While paper comes from renewable resources, the time it takes to raise trees to the age that makes them suitable for paper is measured in years. Recycling old paper into new paper allows manufacturers to maintain supplies of paper to consumers while conserving resources. So, how is paper recycled?
How Paper is Made
Paper was made approximately 2000 years ago by a Chinese government official named Ts'ai Lun. Paper is essentially made from trees and water. Trees are harvested from farms and sent to mills where they are turned into much smaller wood chips. These wood chips are then turned into pulp. The pulping process separates the fibers of the wood, and mixes them with water, until a mushy soup is greeted.
The soup is layered onto a screen. The pulp is pressed with felt rollers. This forces up to 60 percent of the water out of the soup allowing it to move into the next phase of the process where the paper pulp is run through a series of rollers. Each set of rollers presses more and more water out, and the fibers in the pulp bond together into thin sheets of paper.
Why Recycling is Necessary
It's an interesting recycling fact that paper makes up the majority of the waste found in land fills, according to the United States Environmental Protection Agency. The recycling of paper helps reduce the size of landfills, the amount of natural resources used in paper production and green house gasses. The United States alone uses nearly 68 million tons of paper a year, or the equivalent of a single 100 foot Douglas Fir tree per person.
The EPA reports that 60 percent of the paper used for residential and commercial purposes was recycled. This equates to almost 43 million tons of paper in 2009. In 2007 approximately 360 pounds of paper per person was recycled. So, let's take a look at how paper is recycled.
Collecting and Sorting
Many companies and households have special bins to collect paper for recycling. These bins get collected and the paper sent to a recycling plant where it is sorted. Paper contaminated with food or other substances are separated from clean paper. Cardboard boxes and newspaper is separated from office and general use paper, because each type is recycled differently depending on the type of paper being made from recycled materials.. The clean paper is bundled into bales and stored until the plant is ready to process and recycle it.
Re-pulping the Paper
The process of recycling paper is similar to its original creation. The paper is put into large vats with water and other chemicals to reduce the paper back into pulp. Blades chop the paper up into smaller bits to aid the pulping process and the material heated to break the paper back down into fine fibers. Rollers press the pulp on screens to remove contaminants like glue and binding materials. Other contaminants like staples and paper clips are removed from the pulp as the paper is de-inked (the process that cleans the pulp of the inks previously printed on it). Surfactants injected into the pulp attract and capture the ink and any remaining contaminants. The bubbles formed by this process float to the top and are skimmed off.
Bleaching and Making the New Paper
Chemicals and bleach remove colors from the pulp and return the paper to its original white state for office and general use. Brown paper, used in bags and coffee cup insulators do not need bleaching. At this point the pulp is sprayed onto more screens and pressed to remove the water, and the process of turning it back into paper begins. Ultimately, according the EPA, paper can only be recycled five to seven times before the paper fibers become too short to bond properly. In some cases new paper pulp is added. Looking carefully at paper packaging it often indicates what percentage of the product is recycled versus new.
EPA.gov, Paper Recycling Frequent Questions: http://www.epa.gov/osw/conserve/materials/paper/faqs.htm
Tappi.org, The Amazing History of Paper: http://www.tappi.org/oldtappi/paperu/all_about_paper/paperHistory.htm
Tappi.org, How Paper is Made: http://www.tappi.org/oldtappi/paperu/all_about_paper/paperMade.htm
Tappi.org: How Paper is Recycled: http://www.tappi.org/paperu/all_about_paper/earth_answers/Recycle1.htm
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