Environmental impact of paper
The environmental impact of paper is significant, 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, disposable 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 organizations and with increased government regulation there is now a trend towards sustainability in the pulp and paper industry.
- 1 Issues
- 2 Mitigation
- 3 Inks
- 4 See also
- 5 References
- 6 Further reading
- 7 External links
The production and use of paper has a number of adverse effects on the environment which are known collectively as paper pollution. Pulp mills contribute to air, water and land pollution. Discarded paper is a major component of many landfill sites, accounting for about 35 percent by weight of municipal solid waste (before recycling). Even paper recycling can be a source of pollution due to the sludge produced during de-inking.
According to a Canadian citizens organization, "People need paper products and we need sustainable, environmentally safe production." The amount of paper and paper products is enormous, so the environmental impact is also very significant. It has been estimated that by 2020 paper mills will produce almost 500,000,000 tons of paper and paperboard per year, so great efforts are needed to ensure that the environment is protected during the production, use and recycling/disposal of this enormous volume of material.
Pulp and paper is the third largest industrial polluter to air, water, and land in both Canada and the United States, and releases well over 100 million kg of toxic pollution each year.
Worldwide, the pulp and paper industry is the fifth largest consumer of energy, accounting for four percent of all the world's energy use. The pulp and paper industry uses more water to produce a ton of product than any other industry.
Worldwide consumption of paper has risen by 400% in the past 40 years, with 35% of harvested trees being used for paper manufacture. 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.
Waste water discharges for a pulp and paper mill contains solids, nutrients and dissolved organic matter such as lignin. It also contains alcohols, and chelating agents and inorganic materials like chlorates and transition metal compounds. 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 worst-case scenarios leads to death of all higher living organisms. Waste water may also be polluted with organochlorine compounds. Some of these are naturally occurring in the wood, but chlorine bleaching of the pulp produces far larger amounts.
Paper waste accounts for up to 40% of total waste in the United States, which adds up to 71.6 million tons of waste per year in the United States alone. Paper waste like other wastes faces the additional hazard of toxic inks, dyes and polymers that could be potentially carcinogenic when incinerated, or comingled with groundwater via traditional burial methods such as modern landfills. Paper recycling mitigates this impact, but not the environmental and economic impact of the energy consumed by manufacturing, transporting and burying and or reprocessing paper products.
Wood pulping process
Chlorine and chlorine-based materials
Chlorine and compounds of chlorine are used in the bleaching of wood pulp, especially chemical pulps produced by the kraft process or sulfite process. Plants using elemental chlorine produced significant quantities of dioxins. Dioxins are persistent organic pollutants that are generally recognized among the most toxic human-released pollutants in existence. Elemental chlorine has largely been replaced by chlorine dioxide and dioxin production very significantly reduced.
As a result, from the 1990 onwards the use of elemental chlorine in the delignification process was substantially reduced and replaced with ECF (Elemental Chlorine Free) and TCF (Totally Chlorine Free) bleaching processes. In 2005, elemental chlorine was used in 19–20% of kraft pulp production globally, down from over 90% in 1990. 75% of kraft pulp used ECF, with the remaining 5–6% using TCF. A study based on U.S. Environmental Protection Agency (EPA) data concluded that "Studies of effluents from mills that use oxygen delignification and extended delignification to produce ECF (elemental chlorine free) and TCF pulps suggest that the environmental effects of these processes are low and similar." Most TCF pulp is produced in Sweden and Finland for sale in Germany, all markets with a high level of environmental awareness. In 1999, TCF pulp represented 25% of the European market.
TCF bleaching, by removing chlorine from the process, reduces chlorinated organic compounds to background levels in pulp mill effluent. ECF bleaching can substantially reduce but not fully eliminate chlorinated organic compounds, including dioxins, from effluent. While modern ECF plants can achieve chlorinated organic compounds (AOX) emissions of less than 0.05 kg per tonne of pulp produced, most do not achieve this level of emissions. Within the EU, the average chlorinated organic compound emissions for ECF plants is 0.15 kg per tonne.
However, there has been disagreement about the comparative environmental effects of ECF and TCF bleaching. On the one hand, paper and chemical industry-funded studies have generally found that there is no environmental difference between ECF and TCF effluents. On the other hand, independent peer-reviewed study has found that, comparing conventional, ECF and TCF effluents before and after secondary treatment, “TCF effluents are the least toxic”.
Sulfur, hydrogen sulfide, and sulfur dioxide
Sulfur-based compounds are used in both the kraft process and the sulfite process for making wood pulp. Sulfur is generally recovered, with the exception of ammonia-based sulfite processes, but some is released as sulfur dioxide during combustion of black liquor, a byproduct of the kraft process, or "red liquor" from the sulfite process. Sulfur dioxide is of particular concern because it is water soluble and is a major cause of acid rain. In 2006 the pulp and paper industry in Canada released about 60,000 tonnes of sulfur oxides (SOx) into the atmosphere, accounting for just over 4% of the total SOx emission from all Canadian industries.
A modern kraft pulp mill is more than self-sufficient in its electrical generation and normally will provide a net flow of energy to the local electrical grid. Additionally, bark and wood residues are often burned in a separate power boiler to generate steam.
Air emissions of hydrogen sulfide, methyl mercaptan, dimethyl sulfide, dimethyl disulfide, and other volatile sulfur compounds are the cause of the odor characteristic of pulp mills utilizing the kraft process. Other chemicals that are released into the air and water from most paper mills include the following:
- carbon monoxide
- nitrogen oxide
- volatile organic compounds, chloroform.
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 and sodium dithionite) produce benign byproducts (water and, eventually, sodium sulfate, respectively).
However, the bleaching of chemical pulps has the potential to cause significant environmental damage, primarily through the release of organic materials into waterways. Pulp mills are almost always located near large bodies of water because they require substantial quantities of water for their processes. An increased public awareness of environmental issues from the 1970s and 1980s, 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. Environmental NGO pressure was especially intense on Swedish and Finnish pulp and paper companies.
Conventional bleaching using elemental chlorine produces and releases into the environment large amounts of chlorinated organic compounds, including chlorinated dioxins. Dioxins are recognized as a persistent environmental pollutant, regulated internationally by the Stockholm Convention on Persistent Organic Pollutants.
Dioxins are highly toxic, and health effects on humans include reproductive, developmental, immune and hormonal problems. They are known to be carcinogenic. Over 90% of human exposure is through food, primarily meat, dairy, fish and shellfish, as dioxins accumulate in the food chain in the fatty tissue of animals.
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.
The move to non-elemental chlorine for the bleaching process reduced the emission of the carcinogenic organochlorines. Peracetic acid, ozone and hydrogen peroxide and oxygen are used in bleaching sequences in the pulp industry to produce totally chlorine free (TCF) paper.
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. 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.
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.
The United States Environmental Protection Agency has found that recycling causes 35% less water pollution and 74% less air pollution than making virgin paper. Pulp mills can be sources of both air and water pollution, especially if they are producing bleached pulp. 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.
Mechanical pulp mills
Wood pulp produced primarily by grinding wood is known as "mechanical pulp" and is used mainly for newsprint. These mechanical processes use fewer chemicals than either kraft or sulfite mills. The primary source of pollution from these mills is organic material such as resin acids released from the wood when it is processed. Mechanical wood pulp is "brightened," as opposed to bleached, using less toxic chemicals than are needed for chemical pulps.
Three main issues with the environmental impact of printing inks is the use of volatile organic compounds, heavy metals and non-renewable oils. Standards for the amount of heavy metals in ink have been set by some regulatory bodies. 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.
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.
- Totally chlorine free paper
- Elemental chlorine free paper
- List of environmental issues
- Life cycle assessment
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Life Cycle Assessment
- Forest Products Association of Canada, Life Cycle Assessment and Forest Products:A White Paper, September 2010
- United States Environmental Protection Agency, Available and Emerging Technologies for Reducing Greenhouse Gas Emissions from the Pulp and Paper Manufacturing Industry, Office of Air and Radiation, October 2010.