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  • 11Jul

    Environmental issues with paper

    From Wikipedia, the free encyclopedia

    A pulp and paper mill in New Brunswick, Canada. Although pulp and paper manufacturing requires large amounts of energy a portion of it comes from burning wood waste.

    There are a number of environmental issues with paper, which has led to changes in industry and behaviour at both business and personal levels.

    With the use of modern technology such as the printing press and the highly mechanised harvesting of wood, paper has become a cheap commodity. This has led to a high level of consumption and waste. With the rise in environmental awareness due to the lobbying by environmental organisations and with increased government regulation there is now a trend towards sustainability in the pulp and paper industry.

    Contents

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    [edit]Issues

    [edit]Deforestation

    Worldwide consumption of paper has risen by 400 percent in the past 40 years with 35 percent of harvested trees being used for paper manufacture. Logging of old growth forests accounts for less than 10% of wood pulp[1], but is one of the most controversial issues. Plantation forest, from where the majority of wood for pulping is obtained, is generally a monoculture and this raises concerns over the ecological effects of the practice.

    Deforestation is often seen as a problem in developing countries but also occurs in the developed world. Woodchipping to produce paper pulp is a contentious environmental issue inAustralia.[2] In the 1990s the New Zealand government stopped the export of woodchips for native forests after campaigning by environmentalists.[3]

    [edit]Air pollution

    Nitrogen dioxide(NO2sulfur dioxide (SO2) and carbon dioxide (CO2) are all emitted during paper manufacturing. They all cause acid rain and CO2 is a major greenhouse gas responsible forclimate change. However, since wood waste is burnt by pulp and paper mills some of the CO2 is from renewable sources and may be sequestered make into plantation forests.

    [edit]Water pollution

    Waste water discharges for a pulp and paper mill contains solids, nutrients and dissolved organic matter, and unless at low levels these are classed as pollutants. Nutrients such as nitrogen and phosphorus can cause or exacerbate eutrophication of fresh water bodies such as lakes and rivers. Organic matter dissolved in fresh water, measured by Biological Oxygen Demand (BOD), changes ecological characteristics, and in worse case scenarios leads to death of all higher living organisms. Waste water may also be polluted with organochlorinecompounds. Come of these are naturally occurring in the wood but but chlorine bleaching of the pulp produces far larger amounts.[4]

    Discharges can also discolour the water leading to reduced aesthetics. This has happened with the Tarawera River in New Zealand which subsequently became known as the “black drain”.

    [edit]Wood pulping process

    Bleaching mechanical pulp is not a major cause for environmental concern since most of the organic material is retained in the pulp, and the chemicals used (hydrogen peroxide andsodium dithionite) produce benign byproducts (water and sodium sulfate (finally), respectively).

    Delignification of chemical pulps releases considerable amounts of organic material into the environment, particularly into rivers or lakes. Pulp mills are almost always located near large bodies of water because of they require substantial quantites of water for their processes.

    Bleaching with chlorine produced large amounts of organochlorine compounds, including dioxins[4]. Increased public awareness of environmental issues, as evidenced by the formation of organizations like Greenpeace, influenced the pulping industry and governments to address the release of these materials into the environment[5] . The amount of dioxin has been reduced by replacing some or all of the chlorine with chlorine dioxide[6]. The use of elemental chlorine has declined significantly and as of 2005 was used to bleach 19-20% of all kraft pulp[7]. ECF (elemental chlorine-free) pulping using chlorine dioxide is now the dominant technology worldwide (with the exception of Finland and Sweden), accounting for 75% of bleached kraft pulp globally.[7]

    The promise of complete removal of chlorine chemistry from bleaching processes to give a TCF (totally chlorine-free) process, which peaked in the mid-1990s, did not become reality[7]. The economic disadvantages of TCF[8], the lack of stricter government regulation and consumer demand meant that EFC has not been replaced by TCF. As of 2005 only 5-6% of bleached kraft is made using TCF sequences, mainly in Finland and Sweden.[7] This pulp and paper goes to the German market, where regulations and consumer demand for TCF pulp and paper makes it viable.

    A study based on EPA data demonstrated that TCF processes reduce the amount of chlorinated material released into the environment, relative to ECF bleaching processes which do not use oxygen delignification. The same study concluded that “Studies of effluents from mills that use oxygen delignification and extended delignification to produce ECF and TCF pulps suggest that the environmental effects of these processes are low and similar.” [9] The energy needed to produce the bleaching chemicals for an ECF process not using oxygen delignification is about twice that needed for ECF with oxygen delignification or ECF processes.[9]

    [edit]Non-renewable resources

    Clay or calcium carbonate are used as fillers for some papers. Kaolin is the most commonly used clay for coated papers.

    [edit]Mitigation

    Waste paper awaiting recycling in the Netherlands.

    Some of the effect of the pulp and paper industry can be addressed and there is some change towards sustainable practices. The use of wood solely from plantation forests address concerns about loss of old growth forests.

    [edit]Bleaching

    The move to non-elemental chlorine for the bleaching process reduced the emission of the carcinogenic organochlorinesPeracetic acidozone[10] andhydrogen peroxide and oxygen are used in bleaching sequences in the pulp industry to produce totally chlorine free (TCF) paper.

    [edit]Recycling

    There are three categories of paper that can be used as feedstocks for making recycled paper: mill broke, pre-consumer waste, and post-consumer waste.[11] 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 such as old magazines, old telephone directories, and residential mixed paper.[12]

    One concern about recycling wood pulp paper is that the fibers are degraded with each and after being recycled four or five times the fibers become too short and weak to be useful in making paper.[13]

    The United States Environmental Protection Agency‎ has found that recycling causes 35% less water pollution and 74% less air pollution than making virgin paper.[14] Pulp mills can be sources of both air and water pollution, especially if they are producing bleached pulp. Modern mills produce considerably less pollution than those of a few decades ago. Recycling paper decreases the demand for virgin pulp and thus reduces the overall amount of air and water pollution associated with paper manufacture. Recycled pulp can be bleached with the same chemicals used to bleach virgin pulp, but hydrogen peroxide and sodium hydrosulfite are the most common bleaching agents. Recycled pulp, or paper made from it, is known as PCF (process chlorine free) if no chlorine-containing compounds were used in the recycling process.[15]

    [edit]Inks

    Three main issues with the environmental impact of printing inks is the use of volatile organic compoundsheavy metals and non-renewable oils. Standards for the amount of heavy metals in ink have been set by some regulatory bodies.[16] There is a trend toward using vegetable oils rather than petroleum oils in recent years due to a demand for better sustainability.

    Deinking recycled paper pulp results in a waste slurry which may go to landfill. De-inking at Cross Pointe’s Miami, Ohio mill in the United States results in sludge weighing 22% of the weight of wastepaper recycled.[17]

    In the 1970s federal regulations for inks in the United States governed the use of toxic metals such as lead, arsenic, selenium, mercury, cadmium and hexavalent chromium.[18]

    Posted by herman @ 9:26 pm

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