Paper recycling is the process of recovering waste paper and then remaking it into new paper products. There are three categories of paper that can be effectively used as feed stocks for making recycled paper.

The first is mill broke, followed by pre-consumer waste, and then post-consumer waste. Mill broke is paper trimmings and other paper scrap leftover from the manufacturing of paper, and is recycled internally in a paper mill.

Pre-consumer waste is material that was discarded prior to consumer use. And post-consumer waste is material discarded after consumer use, such as OM (old magazines), OTD (old telephone directories), and RMP (residential mixed paper). Any paper that is suitable for recycling is referred to as scrap paper.

Over 90% of paper pulp is made from wood, holding paper production accountable for around 35% of felled trees. Recycling of newsprint saves around 1 ton of wood while recycling 1 ton of printing paper saves a little more than 2 tons of wood.

This is due to kraft pulping, which requires twice as much wood since it removes lignin to manufacture higher quality fibers than mechanical pulping processes. By recycling paper, energy consumption is greatly reduced and the need for masses of forestland devastated is also decreased. The EIA claims a 40% reduction in energy when paper is recycled verses paper made with fresh pulp.

Recycling paper is in everyone’s best interest. It’s easy to do and will greatly reduce the amount of energy needed to create new paper, and also help to conserve trees. In order to recycle paper, the scrap paper is sent through a 10-step process.

1. Pulping: The process of pulping is done by adding water and applying mechanical action to separate fibers from each other.
2. Screening: Contaminants larger than pulp fibers are removed by using screens with either slots or holes
3. Centrifugal cleaning: This occurs by spinning the pulp slurry in a cleaner, causing materials that are denser to move outward.
4. Flotation: By passing air bubbles through the pulp slurry, ink particles collect with the foam on the surface. When the contaminated foam is removed, the pulp becomes brighter.
5. Kneading: This mechanical action is applied to fragment contaminant particles.
6. Washing: By passing water throughout the pulp, small particles are removes, thus leaving the pulp cleaner and ready to be processed.
7. Bleaching: If white paper is being made, bleaching (using peroxides or hydrosulfites) is used to remove any color from the pulp.
8. Papermaking: The clean or bleached fiber is formed into a “new” paper product in the same way that the virgin paper was made.
9. Dissolved air flotation: The water used in the original process is cleaned for reuse in future processing.
10. Waste disposal: This is the unusable material left over from processing. This material is mainly ink, plastics, fillers, and other short fibers that are called sludge. The sludge is taken out and buried in a landfill, and then burned to create energy at the paper mill or used as a fertilizer by local farmers.

Tags: paper recycling, pulping

This entry was posted on Monday, August 11th, 2008 at 7:43 am and is filed under recycling. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.