Recycling Plastics
by Seth Gleiman

Recycling plastics can help remove a potentially nuisance waste stream from landfills, reduce the strain on non-renewable energy resources, and create an economic commodity for the future. Technologies used for recycling co-mingled plastics are being developed, yet some processes exist which produce high-grade feedstock. Currently on the Mines campus, there is a plastic recycling facility located behind the dormitories. Beyond campus, local supermarkets collect most types of plastic, while private companies offer curbside recycling programs.

Background

"Plastics" is the general term used to describe materials composed of carbon-chain macromolecules similar to cellulose (paper). These macromolecules (polymers) are made from building blocks (monomers). Plastics are engineered through specific monomer combination and concentration for a variety of end-uses. These include plastic grocery bags, milk containers, shampoo bottles, 2-liter cola bottles, etc. as well as synthetic fabrics, environmental barriers, computer housings, automobile parts (including tires), and bullet-proof vests.

Most plastics are derived from oil and natural gas. From these common building blocs, plastics manufacturers create a family of materials used to make everything from tough, resilient composite car fenders to clear, flexible plastic wrap. The oil and natural gas used as raw materials for plastic account for only 1.5 percent of total U.S. energy consumption. Many plastics use lass raw materials to make than other products. A study conducted in Germany found that 400 percent more material by weight would be needed to make packaging if there were no plastics.

Plastic products often require less energy to make than comparable products made of other materials. Plastic grocery bags require about 40 percent less energy to make than paper bags - even when you count the energy value of plastics' raw materials. Polystyrene foam cups use about 30 percent less energy than paperboard cups; these also take up approximately 1 percent of landfill volume. Without plastics, the energy required to make packaging would increase dramatically. The plastics packaging used in 1990 saved the energy equivalent of Philadelphia's electricity needs for more than two and a half years.

Plastics are lighter than many alternative materials. In shipping, lighter weight means better fuel efficiency. The same is true for cars - lighter cars get better gas mileage. This plastic shrink-wrap keeps products secure while allowing manufacturers to ship more goods per truckload, reducing overall fuel consumption. Automakers choose plastic parts for their durability, resilience and lightweight. Plastics reduced the weight of the average passenger car built in 1988 by 145 pounds. That saves millions of gallons of gas each year and will save the energy equivalent of 21 million barrels of oil over the cars' lifetime.

Plastics prevent waste; they help keep perishable goods fresh and protect high-tech electronics from damage. Shatter-resistant plastic containers reduce waste due to breakage. Heat-sealed plastic wraps help keep food fresh in the store. At home, plastic food storage containers and re-sealable bags reduce food waste due to spoilage. Every pound of plastic packaging used helps prevent 1.7 pounds of food waste. Manufacturers of appliances, electronics and other sensitive products have reduced their shipping damages by 50 percent or more by using plastic packaging materials.

The best way to have less waste to throw away is to create less waste in the first place. Plastics, strength and lightweight help product manufacturers use resources more efficiently. Plastics often deliver more product with less packaging. For example, it takes 4.3 pounds of 16-ounce glass bottles to deliver a gallon of beverage, but it takes less than a quarter pound of 2-liter plastic bottles to deliver that same gallon. Without plastics, durability and resistance to corrosion, the useful life of major appliances would be shortened by up to 40 percent. By helping them last longer, plastics keep these appliances out of the waste stream. Plastic bags contribute up to 80 percent less solid waste by volume than paper sacks.

Plastics are tough and durable and are used for everything from car parts to safety helmets to park benches. That durability also makes plastic the product of choice for commonly reused items such as toothbrushes, food storage containers and refillable sports bottles. More than .200 schools in seven states and Ontario, Canada have switched to refillable 8-ounce plastic milk bottles than can be washed, refilled and reused up to 100 times before being recycled. Laundry products are being packaged in reusable plastic bottles and small, refill packages of concentrated product, helping to reduce total packaging waste. As much as 40 percent of selected plastic parts from damaged or discarded cars are repaired and reused, reducing the amount of automotive components sent to landfills.

An ever-increasing quantity and variety of plastics are being recycled in communities across the country. With a commitment to quality and performance, plastics recycling will keep growing. Consumers can help by recycling only those items requested by their local recycling programs and preparing them as instructed. The recycling rate for plastic bottles and containers rose to 15 percent in 1992, an increase of 45 percent from 1991. More than 1,000 quality products made with or packaged in recycled plastic are now commercially available. Several companies are exploring advanced recycling technologies - taking plastics back to their raw materials, which can be refined and recycled into new plastics or other petroleum-based products.

Many communities now send their trash to state-of-the-art waste-to-energy facilities that reduce the volume of waste going to landfills by as much as 90 percent. Plastics have as inherent energy value higher than any other material commonly found in the waste stream. When plastics are processed in modern waste-to-energy facilities, they can help other wastes combust more completely, leaving less ash for disposal. One pound of plastics can generate twice as much energy as Wyoming coal and almost as much energy as fuel oil.

Plastics are essentially inert in landfills. That means they aren't likely to contribute to groundwater contamination or the generation of methane gas. Modern landfills use plastic liners to prevent the potentially hazardous liquid produced by decomposing trash from contaminating groundwater. Over the past 30 years, the percentage (by weight) of packaging in the waste stream has actually decreased, largely because of the use of more lightweight, efficient plastics.

Five major myths about garbage:

1) Fast-food packaging, polystyrene foam and disposable diapers are major constituents of American garbage. Less than one-half of 1 percent of the landfill material is fast-food packaging and no more than one-third of 1 percent of the total volume of the average landfills, contents. All the expanded polystyrene foam that is thrown away in the United States every year accounts for no more than 1 percent of the volume of landfilled garbage. Disposable diapers make up no more than 1 percent by weight of a typical landfill's total solid-waste content - and no more than 1.4 percent by volume.

2) Plastic is also a big problem. Paper is the most commonly encountered trash found in landfills - 40 percent of a landfill's contents. The volume of all plastics - foam, film and rigid; toys utensils and packages - amounted to between 20 and 24 percent of all garbage, as sorted; when compacted along with everything else, as it is in landfills, the volume of plastics fell to only about 16 percent.

3) A lot of biodegradation takes place in modem landfills. Biologically and chemically, a landfill is much more static than we commonly suppose. For some kinds of garbage, biodegradation goes on for a while and then slows to a virtual standstill. For other kinds, biodegradation never gets under way at all.

4) America is running out of safe places to put landfills. In areas such as the congested Northeastern part of the United States, yes, there is as acute shortage of landfills that are still available for deposits. Yet, a study concluded that at the current rate of waste generation, all of America's garbage for the next 1,000 years would fit into a single landfill space only 120 feet deep and 44 miles square - a patch of land about the size of three Oklahoma City.

5) On a per capita basis, Americans are producing garbage at a rapidly accelerating rate. The average American throws out about 1,500 pounds of garbage a year. It is undeniable that Americans as a whole are producing more municipal solid waste than they did 50 or 100 years ago. But this is largely because there are more Americans that there were 100 or even 50 years ago.

The effort to recycle plastics has taken on new dimension in the last decade. Prior to 1988, fewer than one thousand plastics recycling programs existed. As of 1995, there were more than seven thousand such programs collecting recyclables from over 100 million people.

Nationwide, six plastics account for over 70 percent of all plastic sales. These are low-density polyethylene (#4 LDPE - 17 percent), polyvinyl chloride (#3 PVC - 15 percent), high-density polyethylene (#2 HDPE - 14 percent), polypropylene (#5 PP - 13 percent), polystyrene (#6 PS - 9 percent), and polyethylene terephthalate (#l PETE - 4 percent).

About 80 percent of plastics cane from residential sources, 20 percent from commercial and industrial sources. About 28 percent of plastics that are discarded are in durable products (appliances, furniture, etc.), about 25 percent are in non-durable products (plates, cups, trash bags, etc.), and about 48 percent are in containers and other packaging. The plastics that are most commonly recycled - PETE soda bottles and other containers, HDPE milk jugs, and other HDPE containers - account for 3 percent, 3 percent, and 5 percent, respectively, of all plastics that are discarded (0.2 percent, 0.3 percent, and 0.5 percent by weight of all municipal solid waste).

Recycled plastics are typically chipped, washed, and heated to produce pellets or flakes that can be manufactured into secondary products. Some mixed plastic items can be separated by weight into their component resins, but in general plastics must be separated before they are input into a secondary manufacturing process. Technologies to automatically sort mixed plastics are still several years away from widespread use.

Items manufactured from recycled PETE include carpet fiber, fiberfill insulation for jackets and sleeping bags, appliance casings and handles, and floor tiles; only a limited volume is currently recycled back into containers. Recycled HDPE is manufactured into items such as flowerpots, pipes, toys, and pails and drums; the proportion recycled back into containers is small but growing. Mixed plastics can be recycled for relatively non-demanding applications such as "lumber" for docks, traffic stops and park benches.

Historically, markets for recycled plastics have been subject to significant fluctuation. Prices for recycled plastics are directly related to prices for oil and natural gas and worldwide virgin plastic production. Like all recyclable commodities, prices tend to fluctuate as a result of supply and demand. Buying products made from recycled materials helps keep the markets strong.

General Perceptual Barriers and Solutions to Procuring Recycled Plastic Products

What people think or perceive about a recycled plastic product prevents them from buying it, not the product's ability to perform or meet specifications.

1) Price: Sometimes, the cost of recycled products is higher than those made with virgin materials.

2) Performance: Some believe products made with recycled materials will not perform as well as those made with virgin materials.

3) Prohibitive Standards: Some construction standards prohibit the use of recycled materials in construction applications.

4) Independent Contractors: State governments can specify in the request for bid that in order to win the award, a contractor must use recycled plastic products in appropriate applications.

5) Lack of Information on Recycled Content: Procurement officials need to know if products actually contain recycled material, how much, and how recycled content is defined.

6) Lack of Standards: blah blah blah...

Polyethylene Terephthalate (PETE)

Primarily used to make soft drink bottles. Peanut butter, salad dressing, and other household consumer products are also packages in PETE bottles. Other forms of PETE packaging include trays and sheeting for cups and food trays.

- Weight: PETE soft drink bottles - which constituted two-thirds of PETE packaging in 1993 - contributed 560,000 tons or 0.3 percent of the municipal solid waste stream before recycling.

- Volume: PETE soft drink bottles comprised 0.4 percent of landfilled municipal solid waste by volume in 1993.

- Recycling Rate: The PETE bottle recycling rate in 1993 was 8.6 percent.

- Recycling Content: most PETE bottle have no recycled content.

- Value: PETE has a relatively high per-ton value, but a low per-container value. - Composting as Waste Management: PETE is inorganic. Composting operations will attempt to exclude PETE by handpicking, or will grind it into a grit-like substance that will not biodegrade.

- Color Separation: Generally, green or brown PETE bottles must be kept separate from clear PETE bottles because markets for mixed colored PETE are limited.

- Collection: PETE's high volume-to-weight ratio (2.5 to 1.0) creates problems in collecting PETE in curbside collection programs.

High-Density Polyethylene (HDPE)

HDPE packages are made from resin produced from the chemical compound ethylene. The reason is either blow-molded to make bottles or injection-molded to make containers. HDPE resin is naturally milky white and is commonly used for milk, water, and juice bottles. Colorado residents can be added to the reason to make bottles for household and consumer products such as detergents, shampoos, and motor oil.

- Weight: In 1993, milk bottles made up 0.5 percent of landfilled municipal solid waste by volume. All HDPE bottled and containers made up 1.8 percent of landfilled municipal solid waste by volume.

- Recycling Rate: In 1991, approximately 135,000 tons of HDPE bottles and containers were recycled in the U.S., a 23.6 percent recycling rate.

- Recycling Content: The use of recycled content is limited in packaging; 25 percent post-consumer recycled content is most common.

- Value: Mixed color HDPE has a lower value than single color HDPE, which is market variable. In 1993, processors generally par up to $20 per ton.

- Composting as Waste Management: HDPE is inorganic.

- Color Separation: Automatic systems for color separation are not commercially available.

- Collection: HDPE's high volume-to-weight ratio creates collection problems in curbside programs.

Difficulties in Recycling Plastics

-Economic

-Thermodynamic

-Infrastructure

-Technologies

-Perceived barriers to using recycled materials

- Market does not drive recycling (price of recycled vs. virgin)

- Sorting - etc, etc, etc.

Glossary:

Commingled plastic - a mixture of plastics, the components of which way have widely differing properties.

Industrial plastic scrap - material originating from a variety of in-plant operations that may consist of a single material or a blend of materials.

Off-spec or off-grade virgin plastics - resin that does not met its manufacturer's specifications.

Performance standards - a document that defines levels of performance and provides both evaluation techniques and end-use criteria.

Plastic container - a receptacle used to hold material for shipment, transport, or storage and composed of thermoplastic or thermoset plastic materials.

Plastic recycling - a process by which plastic materials that would otherwise become solid waste are collected, separated, or processed and returned to use.

Post-consumer materials - those products generated by a business or consumer that have served their intended end uses, and that have been separated or diverted from solid waste for the purpose of collection recycling, and disposition.

Purge (plastic) - material resulting from the passing of polymer through a molding machine or extruder to clean the machine, or when changing from one polymer to another, or one color or grade of polymer to another.

Recovered material - materials and byproducts that have been recovered or diverted from solid waste, but not including those materials and byproducts generated from, and commonly reused within, and original manufacturing process.

Reconstituted plastic - a materials made by chemical or thermal breakdown of plastic waste into components followed by their conversion into final composition by chemical reaction.

Recycled plastic - those plastics composed of post-consumer material or recovered material only, or both, that may or may not have been subjected to additional processing steps of the types used to make products such as recycled-regrind, or reprocessed or reconstituted plastics.

Regrind (plastic) - a product or scrap such as spruces and runners that have been reclaimed by shredding and granulating for use in-home.

Reprocessed (plastic) - regrind or recycled-regrind material that has been processed for reuse by extruding and forming into pellets or by other appropriate treatment.

Reuse - the use of a product more than once in its original form.

Reworked plastic - a plastic from a processor's own production that has been reground, pelletized, or solvated after having previously processed by molding, extrusion etc.

Source reduction - a system including design, manufacturing, acquisition, and reuse of materials (including product and packaging), that reduces the quantity of waste produced.

Virgin plastic - plastic material in the form of pellets, granules, powder, floor or liquid that has not been subjected to use or processing other than that required for its initial manufacture.

References:

American Plastics Council, "Plastics: An Energy-Efficient Choice" pamphlet, 1996.

-------- "Purchasing Recycled Plastic Products", report, 1991.

-------- "Leaving a Lighter Footprinting - Plastics Make it Possible* pamphlet, 1993.

The Council for Solid Waste Solutions, *Resource and Environmental Profile Analysis of Polyethylene and Unbleached Paper Grocery Sacks', pamphlet, 1990.

Recycling Handbook

Ehrig, R. J., Editor, Plastics Recycling - Products and Processes, Hanser Publishers, New York, 1989.

New Hampshire Department of Environmental Services, "Recycling Plastics NHDES Technical Bulletin, 1996.

Rathje, William and Cullen Murphy, "Five major myths about garbage, and why they're wrong', Smithsonian magazine, July 1992.

Rader, Charles et al, Editors, Plastics, Rubber, and Paper Recycling: A Pragmatic Approach, ACS Symposium Series #609, American Chemical Society, Washington, 1995.

Andrews, Gerald D. and Pallatheri M. Subramanian, Emerging Technologies in Plastics Recycling, ACS Symposium Series #513, American Chemical Society, Washington, 1992.