THE CHLORINE ALTERNATIVES
FAIRY-TALE
This card is printed on Totally Chlorine Free (TCF) paper
100% environmentally friendly.
Greenpeace on their Christmas Greetings cards, December 1995.
FACTS AND FIGURES
STATEMENT
Nothing is chlorine free and nothing is 100% environmentally friendly.
Parts of this page
THE BLEACHING OF PULP FOR PAPER.
The simplest method
When wood is used to make paper, several methods exists to process the
wood. The simplest method is by mechanical treatment: the wood is heated,
then grinded, the resulting pulp is bleached with air or oxygen and the
filtered and dryed product is paper. This is called TMP or thermo-mechanical
paper.
There is one advantage and two drawbacks on this process: The advantage
is that all the wood - except the bark - is used. The disadvantages: poor
mechanical and recycling quality, because of much short fibers are formed.
About one quarter of the wood is lignine, the glue that makes the strength
of near all plants. This remains in TMP paper. Although it is bleached,
the lignine will rapidely turn yellow when it comes in direct sunlight.
That is what you see when your daily newspaper, made from TMP, is lying
in the sun.
For newspapers that is not a problem. If it can survive one day, that
will do the job. But if you want magazines and books, with a higher quality
and which have to withstand longer times, or you need a better strength
like as for cardboard, you have to use other procedures.
The Kraft process
The process which combines good quality with an affordable price, is the
Kraft process. In that process, wood is cut in parts, called chips and
these are cooked in caustic soda, which removes most of the lignine, without
attacking the remaining cellulose too much.
When the remaining pulp of the Kraft process is not further bleached,
it is used as cardboard: the rather dark colour is from the remaining lignine
after the cooking process. If you want to have more or less white paper,
there are different methods for bleaching: that can be done with chlorine,
chlorine dioxyde, oxygen, ozone or hydrogen peroxyde.
Chlorine gives the best result: all remaining lignine is dissolved,
without attacking the cellulose and the remaining cellulose is bright white
and remains white for tens of years...
The drawback of this method is that some minor amounts of dioxins are
formed and released, about 1 microgram per ton of pulp. That meand a few
years ago for Sweden about 10 grams per year for 10 million tons of pulp.
Not the biggest dioxin problem of that time: the steel industry was discharging
much more. The main problem was in fact not the dioxins, it was the dissolved
chlorinated lignine, which was rather persistent, wat means quite difficult
to break down by bacteria. The amount of dissolved chlorinated organics
in the effluent can be measured as AOX (absorbable
organic halogens), that is the amount of organochlorines which can be absorbed
by active carbon. For this type of process the AOX was 3-5 kg/ton pulp
on about 50 kg total discharged organics per ton. That did give an enormous
amount of organics per year per paperwork!
The effect on fish.
The AOX does not mean anything to the toxicity of what is released. But
that the total effluent was toxic was clear: the effluent had an unpleasant
effect: fish swimming offstream changed external sexual behaviour! That
was quite alarming and the use of chlorine with the released dioxins and
other chlorinated stuff was accused to be the origin of all evil. Also
in chlorine bleached paper there were found small amounts of dioxins, which
did give a lot of commotion in the media in Sweden and later in other countries.
Strange enough there was no commotion about the amounts of dioxins found
in recycled paper and cardboard, although the levels were about ten times
higher than of fresh chlorine bleached paper.
Elementary chlorine free (ECF).
With a lot of cooperation from universities and paper works, alternatives
were found for chlorine bleaching: with prolonged cooking times, prebleaching
with oxygen and the main bleaching with chlorine dioxyde, about the same
quality of paper was reached, without the drawbacks of elementary chlorine:
No measurable levels of dioxin were found in the pulp, neither in the effluent
and the AOX was reduced to 400-800 g/ton. The paper made by this process
is called ECF, or Elementary Chlorine Free paper. The remaining effluent
was reduced in load to 5 kg/ton of organics by using waste water treatment
systems. Although the effluent was more biodegradable and one can find
about the same AOX in rivers far away from any paper works as in the river
Rhine (with many paper works), it remained toxic for fish...
Totally chlorine free (TCF).
Another process was introduced and heavely promoted by Greenpeace. Instead
of chlorine and chlorine dioxyde, hydrogen peroxyde is used in the bleaching
process. That process is called TCF or Totally Chlorine Free. That has
some drawbacks: to make more or less the same quality of paper, about 10%
more wood has to be used, but even then the fibers remain shorter, what
has as consequence that the recyclability will be reduced. Each time paper
or cardboard is recycled, the remaining fibers become shorter, with as
effect that more new pulp must be added and more too short fibers have
to be discarded. In average, recycling gives 11% of waste, to some extend
polluted with heavy metals, from the kaolin (clay) used to absorb inks
in paper and sometimes from the inks themselves.
But at the other side, no measurable dioxins were found in the effluent
and the AOX was virtually zero. Although the effluent is dioxin and AOX-free,
fresh TCF paper contains at least 35 times more dioxins than ECF paper!
And more... the effluent was readably biodegradable but it remained toxic
for fish...
Natural plant hormones.
There must be another origin of the strange response of fish to the paper
mill effluents. That was found in natural remainders of the wood: phytosteroles
(natural plant hormones), phenols, fatty acids and resins are the possible
culprits. So the beginning of the anti-chlorine-bleaching story was in
fact wrong.
That doesn't mean that the new processes are not better for the environment:
less organic effluent and better biodegradability and less dioxins is in
fact better in this case. But we don't see why Greenpeace so heavely promotes
TCF paper, although it needs more wood and gives a lesser quality and it
contains more dioxins, except if they do that because the word chlorinedioxyde,
still contains the word 'chlorine', or is it the difference between working
for a better environment and anti-chlorine hate (or fundamentalism)...
Dioxins in pulp and papers.
To give you an impression of the amount of dioxins, found in different
pulps and papers:
Dioxin found in different pulp and papers.
All figures as microgram (µg)I-TEQ/ton.
| Dioxin found in different pulp and papers |
| Material |
average |
maximum |
|
|
|
| Recycled linerboard (chlorine free): |
2.50 |
|
| Totally chlorine free (TCF) Kraftpaper: |
0.35 |
|
| Deinked recyclepulp (newsprint): |
0.19 |
|
| Fresh newsprint: |
0.07 |
|
| Unbleached Kraft: |
0.02 |
|
| Bleached Kraft (ECF): |
|
0.01 |
Source: Ubiquitous nature of dioxins [7].
The same order of dioxin amounts were found in Swedish investigations.
The researchers first thought that the pre-treatment with chlorine of the
water used for the cooking could be the origin of the dioxin formation
in TCF pulp, but that was not the case: the amount of chlorinated phenols
formed by chlorination of the water was not enough to explain the amount
of dioxins formed. Probably the oxydation of chloride from salt to elementary
chlorine by the peroxyde can be the origin of the higher dioxin content.
See also Sources of dioxins.
Further improvements.
Pulp and paper researchers are hard at work to find a solution for the
still high amount of organic material, chlorinated or not, which is in
the effluent of paper works. This can be done by a Totally Effluent Free
(TEF) process, where all liquids are recycled internally in the paper works,
by destillation of the remaining effluents and incineration of the organic
solid waste in well equiped incinerators. This needs further research,
because the remaining salts from the process must be reused or discarded
too.
THE ALTERNATIVES
It is true that the change from only elementary chlorine use in paper bleaching
to alternatives was better for the environment. But it is ecological nonsense
to promote TCF paper against ECF paper, only because 'chlorine'dioxyde
is used as the bleaching agent. The TCF alternative is clearly not better
for the environment than ECF paper.
CONCLUSION
At this moment ECF paper seems to be the least polluting type of quality
paper. But paper making (or recycling) is clearly not 100% environmentally
friendly. In short terms a further reduction of the (organic) effluent
will be necessary to reduce the overall pollution.
You are at level one of the Chlorophiles pages
Created: March 24, 1996.
Last update: September 8, 2001.
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