Reducing the bioburden is not the same as removing all bacteria. In fact, removing all bacteria, otherwise known as sterilizing filtration, is defined by a different set of performance measures and is usually only performed as the last filtration step before final product packaging.
Reducing the number of organisms, the "bioburden" is done by using filters similar to those used for sterilizing filtration, but the performance requirements are not as stringent. That does not mean that bioburden control is a secondary consideration. Reducing the bioburden in a system keeps the system operating more efficiently and, most important, protects the expensive sterilizing filters from excessive loading which would shorten their life and increase costs.
Sources of Bioburden
While bacteria and other microorganisms may enter any system with ingredients from outside sources, the most likely source is the environment in and around the facility. Molds, yeasts and bacteria that are endemic to the plant location are more 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. 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.
Filters in API Production
The figure shows the possible locations of several bioburden reduction filters. Reducing the possible bioburden that might be in product components is seen on the left. These filters are not specifically protecting downstream filters, but assuring the quality of the product components. They protect process integrity.
Protecting final product quality requires that the containers are clean and bacteria-free. The wash systems to the right in the figure clean and rinse the containers so that the final product is pure. The highlighted bioburden reduction filters are there to protect the more expensive and critical sterilizing filters used for wash solution and rinse water.
The most critical of the bioburden reduction filters is in the center of the figure. It is protecting the final, product sterilizing filters. The filter combination is designed as a single functioning unit that removes all bacteria. The design is based on the expected bacterial load and the organisms that make up that load.
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. In general, as mentioned above, organisms 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.
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 API 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|
|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|
|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.|
|BNM||Nylon 6,6 Membrane||Biophamaceutical||0.1, 0.22, 0.45, 0.65||For bioburden reduction in water and feedstocks.|
|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.|
|BCWPS||High Capacity Polyethesulfone (PES) Membrane||Biopharmaceutical||0.2 single layer, 0.5 single layer, 0.5/0.2 dual layer||High capacity membrane with single or dual layer configurations for bacteria and particulate reduction, low product adsorption and protection of final 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.