Filtration removes solid particles from the liquid or gaseous state of Pharma products, that are have become infected with any contaminants. If filtration is not applied, it will affect the pharma process and the final product will become hazardous for human consumption.
The type of products that can be subject to filtration are various such as raw material, final finished product, and intermediate form of product. Some test samples used in the QC laboratory also require filtration. For specific filtration requirement, regulatory guidelines should be consulted for developing filtration strategy for a given product.
Mainly, filtration is a process that is applied as a part of a contamination control strategy for removing impurities, controlling contamination, and improving product quality. Without filtration, it is impossible to implement contamination control strategies across many pharmaceutical processes.
Different types of methods and equipment for filtration in the pharmaceutical industry exist. It depends upon the type of product, active contamination, and degree of purification required for implementing the filtration method.
Filtration methods
Let's discuss some filtration methods employed in the pharmaceutical industry.
Surface filtration
Surface filtration is the most common method in the pharmaceutical industry. In this method, impurities remain on the surface of filter media as a pharma product.
In this method, as the contaminants build up on the surface of filter media, flow decreases due to the resistance offered by the impurities. When a maximum quantity of material builds up, the surface must be cleaned to allow efficient filtration and to operate the filter equipment as per its standard speed.
During changing filter or maintenance activity, the equipment or system must be stopped and cannot be performed during equipment operation.
The filter size depends upon the filtration requirement, i.e., particle size and the speed of filtration equipment.
Membrane-based filtration systems are examples of surface filtration systems.
Depth filtration
Depth filtration is a specialized mechanism where material (to be filtered) flows downward. It is mainly used for soluble materials and suspended particles that cannot be dissolved in liquid substances.
The depth filtration system employs a wise stage mechanism, where large particles are removed at the initial stage and smaller-sized impurities are removed later.
The action of backflow in the material cleans filters. The material (to be filtered) flows in opposite directions, i.e., from product outfeed to product infeed. This enables the impurities retained on the filter surface to leave, causing the blocked pores to open. The deposited impurities are collected through discharge or reject output.
Compared to surface filtration, depth filtration equipment are expensive. However, its high price is compensated by the extended life of the operation.
Cross flow filtration
Cross filtration includes a filtration membrane that can filter impurities of sizes in the range of nanometers or below.
These types are typically used to filter out total dissolved substances.
Since the pores of the nanometer membrane are small, the filtration membrane can be affected by fouling and scaling. This can significantly decrease the filtration efficiency, so these filters require constant maintenance and inspection.
Ultrafiltration
Ultrafiltration filters out ultra-small substances, typically less than 0.01 microns. This filtration is specifically designed to filter out extremely small particles. Ultrafiltration is commonly employed at the last stage when the material has been filtered with all the large-sized impurities.
In addition to particles and impurities, ultrafiltration can remove microorganisms and bacteria.
A semipermeable membrane is often used...
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