Integrated Membrane Process Research Articles

Integrated Membrane Processes for Separation and Purification of Organic Acid from a Biomass Fermentation Process

During biomass (e.g., waste wood chips) decomposition under an anaerobic fermentation process, organic acids such as acetic acid and butyric acid are continuously produced from controlled microbial activity. Since the accumulation of organic acids hinders the microbial metabolism in the fermentation broths, the organic acids should be removed by using appropriate separation processes. A few separation processes such as extraction, electrodialysis, and distillation have been reported, but they still have many limitations such as high energy input and environmental problems (e.g., toxic chemical effluents). The integrated membrane processes proposed here, including the three steps of (1) clarification of fermentation broth, (2) organic acid separation, and (3) dewatering, can be applied to achieve energy-efficient and environmentally friendly organic acid removal and recovery. First, microorganisms and large insoluble particles in fermentation feed can be mostly removed by clarification steps using microfiltration or ultrafiltration processes. In this study, we focused only on organic acid separation and dewatering processes using nanofiltration and forward osmosis membrane processes. Using nanofiltration (or high-flux reverse osmosis) membranes, aqueous organic acids can be selectively separated from pretreated fermentation feed solutions while other organics and many salts can be rejected using these processes by varying pH conditions in the feed. Finally, a low-energy-consuming forward osmosis process was applied for dewatering in the aqueous organic acid solutions to concentrate organic acid. The concentrated organic acid was successfully obtained by using conventional desalination and/or commercial forward osmosis membranes.

Full scale plant with membrane based concentration of blackcurrant juice on the basis of laboratory and pilot scale tests

A conceptual process design with the use of integrated membrane processes is prepared for blackcurrant juice concentrate (BCJC) production to replace traditional multiple step evaporators and aroma recovery. The combination of membrane processes includes aroma recovery with vacuum membrane distillation and water removal by reverse osmosis, nanofiltration and direct contact membrane distillation. It has been combined with optimization of membrane performance and juice quality in mind. The annual production scale is 17,283ton of 66°Brix out of single strength juice. The operation cost is 0.40€/kg BCJC, which is lower than the price of a traditional operation by about 43%. Therefore, the economical potential of the process is very promising and could supersede conventional evaporators.

Techno-economic analysis of processes for Aspergillus carbonarius polygalacturonase production

A techno-economic analysis of submerged (SmF) and solid state fermentation (SSF) processes for Aspergillus carbonarius polygalacturonase production was performed to make an appropriate process selection. The downstream processing involved integrated membrane process (IMP) and alginate affinity precipitation (AAP). For a production scale of 30kL purified polygalacturonase concentrate per year, the total upstream cost of SmF was 14% lower than the SSF process. Downstream processing cost by IMP was 47% lower than AAP. The SmF-IMP process required a total capital investment that was 15-24% lower than the SmF-AAP and SSF-AAP processes. The corresponding unitary product cost was also lower by 24-36% in SmF-IMP process. Thus the SmF-IMP process proved to be very attractive from an economic point of view.

Techno-economic analysis of textile dye bath wastewater treatment by integrated membrane processes under the zero liquid discharge approach

The present study was intended to determine the usefulness of the zero liquid discharge ( ZLD) approach in treating textile dye bath wastewater via integrated membrane processes. These processes included various combinations of ultrafiltration (UF), loose nanofiltration (NF 1), tight nanofiltration (NF 2) and reverse osmosis (RO). The technological and economic performance of four scenarios (UF/NF 2 ( S (I)), NF 1/NF 2 ( S (II)), NF 1/RO ( S (III)) and UF/NF 2/RO ( S (IV))), each followed by membrane distillation (MD), were comparatively analysed. The factors considered were capital and operating costs, revenues, benefit/cost (B/C) ratios and pay-back times. The last two scenarios, those including RO, provided the best effluent quality at the end of the pressure-driven membrane filtration process. However, these scenarios were not the most economical options because of the decreased benefits of recycling soda ash and NaCl obtained from the treated wastewater. The unit treatment costs of the scenarios were 1.37, 1.38, 2.16 and 2.01 $/m 3 of influent for S (I), S (II), S (III) and S (IV), respectively, with return periods of 0.87, 0.91, 2.07 and 1.51 years. The best technological and economic performance was estimated for S (I) and S (II), as indicated by the B/C ratios 3.58 and 3.55, respectively. At the break-even point of 15 years, S (I) required an incineration cost of 77.5 $/m 3 of MD concentrate, whereas the corresponding costs associated with the other three scenarios were estimated to be 75.7, 43.0 and 35.5 $/m 3 of MD concentrate, respectively. It was finally concluded that the ZLD approach is most useful in processing textile dye bath waste and recycling treated wastewater. This process is both technically feasible and economically viable, as indicated by the high B/C ratio. However, the unit incineration cost associated with the concentrate would limit the return period of the investment, and the success of this method would also depend principally on the real volume of MD processed due to its large contribution (70–90%) to the B/C ratio.

Recent Patents Review on Electrodeionization

The recent patents and progress of electrodeionization (EDI) in fields of water deionization and wastewater treatment are reviewed in the present paper. The discussion focuses on such major aspects: applied ion exchange media, inner configuration and operation manner of the EDI, integrated membrane processes based on EDI and new applications of the technology. As the newest outstanding technology for water deep desalting, EDI has been widely used for ultrapure water production in many industries and laboratories together with important improvements in recent years. Durative advancements have been achieved by inventors such as more even current distribution, higher contact efficiency between water and ion exchanger, more effective precipitation preventing and lower energy consumption. Besides, some improvements also have been achieved in other new fields in addition to pure water production. The application in water softening, seawater desalination and wastewater treatment were introduced for example. It is believed that the electromembrane process of EDI will play an important role in water desalting, wastewater reclamation and cleaner production of chemical engineering near future. Keywords: Electrodeionization, continuous deionization, ultrapure water, ion exchange resins, electroregeneration

Clarification and concentration of pomegranate juice ( Punica granatum L.) using membrane processes

The production of concentrated pomegranate juice was investigated by using a two-step membrane process based on: (1) a clarification step of the fresh non-depectinized juice performed by hollow-fiber ultrafiltration (UF) membranes; (2) a concentration step of the clarified juice by using an osmotic distillation (OD) apparatus. Both processes were performed at ambient temperature (25 ± 2 °C) producing a clear juice and a concentrated juice with a total soluble solids (TSS) content of 162 g kg −1 and 520 g kg −1, respectively. The performance of UF and OD operations was evaluated in terms of productivity (permeate and evaporation fluxes) and quality of the processed juice. Suspended solids were completely removed in the clarification step, while soluble solids and organic acids were recovered in the permeate stream of the UF process. Rejections of the UF membrane towards polyphenols and anthocyanins were of 16.5% and 11.7%, respectively. The antioxidant activity of pomegranate aril juice, attributed to a great extent to total phenols and anthocyanins content, was efficiently preserved during the concentration step independently on the achieved level of total soluble solids. An integrated membrane process scheme for the production of concentrated pomegranate juice with potential applications for food, pharmaceutical and cosmetic sectors was proposed.

Performance of UF–NF integrated membrane process for seawater softening

Nanofiltration (NF) membranes are playing a more and more important role in brackish and seawater softening process, wastewater reclamation and other industrial separation. In this study, ultrafiltation (UF) and NF (ESNA3, Hydranautics) were assembled to an integrated membrane system (IMS) as pretreatment prior to seawater reverse osmosis (SWRO) to evaluate the NF efficiency of seawater softening. The influences of NF feed property (the feed from UF1 with 100kDa MWCO and UF2 with 20kDa MWCO, respectively), operating pressure (0.5–3.0MPa), cross-flow velocity (0.028–0.048m/s) and feed temperature (5–17°C) on the softening efficiency in terms of the NF flux and ion rejection were investigated. The results showed that the high softening efficiency of NF membrane could be achieved using UF membrane with smaller MWCO (20kDa). NF system using UF2 as pretreatment process yielded a higher flux of 61.4L/(m2h) with Ca2+, Mg2+, SO42− rejection of 44.37%, 73.26% and 99.82%, respectively, under the optimum operating conditions of operating pressure at 1.5MPa, cross-flow velocity at 0.035m/s and feed temperature at 12.5°C. And, the relatively excellent selectivity of divalent ions and univalent ions can be obtained by ESNA3 membrane compared to that of other NF membranes reported in the literature, indicating that the ESNA3 membrane seems to be appropriate for seawater softening process.

Concentration of acerola (Malpighia emarginata DC.) juice by integrated membrane separation process

Acerola is a tropical fruit with a high antioxidant activity which may be attributed to its high vitamin C and anthocyanins content. The aim of this work was to produce a high quality concentrated acerola juice by an integrated membrane process, alternative to thermal evaporation. Acerola juice was clarifi ed by the microfiltration process. The clarifi ed juice was preconcentrated by reverse osmosis process up to a total soluble solid content (TSS) of 28° Brix and after that the osmotic evaporation process (OE) was used to reach a TSS up to 55° Brix, corresponding to a concentration factor of 1.93. The vitamin C, anthocyanins content and antioxidant activity increased, respectively, 2.21, 1.41 and 2.28 folds in relation to the pre-concentrated juice when the OE was performed. The results showed that there was no change on the vitamin C content and antioxidant activity of the juice after its processing. However, it was verified a reduction on the anthocyanins content, probably due to the great instability ...

Recovery of process water from spent emulsions generated in copper cable factory

Treatment of waste emulsions generated in the cable factory from copper wire drawing was investigated using the integrated membrane processes: ultrafiltration (UF) and nanofiltration (NF). The application of UF tubular membranes (MWCO 100kDa) resulted in 98% retention of oil and lubricants, whereas the degree of passage of copper ions (the major component of effluents from cable factory) was 99%. The average permeate flux amounted to 45l/m2h for the transmembrane pressure of 3.5bar during the UF pretreatment of waste emulsions. The Silt Density Index (SDI) values of UF permeates were appropriate for the application of spiral wound membranes in the NF process. The complete removal of oil and lubricants was achieved in NF process and the content of TOC was reduced by more than 90%. The rejection of copper ions in the NF process was 90% and 98% for NF270 and NF90 membranes (FILMTEC), respectively. The quality of NF permeates allows a direct reuse of treated water for the preparation of fresh emulsion.

Aspergillus carbonarius polygalacturonases purified by integrated membrane process and affinity precipitation for apple juice production

Aspergillus carbonarius, when grown by submerged and solid-state fermentation, produces different molecular forms of polygalacturonase (PG; EC 3.2.1.15), among them a 42 kDa PG with a high specific activity of 7000 U/mg protein. When the enzymes were purified by integrated membrane process (IMP) and alginate affinity precipitation (AAP), the two processes concentrated different forms of the enzyme. The AAP process selectively purified and concentrated the high active PG whereas the IMP yielded different PGs and also amylase and protease. Evaluation of the AAP enzyme preparations for apple juice preparation under conditions usually employed commercially demonstrated that the high activity PG did not result in good juice clarity. With IMP processed enzymes, juice yields and clarity were similar to that obtained with commercial PG from A. niger.

Pure water production from aqueous solution containing low concentration hardness ions by electrodeionization

The integrated membrane process of “reverse osmosis-electrodeionization (RO/EDI)” has been widely used for pure water production in recent years. However, in most cases, a single pass RO system still can not meet the feed standards of EDI, therefore the “RO/RO” system should be applied for scale averting. In this paper, a specially designed EDI process was developed with improvements on resins packing and inner configuration, and performances of six EDI stacks with different inner configurations were investigated and compared with each other. When with feed hardness of 11.7 mg · L−1 (as CaCO3), the improved EDI process could give a hardness rejection of 99.8% while the energy consumption was as low as 0.26 KW · h · m−3, and the steady product resistivity that could be achieved was 14.6 MΩ · cm. In durative experiment of 130 hours, the EDI had been operated with good stability and without precipitation.

Membrane distillation and novel integrated membrane process for reverse osmosis drained wastewater treatment

An integrated membrane process was constructed, which composed of immersing ultrafiltration(UF) cell as pretreatment step and vacuum membrane distillation (VMD) cell for both pure water reclamation from reverse osmosis (RO) drained wastewater and discharge reduction. The effect of feed temperature, velocity, and vacuum pressure at the pump side on the membrane performance in VMD process was studied. The performance of VMD process in the concentration of pretreated and untreated RO drained wastewater was compared. The surface morphology of the hydrophobic polyvinylidene fluoride hollow fiber membrane was observed by scanning electronic micrograph. Energy Dispersed Spectroscopy was also adopted to analyze the composition of the deposition on the membrane surface. Using un-pretreated RO drained water as the feed, the initial flux of VMD was 22.6 kg/m2h, and declined to 15.6 kg/m2h as the concentration multiple reached four. The composition of contamination on membrane surface contains 32% calcium, 1.92% magnesium, and 1.41% sodium. Whereas the RO drained water was pretreated by hardness removal and UF, the VMD initial flux reached 25.6 kg/m2h, and declined to 17.8 kg/m2h as the concentration multiple got 10. The flux decreased to 11.8 kg/m2h as the concentration multiple enhanced to 20. The contamination contains 26% sodium, 37% chlorine, and 2% calcium.

Integrated Membrane Process for the Treatment of Desulfurization Wastewater

In the desulfurization process for purification of coking gas, a huge amount of wastewater is generated. In order to recover the usable substances such as suspended sulfur (SS) and ammonium salts, e.g., (NH4)2S2O3 and NH4SCN, in the wastewater and also to avoid severe environmental problems in the case of improper disposal, an integrated membrane process mainly consisting of ultrafiltration (UF), nanofiltration (NF), and reverse osmosis (RO) was proposed to treat the wastewater. In the UF process, a ceramic membrane was employed to remove SS and an efficiency of 99.9% and a steady flux of about 500 L·m−2·h−1 were achieved. In the NF step, (NH4)2S2O3 was separated from NH4SCN with a retention ratio of 95.0%, and finally 83.0% of (NH4)2S2O3 was recovered in the retentate, whereas 99.2% of NH4SCN was recovered in the permeate via dialysis with deionized water. In the RO process, NH4SCN can be recovered with an efficiency of 99.0% through a four-pass filtration process. Meanwhile, the RO permeate can be reuse...

Clarification and the concentration of apple juice using membrane processes: A comparative quality assessment

The aim of this study was to evaluate the potential of integrated membrane processes for the clarification and the concentration of apple juice, taking into account the impact on the product quality. The fresh apple juice, with a total soluble solids (TSS) content of about 12°Brix was previously clarified by combined application of fining agents (gelatin and bentonite) and ultrafiltration (UF) through 10 kDa or 100 kDa molecular weight cut-off (MWCO) membranes on laboratory scale. The clarified juice was then concentrated by osmotic distillation (OD), membrane distillation (MD), coupled operation of OD and MD or by conventional thermal evaporation up to 65°Brix. The effect of different clarification and concentration processes on formation of 5-hydroxymethylfurfural (HMF), retention of bioactive compounds (phenolic compounds, organic acids, glucose, fructose and sucrose) and their efficiency in preserving natural color and aroma (trans-2-hexenal, the most relevant compound in apple juice aroma) were evaluated in order to maintain a high quality product. The new membrane-based concentration techniques were very efficient since the product characteristics were very similar to that of the initial apple juice especially regarding the retention of bright natural color and pleasant aroma, which are significantly lost during thermal evaporation. Furthermore, among all the concentration treatments applied, only thermally evaporated samples resulted formation of HMF. Phenolic compounds, organic acids and sugars were very stable against all concentration processes, including thermal evaporation. Coupled operation of OD and MD reduced trans-2-hexenal losses drastically tending towards that of the initial juice and hence can be proposed as the most promising alternative to conventional thermal evaporation technique.

Purification of polygalacturonase from solid-state cultures of Aspergillus carbonarius

Purification of polygalacturonase (PG) from the cultures of Aspergillus carbonarius obtained by acetate buffer extraction after solid-state fermentation was attempted by integrated membrane process and alginate affinity precipitation. The carbohydrates were completely eliminated (98%-99%) with a PG recovery of 72%-80% during integrated membrane process, which would otherwise interfere with the purification process and lead to enzyme loss. However, specific activity of PG did not improve (1.19-1.21 fold) due to the presence of other similar molecular mass proteins. Under optimum conditions of affinity precipitation, the specific activity of PG enhanced to 2450 U/mg (4 fold) with almost complete elimination of carbohydrates and colour compounds resulting in a PG recovery of 61%. PG purity obtained with ultrafiltration (UF) was comparable with the conventional dialysis during desalting eluted PG, besides UF rendered a concentrated PG. The enzyme purity stated was as descend by SDS-PAGE. The results suggested suitability of affinity precipitation for PG purification from solid-state cultures and the potential of UF as a single step process for handling eluted PG.

Fractionation of Skim Milk by an Integrated Membrane Process for Yoghurt Elaboration and Lactose Recuperation

A combined membrane process has been used to fractionate skim milk. Microfiltration and ultrafiltration were employed to obtain concentrates with different protein/lactose ratios depending on the volume concentration ratio to produce protein enriched yoghurt. Nanofiltration has been used for lactose recovery from the ultrafiltration permeate with partial demineralization, while the permeate water of NF can be reused or recycled. Feed, permeate, concentrates and yoghurt have been physicochemical characterized and compared with commercial products. The obtained yoghurts have a smooth aroma and an agreeable taste, the protein content increased up to 50 % and the lactose content decreased approximately 50 % in comparison with commercial yoghurts, while calcium and iron were also increased, leading to a product with special characteristics and high commercial value. Lactose powder has been obtained by lyophilization; the product has good solubility and has 90% purity which can be used in different food preparations or for other applications.

Photocatalytic activity of size and phase selective TiO 2 nanoparticles prepared by the membrane processing

In order to investigate the photocatalytic degradation of phenol and methylene blue (MB) in aqueous solutions containing TiO 2 nanoparticles with different particle sizes and crystalline phases, an integrated membrane process combining microfiltration (MF) and ultrafiltration was introduced for the production and size separation of TiO 2 nanoparticles. TiO 2 nanoparticles obtained were characterized by XRD, TEM, SEM and BET techniques. The characterization results show that TiO 2 nanoparticles with various sizes and BET surface areas were obtained after MF fractionation. The size of TiO 2 nanoparticles from large to small follows the order: the retentate > the feed > the permeate while the sequence of BET surface area follows the order: the permeate > the feed > the retentate. Furthermore, a smaller disperse coefficient was achieved for both the permeate and the retentate in comparison with the feed. The studies on the photocatalytic oxidation of phenol and MB with TiO 2 nanoparticles before and after MF fractionation concluded that both the particle size and crystallite phase had strong influence on their photocatalytic performances.

Integrated membrane process for blackcurrant ( Ribes nigrum L.) juice concentration

The concentration of pretreated blackcurrant ( Ribes nigrum L.) juice by reverse osmosis (RO) membrane was investigated in this study. The pretreatment steps were crushing, enzyme dosage, pressing and then clarification of the raw juice by ultrafiltration (UF). Polyethersulphone, tubular UF membrane on low pressure and temperature (4 bar, 258 °C) was used for this last pretreatment step. RO process was studied on a laboratory plant unit with flatsheet membranes to preconcentrate the clarified blackcurrant juice. The RO experiments were carried out on different transmembrane pressures (30–50 bar) and on low temperature (30 °C) for a mild concentration of the juice. At higher pressure the permeate flux was higher and the time of concentration decreased. The initial total soluble solid content of the juice was 8–108 °Brix, the concentrate of the RO was 22–25 °Brix. The quality of the RO product was evaluated: the antioxidant capacity, monomeric anthocyanin content, total acid content and total phenol content were determined in the samples. Mathematical modelling of the RO process was used to calculate the permeability coefficient.The RO can be applied as the first step of concentration, because it retains all the examined compounds over 99%, and it is an economic procedure. For further concentration membrane distillation or osmotic distillation can be proposed.

Process Assessment for the Purification of Aspergillus carbonarius Polygalacturonase Produced by Submerged and Solid-State Fermentations

Integrated membrane process (IMP) and alginate affinity precipitation (AAP) were assessed for the purification of Aspergillus carbonarius polygalacturonase (PG) obtained after submerged (SmF) and solid-state fermentations (SSF). IMP enhanced the purity (4.69 fold) and recovery (76%) of SmF-PG, but did not improve the purity of SSF and commercial PG due to the presence of other similar molecular mass proteins. AAP enhanced the PG purity and recovery in all the PG samples (SmF, SSF and commercial PG). IMP offers several process advantages over AAP but not suitable for purification of all types of PGs. Our studies on SmF- and SSF-PG had shown that downstream process needs are specific for individual cases and warrants careful considerations.

The treatment of wastewater of paper mill with integrated membrane process

The wastewater of the Chinese Paper Mill is currently treated with the conventional A–O–O method, which consists of a balance tank, a first sedimentation tank, an anoxic tank, an aerobic tank and a secondary sedimentation tank. The conventional treatment cannot meet the requirements of water quality for the paper making process. The integrated membrane process in pilot scale which consists of the membrane bioreactor (MBR), the continuous membrane filtration (CMF) and the reverse osmosis (RO) is used to treat the wastewater of this paper mill. The discharged water from the first sedimentation tank was treated with the anoxic/aerobic/MBR membrane system to eliminate NH 3–N and organic compound dissolved or undissolved. Although the permeate met the quality standards of feed for RO system, the CMF unit before RO system is still used in this integrated system in order to keep RO system operation safely, in case the bad water input the RO unit when the MBR system have some trouble. In this system a low-pressure RO unit with the form of anti-fouling spiral-wound membrane was accepted to purify the influent from CMF unit. The recovery of water for RO system was over 65%. The result showed that the RO permeate with the high quality could meet the whole standards of process water of paper mill. The conductivity of RO permeate was less than 200 μS/cm, COD less than 15 mg/L, the turbidity less than 0.1 NTU, and the chroma of RO permeate was less than 15 PCU. As the result, the treated water by the integrated membrane process could be reused in paper manufacturing process perfectly.