WHEY CROSS-FLOW MICROFILTRATION USING AN M14 CARBOSEP MEMBRANE - INFLUENCE OF INITIAL HYDRAULIC RESISTANCE

Membrane hydraulic resistance (Rm) for the same nominal M14 Carbosep membrane (pore diameter 0.14 gm) was found to vary significantly from 0.85 +/- 0.05 to 1.22 +/- 0.09 10(12) m-1. Pretreated whey microfiltration experiments carried out using these new membranes resulted in shorter operating time and lower protein transmission for the low Rm membranes. When the same membrane was used new, irreversibly fouled or cleaned (Rm = 1.14, 2.48 and 1.26 10(12) m-1 respectively) fouling evolution was positively correlated with Rm increase. It was assumed that a low Rm of a new membrane indicated a larger population of large pores which under constant permeation flux experiments filtered larger volumes and thus fouled faster. Residual fouling after cleaning was found to have a negative effect on performance presumably due to alteration of the membrane's morphological characteristics and to electrostatic and hydrophobic interactions of the feed stream with the residual fouling layer.