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Operations in the biopharmaceutical industry often use normal flow filtration (NFF) to clarify, polish, and reduce bioburden when purifying biomolecules. This process helps to separate colloidal materials, viruses, and bacteria for complex mixtures such as bioprocess intermediates and cell culture media. We offer filtration solutions and support for bioprocessing applications at every step and every scale of the drug development, validation, and manufacturing process. There are three major categories of NFF operations:

Buffer filtration

Buffer solutions are key components of almost all biopharmaceutical production processes. This makes buffer filtration the most common filtration operation. During bioreactor operation, buffers help control pH and osmolality of cell culture media. At cell harvest, buffers precondition filters to aid in product recovery. Chromatography separation processes use a broad range of buffers for column conditioning, elution, and regeneration. Buffers are also an integral part of automated clean-in-place (CIP) operations. Biological contaminants in buffers have a great impact on process efficiency. Buffer filtration is key to protection of chromatography columns and ultrafiltration operations and to production of an endotoxin-free final product.

Cell culture media filtration

A key operation in any biopharmaceutical process is the preparation of cell culture media. This operation includes sterilization of the growth media to prevent contamination. Cell culture media are buffered solutions that contain nutrients like vitamins, amino acids, and energy to promote optimal cell growth. When selecting cell culture media filters, consider the following:

  • Low extractables: Media filters should not only retain contaminants but also be biologically and chemically compatible with cell culture media.
  • Low nonspecific binding: Membranes used in media sterilization should feature low nonspecific binding. This helps minimize the chances of accidental removal of important media supplements during filtration.
  • High permeability: Highly permeable filters offer increased throughput to reduce filtration for bio-processing batch times.
  • Physical robustness: Filters should be able to withstand physical, thermal, and chemical stress.
  • High capacity: Go for sterile media filters with high-capacity ratings. Sterilizing grade filters often have on-board prefilters with pore sizes of 0.4 to 0.8 microns.

Product-stream filtration

Biopharmaceuticals undergo multiple filtration steps during bioprocesses. Sterilizing-grade filtration for bioprocessing is an important step in downstream operations and helps control bioburden and removes precipitates and solid contaminants. Sterilizing-grade filters are often used for product-stream filtration.

Normal flow filtration FAQs

Here are answers to some frequently asked questions about normal flow filtration.

What is normal flow filtration?
Normal flow filtration is a technique used in biopharmaceutical operations to remove colloidal materials and contaminants from growth media, buffers, or biomanufacturing products.

What is the difference between TFF and normal flow filtration?
In normal flow filtration, the feed stream moves perpendicularly to the filter. Impurities collect on the filter surface while the liquid and any components smaller than the filter pore size pass through. In tangential flow filtration (TFF), the feed moves parallel to the membrane surface. TFF can be better for use on feeds with a high solids content, as the tangential flow helps prevent filter clogging.

How does flow rate affect filtration?
Flow rate refers to the amount of time it takes for a feed stream to pass through a filter. Filter flow rates have a direct impact on equipment scheduling and production capacity. Fast flow rates allow rapid filtration.