Paper 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.^[1] Mill broke is paper trimmings and other paper scrap from the manufacture of paper, and is recycled in a paper mill. Pre-consumer waste is material which left the paper mill but was discarded before it was ready for consumer use. Post-consumer waste is material discarded after consumer use, such as old corrugated containers (OCC), old magazines, and newspapers.^[1] Paper suitable for recycling is called "scrap paper", often used to produce molded pulp packaging. The industrial process of removing printing ink from paperfibers of recycled paper to make deinked pulp is called deinking, an invention of the German jurist Justus Claproth.

 

Paper recycling process

The process of waste paper recycling most often involves mixing used/old paper with water and chemicals to break it down. It is then chopped up and heated, which breaks it down further into strands of cellulose, a type of organic plant material; this resulting mixture is called pulp, or slurry. It is strained through screens, which remove any glue or plastic (especially from plastic-coated paper) that may still be in the mixture then cleaned, de-inked, bleached, and mixed with water. Then it can be made into new recycled paper.^[2]
The share of ink in a wastepaper stock is up to about 2% of the total weight.^[3]

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).^[4]
Today, 40% of paper pulp is created from wood (in most modern mills only 9-16% of pulp is made from pulp logs; the rest comes from waste wood that was traditionally burnt). Paper production accounts for about 35% of felled trees,^[5] and represents 1.2% of the world's total economic output.^[6] Recycling one ton of newsprint saves about 1 ton of wood while recycling 1 ton of printing or copier paper saves slightly more than 2 tons of wood.^[7] This is because kraft pulping requires twice as much wood since it removes lignin to produce higher quality fibres than mechanical pulping processes. Relating tons 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.^[8] 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.^[5] Most pulp mill operators practice reforestation to ensure a continuing supply of trees.^{[citation needed]} The Programme for the Endorsement of Forest Certification (PEFC) and the Forest Stewardship Council (FSC) certify paper made from trees harvested according to guidelines meant to ensure good forestry practices.^[9] It has been estimated that recycling half the world’s paper would avoid the harvesting of 20 million acres (81,000 km²) of forestland

Energy

Energy consumption is reduced by recycling,^[11] although there is debate concerning the actual energy savings realized. The Energy Information Administration claims a 40% reduction in energy when paper is recycled versus paper made with unrecycled pulp,^[12] while the Bureau of International Recycling (BIR) claims a 64% reduction.^[13] Some calculations show that recycling one ton of newspaper saves about 4,000 kWh (14 GJ) 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.^[14] Recycling paper to make pulp actually consumes more fossil fuels than making new pulp via the kraft process; these mills generate most of their energy from burning waste wood (bark, roots, sawmill waste) and byproduct lignin (black liquor).^[15] Pulp mills producing new mechanical pulp use large amounts of energy; a very rough estimate of the electrical energy needed is 10 gigajoules per tonne of pulp (2500 kW·h per short ton).^[16]

Landfill use

About 35% of municipal solid waste (before recycling) in the United States by weight is paper and paper products.^[17]

Water and air pollution

The United States Environmental Protection Agency (EPA) has found that recycling causes 35% less water pollution and 74% less air pollution than making virgin paper.^[18] 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, thus reducing 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.^[19] However, recycling mills may have polluting by-products like sludge. De-inking at Cross Pointe's Miami, Ohio mill results in sludge weighing 22% of the weight of wastepaper recycled.^[20]

Recycling facts and figures

In the mid-19th century, there was an increased demand for books and writing material. Up to that 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.^[21]
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.^[22]
Some statistics on paper consumption:

• In 1996 it was estimated that 95% of business information is still stored on paper.^[23]
• Recycling 1 short ton (0.91 t) of paper saves 17 mature trees,^[24] 7 thousand US gallons (26 m³) of water, 3 cubic yards (2.3 m³) of landfill space, 2 barrels of oil (84 US gal or 320 l), and 4,100 kilowatt-hours (15 GJ) of electricity – enough energy to power the average American home for six months.^[25]
• 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.^[26]
• 115 billion sheets of paper are used annually for personal computers.^[27] The average web user prints 16 pages daily.^{[28][citation needed]}
• Most corrugated fiberboard boxes have over 25% recycled fibers^{[citation needed]}. Some are 100% recycled fiber.
• In 1997, 299,044 metric tons of paper was produced (including paperboard).^[29]
• In the United States, the average consumption of paper per person in 1999 was approximately 354 kilograms. This would be the same consumption for 6 people in Asia or 30 people in Africa.^[24]
• In 2006-2007, Australia 5.5 million tons of paper and cardboard was used with 2.5 million tons of this recycled.^[30]
• Newspaper manufactured in Australia has 40% recycled content.^[