Filterkoek

Filterkoek, the Dutch term for filter cake, refers to the layer of solids that accumulates on a filter medium during the filtration of a suspension. It is the material retained by the filter while the liquid passes through.

Formation and properties: A filter cake forms when particles in the suspension are too large or otherwise unable to pass the filter membrane. The cake’s structure depends on particle size and shape, surface chemistry, and the filtration conditions, including filtration rate and applied pressure. Over time the cake may become compressed, reducing porosity and increasing the resistance to filtrate flow. Moisture content varies, and some entrained liquid may remain within the cake.

Applications and operation: Filter cakes are common in chemical processing, water treatment, food and beverage production, pharmaceuticals, and mining. Controlling cake properties is important for filtration efficiency, filtrate clarity, product recovery, and downstream drying or washing costs. In many processes, the cake is washed to recover adsorbed products or remove impurities, and it may be pressed or dried to reduce moisture before disposal or further processing. Backwashing or cake-scraping strategies are used in some systems to manage buildup and maintain flow.

Measurement and modeling: Key parameters include dry solids content, cake thickness, porosity, and specific cake resistance. Filtration models relate the filtration rate and pressure drop to cake properties and time, aiding in process design and optimization.

See also: Filtration, Cake filtration theory, Filtration equipment, Cake washing.