composition) on the content of total phenolic compounds (TPC) extracted from olive leaves was investigated. Experimental results showed that ethanol:water, 75 %/25 % (v/v), gives the highest TPC. Thus, to establish the parameters to obtain hydroethanolic olive leaves extract with the highest content of total phenolic compounds, a Central Composite Design was performed. The extract obtained at 50 °C for 90 min, within 0.03 g/ml, was subjected to crossflow ultrafiltration (UF) to remove suspended solids in the feed and to reduce fouling phenomena, followed by a stirred dead-end nanofiltration (NF) using a commercial flat sheet membrane at different pressure (10, 20 and 30 bar). The nanofiltration (at 30 bar) showed a high rejection coefficient towards phenolic compounds and flavonoid contents. Fractions coming from UF and NF (at 30 bar) revealed that the highest content of oleuropein was 119.01 mg/g corresponding to NF retentate, high antioxidant capacity (DPPH method). Conductivity, sanity, turbidity, pH, TDS, and TSS of different fractions were also determined. It can be concluded that the integration of solvent extraction and membrane separation technology is efficient for the recovery and concentration of oleuropein and phenolic compounds from olive leaves. The obtained concentrate is of interest for preparing formulations to be used in the food, cosmetic and pharmaceutical industries.

Aeration pipe design for free bubbling hydrodynamic optimization of flat sheet MBRs

An open-end aerator for free bubbling has been found previously for hydrodynamic effect enhancement. This study is focused, through two modifications, on its further optimization for aeration homogeneity in a commercial flat sheet membrane bioreactor (FSMBR). One relates to the aerators themselves, the other to the central aeration air supply pipe. The aerators are tapered, or to be more precise each one is a frustum i.e. that portion of cone which remains after the upper part has been cut off by a plane parallel to its base. A validated computational fluid dynamics (CFD) model is constructed, hydrodynamic features were predicted for various implementations of the new design. An extensive study found that to achieve a very high degree of uniformity between different aerators for a full-scale FSMBR (160 sheets), the optimal design featured frustum-designed aerators of length 180 mm with the diameter decreasing from 18 to 9 mm at the open end. Each aerator had four top nozzles of diameter 4 mm, and 20 aerators were attached to a pipe of 1760 mm. Based upon this aerator design, the central aeration pipe diameter was optimized, the shear stress was enhanced and corresponding number of effective channel coverage was enhanced by 25–75%.

Electrically conducting duplex-coated gold-PES-UF membrane for capacitive organic fouling mitigation and rejection enhancement

Recent studies showed that the application of an electrical potential onto an ultrafiltration membrane surface exhibit several advantages with respect to the fouling and rejection behaviour. Sputter deposition of ultra-thin metal layers onto commercial flat sheet membranes proved to be a simple way of producing conductive metal-polymer-composite membranes. Adopting the novel approach of duplex-coating the active and support layer of a flat sheet membrane eliminates the need for an additional counter electrode and significantly simplifies module design for conductive flat sheet systems. Cross-flow filtration experiments were conducted with organic model foulants such as sodium alginate, bovine serum albumin (BSA), humic acids as well as with natural organic matter (NOM) from Hohloh lake water. The duplex-coating induced an additional electric field through the membrane itself, resulting in enhanced performance not only for cathodic but also for anodic charging of the active membrane layer. Hohloh lake water fouling experiments showed decreased permeability of 47% for the uncharged membrane to 16% and 38% for the cathodic and anodic charging, respectively. Moreover, a significant increase in NOM-rejection was observed with 27% for the uncharged membrane and 72% and 49% for the cathodic and anodic potentials, respectively. Finally, the effectiveness of externally charged duplex-coated membranes was demonstrated by comparing rejection and fouling rates with conventional membrane-electrode vs. counter electrode configuration, showing an almost similar enhancement in performance.

Membrane distillation treating a real petrochemical reverse osmosis concentrate: Influence of membrane characteristics on the process performance

The present study investigated the applicability of direct contact membrane distillation (DCMD) in the treatment of a reverse osmosis concentrate (ROC) from petrochemical wastewater. Three commercial flat sheet membranes made of polyethylene or polytetrafluoroethylene, having different contact angles, pore sizes, porosities, and thicknesses, were supplied by Aquastill with the following membrane designation: Standard, Oleophobic and Teflon. Firstly, the different DCMD membranes were characterised in experiments with deionised water. Then, tests with ROC, with a temperature setting to 60 °C in the feed and 20 °C on the distillate side, were performed in full recirculation mode (along 250 h operating time) and in concentration mode (along 72 h operating time, achieving volumetric concentration factors around 10). The DCMD performance, in terms of flux and quality of the distillate, was evaluated during all experiments under different operating conditions. After obtaining the results, all membranes satisfactorily achieved a final water recovery ratio close to 90 %, as well as high rejection factors (above 99.5 %) for all parameters analysed. They also produced high quality water with low electrical conductivity (around 2–7 μS cm–1). All conditions met the requirements for water reuse in the petrochemical sector. In this case, to treat wastewater with the tested characteristics, the oleophobic membrane from Aquastill presented better efficiency, with a minimum water vapour flux reduction and a water recovery ratio of 90 %.

Concentration of bioactive compounds from grape marc using pressurized liquid extraction followed by integrated membrane processes

The integration of pressurized liquid extraction (PLE) with membrane separation technology was used to recover and concentrate monomeric anthocyanins and total phenolics from grape marc. The extracts obtained by PLE were subjected to a preliminary study of stirred dead-end filtration using different commercial flat sheet membranes of nanofiltration (NF). In addition, to reduce membrane fouling and the content of solids in the feed, previous microfiltration (MF) and ultrafiltration (UF) processes were evaluated. The membranes that presented the best performances were selected for cross-flow filtration. The flux of permeate, the retention of bioactive compounds and antioxidant capacity, and the characterization of the membrane surfaces were used to evaluate the performance of the filtration processes. The results obtained in this study suggest that the sequential process based on the previous MF with the MV020 membrane of the grape extract obtained by PLE, followed by the NF step with the NP010 membrane, was the most effective in the concentration of bioactive compounds. The sequential process MV020-NP010 provided excellent results in terms of permeate flux, concentration factor (2.4), retention coefficients of monomeric anthocyanins (78.2%) and total phenolics (71%), and high antioxidant capacity (52%) compared to other tested NF membranes. Fifteen anthocyanins were concentrated in the extracts by UHPLC-UV–Vis. The NP010 membrane had the smallest change in membrane roughness and functional groups after NF. It is concluded that the integration of PLE with the projected sequential process (MV020-NP010) is efficient for the recovery and concentration of bioactive compounds from grape marc, being promising for obtaining functional products with high added value.

Complementary membrane-based processes for recovery and preconcentration of phosphate from industrial wastewater

The feasibility of recovering phosphate from Algerian industrial wastewater was evaluated by a combination of membrane processes: nanofiltration, diananofiltration and Donnan dialysis. First, the separation of phosphate from a synthetic target effluent with an ionic composition resembling that of the industrial one was tested by nanofiltration using three commercial flat sheet membranes NF270, NF90 (Dow Filmtec) and Desal 5-DK (GE Osmonics) investigating the effect of the effluent pH. The results obtained show that the NF270 membrane assures the highest transport and recovery of phosphate. Afterwards, a diananofiltration process was developed with the optimal process parameters identified. A complete recovery of phosphate was achieved with one additional step of diananofiltration. Finally, Donnan dialysis was also investigated for further purification and preconcentration of phosphate from the permeates previously obtained. The performance of four anion exchange membranes with distinct properties: Neosepta AXE01, Neosepta ACS, Ralex AMH-PES and PC200D was investigated and compared, using chloride as a “driving” counterion in a KCl containing receiver solution. It was found that the AXE01 membrane gives the highest transport and phosphate recovery, achieving a 6-fold increase of the phosphate concentration in the receiver solution, in just one Donnan dialysis step.

Dye synthetic solution treatment by direct contact membrane distillation using commercial membranes

ABSTRACT The reuse of treated dyeing wastewater has become a viable option to minimizing water scarcity problems and environmental impacts in the textile industry. The potentiality of commercial flat sheet membranes of polytetrafluoroethylene (PTFE) and polypropylene (PP) in direct contact membrane distillation (DCMD) for dye synthetic solution treatment has been explored in this work. DCMD is interesting for the textile industry since a recovery of heat by hot dyeing wastewater for thermal energy is possible. Moreover, DCMD enables water and dye reclamation with possible reuse in the textile process. The commercial availability of membranes may expedite the DCMD commercialization in the textile industry. Experiments were conducted in a laboratory-scale circulating unit with synthetic solutions containing reactive or disperse dye. High mean permeate flux up to 18.8 kg m−2 h−1 with complete colour rejection was obtained. The dyes tested in this study are not able to completely wet the membranes and the increase of the permeate flux when compared to distilled water is attributed to electrostatic interactions between the dyes and the membranes. Moreover, a partial wetting reduced vapour diffusion path and the permeate flux was increased. PP membrane showed higher performance due to higher porosity when compared to the PTFE membrane. In addition, an influence of dye class on permeability was observed. The results were promising when compared to other studies, which used commercial or lab-scale membranes.

Influence of nanofiltration membrane features on enrichment of jussara ethanolic extract (Euterpe edulis) in anthocyanins

Anthocyanins were concentrated from ethanolic jussara (Euterpe edulis) extract by nanofiltration. Six commercial flat-sheet membranes with nominal molecular weight cut-off ranging from 150 to 1000 g mol−1 (NF270 and NF90 from Filmtec Dow, NP010 and NP030 from Microdyn Nadir and Desal 5-DK and Desal 5-DL from GE Osmonics) were characterized in terms of their textural properties, surface morphology and further evaluated for jussara extract nanofiltration performance. Nanofiltration trials were conducted on a stainless steel stirred dead-end cell, in which permeate fluxes were recorded by keeping operational conditions constant at 25 bar and 25 °C. N2 adsorption isotherms and atomic force microscopy images revealed a nanoporous bulk for all membranes. Changes in roughness and contact angle of membranes were observed to occur after nanofiltration trials. The Desal 5-DK membrane showed the highest efficiency for jussara extract nanofiltration due to its highest flux and smallest flux decline, in addition to the highest anthocyanins retention capacity in relation to the other commercial nanofiltration membranes.

Purification of galacto-oligosaccharides (GOS) by three-stage serial nanofiltration units under critical transmembrane pressure conditions

A purification process of galacto-oligosaccharides (GOS), using three-stage serial nanofiltration (NF) units, operating under critical transmembrane pressure (TMPc) was designed. Three commercial flat-sheet membranes were tested at 53.5°C and 65°C, using GOS solutions at 20 and 40°Brix. Since one of the main drawbacks of NF for the purification of raw GOS is the removal of lactose, an enzymatic pre-hydrolysis step was also tested for producing a prehydrolyzed GOS and compared with non-hydrolyzed raw GOS. An empirical model showed that due to the increase in the solute concentration during batch NF, TMPc must be decreased with time to prevent fouling effects. Using NF serial system, the maximum GOS concentration achieved for raw GOS was 241g/L and 156.8g/L for pre-hydrolyzed GOS. Despite filtration times of the later were shorter, after three sequential batches, similar purities (∼55%) were obtained with both GOS solutions. Thus, the use of pre-hydrolyzed raw GOS as substrate for NF purification had two opposite effects: an improved flux due to lower lactose deposition on membrane, but also a lower GOS retention by the membrane, revealing a marginal gain in purification. The purities achieved were similar to those of commercial GOS, currently obtained by using conventional processes.

Application of forward osmosis for reducing volume of produced/Process water from oil and gas operations

Produced water management is one of the key challenges faced by the oil and gas industry globally. Specifically, the gas industry in Qatar is challenged to minimize the produced/process water (PPW) volumes injected into disposal wells to ensure long term sustainability of the reservoirs. This research evaluated a novel application of forward osmosis (FO) to reduce the volumes of PPW disposed of by deep well injection using brine from thermal desalination plants or seawater as draw solutions. In the case of brines, this process also provides some environmentally beneficial dilution before discharge.In order to verify the PPW volume reduction concept, bench-scale FO experiments were carried out using commercial flat sheet membranes. FO performance was evaluated using PPW with and without pretreatment and results confirm that pretreatment is key to the successful implementation of FO for the treatment of PPW. Experimental results indicate that FO is effective in achieving 50% volume reduction of pretreated PPW with stable flux of 12LMH. Lab analyses show that the TOC in the diluted draw solution was below the detection limit indicating that the TOC from the feed did not appear in the draw solution and hence would not be discharged to the environment.

A novel dual-layer bicomponent electrospun nanofibrous membrane for desalination by direct contact membrane distillation

• A nanofibrous membrane composed of two layers was fabricated for DCMD. • The membrane was composed of PVDF- co -HFP nanofibers and PAN micro/nanofibers. • The PVDF- co -HFP nanofibers showed a superhydrophobic property and high porosity. • A high flux performance was obtained for the dual-layer nanofibrous membrane. • The present dual-layer nanofibrous membrane showed good potential for DCMD. In this study, a bicomponent nanofibrous composite membrane was fabricated by electrospinning and was tested for desalination by direct contact membrane distillation (DCMD). The nanofibrous membrane was composed of a dual-layered structure of poly(vinylidene fluoride- co -hexafluoropropylene) (PH) nanofibers and polyacrylonitrile (PAN) microfibers. Morphological characterization showed slightly beaded cylindrical PH nanofibers with porosity of about 90%. The contact angles of PH and PAN nano/microfibers were 150° and 100°, respectively. The nanofibrous membranes were tested by DCMD and a high water flux of 45 and 30 L m −2 h −1 was obtained for distilled water and 35 g L −1 NaCl solutions as feed, respectively using DL2 membrane (i.e., 25/75 PH/PAN thickness ratio). The present dual-layer membrane showed better flux performance compared to a commercial flat-sheet membrane. The results suggest the potential of the dual-layer nanofibrous membrane for DCMD applications.

Two years of the operation of a domestic MBR wastewater treatment plant

Two years of the operation of a domestic MBR wastewater treatment plantThe paper evaluates the results of data obtained from two years of observing an actual domestic wastewater treatment plant (WWTP) with an immersed membrane module. The domestic MBR (membrane bioreactor) WWTP was linked to a dwelling with four residents. Two different commercial flat sheet membrane modules were investigated. The membrane modules, as well as the whole WWTP, were tested with different fluxes as well as the response of the membrane and activated sludge to different conditions, such as actual peak wastewater flows, extremes temperatures (a winter below 5 °C), and high pH values.

Enhancing the production of hydrogen via water–gas shift reaction using Pd-based membrane reactors

In this work, it is described an experimental study regarding the performance of a Pd–Ag membrane reactor recently proposed and suitable for the production of ultra-pure hydrogen. A dense metallic permeator tube was assembled by an innovative annealing and diffusion welding technique from a commercial flat sheet membrane of Pd–Ag. A “finger-like” configuration of the self-supported membrane has been designed and used as a packed-bed membrane reactor (MR) for producing ultra-pure hydrogen via water–gas shift reaction (WGS). A CuO/ZnO/Al 2O 3 catalyst, from REB Research & Consulting, was used for packing the WGS membrane reactor. The performance of the reactor was evaluated in terms of CO conversion and H 2 recovery in a wide range of conditions: temperature from 200 °C to 300 °C, feed pressure from 1.0 bar to 4.0 bar, vacuum and sweep-gas modes and with a simulated reformate feed (4.70% CO, 34.78% H 2O, 28.70% H 2, 10.16% CO 2 balanced in N 2). Also, the effect of the reactants feed composition was investigated and discussed. CO conversions remained in most conditions above the thermodynamic equilibrium based on feed conditions. In particular, it is worth mentioning that around 100% of CO conversion and almost complete H 2 recovery was achieved when operating the MR at 300 °C with a GSHV = 1200 L N kg cat −1 h −1, P feed = 4 bar, P perm = 3 bar and using 1000 mL N min −1 of sweep-gas.

Direct nanofiltration of surface water using capillary membranes: comparison with flat sheet membranes

This article explores the possibilities of a new capillary nanofiltration membrane (manufactured by Stork/X-Flow, The Netherlands), designed to reduce membrane fouling and thus allowing to omit or reduce the extensive pretreatment usually required for the implementation of nanofiltration in drinking water production. In the laboratory, the membrane performance (flux decline and flux recovery) during nanofiltration of surface water from the river Dijle, Flanders, Belgium was compared with that of a series of nine commercial flat sheet membranes. All membranes showed flux decline to some extent. For the capillary membrane, the water flux could, however, easily be increased and maintained at a stable level by a combination of forward flushing and airflushing, which is not possible with the flat sheet membranes. Furthermore, the water permeability for the capillary membrane was three to 15 times higher than for the commercial flat sheet membranes, which leads to lower operating pressure and a correspondingly lower energy consumption. For the capillary membrane rejections of organic and inorganic compounds were satisfactory to reach for COD and conductivity standards in one step starting from the Dijle water. Rejections for most flat sheet membranes were comparable to the rejections obtained with the capillary membrane, but the rejection of ions was usually higher, except for the N30F and NF PES 10 membranes (Nadir, Germany). Low ion rejections are advantageous for drinking water production because demineralization is avoided.