MF/ UF (microfiltration/ ultrafiltration)

Gemwater is able to design and install MF and UF plants. The principle of these technologies is the physical separation through membranes.
Microfiltration and Ultrafiltration require low transmembrane pressure to operate. Both processes remove suspended solids and other substances from water to a lesser extent than Nanofiltration and Reverse Osmosis.

The degree to which suspended solids, organic matters, turbidity and microrganisms are removed is determined by the size of the pores in the membranes. Substances that are larger than the pores in the membranes are fully removed, while substances that are smaller than the pores of the membranes are partially removed.

UF / MF membranes can operate in either crossflow separation or dead-end filtration. Cross flow separation is where only part of the feed stream is treated and the remaining of the water is passed through the membrane untreated. In dead-end separation, all of the feed water is treated.
Typical recoveries can range from 85% to 95%.

Membranes with a pore size of 0.1 – 10 µm perform micro filtration. Microfiltration membranes remove all bacteria and part of the viral contamination.
In terms of pore size, MF fills in the gap between ultrafiltration and granular media filtration.
Typical applications of Microfiltration are:
pre-treatment of water for Nanofiltration or Reverse Osmosis;
cold sterilization of beverages and pharmaceuticals;
separation of bacteria from water (biological wastewater treatment);
effluent treatment;
separation of oil/ water emulsions;
turbidity reduction;
removal of Giardia and Cryptosporidium;
solid/liquid separation for food or pharmaceutical industries.

For complete removal of viruses, ultrafiltration is required. The pores of Ultrafiltration membranes can remove particles of 0.001 – 0.1 µm from fluids.
Examples of fields where ultrafiltration is applied are:
pre-treatment of water for Nanofiltration or Reverse Osmosis;
removal of viruses, color, odor and some colloidal organic matter;
drinking water;
wastewater treatment and reuse;
membrane bioreactor (MBR);
dairy industry (milk, cheese);
food industry (proteins);
metal industry (oil/water emulsions separation, paint treatment);
textile industry.

Most UF membranes use polymer materials (polysulfone, polypropylene, PVDF, cellulose acetate), however ceramic membranes are used for high temperature applications.

One of the most important use of ultrafiltration lies in the application of membrane bioreactors (MBR) for wastewater treatment. The combination of activated sludge with membrane separation in the MBR results in efficiencies of footprint, effluent quality and residuals production that cannot be obtained when these same processes are operated in sequence.