Membrane technology is a term that refers to a number of different filtration processes that are used to separate substances. With this technology, membranes are used as filters in separation processes, with a wide variety of applications, both industrial and scientific. They provide effective alternatives to related technologies such as adsorption, ion exchangers, and sand filters. The membranes used in membrane technology may be regarded as barriers separating two fluids and allowing certain substances to be transported across the membrane.
At its simplest, the technological use of membranes may consist of setting up a permeable membranous filter which allows water to flow through, but traps suspended solids. There are various forces which may be used to cause water to penetrate through the membrane. These may include gravity, pressure, electrical current, or maintaining a concentration gradient across the membrane.
One of the major uses of this type of technology is in the field of water filtration and purification. This includes desalination, or creation of drinking water from salt water, as well as purification of ground water or waste water. Other areas of industry that utilize membrane technologies include biotechnology, food and drink manufacturing, and medical uses such as dialysis for kidney failure patients.
Some of the different types of membrane technology include reverse osmosis, microfiltration, ultrafiltration, and nanofiltration. Reverse osmosis is a membrane technology process that employs the use of pressure to force a fluid through the membrane. It is the opposite of the natural osmosis function, in which a substance moves across a membrane from an area of high concentration to an area of low concentration. Applications of this specific type of membrane technology include the production of concentrated fruit juice, the creation of artificial seawater for aquaria, and the production of maple syrup.
Microfiltration, ultrafiltration, and nanofiltration are membrane technologies that differ from each other mainly in pore size of the membrane used. Microfiltration typically uses membranes with a pore size of 0.1 to 10 micrometers. Ultrafiltration membrane pore size is typically 0.1 to 0.001 micrometers. Nanofiltration membranes have the very smallest pore size, usually measured in nanometers, where one nanometer is equal to 0.001 of a micrometer.
Membrane technology is a highly complex area of scientific research. Many other specific techniques and applications exist in a wide variety of industries. Some of these include specialist membrane technology applications such as separation of gases, controlled drug delivery in medicine, and blood oxygenation in artificial lungs.
