Flocculation is used in water treatment to separate and remove hazardous sediments from wastewater.
Flocculation refers to the separation of a solution, and most commonly this word is used to describe the removal of a sediment from a fluid. In addition to occurring naturally, it can also be forced through agitation or the addition of flocculating agents. Many manufacturing industries use it as part of their processing techniques and it is also widely used in water treatment. The technique is also widely used in the medical world to analyze various fluids.
Milk is a common colloid, a substance made up of many components, but which externally appears as one component until flocculation occurs.
The term is derived from flakes, another word for flakes of material. When a solution flocculates, the sediment forms into groups of aggregates that are easier to see. When this is started intentionally, the floc is usually removed with filters or screens. When a solution has been accidentally detached, attempts can be made to convert it back into a solution so that it can be used again.
Centrifuges spin the substances to obtain flocculation.
The technique can be used to separate sediments and visible materials and to treat colloids. A colloid is a solution that appears uniform but actually consists of one or more components combined. Some common examples of solutions with visible sediment are swimming pools and sewage, which is flocculated for purity purposes. Commonly encountered colloids include meerschaum, milk, glues, and paints. The separated elements within the colloid mix completely to create a new compound and can be separated again.
Depending on the circumstances, flocculation may be desired or undesired. It is often achieved deliberately in wastewater treatment, removing harmful substances so that they can be treated separately. Other examples of deliberate processing include grease traps in commercial kitchens, centrifuges to process blood, and facilities to extract salt from seawater. A classic case of unwanted flocculation is sour milk, where the milk colloid separates and forms a layer of flaky material on top. If this separation is not desired in a manufacturing environment, steps are taken to minimize it.
There are several ways to separate a solution. Shaking is a common technique, as it can cause the sediment flakes to clump together and collect on the bottom or top, depending on weight. Chemical flocculants are also used to encourage the formation of clumps in a solution. They generally have a different electrical charge than substances that precipitate from solution, thus attracting the material into clumps of particles.