ABSTRACT
Expression is the operation squeezing the liquid from solid–liquid mixtures by compression under conditions that allow the liquid to pass while the solid particles are retained between the supporting porous media. Operational expressions have become increasingly important in such widely divergent fields as food processing and fermentation industries, wastewater treatments, and chemical process industries, because the energy required to squeeze liquid from cakes is negligible compared to the heat required for thermal drying. The expression is made up from two stages comprised of filtration and consolidation according to the flow mechanism within the porous materials. Various types of equipment for expression are available in industry. After feed slurry is forced into the chamber under pressure, filtration occurs and the diaphram is pressed against the expression plate. The belt press as an example of continuous expression equipment has a horizontal gravity dewatering zone of belt preceding the pressure dewatering zone.
