Short Stories for Teachers
Paper is an example of a valuable material that can be recycled. Its wood fibers are reused five to seven times before they become too short and brittle. Possible products are paper and corrugated cardboard, egg cartons, fruit trays, ceiling and wall insulation and many others.
However, paper has not always been made from wood pulp. The Chinese government official and scholar Ts'ai Lun is said to be the first who developed paper from bamboo fibers, mulberry bark, linen and China grass in the year 105 A.D.
Newer research proves that paper was already produced 200 years earlier. Beside the already mentioned non-wood papermaking fibers, hemp, rags and fishing nets were used as source of material for the first recycled paper.
Paper has its name from the papyrus plant. In Ancient Egypt about 4,000 years ago, its leaves were pounded flat and used to write on.
The secret of paper production was protected for many years. The Japanese got to know it only in the year 610 A.D. The art of making paper spread slowly all over the world; it came to the Arab world by the eighth century and via the Middle East to Spain. In Europe, the first paper was produced in the 12th century (1144 in Xativa near Valencia).
Until Gutenberg's Bible (1456) the manuscripts consisted of parchment - the skin of a sheep or goat prepared for writing - or of vellum (skin of a calf). Most of the time there was a shortage of linen - the main source of material for paper.
In 1719, the French scientist Rene de Reaumur observed wasps chewing slivers of wood and building their nest from the fiber paste. He had the idea that paper could be made of wood fibers. He wrote it down, but never tested it himself. Still until the 19th century almost exclusively old cloth rags were used for paper production.
The chemical process of breaking down wood was invented in 1829 and the German Friedrich Keller found a method of grinding wood efficiently in 1843. This was the starting point of the success story of making paper from wood pulp and paper recycling.
The process of converting waste paper into a usable product
Waste paper is pre-sorted and collected by the consumer. He takes it to a local recycling center or recycling bin.
The collected papers are brought to a plant where they are sorted and pressed to bales. Lighter papers can be separated from heavier papers and contaminants by a stream of air. The bales are stored in warehouses until they are needed.
In a repulping process, the waste paper is chopped and broken down into fibres and mixed with water creating the pulp.
This pulp must be cleaned from contaminants in a deinking process, which can combine washing, separating, sieving and rotating the fibers. The excess materials, mainly old ink and weak fibers, are skimmed off or dropped through centrifugal force into the sludge. It is then landfilled, burned or used otherwise.
Now the fibre is ready to be made into a new paper product. If white paper is needed a bleaching process follows using hydrogen peroxide, chlorine dioxide or oxygen. The clean pulp is either mixed with virgin fibres or used alone.