Final answer:
In filtration, the residue is the material that remains on the filter medium after the liquid has passed through. It includes the solid particles from the mixture being filtered, like sand in water or floc from sedimentation tanks, and is found at the point of filtration.
Step-by-step explanation:
In filtration, the residue is the material that is captured on the filter medium and does not pass through with the filtrate (the liquid that has passed through the filtration process). During the filtration process, as a heterogeneous mixture—such as water containing sand—is passed through a filter, the solid particles, or the sand in this case, are trapped by the filter paper or material. This trapped material, or the sand, is what is referred to as the residue.
For example, in a water treatment facility, sedimentation tanks allow floc particles to settle at the bottom of the tank, and the clear water then proceeds to filtration. The filtration unit removes small particles from the water by passing it through layers of media like sand, gravel, and charcoal. Here, the residue would consist of floc particles and any additional solids caught by the filtration media.
In a laboratory or medical context, the filtration process can also be involved in separating solids from a hot solution or in the treatment of bodily fluids where microbes and other unwanted substances are filtered out. Any solids collected after such a process are considered the residue and can be subject to further analysis or disposal.