Let's take a quick look at how a used filter press operates. The slurry, the mix of solid and liquid, is pumped into the press. As pressure builds, slurry is passed through the straining plates. The solid part of the mixture starts to build up on the filter cloth. At first, the cloth won't be able to catch all the solids being passed through. But as more and more solid builds up on the cloth, a layer of filter cake starts to build up, creating a sort of wall of particles. This layer does most of the purifying, as it can catch more and more of the solid as the slurry passes through. Once the cloths are full of cake, the cycle is complete, and you'll be left with de-watered solid product and purified water.


There are numerous types of used filter presses, but the first of its kind was used in Great Britain in the 1850s to obtain seed oil. The first prototype that led to the modern incarnation of the machine was made in the 1950s. It has remained largely unchanged since though it has found many uses outside of its first intended use.


Although industrial in nature, a used filter press has application in the maple syrup business. When the syrup is first collected from the trees, it often comes with lots of sand, dirt, and even excess sugar. The syrup is heated to almost 200°F, passed through the machine and presto! You've got syrup. Similar processes are used for the honey and beer brewing industries.