Ultrafiltration: Efficiency in Filtration Processes

Ultrafiltration is one of the most advanced filtration methods and is positioned between microfiltration and nanofiltration, depending on the degree of particle separation required in the medium being filtered.

• Microfiltration separates particles > 0.1 µm,
• Ultrafiltration operates in the range of 0.1 µm to 0.01 µm,
• Nanofiltration targets 0.01 µm to 0.001 µm,
• Reverse osmosis is effective for particles < 0.001 µm.

The effectiveness of ultrafiltration membranes is often defined by the NMWC (Nominal Molecular Weight Cut-Off) or MWCO (Molecular Weight Cut-Off), expressed in Daltons. This value represents the minimum molecular weight that is retained by 90% of the membrane. It is recommended that the NMWC be at least 20% lower than the molecular weight of the molecule to be filtered.

Ultrafiltration in Wastewater Treatment

Ultrafiltration is increasingly used in wastewater treatment. It can either serve as a supplementary measure to existing treatment processes or be applied directly in the aeration tank to save space and enhance degradation performance. This is particularly relevant in the treatment of persistent substances such as pharmaceutical residues. Another advantage is near-sterile filtration thanks to the defined separation threshold.

Other applications include:

• Protein separation, e.g., from milk
• Cold sterilization in the pharmaceutical industry
• Metal recovery in metallurgy
• Food processing
• Dialysis
• Cheese production through milk concentration
• Protein fractionation
• Clarification of fruit juices
• Production of vaccines and antibiotics