Whey fouling

Belmar-Beiny, M.T., Gotham, S.M., Fryer, P.J. and Pritchard, A.M., 1993, The effect of Reynolds number and fluid temperature in whey fouling. J. Food Eng. 19, 119-139. 

Also, pilot plant and laboratory scale anaerobic studies have demonstrated successful treatment of wastewaters of 5,000 to 50,000 mg/L GOD from corn chips containing soluble and colloidal corn starch and protein, cheese whey, organic chemicals, food, bakeiy, breweiy, paper mill foul condensate, paint, and numerous other hazardous anci non-hazardous materials. 

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]. 

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]. 

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]. 

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... 

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,... 

Fat or lipid materials and calcium-lipid complexes also contribute to fouling and flux decline in membrane processing of milk or whey. The transport properties of the feed stream and the changes they undergo as the concentration process proceeds also affect the rate of permeation. At high concentrations, the increased fluid viscosity near the membrane surface limits back-diffusion of solids from the polarized layer to the bulk phase, thereby, depressing flux rate [46]. 

Most chemical cleaning protocols consist of an alkali detergent step followed by an acid step, with appropriate rinses in between. However, for polymeric membranes, it is also common to follow the acid cleaning step with a second alkali cleaning step supplemented with chlorine as this further improves flux [176,179]. In some cases, acid cleaning has been recommended as the first step, especially for whey applications, where mineral fouling maybe more important than protein fouhng [176]. 

Using light microscopy, Bird and Bartlett [170] observed that the deposit on sintered stainless steel MF membrane (2.0 pim) fouled with whey consists of a loose sheet-like protein-rich stmcmre which is removed during the first few minutes of chemical cleaning (Figure 22.11). Cleaning with sodium hydroxide removes the loose top proteinaceous layer, which results to the sharp... 

Nilsson, J.L., Fouling of an ultrafiltration membrane by a dissolved whey protein concentrate and some whey proteins, J. Membr. Sci., 36, 147, 1988. 

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

Gesan, G., Daufin, G., Merin, U., Labbe, J.-P., and Quemerais, A., Fouling during constant flux crossflow microflltration of pretreated whey. Influence of transmembrane pressure gradient, J. Membr. Sci., 80, 131, 1993. 

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. 

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