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Outline
Consumption Production Pollution Recycling Biodegradable? Negatives of both What should we do? Discussion
Consumption - Paper
Americans use over 10 billion paper bags per year
14 million trees cut down annually for paper bag production
Consumption - Plastic
Americans use 100 billion plastic bags annually Equivalent to 12
million barrels of oil Worldwide, 4
billion plastic bags per year end up as waste Enough to circle the
Earth 63 times
Production - Paper
Paper comes from trees
Logs are stripped of bark and chipped into small squares in debarker
Chips are placed in a pressure cooker with water and other chemicals and digested into pulp
Pulp is washed, refined and cleaned
Production - Paper
Pulp is placed in a beater and turned to slush
Slush moves down wire screen where water is drained and recycled
Crude paper sheet is squeezed between rollers to remove remaining water
Paper runs through heater dryer rollers
Paper is cut, printed, packaged, and shipped
Production - Plastic
Plastic bags are made from polyethylene
Polyethylene comes from oil refineries as small resin pellets
Plastic resin is extruded, forming a thin tube
Production - Plastic
Air enters into the tube and causes it to expand
Tube moves upward on nip rollers, which flatten the bag into double-layered film
Film is cut into sheets/rolled up
Production
It takes more than four times as much energy to manufacture a paper bag than a plastic bag.
Safeway bag Energy to produce bag (BTU)Paper 2,500 BTUPlastic 600 BTU
Pollution - Paper
Paper production involves toxic chemicals Air and water
pollution Take up more space
in landfills than plastic
Production of plastic bags requires fewer pollutants than paper bags
Pollution - Plastic
5 of the top 6 chemicals that generate the most waste are commonly used in the industry
Thousands of marine animals die annually from eating plastic bags
Recycling - Paper
Paper bags have higher recycle rate than plastic
Paper must be returned to pulp Requires bleach and
other chemicals Recycled bags
often turn into corrugated cardboard
Recycling - Plastic
Recycling involves re-melting and reforming Bags must first be
separated into type of plastic they’re made from Time consuming and
expensive $4,000 per ton
Bags collected for recycling are often not recycled Sent to other
countries for incineration
Recycling
Takes 98% less energy to recycle 1 lb of plastic than 1 lb of paper
Recycling rates are low!
Type of bag Energy to recycle bag (BTU) % of bags recycledPaper 1,400 10 to 15Plastic 20 1 to 3
Biodegradable? - Plastic
Petroleum-based plastics are non-biodegradable
Plastic bags take up less space in the landfill than paper 2,000 plastic bags
= 30 lbs 2,000 paper bags
= 280 lbs
Biodegradable? - Plastic
Some stores use biodegradable plastic bags
Do not break down as quickly as believed
Require oxygen to degrade
Additives in the bags are potentially harmful to the natural world
Generate greenhouse gas emissions
Negatives of each
Paper: Causes more
pollution Consumes more
energy Produces more
waste
Plastic: Contributes to
litter Danger to wildlife Recycling
difficulties Not
biodegradable (most)
What should we do?
Invest in reusable bags Eliminate the use of
~1,000 disposable bags in their lifetime
Not convenient for everyone
Don’t take a bag for 1-2 items
Reuse bags to line trash cans, litter boxes, etc.
Discussion
Which bag has more negative effects? What are other materials bags could be
made from? Other thoughts…
References
http://www.madehow.com/Volume-2/Paper.html
http://www.projectgreenbag.com/paper-bag-are-no-better-than-plastic/
http://www.washingtonpost.com/wp-dyn/content/graphic/2007/10/03/GR2007100301385.html
http://science.howstuffworks.com/environmental/green-science/paper-plastic1.htm
http://www.msnbc.msn.com/id/18538484/
http://www.telegraph.co.uk/earth/earthnews/7422006/Biodegradable-plastic-bags-may-not-be-as-eco-friendly-as-thought.html
http://www.thomasnet.com/articles/plastics-rubber/designing-plastic-bags
http://www.aza.org/uploadedFiles/Member_Resource_Center/Green_Practices/paper_plastic.pdf?n=8191