What does ultrafiltration remove from water?

Ultrafiltration removes bacteria, viruses, sediment, turbidity, and particles larger than 0.01 micrometres from water through membrane filtration technology. This process effectively eliminates harmful microorganisms while allowing water and dissolved minerals to pass through. Understanding what ultrafiltration can and cannot remove helps you determine whether this filtration method suits your specific water treatment needs.

What exactly is ultrafiltration and how does it work?

Ultrafiltration is a membrane filtration technology that uses pressure to separate particles from water based on size. The process employs semi-permeable membranes with pore sizes ranging from 0.01 to 0.1 micrometres (10–100 nanometres), creating a physical barrier that blocks contaminants while allowing clean water to pass through.

The system works by forcing water through hollow-fibre membranes under pressure, typically 1–3 bar. These membranes feature microscopic pores that act like molecular sieves, capturing particles larger than the pore size while permitting smaller molecules to flow freely. The contaminated water enters one side of the membrane, and clean, filtered water emerges from the other side.

Modern ultrafiltration systems often use multibore or seven-bore hollow-fibre configurations, which provide greater surface area and improved durability compared with traditional single-bore designs. The membranes are commonly made from materials such as PVDF (polyvinylidene fluoride) or PES (polyethersulfone), chosen for their chemical resistance and filtration performance.

What specific contaminants does ultrafiltration remove from water?

Ultrafiltration effectively removes bacteria, viruses, and suspended particles with impressive efficiency rates. The technology achieves a 6–7 log reduction for bacteria (up to 99.99999% removal) and a 4 log reduction for viruses (99.99% removal), making it highly effective for microbiological contamination control.

The system removes a comprehensive range of contaminants, including:

• Bacteria such as E. coli, Salmonella, and Legionella
• Viruses including hepatitis and norovirus
• Protozoa like Giardia and Cryptosporidium
• Suspended solids and sediment particles
• Turbidity-causing materials
• Colloids and macromolecules
• Some organic compounds and endotoxins
• Amoebae and other microorganisms

The removal efficiency depends on the particle size relative to the membrane pore size. Anything larger than the membrane’s pore diameter is physically blocked, while smaller substances pass through with the filtered water.

What doesn’t ultrafiltration remove from drinking water?

Ultrafiltration cannot remove dissolved minerals, salts, or small molecules that are smaller than its membrane pores. This limitation means certain contaminants pass through unchanged, requiring additional treatment methods if their removal is necessary.

Substances that ultrafiltration does not remove include:

• Dissolved salts and minerals (sodium, calcium, magnesium)
• Chlorine and chloramines
• Heavy metals in dissolved form
• Pesticides and herbicides
• Pharmaceutical residues
• Volatile organic compounds (VOCs)
• Nitrates and fluoride
• Dissolved gases and odours

This selective removal actually benefits drinking water quality by preserving beneficial minerals that contribute to taste and nutritional value. However, if your water contains dissolved chemical contaminants, you will need additional treatment technologies alongside ultrafiltration.

How does ultrafiltration compare to other water filtration methods?

Ultrafiltration sits between microfiltration and nanofiltration in terms of pore size and removal capabilities. Microfiltration (approximately 0.1–10 micrometres) removes larger particles but allows some bacteria and most viruses through, while nanofiltration (0.001–0.01 micrometres) removes smaller dissolved substances but requires higher pressure.

Compared with reverse osmosis, ultrafiltration operates at lower pressure and retains beneficial minerals, making it more energy-efficient for biological contamination removal. However, reverse osmosis removes dissolved contaminants that ultrafiltration cannot capture.

Compared with carbon filtration, ultrafiltration excels at removing microorganisms but does not address many chemical contaminants such as chlorine or organic compounds. Carbon filters improve taste and odour, while ultrafiltration focuses on microbiological safety.

The key advantage of ultrafiltration lies in its ability to provide reliable microbiological protection without removing beneficial minerals, operating at relatively low pressure with consistent performance over time.

When should you choose ultrafiltration for your water treatment needs?

Choose ultrafiltration when your primary concern is microbiological contamination and you want to retain beneficial minerals in your water. This technology works particularly well for surface water sources, well water with bacterial concerns, or situations requiring Legionella prevention in water systems.

Ultrafiltration is ideal for:

• Treating surface water or shallow wells prone to bacterial contamination
• Legionella prevention in commercial and healthcare facilities
• Pre-treatment before other filtration systems
• Applications requiring consistent microbiological removal
• Situations where mineral retention is important
• Industrial processes needing reliable particle removal

Consider alternative or additional technologies if your water contains dissolved chemicals or heavy metals, or if it requires complete demineralisation. Ultrafiltration works best as part of a comprehensive water treatment strategy, potentially combined with carbon filtration or other technologies to address specific water quality challenges in your situation.

Understanding ultrafiltration’s capabilities helps you make informed decisions about water treatment. This technology excels at biological contamination removal while preserving water’s natural mineral content, making it valuable for many residential and commercial applications. We offer various ultrafiltration modules and can help you determine whether ultrafiltration meets your specific water quality requirements. For personalised recommendations on appropriate system configurations for your needs, contact us for expert advice.