A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering, School of Environment, Resources and Development

Thesis (M. Eng.) - Asian Institute of Technology, 1987

Crossflow microfiltration is a pressure driven membrane process in which the fluid to be filtered flows parallel to the membrane surface, which reduces the formation of filter cake allowing better permeate flow. Laboratory-scale microfiltration experiments with kaolin clay and latex suspension were carried out to study the membrane filter performance with respect to operating parameters. The operating parameters choosen were membrane pore size , particle size , particle concentration, crossflow velocity and applied pressure. It was found that clogging in the membrane occurs fast in case of bigger membrane pore size and finer particles. Also the existence of a optimum crossflow velocity (for which the filtration rate is maximum) was noticed . This filtration rate could be increased by increasing the module entrance pressure . The filtrate quality continued improving as the filtration proceeds. In this study, a mathematical model was formulated to predict the filtrate efficiency of the membrane filter. The developed model , was verified with the laboratory-scale experiments. The filtrate efficiency predicted by t his model differed from that of experimental value as t he assumptions made in t he development of model were suitable only for ideal cases. Also an empirical model to correlate the membrane fouling of different pore sizes was found. A standard curve was developed between percentage of pores blocked and total solids deposited on the membrane, to predict the fouling of t he membrane of different pore sizes which may be useful in extrapolation of data.