Monthly Archives: July 2011

The Silt Density Index is most frequently used to determine fouling potential prior to RO filtration. You can think of SDI as a bouncer, keeping the riff-raff out of the RO feed water. The higher the number, the greater the likelihood of fouling. The maximum SDI number allowed depends on the type of RO membrane being used; most manufacturers recommend a maximum SDI of 4 or 5. SDI is found by calculating the rate at which a membrane filter is plugged. ASTM standard D4189-07 defines that the nominal filter for this application is a white hydrophilic MCE membrane filter, with 0.45 ?m pore size and a 47 mm diameter. The reason this particular membrane is used is that it is more susceptible to plugging from colloidal material than from hard particles such as sand, therefore giving a better indication of the factors that might plug an RO membrane down the line. Other measures that can be derived from the SDI include the plugging factor and the Modified Fouling Index (MFI). The plugging factor

Of all the membrane disc filter accessories that we carry, the static eliminator probably gets the most technical questions. Whereas items like the cytoclear glass slides and stainless steel membrane filter tweezers are very straightforward in their purpose and operation, how a static eliminator works may not be as intuitive. Static eliminators are used on Polycarbonate or Polyester membranes when they are going to be subject to precise analytical balance measurements that could be affected by the presence of static or dust particles on the filter. Static eliminators can perform this function in a few different ways, such as by using alternating current or by using small amounts of a radioactive element to remove electrons. The static eliminators that we carry use a naturally occurring radioactive element called Polonium-210 (It was discovered by Marie and Pierre Curie and named after Marie Curie’s homeland of Poland) in order to function. This type of static eliminator is referred to

This study from the ACS journal Applied Materials & Interfaces has been making headlines recently for introducing a new way to purify drinking water. Scientists from Rice University have created a new filter material, dubbed “super sand,” by coating regular sand with the nanomaterial graphite oxide. Their tests have shown that this super sand has the potential to be a cheap form of water filtration for developing areas.

The use of sand as a water filter isn’t anything new – it’s actually been done for around 6,000 years. However, by combining this old world technique with cutting edge nanotechnology scientists have made sand filtration at least 5 times more efficient. Their report indicates that the modified sand adsorbed 6 times the amount of liquid mercury and 5 times as much heavy metal and organic dye than regular sand. In addition to the improved filtration capacity, there are other benefits of super sand that increase its prospects for real-world integration. The materials needed