Waste paper from various paper collections is intensively stirred with water in the paper mill's pulper. This separates the fibers from the fibers. In a first cleaning step, wet-strength paper and rejects are separated from the fibers. These rejects, known as rejects, have a very coarse structure. The plastic content is high, between 70 and 80%.

Other ingredients include metals, stones, rubber parts, sand, and all types of household waste. They are mechanically dewatered and are collected in bulk with a residual moisture content of 25-45%.

After the rejections have been eliminated, the next step in the waste paper processing process is the sorting stage, which separates the captured material from the accepted material. This finer reject consists of over 50% fibers that are too fine, as well as a large amount of fine debris such as plastic and Styrofoam residues and sand. The fiber material consists primarily of paper fibers and dyes. The fibers retain the water from the dissolution processes in the form of cellular and capillary water, which is difficult to separate through mechanical processing. Like the other residues, the captured material is mechanically dewatered using presses and is produced in bulk with a residual moisture content of 30 to 60%.

In the deinking tower, tiny air bubbles blown into the bottom of the tower lift the fibers, which are too fine for the papermaking process, to the surface. Dislodged printing ink particles also adhere to the air bubbles. The printing ink, along with the very fine fibers, is skimmed off at the top of the deinking tower. This so-called deinking sludge is then pressed and thus separated from most of the water. This creates a moist, loose paper pulp with a grayish tinge caused by the printing ink and containing 60 to 70% dry matter. This pulp can be shaped by hand but is not actually sludge. The system operates with a closed water circuit and has only minimal fiber loss.