FLUX ENHANCEMENT BY AIR DISPERSION IN CROSS-FLOW MICROFILTRATION OF A FINE COLLOIDAL SYSTEM THROUGH SPIRAL WOUND MODULE

摘要

To increase the permeate flux by air dispersion in cross flow microfiltration with spiral element, an air-liquid two phase flow has been investigated. Fouling of membranes due to cake formation by colloids is the major cause of flux decline in the MF process. In recent years significant research work has been carried out to enhance membrane processes. For this purpose, different techniques like modification of membrane surface and change of hydrodynamic conditions have been used. The technique of air dispersion has been found successful for the control of fouling in ultrafiltration and cross flow microfiltration with tubular and hollow fiber membranes for various systems of suspensions with high loads of solid matter. The control of fouling in the cross flow microfiltration of liquids with low loads of fine particles still needs to be studied extensively. This paper focuses on the increase in permeate flux by air dispersion in cross flow microfiltration with a spiral wound element for a suspension consisting of fine particles in the size range between 100 nm to 1 urn with a low concentration of 0.3-0.5 percent w/v of the particles. Yeast suspension was used as a model system for comparison of results due to its know granulometric properties. Different air-to-liquid ratios were applied during the microfiltration process. It was found that the permeate flux increased up to 80% as compared to the permeate flux attained when microfiltration was conducted without air dispersion. It is concluded from the experimental results that air dispersion is effective in enhancing the permeate flux by reducing the rate of particle deposition on membrane surface in a spiral wound module for fine systems of suspensions.