Sedimentation is the settling of matter to the bottom of a liquid by gravitational force, separating suspended solids from fluids. It is used to clarify juices, wines, and beers, to settle starch from wash water, and in wastewater treatment at food plants. The rate depends on particle size and liquid viscosity, principles that also govern centrifugation. It is one of the simplest and oldest separation techniques. It is elegant in its simplicity and widely applied. Gravity does the work for free.