Integrated membrane separation processes are gradually becoming consolidated sys-tems for the industrial production of highly concentrated fruit juice. Concentration of fruit juice with high solid and polysaccharide content by RO or OD results in a lower permeate flux due to an increase in the viscosity of concentration boundary layer near
the membrane surface. Enzymatic treatment of fruit juice followed by membrane clarification by UF or MF treatment has been shown to decrease the levels of solid contents, polysaccharides, and proteins significantly, leading to a decrease in viscos-ity and turbidity of the clarified juice. If the concentration processes such as RO or OD are combined with enzymatic treatment, UF, MF, etc., the viscosity in the con-centration boundary layer decreases resulting in an increase in permeate flux. Hence, studies have mainly focused on increasing the effectiveness of the concentration pro-cess in terms of permeate flux, retention of color, aroma compounds, and TAA by integration of other membrane processes, namely, UF and MF. Therefore, the benefits in terms of low energy consumption, preservation of aroma, nutritional value, and organoleptic properties of juice, quality improvement of final product, and increase in permeate flux could be achieved using integrated membrane process.
The combination of UF and RO as an integrated membrane process for the con-centration of fruit juice was disclosed by Lawhon and Lusas (1987) in their patent.
At the beginning, UF was used to clarify the juice. The permeate containing almost all the flavor and aroma characteristics was concentrated by RO more than 42 °Bx.
The retentate containing all the SSs, pectins, and the spoilage microorganisms was subjected to heat treatment to inactivate the spoilage microorganisms and to improve the stability of the finished product when mixed with RO concentrate. The reconstituted juice was found to have a quality close to that of fresh juice. Walker (1990) illustrated the concept of two-stage RO system after MF or UF to produce concentrated juice (Figure 4.28). UF or MF was first used to clarify (to separate out the pulp from the serum) orange juice. The clarified juice was concentrated by RO (three units in series) with high-retention polyamide hollow fiber membranes (98.5%
salt retention). The retentate leaving the final high-retention RO unit was further concentrated by low-retention RO membranes (two units in series, first with 93%
and second with 97% salt retention). The finished product of 54 °Bx was obtained by blending the retentate from the second low-rejection unit having a sugar concentra-tion of 63 °Bx with the pasteurized UF retentate.
Pasteurizer Fresh
juice
Water
UF HR RO HR RO HR RO
LR RO LR RO
18 °Brix 40 °Brix 31 °Brix
63 °Brix
54 °Brix product 50 °Brix
FIGURE 4.28 Schematic of the combined high-retention (HR)-low-retention (LR) RO pro-cess for juice concentration.
Yu and Chiang (1986) used the combination of UF and evaporation for concen-trating passion fruit juice. Raw juice was clarified by UF after the pretreatment with pectinase, centrifugation, and pasteurization. UF-clarified passion fruit juice showed higher evaporation rate than juice with solid due to improved heat transfer.
The final concentrated product was obtained after blending the evaporated con-centrate with the UF retentate. The reconstituted juice and the fresh juice were not significantly different in terms of the desired components although the evaporation caused 20% flavor loss. Johnson (1993) studied a combined membrane-evaporation process for concentrating orange juice. He used UF membrane to separate SSs from the raw juice. The UF-clarified juice was then concentrated by a conventional evap-orator. The UF retentate may be pasteurized by a heat exchanger. This combined membrane-evaporation technique can produce concentrated juice more than 80 °Bx, which may be used to formulate new fruit beverage juice blends. The combination of enzyme membrane reactor (EMR), RO, and pervaporation (PV) was success-fully performed in laboratory and pilot plant unit for the production of apple juice and apple juice aroma concentrates (Alvarez et al., 2000). In the proposed scheme (Figure 4.29), the raw apple juice was clarified in an enzyme membrane reactor followed by the preconcentration of the clarified juice up to 25 °Bx in RO with the permeate flow of 75–110 L/h. Then the RO retentate was fed to the pervaporation unit to recover and concentrate the aroma compounds followed by a final evapora-tion step to concentrate apple juice up to 72 °Bx. More than 90% rejection of aroma
Aroma-enriched concentrated
apple juice Concentrated juice
(70°C–72 °Brix) Dearomatized
juice
Evaporation (60°C–80°C) 20°C 20°C
20°C–25°C Preconcentrated juice, 25 °Brix Clarified
juice
Aroma compounds PV
RO EMR
Water
Retentate and enzyme recirculation Fresh apple
juice
FIGURE 4.29 Integrated membrane process for the production of clarified apple juice con-centrate and apple juice aroma. EMR, enzymatic membrane reactor; RO, reverse osmosis;
PV, pervaporation. (From Alvarez, S. et al., J. Food Eng., 46, 109, 2000.)
compounds was achieved for most of the compounds considered. They also reported that for the production of clarified apple juice, the use of membrane reactor could be handy in terms of lower enzyme cost, fouling, and cleaning.
An integrated RO–NF membrane system for concentrated fruit juice was pro-posed by Nabetani (1996). The fresh juice (10 °Bx) is initially concentrated to 30 °Bx with RO membranes and then the RO retentate is concentrated up to 45 °Bx using NF membranes. The NF permeate is recycled to the feed of RO unit. This system is shown to be suitable for concentrating various fruit juices, with advan-tages of not only retaining the fresh juice flavor but also of energy savings of 12.5%
and 20% when compared with evaporation and freeze concentration, respectively.
An integrated membrane process for producing blood orange juice was proposed by Galaverna et al. (2008). The process was based on the initial clarification of fresh blood orange juice by UF. Then the clarified orange juice was concentrated to a final value of 60 °Bx in two different configurations such as UF–RO–OD or UF–OD. The process, UF–RO–OD, in which RO, used as a preconcentration technique (up to 25–30 °Bx), followed by OD, up to a final concentration of about 60 °Bx and the process, UF–OD, in which the RO treatment was omitted. Results revealed that the value of TAA in the final product obtained by UF–OD was not significantly different from that obtained by UF–RO–OD. The final products had a brilliant red color with high antioxidant activity, large amounts of natural bioactive components, and aroma, characteristics that were significantly lost during conven-tional thermal evaporation. For the production of concentrated citrus and carrot juice with high nutrition value, a similar type of integrated membrane process scheme was used (Cassano et al., 2003) shown in Figure 4.30. The clarification of raw juice was first carried out by UF. Then the UF permeate was preconcentrated by RO; a further concentration of RO retentate was performed by OD. This juice was finally concentrated with 60–63 °Bx with high antioxidant activity.
Cassano et al. (2004) proposed an integrated membrane process by a sequence of UF and OD for the production of concentrated kiwifruit juice of high quality and high nutrition value. The raw juice after enzyme treatment was initially clari-fied by UF. Then the clarified juice was submitted to the concentration step by OD.
Pasteurizer
Permeate Pulp
Fruit juice (10–11 °Brix)
Preconcentrated juice
(25–26 °Brix) Concentrated juice (63–65 °Brix)
CaCl2 CaCl2
UF RO
OD
FIGURE 4.30 Integrated membrane processes for the clarification and concentration of citrus and carrot juices. (Reprinted from Cassano, A. et al., J. Food Eng., 57, 153, 2003.
With permission.)
The concentrated juice with a final concentration of TSS of 65.8 °Bx was achieved at an average throughput of about 1 kg/m2 h. However, a little decrease in TAA was observed during the UF-OD operation, whereas the contribution of ascorbic acid to the TAA remained unchanged. The fresh kiwifruit juice and the samples obtained from UF and OD operation were characterized in terms of TSS, pH, SS, turbidity, ascorbic acid, and TAA, which are shown in Table 4.11.
Cassano et al. (2007) also studied the potentiality of a membrane-based process for the clarification and the concentration of the cactus pear fruit juice. The fresh juice, with a TSS content of about 11 °Bx, was initially clarified by a UF step, on laboratory scale, according to the batch concentration procedure at a TMP of 2.15 bar, an axial retentate flow rate of 18 L/h, and a temperature of 25°C ± 2°C. The clarified juice was then concentrated by OD up to TSS content of 61 °Bx at 28°C. An initial evaporation flux of 1.16 kg/m2 h was obtained using a calcium chloride dehy-drate solution at 60 w/w% as stripper. During the concentration by OD, the TAA of the juice remained almost constant for the various levels of the TSS achieved.
4.5 CONCLUSION
The evolution of the use of membrane applications in fruit processing has been reviewed. The process of clarification and concentration of fruit juice using a variety of membrane processes including types of membranes used, membrane fouling and its control, membrane modules, and existing models are discussed in detail. Different flux enhancement techniques, for example, electric field, pulsatile flows, etc., are intro-duced with applicative examples. The use of reverses osmosis (RO), direct osmosis concentration (DOC), membrane distillation (MD), and osmotic distillation (OD) for the concentration of fruit juice using different membrane processes are described along with the underlying physical principles for each of them; design features of each process and the effect of different process parameters on permeate flux and retention are discussed. Finally, the concepts of integrated membrane separation processes are introduced for the industrial production of highly concentrated fruit juice. The applica-tions of membrane processes for fruit juice processing are legion.
TABLE 4.11
Analytical Measurement of Fresh Kiwifruit Juice and Samples from UF and OD Treatments
Sample TSS (°Bx) pH SS (w/w%)
Turbidity (NTU)
Ascorbica Acid (mg/100 g)
TAAa (mM trolox)
Fresh juice 12.5 3.58 5.16 299.5 69.6 16.0
UF permeate 12.1 3.60 0 0 63.3 15.3
UF retentate 13.5 3.58 51.5 1336.7 62.8 15.6
OD retentate 65.8 3.40 0 0 69.6 14.1
Source: Reprinted from Cassano, A. et al., Food Res. Int., 37(2), 139, 2004. With permission.
a Values referred to 12.5 °Bx. With permission.
REFERENCES
Alvarez, V., S. Alvarez, F.A. Riera, R. Alvarez, Permeate flux prediction in apple juice concen-tration by reverse osmosis, J. Membr. Sci., 127 (1997) 25–34.
Alvarez, S., R. Alvarez, F.A. Riera, J. Coca, Influence of depectinization on apple juice ultra-filtration, Colloids Surf. A Physicochem. Eng. Aspects, 138 (1998a) 377.
Alvarez, V., L.J. Andres, F.A. Riera, R. Alvarez, Microfiltration of apple juice using inor-ganic membranes: Process optimization and juice stability, Can. J. Chem. Eng., 74 (1996) 156.
Alvarez, S., F.A. Riera, R. Alvarez, J. Coca, Permeation of apple aroma compounds in reverse osmosis, Sep. Purif. Technol., 14(1–3) (1998b) 209–220.
Alvarez, S., F.A. Riera, R. Alvarez, J. Coca, F.P. Cuperus, S. Bouwer, et al., A new integrated membrane process for producing clarified apple juice and apple juice aroma concen-trate, J. Food Eng., 46 (2000) 109.
Alves, V.D., I.M. Coelhoso, Orange juice concentration by osmotic evaporation and mem-brane distillation: A comparative study, J. Food Eng., 74 (2006) 125.
Amar, R.B., B.B. Gupta, M.Y. Jaffrin, Apple juice clarification using mineral membranes:
Fouling control by backwashing and pulsating flow, J. Food Sci., 55 (1990) 1620.
Andersson, S.L., N. Kjellander, B. Rodesjo, Design and field tests of a new membrane distil-lation desalination process, Desalination, 56 (1985) 345.
Arroyo, G., C. Fonade, Use of intermittent jets to enhance flux in cross flow filtration, J.
Membr. Sci., 80 (1993) 117–129.
Bailey, A.F.G., A.M. Barbe, P.A. Hogan, R.A. Johnson, J. Sheng, The effect of ultrafiltration on the subsequent concentration of grape juice by osmotic distillation, J. Membr. Sci., 164 (2000) 195.
Barbe, A.M., J.P. Bartley, A.L. Jacobs, R.A. Johnson, Retention of volatile organic flavour/
fragrance components in the concentration of liquid foods by osmotic distillation, J.
Membr Sci., 145(1) (1998) 67–75.
Bargeman, G., J. Houwing, I. Recio, G.H. Koops, H.C. Van der Horst, Electromembrane fil-tration for the selective isolation of bio-active peptides from an αs2-casein hydrolysate, Biotechnol. Bioeng., 80 (2002) 599.
Beaudry, E.G., K.A. Lampi, Membrane technology for direct osmosis concentration of fruit juices, Food Technol., 44(6) (1990) 121.
Bellara, S.R., Z.F. Cui, D.S. Pepper, Gas sparging to enhance permeate flux in ultrafiltration using hollow fibre membranes, J. Membr. Sci., 121 (1996) 175.
Blatt, W.F., A. Dravid, A.S. Michaels, L. Nelson, Solute polarization and cake formation in membrane ultrafiltration: Causes, consequences and control techniques, in: J.E. Flinn (Ed.), Membrane Science and Technology, Plenum Press, New York, 1970.
Bowen, W.R., R.S. Kingdon, H.A.M. Subuni, Electrically enhanced separation processes: The basis of in situ intermittent electrolytic membrane cleaning (IIEMC) and in situ electro-lytic membrane restoration (IEMR), J. Membr. Sci., 40 (1989) 219.
Bowen, W.R., H.A.M. Subuni, Pulsed electrokinetic cleaning of cellulose nitrate microfiltra-tion membrane, Ind. Eng. Res., 31 (1992) 515.
Bowen, W.R., H.A.M. Subuni, Electrically enhanced membrane filtration at low cross-flow velocities, Ind. Eng. Res., 30 (1991) 1573–1579.
Calabro, V., B. Jiao, E. Drioli, Theoretical and experimental study on membrane distillation in the concentration of orange juice, Ind. Eng. Chem. Res., 33 (1994) 1803.
Carlsson, L., The new generation in sea water desalination: SU membrane distillation system, Desalination, 45 (1983) 221.
Cassano, A., E. Drioli, G. Galaverna, R. Marchelli, G. Di Silvestro, P. Cagnasso, Clarification and concentration of citrus and carrot juices by integrated membrane processes, J. Food Eng., 57 (2003) 153.
Cassano, A., B. Jiao, E. Drioli, Production of concentrated kiwifruit juice by integrated mem-brane processes, Food Res. Int., 37(2) (2004) 139.
Cassano, A., C. Conidi, R. Timpone, M. D’Avella, E. Drioli, A membrane-based process for the clarification and the concentration of the cactus pear juice, J. Food Eng., 80 (2007) 914–921.
Cheng, D.Y., S.J. Wiersma, Composite membrane for a membrane distillation system, U.S.
Patent 4,316,772 (1982).
Cheryan, M., Ultrafiltration and Microfiltration Handbook, Technomic Publishing Company, Lancaster, PA, 1998, p. 83.
Chiang, B.H., Z.R. Yu, Fouling and flux restoration of ultrafiltration of passion fruit juice, J. Food Sci., 52 (1987) 369.
Chou, F., R.C. Wiley, D.V. Schlimme, Reverse osmosis and flavor retention in apple juice concentration, J. Food Sci., 56 (1991) 484.
Chua, H.T., M.A. Rao, T.E. Acree, D.H. Cunningham, Reverse osmosis concentration of apple juice: Flux and flavor retention by cellulose acetate and polyamide membranes, J. Food Process Eng., 9 (1988) 231.
Constenla, D.T., J.E. Lozano, Predicting stationary permeate flux in the ultrafiltration of apple juice, Lebensmittel-Wissenschaftund Technologie, 29 (1996) 587.
Constenla, D.T., J.E. Lozano, G.H. Crapiste, Thermophysical properties of clarified apple juice as a function of concentration and temperature, J. Food Sci., 54 (1989) 663.
Courel, M., M. Dornier, J.M. Herry, G.M. Rios, M. Reynes, Effect of operating conditions on water transport during the concentration of sucrose solutions by osmotic distillation, J. Membr. Sci., 170 (2000) 281.
Cui, Z.F., Experimental investigation on enhancement of cross-flow ultrafiltration with air sparg-ing, in: R. Patterson (Ed.), Proceedings of the 3rd international conference on Effective Membrance Processes-New Perspectives, Mech. Eng. Pub. Ltd., London, U.K., May 12–14, 1993, p. 237.
Cui, Z.F., K.I.T. Wright, Gas-liquid two-phase cross-flow ultrafiltration of dextrans and BSA solution, J. Membr. Sci., 90 (1994) 183.
Cui, Z.F., K.I.T. Wright, D.H. Glass, Experimental evidence on the mechanism of enhance-ment of ultrafiltration with gas sparging, in: Proc. 1996 IChemE Research Event, Leeds, U.K., 1996, p. 304.
Curcio, E., G. Barbieri, E. Drioli, Operazioni di distillazione a membrana nella concentrazione dei succhi di frutta, Industrie delle Bevande, XXIX(April) (2000) 113–121.
de Barros, S.T.D., C.M.G. Andrade, E.S. Mendes, L. Peres, Study of fouling mechanism in pineapple juice clarification by ultrafiltration, J. Membr. Sci., 215 (2003) 213.
Ding, L., J.M. Laurent, M.Y. Jaffrin, Dynamic filtration of blood: A new concept for enhancing plasma filtration, Hemapheresis, 14 (1991) 365.
Drioli, E., B. Jiao, V. Calabro, The preliminary study on the concentration of orange juice by membrane distillation, in: Proceedings of VII International Citrus Congress, Acireale, Italy, March 8–13, 1992.
Durham, R.J., M.H. Nguyen, Hydrophobic membrane evaluation and cleaning for osmotic distillation of tomato puree, J. Membr. Sci., 87 (1994) 181.
Fane, A.G., C.J.D. Fell, A review of fouling and fouling control in ultrafiltration, Desalination, 62 (1987) 117.
Fane, A.G., K.J. Kim, Prospects for improved ultrafiltration membranes, in: Proceedings IMTEC’88, International Membrane Technology Conference, November 15–17, 1988, Sydney, New South Wales, Australia, pp. K10–K14.
Field, R.W., D. Wu, J.A. Howell, B.B. Gupta, Critical flux concept for microfiltration fouling, J. Membr. Sci., 100 (1995) 259.
Field, R.W., D. Wu, J.A. Howell, B.B. Gupta, Critical flux concept for microfiltration fouling, J. Membr. Sci., 100 (1995b) 250.
Finnigan, S.M., J.A. Howell, The effect of pulsed flow on ultrafiltration fluxes in a baffled tubular membrane system, Desalination, 79(2–3) (1990) 181.
Flath, R.A., D.R. Black, D.G. Guadagni, W.H. Mcfadden, T.H. Schultz, Identification and organolep-tic evaluation of compounds in delicious apple essence, J. Agric. Food Chem., 15 (1967) 29.
Galaverna, G., G. Di Silvestro, A. Cassano, S. Sforza, A. Dossena, E. Drioli, R. Marchelli, A new integrated membrane process for the production of concentrated blood orange juice:
Effect on bioactive compounds and antioxidant activity, Food Chem., 106 (2008) 1021.
Garaldes, V., V. Semiao, M.N. de Pinho, Flow management in nanofiltration spiral wound modules with ladder-type spacers, J. Membr. Sci., 203(1–2) (2002) 87.
Ghosh, A.M., M. Balakrishnan, M. Dua, J.J. Bhagat, Ultrafiltration of sugarcane juice with spiral wound modules: On-site pilot trials, J. Membr. Sci., 174 (2000) 205.
Girard, B., L. Fukumoto, Membrane processing of fruit juices and beverages: A review. Crit.
Rev. Biotechnol., 20(2) (2000a) 109.
Girard, B., L.R. Fukumoto, Membrane processing of fruit juices and beverages: A review, Crit. Rev. Food Sci. Nutr., 40 (2000b) 91.
Gladdon, J.K., M. Dole, Diffusivity determination of sucrose and glucose solutions, J. Am.
Chem. Soc., 75 (1953) 3900.
Gore, D.W., Gore-Tex membrane distillation, Proceedings of the Tenth Annual Convention of the Water Supply Improvement Association, Honolulu, Hl, July 25–29, 1982.
Gostoli, C., Thermal effects in osmotic distillation, J. Membr. Sci., 163(1) (1999) 75–91.
Gostoli, C., G.C. Sarti, S. Matulli, Low temperature distillation through hydrophobic mem-branes, Sep. Sci. Technol., 22 (1987) 855.
Gryta, M., Effect of iron oxides scaling on the MD process performance, Desalination, 216(1–3) (2007) 88–102.
Guizard, C., F. Legault, N. Idrissi, A. Larbot, L. Cot, C. Gavach, Electronically conductive min-eral membranes designed for electroultrafiltration, J. Membr. Sci., 41 (1989) 127–142.
Gunko, S., S. Verbych, M. Bryk, N. Hilal, Concentration of apple juice using direct contact membrane distillation, Desalination, 190 (2006) 117.
Gupta, B.B., P. Blanpain, M.Y. Jaffrin, Permeate flux enhancement by pressure and flow pul-sations in microfiltration with mineral membranes, J. Membr. Sci., 70 (1992) 257–266.
He, Y., Z. Ji, S. Li, Effective clarification of apple juice using membrane filtration without enzyme and pasteurization pretreatment, Sep. Purif. Technol., 57 (2007) 366.
Hermans, P.H., H.L. Bredee, Principles of the mathematical treatment of constant-pressure filtration, J. Soc. Chem. Ind., 55T (1936) 1.
Hérmia, J., Constant pressure blocking filtration laws. Applications to power-law non-Newtonian fluids, Trans. IChemE, 60 (1982) 183.
Herron, J.R., E.G. Beaudry, C.E. Jochums, L.E. Medina, Osmotic concentration apparatus and method for direct osmotic concentration of fruit juice, U.S. Patent 5,281,430 (1994) January 25.
Ho, C.C., A.L. Zydney, A combined pore blockage and cake filtration model for protein foul-ing during microfiltration, J. Colloid Interf. Sci., 232 (2000) 389.
Hofmann, R., C. Posten, Improvement of dead-end filtration of biopolymer with pressure elec-trofiltration, Chem. Eng. Sci., 58 (2003) 3847–3858.
Howell, A., V. Sanchez, R.W. Fieldeds, Membrane in Bioprocessing: Theory and Applications, Chapman & Hall, London, U.K., 1993.
Hwang, S.T., K. Kammermeyer, Membranes in Separations, Wiley-Interscience, New York, 1975.
Hwang, K.J., C.Y. Liao, K.L. Tung, Analysis of particle fouling during microfiltration by use of blocking models, J. Membr. Sci., 287 (2007) 287.
Jiao, B., A. Cassano, E. Drioli, Recent advances on membrane processes for the concentration of fruit juices: A review, J. Food Eng., 63 (2004) 303.
Jiraratananon, R., A. Chanachai, A study of fouling in the ultrafiltration of passion fruit juice, J. Membr. Sci., 111 (1996) 39.
Jiraratananon, R., D. Uttapap, C. Tangamornsuksun, Selfforming dynamic membrane for ultrafiltration of pineapple juice, J. Membr. Sci., 129 (1997) 135.
Johnson, J.R., Technical and economical feasibility of a nonconventional method for concen-trating orange juice, PhD thesis, University of Florida, Gainesville, FL, 1993.
Kilara, A., J.P. Van Buren, Clarification of apple juice, in: D.L. Downing (Ed.), Processed Apple Products, Van Nostrand Reinhold, New York, 1989, pp. 83–96, Chapter 4.
Kim, B.S., H.N. Chang, Effects of periodic backflushing on ultrafiltration performance, Bioseparations, 2 (1991) 23.
Kimura, S., S.I. Nakao, S. Shimatani, Transport phenomena in membrane distillation.
J. Membr. Sci., 33(3) (1987) 285.
Kimura, S., S. Sourirajan, Analysis of data in reverse osmosis with porous cellulose acetate
Kozak, A., E.B. Molnar, G. Vatai, Production of black-currant juice concentrate by using membrane distillation, Desalination, 241 (2009) 309.
Lagan, F., G. Barbieri, E. Drioli, Direct contact membrane distillation: Modelling and concen-tration experiments, J. Membr. Sci., 166(1) (2000) 1.
Lakshminarayanaiah, N., Equations of Membrane Biophysics, Academic Press, New York, 1984.
Lamminen, M.O., H.W. Walker, L.K. Weavers, Mechanisms and factors influencing the ultra-sonic cleaning of particle-fouled ceramic membranes, J. Membr. Sci., 237 (2004) 213.
Lawhon, J.T., E.W. Lusas, Method of producing sterile and concentrated juices with improved flavor and reduced acid, U.S. Patent 4,643,902, 7 September, 1987.
Lawson, K.W., D.R. Lloyd, Review membrane distillation, J. Membr. Sci., 124 (1997) 1–25.
Lee, S., M. Elimelech, Salt cleaning of organic-fouled reverse osmosis membranes, Water Res., 41 (2007) 1134.
Li, Q.Y., R. Ghosh, S.R. Bellara, Z.F. Cui, D.S. Pepper, Enhancement of ultrafiltration by gas sparging with flat sheet membrane modules, Sep. Purif. Technol., 14 (1998) 79.
Loeb, S., L. Titelman, E. Korngold, J. Freiman, Effect of porous support fabric on osmosis through a Loeb-Sourirajan type asymmetric membrane, J. Membr. Sci., 129 (1997) 243–249.
Lonslade, H.K., Theory and practice of reverse osmosis and ultrafiltration, in R.E. Lacey and S. Loeb (Eds.), Industrial Processing With Membranes, Wiley-Interscience, New York, 1972.
Matsumoto, Y., T. Miwa, S.-I. Nakao, S. Kimura, Improvement of membrane permeation per-formance by ultrasonic microfiltration, J. Chem. Eng. Jpn., 29(4) (1996) 561.
Matsuura, T., A.G. Baxter, S. Sourirajan, Studies on reverse osmosis for concentration of fruit juice, J. Food Sci., 39 (1974) 704.
Matsuura, T., S. Sourirajan, Physicochemical criteria for reverse osmosis separation of mono-
Matsuura, T., S. Sourirajan, Physicochemical criteria for reverse osmosis separation of mono-