In this work, different kinetic patterns (homographic, exponential-linear and exponential) of hydraulic resistance in ultrafltration process of a colloidal system have been investigated. Exponential kinetic model, as the best approach, was employed for description of dynamic hydraulic resistance of skim milk ultrafltration at different feed flow rates (FR) (10, 30 and 46 L/min), transmembrane pressures (TMP) (0.3, 0.6 and 1 atm), temperatures (30, 40 and 50°C), pH levels (5.6, 6, 6.6, 6.9 and 7.6) and NaCl concentrations (0, 0.03, 0.06 and 0.12 %w/w). Results indicated that the initial resistance (R0), steady-state resistance (R∞), resistance increment rate (k) and resistance increment extent (RE) increased with TMP and ionic strength increasing and FR decreasing. The most sensitive factor for prediction of RT (total hydraulic resistance), R0 and R∞ was the NaCl concentration. Also, the highest sensitive factors for RE and k were temperature (0.77) and TMP (0.60), respectively.

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