Whey membrane fouling

Membrane fouling due to adsorption of polyelectrolytes (such as humic acids, surfactants, and proteins) may severely reduce ion permeability, especially in the anion-exchange membranes. However, exhausted anion-exchange membranes used in the ED of molasses, whey, citric acid, or sodium dodecyl-benzenesulfonate can be reactivated by circulating simultaneously an acidic solution in one compartment and an alkaline solution in the other one, both solutions at titres greater than 0.1 kmol/m3 (Tokuyama Soda Co., 1983). 

Ultrafiltration of whey is a major membrane-based process in the dairy industry however, the commercial availability of this application has been limited by membrane fouling, which has a concomitant influence on the permeation rate. Ultrasound cleaning of these fouled membranes has revealed that the effect of US energy is more significant in the absence of a surfactant, but is less markedly influenced by temperature and transmembrane pressure. The results suggest that US acts primarily by Increasing turbulence within the cleaning solution [91]. 

The efficiency of UF in whey processing is limited by a few factors, the most significant of which are concentration polarization and membrane fouling [6,39 1]. While both factors, which adversely affect permeate flux, may be aggravated by protein-protein and membrane-protein interactions [23,40,42-44], they may also be minimized by choosing suitable membrane material and configuration as well as the appropriate process conditions such as TMP, feed velocity or recirculation rate, temperature, and the chemical environment of whey [42,45,46]. 

Mineral precipitation and complexation with proteins also contribute to fouling considerably. Adsorbed minerals may serve as salt bridges between the protein and the membrane, which aggravates fouling. In physicochemical conditions that promote calcium phosphate precipitation or calcium-protein complexation, membrane fouling in the filtration of nulk or whey is severe,... 

Kuo, K.P. and Cheryan, M., Ultrafiltration of acid whey in spiral-wound unit Effect of operating parameters on membrane fouling, J. 

Mourouzidis-Mourouzis, S.A. and Karabelas, A.J., Whey protein fouling of microfiltration ceramic membranes— pressure effects, J. Membr. Sci., 282, 124, 2006. 

Munoz-Aguado, M.J., Wiley, D.E., and Fane, A.G., Enzymatic and detergent cleaning of a polysulfone ultrafiltration membrane fouled with BSA and whey, J. Membr. Sci., 117, 175, 1996. 

Cabero, M.L., Riera, F. A., and Alvarez, R., Rinsing of ultrafiltration ceramic membranes fouled with whey proteins Effects on cleaning procedures, J. Membr. Sci., 154, 239, 1999. 

One of the important factors determining the process economics is the flux decline that is caused by a build-up of whey components at the membrane surface. It is the aim of this paper to review the application of reverse osmosis to whey processing, and in particular, to discuss the problem of membrane fouling. 

As noted by Matthews ( ), the studies on membrane fouling published so far would suggest that some of the protein components causing fouling are affected by such factors as pH, ionic strength and ionic composition (particularly calcium concentration). Interactions between the various solutes are also Important, as shown by Peri and Dunkley (18). Their results on the reverse osmosis of solutions of whey components showed little Indication of fouling only whole whey gave a steady decline In flux rate with time. 

Prefiltration for UF. In most cases, MF is too expensive for use as a prefilter. However, there are some feed streams which severely foul UF membranes and where prefiltration with cross-flow MF is cost effective. For example, in the UF of milk or cheese whey fat, casein fines, coagulated protein, and microorganisms all cause severe membrane fouling. In the concentration of milk, the use of tubular MF as a prefilter increased the UF flux by 100% on the average. CFF is required because TFF (through-flow filtration) would plug the MF membrane immediately. 

Blanpain-Avet P, Migdal JF, Benezech T (2004) The effect of multiple fouling and cleaning cycles on a tubular ceramic microfiltration membrane fouled with a whey protein concentrate-membrane performance and cleaning efficiency. Food Bioprod Process 82(C3) 231-243. doi 10.1205/fbio.82.3.231.44182... 

It has been proven over the years that the effect of fouling can be lessened to some extent for the application of whey concentration by pretreating the feed streams for the ultrafilters. Whey contains many insoluble solids such as casein fines, lipoprotein complex, mineral precipitates, free fats and microorganisms. Clarification of these debris helps reduce fouling potential during ultrafiltration. In addition, it is quite evident that calcium phosphate minerals in whey are not stable and their precipitation in the membrane pores often results in flux decline. Demineralization of whey before ultrafiltration helps maintain high permeate flux considerably [Muir and Banks, 1985]. 

While a-lactalbumin (a-La) was found to have the greatest gel-forming tendency in UF of whey using polysulfone membranes and is the cause of immediate loss of initial flux, /3-lactoglobulin (/3-Lg) has great effect on long-term fouling... 

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