Different Types of Filtration Techniques

Filtration did not find relevance until about 500 BC when Hippocrates observed value in purifying water and constructed what he referred to as the ‘Hippocratic Sleeve,’ the first bag filter. Beyond trying to obtain pure water, filtration has found use in a wide variety of forms, from separating foreign solids from a fluid to even isolating substances from mixtures such as when gases or oil mix with other fluids.

Since the Hippocrates Sleeve, there have been progressive methods and techniques for filtration, one of which includes a process of filtration that utilizes sand and gravel as recorded by a ‘Sanskrit’ writing from the 4th Century CE. If you have any idea how technology handles filtration now, then you must see that there has been quite the advancement in filtration structures in contrast with the previously mentioned system. Nonetheless, some of these present-day technological efficiencies in filtration are simply a somewhat modernized form of an orthodox filtration system.

Here are different types of principal Filtration Techniques in 2020

  • Gravity Filtration

This filtration technique is an operation commonly practiced in chemical settings. It primarily involves the use of a filter medium, specifically, a filter paper which allows the passage of the fluid alone. The process is kickstarted by placing the filter paper in a funnel fitted to an iron ring and overlaid on a beaker. The process continues by pouring out the liquid into this setup through the filter paper. That is where the name of the technique comes in as gravity ensures that the fluid passes through the pores of the filter paper and accumulates in the beaker while most of the solid particles will remain atop the filter paper.

  • Vacuum Filtration

This technique of filtration finds substantial similarities with gravity filtration in that they both make use of a filter and a filter paper. The difference between them lies in the force which propels the extraction of the fluid into the beaker. Of which for gravity filtration, it is the gravitational force of the earth, whereas vacuum filtration invokes the use of a pressure gradient as that force, and it does this by the aid of a “Buchner’ Flask.” The flask utilizes a vacuum line or aspirator to appropriately draw the fluid through the filter paper into the container. That granted it its other name, suction filtration. The variable rate of suction and general appeal makes it a more proficient choice for gravity filtration.

  • Centrifugal Filtration

The governing concept of centrifugal filtration is the ‘Centrifugal Force,’ and it refers to a naturally occurring force experienced by an object moving in high-speed rotational motion or along a circular path. This inertial force tends to focus the object away from the center of rotation. This effect is responsible for the separation of the states in a mixture. Engineers achieve this effect using specialized equipment that spins measured amounts of fluid in a rotating drum. Whatever solid is in the fluid, because of the impact of centrifugal force spinning the fluid in the drum, sticks to the walls of the machine while the liquid ejects into a storage mechanism.

  • Hot Filtration

Application of this filtration technique is generally for a specific condition, especially, which is for solutions that will crystallize if left to cool. Crystallization is detrimental for filtration as it can clog the funnel and hinder filtration. The entire process is quick and heated continuously to avoid cooling and eventual crystallization in the funnel. To aid this cause, professionals make use of fluted filter paper in place of the quadrant-folded counterpart as well as short-stem or stemless filter funnel.

  • Cold Filtration

Contrary to hot filtration, this method comprises using ice baths to chill the fluid rapidly, which in turn accelerates crystal formation as opposed to a slower room temperature cooling. Cooling the liquid at room temperature usually results in the creation of large crystals that are not desirable for usage in industries such as beer companies, who apply cold filtration to specific fluids to form small protein clusters that they separate and make use of.

  • Granular Media Filtration

This type of filtration technique is common to present-day wastewater treatment industries as a pretreatment for filtration, but it has been in use orthodoxly for quite some time. It consists of a bed of media that is typically granular such as sand, anthracite, or gravel. When fluid flows through the setup, solid particles suspend and are at the end, physically removed.

  • Mechanical Filtration

In comparison with chemical and biological filtration, mechanical filtration is relatively simple. It involves the use of a pump to push fluid through a filter element that traps any unwanted solid suspended in the liquid. Some of the most used filter elements during mechanical filtration are; Porous sintered metal elements, stainless steel woven mesh filter cartridge, cartridge filters, Wedge mesh filter element, filter cloth, bag filters, and filter pads.

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