Microfiltration is a very efficient technology for separating solids and recovering products from all types of liquids. Microfiltration retains a smaller particle size than a conventional filter; cartridges used for microfiltration have a pore size of 0.1–20 µm. As the pores are so small, an additional advantage of these filters is that they retain bacteria and viruses. Despite the fact that viruses are smaller than the pores of a microfiltration membrane, retention is possible because viruses are coupled to bacteria.
Microfiltration can be applied to many different types of water treatments when particles with a diameter in excess of 0.1 mm need to be removed from a liquid.
Some examples of uses:
• Pre-treatment of water for reverse osmosis.
• Treatment prior to ultraviolet sterilisation.
• Separation of water and oil emulsions.
• Cold sterilisation of beverages and pharmaceutical products.
• Clarification of fruit juices, wines and beers.
• Effluent treatment.
• Solid-liquid separation for pharmacies and the food industry.
In drinking water projects, microfiltration is mainly used as a pre-treatment for a finer process, such as reverse osmosis. It can also be used by itself for making surface water potable.
In waste water projects, microfiltration can be used instead of a secondary clarifier, such as in biological membrane reactors. It can serve the same purpose in the treatment of soapy water, to separate suspended solids from the water before continuing with the process.