mikrofiltration

Mikrofiltration, also known as microfiltration, is a pressure-driven membrane separation process in which a liquid is pushed through a porous membrane that retains suspended solids and microorganisms while allowing dissolved substances to pass. Pore sizes in commercially available MF membranes typically range from about 0.1 to 10 micrometers, enabling the removal of bacteria, yeast, and other particulates while preserving most dissolved solutes and nutrients.

The process operates as a pressure-driven system that is commonly configured in crossflow, where the feed flows tangentially to the membrane surface to minimize fouling. There is also dead-end filtration, where flow is perpendicular to the membrane. The retained material forms a concentration layer that is periodically cleaned or backwashed to recover flux. Retention depends on pore size, membrane material, and operating conditions, and fouling is a major design consideration.

Membranes used in mikrofiltration are primarily polymeric, such as polyethersulfone, polysulfone, cellulose derivatives, and PVDF, though ceramic MF membranes are also used in some settings. Modules come in various forms, including hollow-fiber, spiral-wound, tubular, and flat-sheet configurations.

Applications include drinking-water and wastewater pretreatment, clarification and stabilization of beverages and dairy products, and clarification of fruit juices and wines. In biotech and pharmaceutical production, MF is used to remove bacteria and particulates from sterile products, often as part of a multi-barrier approach.

Advantages include moderate energy consumption, low-temperature operation, and retention of flavor and nutrients. Limitations involve fouling susceptibility, the need for pre-treatment, and incomplete removal of viruses or dissolved solutes, requiring integration with other treatment steps for complete sterilization.