WASTE PAPER RECYCLING
Paper recycling is the process of recovering waste paper and remaking
it into new paper products. There are three categories of paper that can
be used as feed stocks for making recycled paper: mill broke
pre-consumer waste, and post-consumer waste. Mill broke is paper
trimmings and other paper scrap from the manufacture of paper, and is
recycled internally in a paper mill. Pre-consumer waste is material that
was discarded before it was ready for consumer use. Post-consumer waste
is material discarded after consumer use. Paper suitable for recycling
is called "scrap paper". Recycling processes include the following
steps:
- Pulping: Adding water and applying mechanical action to separate
fibers from each other.
- Screening: Using screens, with either slots or holes, to remove
contaminants that are larger than pulp fibers.
- Centrifugal cleaning: Spinning the pulp slurry in cleaner,
causes materials that are more dense than pulp fibers to move
outward and be rejected.
- Flotation: Passing air bubbles through the pulp slurry, with a
surfactant present, causes ink particles to collect with the foam on
the surface. By removing contaminated foam, pulp is made brighter.
- Kneading or dispersion: Mechanical action is applied to fragment
contaminant particles.
- Washing: Small particles are removed by passing water through
the pulp.
- Bleaching: If white paper is desired, bleaching uses peroxides
or hydrosulfites to remove color from the pulp.
- Papermaking: The clean (and/or bleached) fiber is made into a
new paper product in the same way that virgin paper is made.
- Dissolved air flotation: Process water is cleaned for reuse.
- Waste disposal: The unusable material left over, mainly ink,
plastics, filler and short fibers, is called sludge. The sludge is
buried in a landfill, burned to create energy at the paper mill or
used as a fertilizer by local farmers.
Rationale for recycling
Industrialized paper making has an effect on the environment both
upstream (where raw materials are acquired and processed) and
downstream (waste-disposal impacts). Recycling paper reduces this
impact. Benefits of recycling are:
Energy: Energy consumption is reduced by recycling,
Landfill use: About 35% of municipal solid waste (before recycling)
by weight is paper and paper products. Recycling 1 tonne of
newspaper eliminates 3 cubic meters of landfill. Incineration of
waste paper is usually preferable to land filling since useful
energy is generated. Organic materials, including paper, decompose
in landfills, albeit sometimes slowly, releasing methane, a potent
greenhouse gas.
Water and air pollution: The EPA has found that recycling causes 35%
less water pollution and 74% less air pollution. Pulp mills can be
sources of both air and water pollution, especially if they are
producing bleached pulp What are the main types of paper in
everyday use which can be recycled?
- Office white paper
- Newspapers, magazines, telephone directories and pamphlets
- Cardboard
- Mixed or coloured paper
What can we do to
reduce the amount of paper being wasted? |
