Selecting the Right Filtration System

Each application requires a specific filtration characteristic. Choosing the right filtration device and media are necessary when selecting the correct filtration system. The following considerations help when deciding which filter device is to be used:

• Objective of filtration.

• Filter parameters required: permeability, capacity and flow rate.

• Physical conditions to which the filtration is required to be subjected.

• Tangential flow filter or dead-end filter.

The choice of filter material, pore size and physical conditions depends on the following factors:

• The chemical and physical condition of the feed.

• Size and shape of molecules.

• Zeta potential and isoelectric point. Filtration carried out at a pH close to the isoelectric point results in reduced electrostatic interactions.

• Hydrophobicity or hydrophillicity.

• Solvent in which solute is dissolved.

• Properties of the filter feed, pH, viscosity, surface tension, ionic strength, osmolarity and chemical functionality.

• Intended use after filtration of the sample

Choice is always application specific. For example, in the bacterial examination of water, the purpose is to retain all the particles on the filter surface. A deadend filtration is used on a 0.2 |im filter. The cross-flow filter is useful for concentrating particles with the removal of solvent. In selecting the filtration system, it is necessary to always consider yield, simplicity, technical reasons and cost.

In some applications, using a combination of different filtration techniques in a certain order is the most efficient method. Sometimes it helps to pre-treat the solution to be filtered. The pretreatment could include coagulation and flocculation, magnetic treatment, pH adjustments, and an electric field. A proper washing procedure is usually employed to have the most efficient filtration.

Two filters supplied by Pall Corporation are shown in Figures 2 and 3.

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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