Ultrafiltration

Ultrafiltration is a pressure-driven membrane process that separates suspended particles and macromolecules from smaller dissolved substances. Its membranes retain smaller particles and macromolecules than microfiltration.

Membrane filtration: Membrane filtration separates components of a fluid by passing it through a selective barrier. Ultrafiltration is one pressure-driven method within this broader separation family.
Water purification: The treatment of water to remove contaminants and make it suitable for a specified use. Ultrafiltration membranes remove suspended matter and many microorganisms from water.
Microfiltration: A pressure-driven membrane process that primarily removes suspended particles and microorganisms. Its membranes generally retain larger particles than ultrafiltration membranes.
Semipermeable membrane: A barrier that allows some substances to pass while restricting others. Ultrafiltration depends on a membrane that selectively passes solvent and smaller solutes.
Permeate flux: The volume of liquid passing through a membrane per unit area and time. Flux is a central measure of ultrafiltration productivity.
Molecular weight cutoff: A nominal measure of the molecular size a membrane retains, commonly expressed in daltons. It helps describe which macromolecules an ultrafiltration membrane is designed to retain.
Wastewater treatment: Processes that remove contaminants from wastewater before discharge or reuse. Ultrafiltration can separate solids and biomass in treatment and reuse systems.
Nanofiltration: A pressure-driven membrane process that separates small organic molecules and multivalent ions. It typically rejects smaller dissolved substances than ultrafiltration.
Pore size: A measure of the openings within a porous material or membrane. Pore structure helps determine the size range of particles a membrane retains.
Retentate: The portion of a feed mixture that remains on the feed side of a membrane after filtration. Ultrafiltration concentrates retained particles and macromolecules in this stream.

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