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 feedstocks for making recycled paper: mill broke, pre-consumer waste, and post-consumer waste.^[1] 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 that was discarded after actually being used by a consumer. The grades of post-consumer recycled paper are OCC (old corrugated containers), WCC (waxed corrugated containers), ONP (old newspapers), OMG (old magazines), OTD (old telephone directories), and RMP (residential mixed paper).^[2] Paper suitable for recycling is called "scrap paper".

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Process

While there are differences depending on the specific type of paper being recycled (corrugated fiberboard, newspaper, mixed office waste), recycling processes include the following steps:

1. Pulping: Adding water and applying mechanical action to separate fibers from each other.
2. Screening: Using screens, with either slots or holes, to remove contaminants that are larger than pulp fibers.
3. Centrifugal cleaning: Spinning the pulp slurry in a cleaner causes materials that are more dense than pulp fibers to move outward and be rejected.
4. 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. This step is sometimes called deinking.
5. Kneading or dispersion: Mechanical action is applied to fragment contaminant particles.
6. Washing: Small particles are removed by passing water through the pulp.
7. Bleaching: If white paper is desired, bleaching uses peroxides or hydrosulfites to remove color from the pulp.
8. Papermaking: The clean (and/or bleached) fiber is made into a "new" paper product in the same way that virgin paper is made.
9. Dissolved air flotation: Process water is cleaned for reuse.
10. 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.

Standards

Since the early 1980's, recycled paper has gone from gray and dingy flecked sheets reported to clog up copy machines to an indistinguishable competitor of traditional bright white paper. ^[3]

However, paper fibers cannot be recycled indefinitely because fiber length and strength are degraded with each use. Individual fibers can only be recycled 4-6 times.^[4] When fibers become too short, they are not retained in the pulp or paper and end up in the sludge for disposal. New fibers are usually added to recycled pulp when new paper products are made. Consequently, most recycled paper will still contain some new pulp.

There is no universal standard for the maximum percentage of virgin pulp in recycled paper.^[1][5] 'Recycled' paper is available that includes anywhere from 10 to 100 percent "post-consumer" paper.^[6] The EPA mandated the use of 50% post-consumer recycled paper by the federal government, state governments that receive federal funding, and many companies that receive money from the federal government. However, this excludes copy paper.^[7] The EPA does not regulate recycled paper used outside of the government; it only sets a minimum guideline.^[1] The UK also does not have any legal standards, only non-mandatory guidelines instituted by a variety of different organizations.^[1]

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).^[8] Recycling paper reduces this impact.

Forest preservation

Today, 90% of paper pulp is made of wood. Paper production accounts for about 43% of harvested wood,^[9] and represents 1.2% of the world's total economic output.^[10] Recycling of newsprint saves about 1 tonne of wood while recycling 1 tonne (1.1 ton) of printing or copier paper saves slightly more than 2 tonnes of wood. This is because kraft pulping requires twice as much wood since it removes lignin to produce higher quality fibers than mechanical pulping processes. Relating tonnes of paper recycled to the number of trees not cut is meaningless, since tree size varies tremendously and is the major factor in how much paper can be made from how many trees.^[11] Trees raised specifically for pulp production account for 16% of world pulp production, old growth forests 9% and second- and third- and more generation forests account for the balance.^[9] Most pulp mill operators practice reforestation to ensure a continuing supply of trees. The Forest Stewardship Council (FSC) certifies paper made from trees harvested according to guidelines meant to ensure good forestry practices.^[12] It has been estimated that recycling half the world’s paper would avoid the harvesting of 20 million acres (80,000 km²) of forestland.^[13]

Energy

Energy consumption is reduced by recycling, although there is some debate concerning the actual energy savings realized. The EIA claims a 40% reduction in energy when paper is recycled versus paper made with unrecycled pulp. ^[14] while the Bureau of International Recycling, BIR, claims a 64% reduction.^[15] Some calculations show that recycling one ton of newspaper saves about 4,000 KWh of electricity, although this may be too high (see comments below on unrecycled pulp). This is enough electricity to power a 3-bedroom European house for an entire year, or enough energy to heat and air-condition the average North American home for almost six months.^[16] It must be noted that recycling paper to make pulp may actually consume more fossil fuels than making new pulp via the kraft process since these mills generate all of energy from burning waste wood (bark, roots) and byproduct lignin.^[17] Pulp mills producing new mechanical pulp use large amounts of energy, a very rough estimate of the electrical energy needed is 10,000 megajoules (MJ) per tonne of pulp (2500 kW·h per short ton),^[18] usually from hydroelectric generating plants. Recycling mills purchase most of their energy from local power companies and since recycling mills tend to be in more urban areas, it is likely that the electricity is generated by burning fossil fuels.

Landfill use

About 35% of municipal solid waste (before recycling) by weight is paper and paper products.^[19] Recycling 1 tonne of newspaper eliminates 3 cubic meters of landfill.^[20] Incineration of waste paper is usually preferable to landfilling since useful energy is generated. Organic materials, including paper, decompose in landfills, albeit sometimes slowly, releasing methane, a potent greenhouse gas. Many larger landfills now collect this methane for use as a biogas fuel. In highly urbanized areas, such as the northeastern US and most of Europe, land suitable for landfills is scarce and must be used carefully. Fortunately, it is in such areas that collection of waste paper is also most efficient.

Water and air pollution

The US EPA has found that recycling causes 35% less water pollution and 74% less air pollution.^[21] 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.^[22] However it should be noted that recycling mills may have polluting by-products, such as sludge. De-inking at Cross Pointe's Miami, Ohio mill results in sludge weighing 22% of the weight of wastepaper recycled.^[23]

Cleaning contaminants from scrap paper

Scrap from paper mills (broke) is the cleanest source for recycling. The high rates of recycling for post-consumer office paper, newspaper, paperboard, and corrugated fiberboard reflect the efficiency of recycling mills to clean and process the incoming materials. Several technologies are available to sort, screen, filter, and chemically treat the recycled paper.

Many extraneous materials are readily removed. Twine, strapping, etc are removed from the hydropulper by a "ragger". Metal straps and staples can be screened out or removed by a magnet. Film-backed pressure sensitive tape stays intact: the PSA adhesive and the backing are both removed together.^[24]

Materials which are more difficult to remove include wax coatings on corrugated cartons and "stickies", soft rubbery particles which can clog the paper maker and contaminate the recycled paper. Stickies can originate from book bindings, hot melt adhesives, PSA adhesives from paper labels, laminating adhesives of reinforced gummed tapes, etc.^[25][26][27]

Criticism

Main article: Recycling criticism

Some of the claimed benefits of paper recycling have fallen under criticism; criticized areas include the claim that recycling saves trees, reduces energy consumption, reduces pollution, creates desirable jobs, and saves money.

Recycling facts and figures

In the mid-19th century, there was an increased demand for books and writing material. Up to this time, paper manufacturers had used discarded linen rags for paper, but supply could not keep up with the increased demand. Books were bought at auctions for the purpose of recycling fiber content into new paper, at least in the United Kingdom, by the beginning of the 19th century.^[28]

Internationally, about half of all recovered paper comes from converting losses ("pre-consumer" recycling), such as shavings and unsold periodicals; approximately one third comes from household or "post-consumer" waste.^[29]

Some statistics on paper consumption:

• The average per capita paper use in the USA in 2001 was 700 pounds (318 kg). The average per capita paper use worldwide was 110 pounds (50 kg).^[30]

• It is estimated that 95% of business information is still stored on paper. [Source: International Institute for Environment and Development (IIED) Discussion Paper (IIED, London, September 1996)]

• Although paper is traditionally identified with reading and writing, communications has now been replaced by packaging as the single largest category of paper use at 41% of all paper used. [Source: North American Factbook PPI, 1995. (Figures are for 1993)]

• 115 billion sheets of paper are used annually for personal computers [Source: Worldwatch Institute]. The average daily web user prints 28 pages daily [Source: Gartner group and HP]

• Most corrugated fiberboard boxes have over 25% recycled fibers. Some are 100% recycled fiber.

United States of America

Recycling has long been practiced in the United States. The history of paper recycling has several dates of importance:

1690: The first paper mill to use recycled linen was established by the Rittenhouse family.^[31]

1897: The first major recycling center was started by the Benedetto family in New York City, where they collected rags, newspaper, and trash with a pushcart.

1993: The first year when more paper was recycled than was buried in landfills.^[32]

Today, over half of the material used to make paper is recovered waste.^[33] Paper products are the largest component of municipal solid waste, making up more than 40% of the composition of landfills.^[34][35] In 2006, a record 53.4% of the paper consumed in the U.S. (or 53.5 million tons) was recovered for recycling.^[36] This is up from a 1990 recovery rate of 33.5%^[37]. The U.S. paper industry has set a goal to recover 55 percent of all the paper consumed in the U.S. by 2012. Paper packaging recovery, specific to paper products used by the packaging industry, was responsible for about 76.6% of packaging materials recycled with more than 24 million pounds recovered in 2005.^[38]

Twenty years ago, only one curbside recycling program existed in the United States, which collected several materials at the curb. By 1998, 9,000 curbside programs and 12,000 recyclable drop-off centers had sprouted up across the nation. As of 1999, 480 materials recovery facilities had been established to process the collected materials.^[39]

European Union

Paper recovery in Europe has a long history and has grown into a mature organization. The European papermakers and converters work together to meet the requirements of the European Commission and national governments. Their aim is the reduction of the environmental impact of waste during manufacturing, converting/printing, collecting, sorting and recycling processes to ensure the optimal and environmentally sound recycling of used paper and board products. In 2004, the paper recycling rate in Europe was 54.6% or 45.5 million tons.^[40]

References

This article incorporates text from http://www.epa.gov/epaoswer/non-hw/muncpl/recycle.htm, a public domain work of the United States Government.