A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering

Thesis (M.Eng.) - Asian Institute of Technology, 1996

Laboratory-scale crossflow microfiltration experiments using artificial calcium carbonate powder (D50 = 14.23 om) suspensions, distilled water and a microfiltration filter of 2 om pores were carried out to study the effects of operating parameters such as filtration pressure, crossflow velocity, feed concentration, and temperature on steady (quasi-steady) state filtrate flux. Higher pressure generally resulted in a higher flux (when the crossflow velocity were in the range of 2.89 to 4.33 mis), while a higher pressure under a higher crossflow velocity of 5.78 m/s resulted in a lower flux. Higher crossflow velocity (in the range of 4.33 mis to 5.78 m/s) generally resulted in lower filtrate flux. An obvious critical concentration (500 mg/l in this study) was found that the effects of concentration on flux are reversed in most of the experimental runs. A very dilute suspension generally results in a lower flux. The effect of temperature on flux did not show a definite tendency and it was believed that the effect of temperature on filtrate flux can be reversed before and after the formation of cake filtration. An interaction of different operating parameters seems dominating the cake formation and the timing of the formation of cake filtration is of prime importance on the consequent filtrate flux. By using multiple regression, it was also found that the relative significance of different operating parameters can be different under different operating conditions.