Theoretical approach was attempted for membrane separation of milk and milk products, which are multi-component systems, with special reference to reverse osmosis of cheese whey.
Equations of membrane transport and concentration polarization for multi-component systems have been applicable in the case without fouling. In the application of the equations for milk products, the terms of molar concentration of the solutes, average molar mass, average solute density were required and the theoretical approach was attempted on reverse osmosis concentration of whey, UF-permeate and whole milk in the present review.
In membrane separation of milk products, we encounter the fouling phenomena. There are at least three factors to cause fouling as follows; (1) solute component
i (2) concentration of
i component in the solution (
c1i) (3) limiting concentration of i component (
c1i lim) to cause fouling. Since all components in milk products have not been analyzed as regards to the various complex form in milk and the conditions to cause fouling have not been quantitatively analyzed, the concerned three factors have not been defined theoretically. However, the limiting concentration of solute on membrane surface (
c1i lim) was determined by the experimental analysis at the moment to generate fouling applying average mass transfer coefficient.
When the reverse osmosis cost, which varies dependent upon the volume flux level, was analyzed keeping
c2, value to the constant level according to the equation for concentration polarization, the cost for 1 m
3-permeate removal was expressed as a function of volume flux only. The optimum operating conditions, to minimize the operation cost, were concluded to be defined from the present theoretical approach.
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