Microfiltration

MF is the most open cross-flow filtration device, with pore sizes from 3 microns to 0.1 microns. Typical application of this low pressure process is the removal of high molecular weight compounds such as bacteria, fats, yeasts and fungi: clarification of chemical, biological, pharmaceutical or food solutions, product purification, waste water treatment.

Ultrafiltration

UF is a low pressure process for selective filtration of molecules of specified size and weight. Material ranging in size from 1000 MW to 1.000.000 MW are retained by UF membrane while lower molecular weight compounds, salts and water are passing through. Typical applications of UF membrane are concentration and recovery of high molecular weight compounds separation/removal of contaminants, clarification, removal of colloids and suspended solids, thus being used as pretreatment for reverse osmosis units.

Nanofiltration

NF is a pressure driven process similar to RO applied in the area between RO and UF. Monovalent ions and low molecular weight organics are passing through the membrane, while bigger compounds are rejected. MW cut off of a NF membrane is in the range 150-500 and typical application is in pharmaceutical preparations, removal of colour, of hardness from water.

Reverse osmosis

RO is a high pressure separation process to remove low molecular solutes (salts, small organics molecules) from a solvent (water). The separation occurs with an imposed pressure higher than the osmotic pressure, forcing the solvent to pass through the membrane while the solute is rejected, monovalent iones included. Operating pressure are required in the range up to 100-120 bar.