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Ultra Filtration – The Membrane Problem Solver

There are very few innovations in the water treatment market these days. Sure the electronic controls have gotten more intuitive and compact, that is about it. Ion exchange hasn’t really made quantum leaps into this either. So before I depress my fellow colleagues and influence young people to seek another career path, there is one exciting application of an innovation that really works, Ultra Filtration (UF). UF isn’t something new, but the membrane technology that makes it work has been refined and tamed over the years. For this Blog, I want to discuss its light commercial applications as they relate to problem well water.

Ultrafiltration membrane fibers that have been magnified
Magnified Ultrafiltration Membrane Fibers

What is an UF filter?

For the uninitiated, a UF filter at first glance looks similar to a Reverse Osmosis membrane, only because it shares the same membrane housing. But that is where it stops. Same on the outside, vastly different on the inside. A UF filter is a bundle of tubes tightly bound together. A UF membrane system doesn’t require pumps and storage tanks like an RO. Depending on conditions your typical 4”x40” UF membrane can yield 7gpm service water and require a backwash every 100-400 gallons of processed water. A UF will effectively filter down to .025 micron. .025 micron is where virus and cysts live! GONE!

What is a good UF application?

Basically, UF’s are applied to water with color or sediments that are not being removed by conventional 1 micron or larger filtration, or sediment that takes days to settle out. In the past a professional would feed Alum into 120-gallon tank(s) to coagulate, precipitate, then filter. Quite messy and labor intensive. Now you can send the same water right through the UF membrane. The result is sparkling clear water. Let me rephrase that, AMAZINGLY clear water. Only use treated water to backwash a UF filter. Failure to use treated backwash water will cause the membrane to foul. Since the backwash cycle is only 30 seconds and uses only 3 gallons of water, most people add a large pressure tank (40 gallons with 15-gallon draw down) after the UF to act as the clean water storage. Short comings? What won't this membrane miracle handle? AVOID anything that "grows." Iron, manganese and sulfur bacteria, for example, could clog the membrane. Oil and grease is also a poor choice. Consider a UF on your next "murky" water job. Be AMAZED.

Posted on October 4, 2011 by Tom Dupnik | Tags: ,

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