Microfiltration uses microporous membrane to remove
contaminants from a fluid. The function of microfiltration in principle
is as same as that of reverse osmosis, ultrafiltration and
nanofiltration. The difference lies in terms of retention of the size of
molecules. The pore size of microfiltration membrane range from 0.1 to
10 µm.
Through microfiltration, suspended solids, bacteria or other impurities
can be easily removed. The membrane used in microfiltration is porous
enough to pass molecules of true solutions, even if they are large. Due
to the small pores used in microfiltration, it can be used for
sterilizing solutions.
Mechanism and Properties of Microfiltration
Adsorption and entrapment are the mechanism used for the conventional
depth filtration whereas, microfiltration uses sieving mechanism. The
filter with different pore sizes are used for retaining larger size
particles than the pore diameter. This technology therefore can be used
for various critical operations like sterile filtration of parental
fluids, free-water for the electronics industry etc.
The materials used for making microfiltration membranes are natural or
synthetic polymers like cellulose nitrate or acetate, polyvinylidene
difluoride (PVDF), polyamides, polysulfone, polycarbonate, polypropylene
etc. Apart from this some inorganic materials like alumina, glass,
zirconia coated carbon etc. are also used for manufacturing the MF
membranes.
Applications of Microfiltration
Microfiltration produces of high purity and quality. The applications
include:
Water Treatment and production
- Prior to other membrane treatment they are used for the
pretreatment of surface water, seawater and municipal effluent.
- They are useful for producing
- Drinking water
- Irrigation
- Industrial water reuse and makeup water
Dairy industry
Microfiltration
is used for removing bacteria and spores from cheese milk, milk for
powder production and market milk- They also serve the same functions for whey
- They help in the fractionation of milk proteins
- For high protein WPC they serve the purpose of defatting the whey
- For sanitation of cheese brine, they remove bacteria, spores,
yeast and mould.
Others
- In chemical industry
- Microelectronics industry
- Fermentation
- Producing sterile water for pharmaceutical industry
- Food & beverages industry where the process is used for
concentrating fruit juices and alcoholic beverages.
- For biomass concentration and separations of soluble products
- Separates solvents from pigments in paints.
Case Study
Lake Erie Continuous Microfiltration Plant Ontario Canada
