Disk filter:

Another category of cartridge filter is the wafer, or disk filter. Within this filter, disks are stacked to form a cartridge and placed down over a middle perforated pipe. Each disk is classically 1/8 inch to 1/4 inch thick and made of asbestos or cellulose fibers.

Liquid which enters the disk filter moves up around the outside of the stack of disks is forced among the disks, travels by the perforations within the central pipe, and then leaves the filter. A filtering action takes place as the liquid is forced among the disks. Since with the smaller cartridges than if a disk filter is used to filter radioactive water, it might be extremely radioactive while it is erased, and must be handled extremely carefully. One way to erase a disk filter is through means of a crane that lifts the filter out of its housing and moves it to a shielded container. The disposal problem is one of the main drawbacks of cartridge and diskcartridge filters.