An Overview of Filtration

Understanding how different filtration methods work leads to a more informed decision when selecting a filtration system Filtration is arguably the most commonly used unit operation in the chemical process industries (CPI). The range of applications for this important unit operation is very broad — everything from beverage clarification to solids removal from mining ores. If you are associated with the CPI, it is highly likely that you are involved with filtration in some form. This article provides an overview of filtration technology, with an emphasis on solid-liquid separation. Definitions Filtration is the physical separation of a solid from a liquid or gas. Although an explicit discussion of gas filtration is outside the scope of this article, the basic concepts discussed here are applicable to gases as well as liquids. The principle of filtration is depicted in Figure 1, which shows a filtration medium situated inside of a housing. Feed is delivered to the housing upstream of the medium, and a pressure difference across the medium is applied. By virtue of this differential pressure driving force, liquid (or gas) passes through the medium and solids are retained. In practice, this simple model is applied in a number of ways,…