{"id":3752,"date":"2026-09-22T10:00:29","date_gmt":"2026-09-22T02:00:29","guid":{"rendered":"https:\/\/www.hosonwater.com\/?p=3752"},"modified":"2026-09-22T14:40:32","modified_gmt":"2026-09-22T06:40:32","slug":"what-is-the-pore-size-of-commercial-ro-uf-and-nf-membranes","status":"publish","type":"post","link":"https:\/\/www.hosonwater.com\/it\/what-is-the-pore-size-of-commercial-ro-uf-and-nf-membranes\/","title":{"rendered":"What Is the Pore Size of Commercial RO, UF, and NF Membranes"},"content":{"rendered":"

\"What<\/p>\n

Commercial membrane specifications use different ways to describe separation performance. UF is commonly specified by nominal pore size, while NF and RO are more often characterized by rejection, water production, and operating conditions. The useful distinction is that UF is commonly described by its pore structure, NF by selective ion and organic rejection, and RO by salt rejection and operating performance rather than by nominal pore size.<\/p>\n

Typical Commercial Ranges<\/b><\/strong><\/h2>\n

UF and NF use different descriptions<\/b><\/strong><\/h3>\n

Commercial values vary by manufacturer and test method, so pore-size figures should be read with the module type, test basis, and intended duty. Our LH pressure-UF line uses a nominal pore size of 0.01 \u03bcm, while the LW pressure-UF line uses 0.02 \u03bcm.<\/p>\n

The same UF membrane pore size<\/u><\/strong><\/a>\u00a0should therefore be read with the module type, test basis, and intended duty.<\/p>\n

NF has a tighter selective structure than UF and is typically characterized by selective ion and organic rejection rather than by a single pore-size value.<\/p>\n

Why RO Is Not a Simple Pore-Size Product<\/b><\/strong><\/h2>\n

Dense selective layers change the comparison<\/b><\/strong><\/h3>\n

RO relies on a highly selective membrane barrier and is normally characterized by salt rejection, water production, and operating conditions rather than by nominal pore size.\u00a0Commercial RO membrane elements are therefore compared using salt rejection rate, water production, operating pressure, temperature, feedwater TDS, and fouling resistance.<\/p>\n

Any commercial RO membrane pore size<\/u><\/strong><\/a>\u00a0figure used for explanation should be treated as an approximation rather than a complete procurement specification.<\/p>\n

UF: Pores, Cut-Off, and Fouling<\/b><\/strong><\/h2>\n

Nominal pore size needs operating evidence<\/b><\/strong><\/h3>\n

UF has a physical pore structure, but effective retention also depends on concentration polarization, hydrodynamics, and the shape of the target particle. Our LH pressure-UF line uses a PVC-alloy membrane with a nominal pore size of 0.01 \u03bcm, while the LW pressure-UF line uses PVDF membranes with a nominal pore size of 0.02 \u03bcm.<\/p>\n

These values help define the barrier, while product water turbidity, SDI, permeability, and integrity testing help confirm whether the installed membrane filtration system is performing as intended.<\/p>\n

NF: The Intermediate Barrier<\/b><\/strong><\/h2>\n

The number cannot predict every ion result<\/b><\/strong><\/h3>\n

NF sits between UF and RO in both structure and duty. Its selective membrane layer can retain multivalent ions, including hardness components such as calcium and magnesium, as well as organic matter, while allowing a higher passage rate for monovalent salts than RO.\u00a0A nominal NF pore-size description should not replace evaluation under the actual feedwater conditions.<\/p>\n

The actual balance changes with pH, ionic composition, pressure, temperature, and recovery. A nanofiltration membrane should therefore be evaluated against the required rejection of target ions or organic matter rather than a pore-size number alone.<\/p>\n

\"NF<\/p>\n

How the Three Membrane Types Compare<\/b><\/strong><\/h2>\n

This comparison keeps commercial membrane terminology tied to the evidence needed for selection.<\/p>\n\n\n\n\n\n\n
Membrane<\/strong><\/td>\nTypical description<\/strong><\/td>\nPrimary evidence for selection<\/strong><\/td>\n<\/tr>\n
UF<\/td>\nNominal pore size; HOSONWATER\u00a0LH: 0.01 \u03bcm, LW: 0.02 \u03bcm<\/td>\nTurbidity, SDI, microbial loading, permeability, cleaning response<\/td>\n<\/tr>\n
NF<\/td>\nSelective membrane layer; performance defined primarily by rejection characteristics<\/td>\nHardness reduction, organic rejection, pressure, ion profile<\/td>\n<\/tr>\n
RO<\/td>\nDense selective layer; pore size not normally used<\/td>\nSalt rejection, permeate flow, pressure, recovery, TDS<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

What Changes the Effective Result<\/b><\/strong><\/h2>\n

Feed conditions change membrane performance<\/b><\/strong><\/h3>\n

Feed-water chemistry can make the same nominal membrane behave differently. Temperature changes viscosity and flux, pH affects charge and material compatibility, and suspended solids increase fouling risk.<\/p>\n

Recovery also concentrates rejected constituents, so a reverse osmosis membrane system must be checked for scaling risk, antiscalant compatibility, concentrate disposal, and cleaning access.<\/p>\n

Pore Size Alone Does Not Establish Microbial or Virus Removal Performance<\/b><\/strong><\/h2>\n

Validation matters more than a label<\/b><\/strong><\/h3>\n

A pore-size label cannot automatically support a claim about every pathogen. Retention depends on organism size, integrity, operating mode, defects, and validation method.<\/p>\n

For potable projects, membrane performance should be combined with disinfection and the applicable local water-quality requirements rather than turning one nominal number into a blanket health statement.<\/p>\n

How to Read a Supplier Datasheet<\/b><\/strong><\/h2>\n

A useful datasheet should state membrane material, module type, nominal or effective pore description, test water, pressure, temperature, flux, rejection, cleaning limits, and warranty scope.<\/p>\n

The most useful fields can be checked in a short sequence:<\/p>\n