Plastics products are ubiquitous throughout the world. As dependency upon these light weight and durable products increased, so too has the need for global innovation in recycling technologies. Over the decades recycling companies developed a variety of processes to turn discarded plastics into hundreds of products from paint brushes to rugs and pillows, boat hulls and railroad ties.
Calling the Consumer
The greatest challenge to recycling manufacturers is educating and engaging the public. About 75 percent of Americans recycle newspaper and cardboard while little more than 25 percent recycle plastic. Industry analysts think this low response rate might be due to a lack of understanding about the coding on recyclable plastics – the small triangle with a number in the center – that identifies what kind of plastic an item is.
The most frequently recycled plastics of the seven groups of polymer plastics are PET 01, used in soft drink bottles and smaller jars; PE-HD 02, a harder and more durable plastic used in milks bottles and large trash bags; and PE-LD 04 that's tough yet flexible and used in frozen food bags, flexible container lids and squeeze bottles.
Although the recycling rate of these and other products is not yet impressive, the numbers have been steadily rising since 1990. In 2006, about 2.2 billion pounds of PET plastic bottles were recycled and 928 million pounds of HDPE (High Density Polyethylene) containers made it to recyclers.
Innovating PET Production
As awareness of the environmental damage done by polymers increased, so too did the urgency to encourage recycling. At the same time, experimentation with processing and application rose. For example, according to a CNN report, a Ph.D. in India, Dr. S. Madhu, included shredded and melted plastic in a roadway surfacing mix. Working for the Kerala Highway Research Institute, Madhu mixed the plastic with aggregate and bitumen to create a surface that withstands the pounding of annual monsoon seasons.
Working in a highly regulated environment, conventional recycling manufacturers focus on producing a long list of common products. Although processes vary, they generally follow a common methodology. First, plastics are sorted according to their PET identification number. This is often done before the recycled products reach the manufacturer. The "dirty" PET containers are also cleaned of labels, glue and other residual materials. A dirty regrind of the PET then goes to re-claimers who process the material into a form that can be used by manufacturers. Re-claimers further clean the materials of contaminants and materials that are lighter than the plastic. The final flakes of PET are washed with a special detergent that gets rid of glues, food or dirt.
Next, the PET materials are further treated with processes that separate the heavier PET particles from the lighter ones – this is called the float-sink stage. The plastics are then dried and ready to become new products in the hands of manufacturers throughout the world.
But, new methods are constantly being developed to recycle PET products, including a de-polymerization process that "reverses" the chemical process used to make the polymer. There are pilot projects using this method, as well as other innovative processes to make plastic recycling more environmentally friendly and economical.
Demand for Recycled Products
The importance of recycled PET and HDPE cannot be ignored. The latter, heavier PET is used to make building materials that become backyard decks that last longer than wood; it becomes lawn furniture, trash cans, office products, buckets, safety cones and much more. HDPE can also be used to manufacture above and below ground water storage tanks that withstand decades of use.
Of five major classes of PET plastics, the most high-end use is to manufacture new PET bottles and containers. Other classes include plastic sheeting or plastic that's used for molding small items such as scoops for laundry detergent; strapping materials for packaging and transportation; resins that are used in molds for automobile components; and material that's combined to make fibers for carpeting, fabrics and fiber fillings.
Recycled PET can show up in unexpected places such as business cards, sleeping bags, baseball caps and the welcome mat at your front door.
In the Hands of the Consumer
Ultimately, it's all up to the consumer. Awareness of the environmental benefits of recycling plastic and the viability of manufacturing with recycled PET can mitigate environmental damage and support a global industry that returns economical and useful products to the marketplace.
In the US, many municipal governments have made it easier for consumers to recycle plastic. Cities accept all plastic products with the recycle symbol and do the sorting themselves before shipping off for further processing. The consumer doesn't have to deal with separating PET numbers or peeling off labels. Many states have passed legislation commonly known as "bottle bills" that charge a small fee for plastic containers. There is greater value to the consumer to recycle when there is the incentive of a redemption value. Some communities have "drop off" recycling centers and others have "buy back" centers that pay consumers for recyclable materials.
Whatever the method of recycling or the process that recreates value from discarded PET products, it's clear that the public, governments and industry share a financial and environmental stake in the practice of plastic recycling.