Docstoc

polution-pulp-paper

Document Sample
polution-pulp-paper Powered By Docstoc
					Papers

The ecological impacts of paper:

1. Deforestation during the collection of raw materials

2. Pollution during its production

3. Landfill waste after use.

To choose eco-friendly paper:

 Know

1. The paper’s fiber source

2. Chemicals processing

3. Ability to be recycled or break down in a landfill.

 Kinds of eco-friendly papers available includes-- totally chlorine free
(TCF), elemental chlorine free (ECF), alternative fiber, and recycled
papers.

Outlines of the major steps and environmental effects of paper
production:

[Attaining and Processing the Paper Fiber]


In Western countries, 90% of all paper comes from wood. Trees are a
renewable resource; it makes sense to harvest them, and the majority
of wood comes from forests managed in a sustainable way.

 However, there are two forestry methods still practiced by some
companies that are incredibly destructive. The first problem is
harvesting in old growth forests which destroys habitats which have
been evolving for hundreds of years. The second problem is clear-

                                                                       1
cutting which is a method of harvesting in which all the trees in an
area are cut even though many of the trees are not usable. This
harvesting method not only destroys the habitat where the trees were
felled but also creates problems like erosion which affect the
surrounding areas.

After the wood is harvested it is washed, debarked, chipped, and
pulped. There are several ways of pulping wood, but they are usually
referred to as either mechanical or chemical pulping processes. Only
about a fourth of the world’s paper is mechanically pulped because
the process not only damages paper fibers, but fails to clean many of
the impurities from the fibers. Mechanically pulped papers consume
less chemicals and are usually bleached with hydrogen peroxide
instead of chlorine, but they are low quality in color, cleanliness, and
strength. Most papers are chemically pulped through a sulfate
process which dissolves the substances binding the fiber together
and removes impurities with minimal damage to the fiber. A lot of
energy is used in both pulping processes.

Bleaching
The next process for almost all papers is chlorine bleaching to whiten
the paper fibers. The chlorine bleaching process involves several
steps. Simply stated, chlorine gas is used to remove impurities from
the pulp; then the pulp is whitened with chlorine dioxide or
hypochlorite. Some of the chlorine combines with organic molecules
in the wood and creates organochlorides (chlorinated organic
compounds) which are discharged in waste waters. Runoff which
taints aquatic life and poisons groundwater is a major hazard of
papermaking. There are hundreds of different organochlorides, and
many are toxic. Dioxins are the most harmful group of
organochlorides because they are mutagenic compounds which have
been linked to reproductive disorders and cancers. The
Environmental Protection Agency as well as several environmental
and health organizations are attempting to limit dioxin production and
prevent its disposal in rivers and streams.

                                                                      2
Recycling Paper Fiber


Not all pulp is made with virgin fiber (fiber that is exclusively from
wood chips). Most pulp is made from a combination of virgin and
recycled fiber. There are two kinds of recycled fiber: mill broke and
post-consumer. Mill broke (also called pre-consumer) includes the
paper scraps produced by the mill which have always been used in
papermaking. Post-consumer fiber includes previously used papers
recovered through recycling that would otherwise end up in a landfill.
Truly recycled paper contains a significant percentage of post-
consumer fiber.

The process of recycling paper fiber requires the paper to be de-
inked, after which the process for preparing the pulp is the same. Yet
manufacturing paper from recycled fiber uses from 27 to 44% less
energy than using virgin fiber. The drawback to paper recycling is the
de-inking process. The de-inking process separates the usable fiber
from the ink, adhesives, paper clips, staples etc… These impurities in
the paper create a sludge which usually ends up either in landfills
where it can contaminate groundwater or in an incinerator where it
generates air pollution and contaminated ash which also ends up in
the landfill.

Specifics
     40% of trees cut in the US are turned into pulp for paper.
     Bleaching virgin fiber requires 75% more bleach than bleaching
     de-inked recycled fiber.
     The by-product of the chlorine bleaching process is more
     harmful than sludge from de-inking.




Kinds of Papers

                                                                     3
Choosing eco-friendly paper goes beyond finding a stock that is
recycled. There are a lot of trade offs between project needs and
environmental impacts. The most eco-friendly papers are either
recycled papers with a high post-consumer waste content, minimal
de-inking, and minimal bleaching or non-tree fiber papers with
minimal bleaching. This page gives an in-depth description of the
kinds of papers available.

Recycled
Overcrowded landfills are an environmental problem which can be
addressed by using recycled papers. All papers can be de-inked and
recycled except UV coated papers which can÷t be recycled at all. It
would take the exact same paper, coated or uncoated, 5-10 times of
recycling before showing any degradation. There are a number of
100% recycled papers, but the majority of the papers available are a
mixture of recycled fiber, virgin fiber, and mill broke. Many papers will
be advertized as recycled because of their mill broke content;
however, true recycled paper contains post-consumer waste (PCW).
Most recycled paper will state its percentage of PCW content as a
figure like 30/10 which means 30% recycled with 10% of this being
post-consumer.

Uncoated Recycled
There are several drawbacks to using uncoated recycled paper
including:
Discrepancies
      Recycled paper tends to vary slightly from one batch to another
      and imperfection and specks are common.
Dot Gain
      Ink tends to spread on uncoated papers, and dot gain can be
      as much as 15%.
Uneven Ink Coverage
      Ink soaks into uncoated papers creating dull colors. More ink is
      often used in printing, and more than one hit of ink is often
      necessary for solid areas that are larger than 4’x5’.

                                                                        4
Picking and Linting
      Recycled fibers are usually shorter than virgin fibers, so the
      tack of the ink is more likely to pull them to the surface of the
      sheet. This can be prevented if the sheets are run through a dry
      press once before printing.

This may seem like many drawbacks, but several of these issues
apply to all uncoated papers not just recycled papers. Designs that
work with the colors and patterns found in some recycled papers can
be very exciting. Another positive aspect is that recycled papers fold
better due to shorter paper fibers, and have less need for scoring.
The costs of recycled papers are comparable to virgin papers, and,
contrary to popular belief, there are recycled papers that have a high
PCW content and a smooth surface that will work well for 4 color
printing. Keep in mind that premium uncoated recycled paper will
probably be heavier than a coated stock and ink will be absorbed into
the paper, so more ink will need to be used and the color and edges
may be faded.

Industrial Grade Papers
The greenest recycled papers are industrial grade papers such as
draft paper, corrugated cardboard, and chipboard. They are usually
made of non-bleached, 100% post-consumer fiber, and they are
inexpensive. They work best for creative projects that do not require
printing because they are not suitable for offset printing. They do
perform well with printing methods like letterpress if it is an option.

Coated Recycled
The industry standard for creating coated recycled paper is 10%
PCW. Manufacturer÷s claim that if the post-consumer content was
any higher impurities could occur. With a 10% PCW content, recycled
coated paper has the same performance quality as virgin coated
paper. The main difference in using coated recycled paper is the
extra cost. Recycled coated stock can cost as much as 20% more
than a comparable virgin coated. This is due to extra processing

                                                                          5
steps which require more time and materials. The recycled paper
must be de-inked and the shorter fibers require extra layers of
coating.

The Environmental Trade-Offs of Using a Coated Recycled Paper:
     Coated recycled papers have a lower PCW content than
     uncoated recycled papers.
     The ink of coated papers sits on the coating instead of being
     absorbed into the paper like it would on an uncoated sheet.
     Therefore, coated papers require less ink and generates less
     sludge in the de inking process. However, this could be
     reversed because most jobs on uncoated papers have light ink
     coverage in comparison to coated papers that carry 4 color
     pictures.
     The ink adheres to the coating of the paper instead of the fiber
     making the separation of ink from the paper easier in the de-
     inking process.
     De-inking sludge from coated paper has a higher ash and clay
     or calcium carbonate content.
     All coated papers are difficult to recycle. Most recyclers will not
     accept coated paper because they don÷t have the technology
     to recycle it, or it is not economically feasible. Recyclers buy
     wastepaper by weight. Coated paper is heavier so it cost more,
     but each coated sheet has less recoverable fiber than an
     uncoated sheet. Recyclers don÷t want to pay more for paper
     they are getting less fiber from.

Chlorine Free and Elemental Chlorine Free
Specifying unbleached paper is a significant step in reducing the
negative environmental impact of the bleaching process. Unbleached
paper and hydrogen peroxide bleached paper are usually called
chlorine free but may also be called TCF for totally chlorine free. As
the name describes unbleached paper is usually colored paper or
paper with a gray or brown tone. TCF may still have been be a
bleached using a hydrogen peroxide process that is much less

                                                                      6
environmentally harmful than chlorine. There is also elemental
chlorine free paper (ECF) which is processed without chlorine gas. In
this bleaching process chlorine compounds are used which some
believe are less harmful than using elemental chlorine. While there
are very few US paper manufactures producing TCF paper there are
several producing ECF paper. Buying TCF bleached paper is
expensive because the major manufacturers are in Europe.

Alternative Fiber
Tree free papers are made from 100% non-wood pulp. Using
alternative fibers addresses not only forestry management issues
such as of old growth destruction and clear-cutting but also reduction
of waste in landfills. Papers made from plant fibers help preserve
forests, and papers made from cotton recycles cloth that would
otherwise be thrown away. There are hundreds of alternatives to
wood fiber including uncommon materials such as coffee beans,
banana peels, and seaweed. Listed here are the main attributes of
the three most common sources of alternative fiber: kenaf, hemp, and
cotton.

Kenaf

Kenaf is a terrific alternative to wood fiber because it is fast growing
and yields more paper per acre, has longer fibers so it is stronger, is
acid free, and does not need to be bleached so it requires less
chemicals and less energy in the pulpmaking process. Kenaf paper
acts similar to a coated paper and performs more consistently on
press than a recycled stock. The problem with kenaf is that it costs
two times as much as virgin paper and 10 to 15% more than premium
recycled paper. The high cost is due to transportation of the paper.
Kenaf can only grow in the southern most US areas, and most mills
have extra costs for small orders.

Hemp
Hemp is also a good alternative fiber because it yields more fiber per
acre and is cleaner to produce than wood pulp. Like Kenaf it is acid
                                                                       7
free and has long fibers, but it can be cultivated over a broader
climatic region than kenaf. Cost of transportation is also a problem
with hemp fiber. Hemp cannot be grown in the US because of
associated marijuana laws even though the kind of hemp grown for
industrial use could not be smoked. Most hemp is imported from
China.

Cotton
Recycling cloth into cotton paper could reduce the one million pounds
of textile wastes that are put in landfills each day. Cotton has been
used in paper making for centuries. It is as durable as wood and low
in acidity. Most of the best art papers are 100% cotton. Unfortunately
cotton papers also cost more than wood based papers.

Specifics
     Use papers with the highest percentage of recycled materials.
     Specify paper made by mills which use timber harvested in
     sustainable yield programs or choose kenaf, hemp, or cotton
     papers.




                                                                     8

				
DOCUMENT INFO
Categories:
Tags:
Stats:
views:1
posted:11/5/2013
language:English
pages:8
Description: pulp and paper industry needs to pay attention to making pollution free manufacture and product life cycle.