Depth Filter

In depth filtration, the filter medium has larger pores than the particles it is meant to remove. The process starts out at the surface of the filter and proceeds in the cake portion of the membrane. The medium traps the particles in the interstices of the internal structure. Particles enter into the filter medium and separate by gravity settling, diffusion, and attachment to the media owing to electrostatic forces. These filters usually have a pressure drop across the filter caused by pressure, vacuum, or cen-trifugation. These filters usually have a long life, but

Figure 1 Tortuous path of micro- and ultrafiltration.

eventually a cake is formed over the medium stopping the flow through the filtration device. When the filter bed is full of solids and the pressure drop is very high, the entrapped solids can be back-washed. Usually less than 0.1% solids concentration is filtered through this type of filter to avoid pressure build up. There is always some liquid left behind in depth filters and some solid material still makes it through the filter medium depending upon the efficiency of the system. To use the system effectively, variations of this procedure using moving-bed filters, radial flow filters, or travelling back-wash filters can be employed. The commercial products available for this kind of filtration are application specific.

Solar Panel Basics

Solar Panel Basics

Global warming is a huge problem which will significantly affect every country in the world. Many people all over the world are trying to do whatever they can to help combat the effects of global warming. One of the ways that people can fight global warming is to reduce their dependence on non-renewable energy sources like oil and petroleum based products.

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