What do you need to know about recycling plastics?
Recycling plastics is one of the environmentally friendly methods of waste disposal supported by the solid waste management industry. More and more products once made from and packaged in paper, metal, glass or wood are now produced from and packaged in plastic. Two of the most commonly used plastic resins found in consumer goods and packaging are HDPE and PET—some of the most-often recycled plastics in the United States.
High Density Polyethylene (HDPE) resin, a recyclable plastic, is used to produce bottles for milk and other beverages, detergents, shampoos, motor oil, drugs and cosmetic products. Injection-molded HDPE plastic containers are used for products such as margarine and yogurt. HDPE plastic resin also can be used to make bottle and container caps and flexible plastic packaging such as sacks and trash bags. HDPE is also used in many non-packaging plastic products. Although the amount of HDPE used in plastic bottles and plastic containers has tripled since 1980, its garbage market share is still less than 1 percent.
Polyethylene terephthalate (PET) is a recyclable plastic resin used to make bottles for soft drinks and other household and consumer products. Soft drink bottles remain the biggest user of PET plastic resin. “Custom” plastic bottles are used for other products such as salad dressing, peanut butter and jellies. PET also is used for film, oven trays, sheeting for cups and food trays, and other plastic packaging. The rise in custom bottles and the increased consumption of water and soft drinks away from home has created challenges for increasing the PET plastic recycling rate.
There generally are two best plastics disposal options: recycling and incineration. These methods recover more value from the plastic than landfilling. Recycling plastic recovers the raw material, which can then be used to make new plastic products. Incineration recovers the chemical energy, which can be used to produce steam and electricity. Putting plastics in a landfill does neither of these things.
Since the early days of plastics recycling in the 1970s, the nation’s recycling infrastructure has grown significantly. The post-consumer plastic packaging collected and recycled has grown every year since 1990. Today, over 80 percent of U.S. households have access to some sort of plastic recycling programs, and in 2005, more than 1.05 million tons of plastic bottles were collected for recycling. Although bottles remain one of the most readily recycled plastics, a growing number of communities are collecting and recycling other rigid plastic containers, such as tubs, trays and lids. Through these programs, plastics are collected, processed for recycling and used to create second-generation products ranging from fleece jackets and detergent containers to carpeting and composite lumber for outdoor decking. Half of all polyester carpet made in the United States is made from recycled plastic PET bottles. Exports, however, are becoming an important market for recycled PET.
Still, despite this progress, plastics recycling rates lag far behind those of other items, such as newspaper and cardboard. One reason is that consumers often don’t understand the types of plastics that can be recycled in their area. Types of plastics are assigned a number, called a “resin identification code,” which is usually stamped or printed on the bottom of plastic containers and surrounded by a recycling symbol (a triangle of arrows). Numbers 1, 2, and 6 are the most-often recycled plastics in the United States. HDPE is #2 in the resin identification code. PET is #1 in the resin identification code.
Recycling plastics is easy. First, you should learn what types of plastics are recycled in your community and only give your waste collector those types of plastics. Consumers can find out which plastics are accepted in their local area and how to recycle plastics, prepare and transfer them by contacting their local solid waste company or public works department.
Resist the temptation to slip plastics that recyclers don’t want into the recycling bin. Plastics have different formulations and should be sorted before they are recycled to make new products. Mixed plastics can be recycled, but they are not as valuable as sorted plastics because the recycled plastic’s physical properties, such as strength, may vary with each batch.
Once you know what kinds of plastics your recycler wants, you generally should follow the wash and squash rule—rinse the plastic container and squash it. You typically may leave the paper labels on the container, but throw away the plastic caps, since they usually are made from a different type of plastic than the container and cannot be easily recycled. While most garbage and recycling collectors do not accept plastic grocery bags, they are often accepted by stores in recycling containers placed near the entranceways.
How is plastic recycled? The plastic recycling process is simple. Workers inspect the plastic trash for contaminants like rock and glass, and for plastics that the plant cannot recycle. The plastic is washed and chopped into flakes. If mixed plastics are being recycled, they are sorted in a flotation tank, where some types of plastic sink and others float. The plastic flakes are dried in a tumble dryer. The dried plastic flakes are fed into an extruder, where heat and pressure melt the plastic. Different types of plastics melt at different temperatures. The molten plastic is forced through a fine screen to remove any contaminants that slipped through the washing process. The molten plastic is then formed into strands. The plastic strands are cooled in water and then chopped into uniform pellets. Manufacturing companies buy the plastic pellets from recyclers to make new products.
HDPE and PET Plastics Municipal Solid Waste (MSW) Facts:
HDPE Plastic Generated: 5.21 million tons according to industry data.*
PET Plastic Generated: 3.53 million tons according to industry data.*
HDPE Recycled Plastic: 590,000 tons or a 11.3 percent recycling rate in 2009, according to industry data.*
PET Recycled Plastic: 730,000 tons, or a 20.7 percent recycling rate in 2009, according to industry data.*
Incinerated or Landfilled Plastic:
- 4.62 million tons of HDPE or 3.5 percent of total discarded MSW by weight.*
- 2.8 million tons of PET or 2.1 percent of total discarded MSW by weight.*
- Highly combustible (HDPE 18,690 BTUs per pound and PET 10,933 BTUs), two to three times that of MSW.
- An empty 1-gallon HDPE plastic milk jug weighs less than 60 grams, compared to 95 grams in 1970.
- The 2-liter PET plastic soft drink bottle weighs 48 grams and is 20 grams, or 29 percent, lighter than 20 years ago.
Plastic Recycling Markets:
- Packaging, drainage pipe, film, pallets, and plastic lumber and exports for HDPE plastic.
- The fiber market — which uses recycled PET plastic bottles for carpet, clothing and other products — and exports are the primary markets for recycled PET plastic.
(sources: “Municipal Solid Waste in the United States: 2005 Facts and Figures,” Office of Solid Waste, Washington; “Design for Recycling, A Plastic Bottle Recycler's Perspective,” Society of Plastics Industries; “Measurement Standards and Reporting Guidelines,” National Recycling Coalition; “Scrap Specifications Circular 2006,” Institute of Scrap Recycling Industries, Washington; American Chemistry Council; EIA Kids Page; *2009 EPA estimates.)
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