school energy&environment

Paper recycling

The Italian paper industry uses more and more waste paper. The terms waste paper or recycled fibers refer to paper which has already served its fabrication purpose and is recycled within a productive cycle. A feature of cellulose, infact, is that it can be used multiple times. Fiber recycling can be made only a limited number of times from 5 to 7 times, as during every recovering cycle, fibers deteriorate. Poor quality material coming from pulping is generally used to make cardboard and the best pulping material, instead, is used to make printing paper or other special papers. Even the collection of waste material is dinstinguished in two categories:

• pulping from industrial and commercial collection which is made of trimmings of paper products, daily newspaper returns and other newspapers, corrugated cardboard, etc. It’s collected at the premises of paper product and editorial firms, department stores, offices and is selected and packed before delivery to the paper mills.
• domestic waste paper which comes from separate garbage collection and is constitued by paper products employed in houses, small shops and offices and is made of newspaper and mixed paper. It must be separated from the beginning from solid urban waste before it’s contaminated by other materials which could make it useless.

The fiber from waste paper has a yield of about 95%, whilst wood yield ranges from 30 to 80% depending on the milling procedure which is employed (semi-chemical, chemithermo-mechanical or chemi-mehanical or mechanical). The traditional semi-chemical procedure which is called kraft employs from 2 to 3,5 tons of wood to produce a ton of pure cellulose paper. Even if deinking is necessary, in paper recycling processes fiber must not be separated from lignin or other encrusting substances. In this way it’s possible to reduce water consumption up to 80% and energy requirement up to 50%. The use of recovery material reduces the request of virgin raw materials and even the quantity of materials destined for landfills with a significant reduction of disposal costs.