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Controlling Bioburden Levels in Biopharmaceutical Production


Microorganisms are the heart of biopharmaceutical operations. They will be present in many of the fluid streams and a desired component in some. You can read more information below about filters and their use in controlling organisms in places they are not wanted, or go to the product selection table at the bottom of this page to review bioburden control filter options.


From the cell harvest process on downstream, any viable microorganisms are an undesirable contaminant in the process stream. Removing at least some of the organisms will protect downstream processes.

Bioburden Control

Bioburden control is also part of the prefiltration process for final product formulation and filling. The final filters, as described in the Sterilizing Filtration page, must be protected from premature fouling by an excess of particles or bacteria. Bioburden control filters are designed into the system to remove most, but not all bacteria. The sterilizing filters are then able to perform their function for an entire batch of product without fouling and causing undue difficulties with batch processing.

It is important to understand that bioburden reduction does not imply complete bioburden removal. These filters are in place to reduce the amount of bacteria and prevent contamination of downstream processes and/or premature fouling of final, sterilizing filters. Bioburden control filters are usually membrane-based filters with pore sizes of 0.45µm to 0.80µm. The filters capture the bulk of the organisms, though not all.

Some users will design systems with the intention of having the bioburden reduction filters act as preliminary sterilizing filters, meaning they are intended to remove all of the bacteria that are expected to be in the system. The final, sterilizing filters are then in place only as a final insurance policy against system upset.. This is a conservative approach that increases the safety of the final product, though it is not a required design according to regulatory authorities.

Sources of Bioburden

While microorganisms are an inherent part of the biopharmaceutical process, additional, unwanted bacteria may enter any system with materials from outside sources. However, the most likely source of microorganisms is the environment in and around the facility. Molds, yeasts and bacteria that are endemic to the plant location are also likely to enter the processes. They may be carried by plant personnel or simply come in with the air.

The type of organisms will depend on the type of environment and climate. A warm moist environment may have numberous molds and bacteria. Dry or cooler environments may also have these, but perhaps in lower numbers, making control somewhat less complex.


Bioburden Reduction Filters in Biopharmaceutical Production

Custom systems are designed for new applications and to solve challenges in existing processes. Critical Process Filtration will work with you to design, build and install a cost-effective system that delivers the results you need. Contact us or visit our custom filtration systems page for more information.


Choosing the Right Filter

The choice of filter to use for bioburden reduction is based on the organisms likely to be found in the process. As mentioned above, both organisms used in the processes and those endemic to the location of the facility (molds, airborne bacteria, yeasts, etc) will be the likely targets of bioburden control filtration. Depending on the size of the organisms, membrane filters with 0.65μm, 0.45μm or 0.22μm ratings may be used. In some cases, operators may choose the bioburden reduction filter based on its ability to remove all of the bacteria that are likely to be found. The sterilizing filter, in those cases, is purely an insurance policy against system upset.

Application Summaries

Critical Process Filtration has multiple filter options for removing bacteria and other microorganisms. To read more about these filters and bioburden reduction and control in biopharmaceutical production, click on one of the links below. Critical Process Filtration has created short explanations of how reducing bioburden is one step in assuring product quality and safety.


The table below shows filter technology options for bioburden control from Critical Process Filtration with links to more detailed data on the filters. Click on the in the appropriate location to download a data sheet for the filter media and configuration that fits your needs.

Media Code Filter Media Filter Grade Cartridge Data Sheet Capsule Data Sheet Disc Filter Data Sheet Pore Sizes Available (µm) Features
PPS Double-Layered Asymmetric Polyethersulfone (PES) Membrane Pharmaceutical
0.03, 0.1, 0.22, 0.45, 0.65, 1.8, 1.0, 1.2 Symmetric, hydrophilic PES membrane for high efficiency filtration of water.
BPS Asymmetric Polyethersulfone (PES) Membrane Biopharmaceutical
0.03, 0.1, 0.22, 0.45, 0.65, 1.8, 1.0, 1.2 Highly asymmetric, hydrophilic PES membrane in single-layer configurations for high efficiency, high flow rates and low product absorption
PNM Nylon 6,6 Membrane Pharmaceutical
0.1, 0.22, 0.45, 0.65 For bacteria removal in pharmaceutical processing. For bioburden reduction and sterilizing filtration.
BNM Nylon 6,6 Membrane Biophamaceutical
0.1, 0.22, 0.45, 0.65 For bioburden reduction in water and feedstocks.
BCWPS High Capacity Polyethesulfone (PES) Membrane Biopharmaceutical
0.22, 0.45, 0.65, 1.2 High void volume membrane for bioburden reduction and protection of sterilizing grade filters
BPVWL High capacity, Hydrophilic Polyvinlyidene fluoride (PVDF) Membrane Biopharmaceutical
0.22, 0.45, 0.65, 1.2 High void volume membrane with high holding capacity for systems that may have high particulate loads
BBC Blended Cellulose Membrane Biopharmaceutical
0.22, 0.45, 0.65, 1.2 High flow membrane for bioburden reduction and fine particle removal

To estimate the number of filters you will need for your application, use our unique sizing tools.

The filter media used for each process must, of course, be compatible with the fluids used in it. Contact Critical Process Filtration for assistance in determining the compatibility of filter media and support materials with your process.