Filtration: Objectives, Applications, Theories & Factors Influencing Filtration : Pharmaguideline

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Filtration: Objectives, Applications, Theories & Factors Influencing Filtration

Separating solids from liquids and gases is the main goal of filtration. To remove contaminant particles from dispersing fluid.



  • Separating solids from liquids and gases is the main goal of filtration. It also includes:
  • To remove contaminant particles from dispersing fluid so that it can be recovered.
  • By removing the dispersing fluid, solid particles can be recovered.
  • Solvents and solids must be of high quality.
  • Particulates can be removed from the air to enable pharmaceutically useful gases to be purified.
  • It is used to sterilize parenteral thermolabile products.

Applications of filtration

Water purification

The most common application of filtration is for the purification of pharmaceutical water. Pharmaceutical industry water must meet a number of specifications found in official pharmacopeias. Here, it is important to distinguish between sterile water for injection, sterile water for injection, and pure water for injection. A filter must first be installed in order to produce potable water that is compliant with these standards. As a secondary treatment step before disinfection, filtering is commonly performed to remove residual biological floc from settled effluents resulting from metal salt precipitation or lime precipitation or phosphate precipitation.

Pharmaceutical industry

Separating materials of different chemical compositions is accomplished through filtering, which is a physical operation. Purifying compounds with this technique is a very important part of a chemist's arsenal. By using filtration, a number of enzymes, amino acids, antibiotics, pharmaceutical intermediates, bulk drugs, medicine, blood products, antibiotics, calcium phytate, Chinese inositol, sand-derived growth, organic phosphorus, glucoamylase, etc. can be purified. A filter and biological digestion device can be combined to process the feed stream simultaneously, such as in the bio-filter.

Biopharmaceutical industry

Filtration is a common technique for removing contaminants from liquids, gases, and air in the biopharmaceutical industry.

Chemical industry

A variety of substances are separated and purified through filtration, including dyes, pesticides, silicic acid, glycerin, white carbon, sodium carbonate, additives, additives, basic chemicals, chemical fillers, pigment, white alumina, manganese, caustic soda, soda ash, mud, saponins, and graphite, among others.

Food industry

Filters have been used to remove particles of unwanted matter from wine, yeast, fruit juices, edible oils, vegetable oils, sugar mills, rice wines, white wines, fruit juices, soft drinks, beer, yeast, citric acid, vegetable protein, plant density sweeteners, glucose, etc.

Environmental engineering

A filter can be used to separate chemical wastewaters, mining wastewaters, domestic wastewaters, leather wastewaters, and salt mud wastewaters.

Clay industry

Activated clay, clay, electronic ceramics clay, kaolin, bentonite, and clay are all separated and purified through filtration.

Heating, ventilation, and air conditioning

Filtration removes micro-organisms, particulates, and volatile organic compounds (VOCs), as well as allergens present in poor-quality air responsible for respiratory illnesses, allergies, asthma, and sick-building symptoms. These triggers are ideally eliminated or dramatically reduced by HVAC filters in buildings. Commercial and institutional buildings can achieve green-building milestones by taking advantage of air filtration technologies that provide superior air and reduce energy costs.

Making new food and beverage products

A microfilter with pore sizes of 0.1 to 20 microns efficiently removes bacteria and spoilage organisms from milk. The molecules of protein molecules which can be retained and added back to fluid milk after ultrafiltration could affect the appearance and sensory properties of the milk. Ultrafiltration units with pores smaller than 0.01 microns have been found to have this effect.

Cane and beet sugar industry

Microfiltration and ultrafiltration are two processes used to remove impurities from cane sugar, such as starch, dextran, gums, waxes, proteins, and polysaccharides, that would otherwise be removed by other separation procedures.

Factors Influencing Filtration

Thickness of filter cake

The thickness of the filter cake affects the rate of flow of filtrate through it. It may be necessary to perform a preliminary decantation in order to reduce the solids and, as a result, increase the filtration rate.

Particle size of solids

Larger particle sizes will generally increase filtration rate (kg/m2/h). The filtration rate is high when average particles are small and the distribution range is narrow.

Flocculation/dispersion of fine solids

The flocculation of fine solids in slurries that are poorly filtered or are dispersed is generally desirable. There is room for significant improvement in filtration rates with the wide variety of polyelectrolyte flocculants. Strong agitation is needed when using flocculants, especially polyelectrolytes, in order to achieve good solids-flocculant contact. The agitation must be kept to a minimum and the aging must be kept to a minimum. There are some slurries that are so viscous that dilution will not be an effective way of gaining fluidity, so a dispersant may be a better option.

Slurry age

In some processes, detention times can modify filter performance through a conditioning effect. When samples are stored for a longer period of time, they may experience some filtration problems as a result of excessive aging.

Agitation speed

The test slurry container or the filter tube tends to classify some slurry, particularly when there is a wide particle size range. If possible, the agitation (or stirring) should be increased to a point where fine and coarse particles are thoroughly mixed. When the speed is too high, cake thickness may be limited, coarser particles may not form, or delicate flocs may flatten.

Cycle time

Usually, the rotational speed of a filter drum is expressed in revolutions per second or minutes. Drum speeds are usually higher the faster they turn. The cake, however, is thinner and, in some cases, wetter under these conditions, so discharge may become impaired. The cake should always be dischargeable.

Cake compression

As part of the filtration process, compressible cakes are normally compressed to reduce their moisture content.

Type of filter medium

Fabric filtering properties are largely determined by yarn type and weave. It is possible to spin monofilament yarns, multifilament yarns, or staple fiber yarns, or a combination of those. Multifilament can perform more like a monofilament if it has a high twist. A cloth's porosity and permeability are important characteristics. Frazier permeability ratings, expressed in cubic feet per minute per square foot, are a measure of air flow at half-inch water pressure through a dry cloth, and are similar to percent open area. Permeability cannot be used to determine porosity or particle retention, since porosity cannot be directly measured.
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Ankur Choudhary is India's first professional pharmaceutical blogger, author and founder of, a widely-read pharmaceutical blog since 2008. Sign-up for the free email updates for your daily dose of pharmaceutical tips.
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