By Susan Stewart, Organic Certification and Sustainability Coordinator

I get many questions about plastics and recycling. Petroleum-based plastic is one of those persistent materials that has some benefits, but like water, its use carries responsibility.

Plastic and plastic recycling affects products from drink containers to shopping bags to PVC pipes. Since plastics are used in the majority of products, plastics are now a large part of the waste stream, and they do not degrade. Ever. To know the best way to recycle these products, it's best to learn more about their life cycles, including what types of plastics are used for different products, so you can decide how and when to use it.

Plastics are "polymers"–something made up of many units. In plastics those units are petrochemical "monomers". There are limitless formulations for monomers to produce a variety of plastic resins with different characteristics, such as strength, flexibility, transparency, or molding capability. Resins are manufactured products used as feedstock to produce plastic products.

Plastics production is classified into two main categories: thermoset and thermoplastic. Thermoset is the rigid plastic that is produced with heat. It is irreversibly solid and used when strength and durability are desired in finished product. Formica, Teflon, Tupperware, and PVC pipe are common thermosetting plastic products. Thermoplastic is soft when heated and returns to its' original condition at room temperature. Thermoplastic can be made into unlimited shapes such as jugs, carpet fibers, bags, and credit cards.

Plant-based plastics are called bioplastics. Their manufacturing produces fewer emissions than petroleum-based plastics, and they don't contain bisphenol A (BPA). Bioplastics have been around for decades. Henry Ford made automotive parts out of corn and soybean oils for the Model T. There are two promising new varieties of bioplastic. Polylactic acid (PLA) is clear in color and costs manufacturers about 20% more to use than petroleum-based plastic. The other, polyhydroxyalkanoate (PHA), biodegrades more easily but is more than double the price of regular plastic. Both are made of fermented corn sugar and come with a major benefit: if disposed of properly, they won't stick around in landfills for thousands of years. But that's a big IF.

PHA is more expensive, but it can handle higher temperatures and is the only bioplastic that will decompose in soil or waterways. In a closed landfill, it will most likely remain intact, like regular plastic. However, in a landfill where moisture seeps in, bioplastics will anaerobically degrade and give off methane, a powerful pollutant. Kitchen scraps and yard waste emit this gas as well, which is one reason many landfills have started capturing methane output and using it for energy.

The market for bioplastics is still relatively small, and until it gets bigger, consumers may have trouble dropping their bioplastics off at recycling facilities or composting centers. PLA is recyclable, but it can't be mixed with the current petroleum-based recycling stream. Some composting and sorting centers have a blanket policy of discarding all plastic that they cannot classify. Many of the disposal issues could be resolved if manufacturers adopted an identification coding system for bioplastic resins.

The Society of the Plastics Industries, Inc. (SPI) introduced its voluntary resin identification coding system in 1988 to assist municipal recycling programs that traditionally target packaging containers. The SPI coding system offered a way to identify and sort the resin content of containers commonly found in the residential waste stream. Plastic household containers are marked with a number that indicates the type of resin, or plastic. Consumers can use this information to determine whether or not certain plastic types are collected for recycling in their area. The numbers 1 and 2 were given to the most common plastic resins.

To identify the plastic, look at the recycling icon, the chasing arrows. Inside the arrows will be a number that identifies the polymer. When the number is omitted, the symbol is known as the universal Recycling Symbol, indicating generic recyclable materials. Because each resin was manufactured into a plastic with very different properties, there are different processes that use and recycle the various plastic materials. According to the American Chemistry Council, more than 1,600 U.S. businesses handle or reclaim post-consumer plastics. There are many more outside the US.

Plastics are usually collected from curbside recycling bins or drop-off sites. They go to a material recovery facility (MRF), where they are sorted from other recyclables. The resulting mixed plastics are sorted by type (resin number), baled, and sent to a reclaimer. At the reclaiming facility, the scrap plastic is passed across a shaker screen to remove trash and dirt, and then washed and ground into small flakes. A flotation tank then further separates contaminants, based on their different densities. Flakes are then dried, melted, filtered, and formed into pellets. The pellets are shipped to product manufacturing plants, where they are made into new, recycled plastic products.

According to the American Plastics Council, plastics production accounts for 4 percent of U.S. energy consumption. By recycling plastics, we make a portion of that energy available for new products or for other purposes. For example, over 4 billion pounds of plastics were recycled in the United States in 2006, which is enough energy to heat over 2.1 million homes.

The success of any recycling concept is in the efficiency of purification and decontamination at the right place during processing. Generally, the sooner foreign substances are removed from the recycling process, and the more thoroughly this is done, the more efficient the process is.

Currently there exists insufficient technology to purify post-consumer plastics for general recycling because there are so many resins it is difficult to manufacture general recycled plastic to meet a desired attribute. And, the recycling stream is contaminated. Until plastic manufacturers decide it is important to standardize resins, colors, and packaging to produce a more consistent post-consumer material, we will continue to see plastic dominate our waste stream. And we can make a difference by cleaning and sorting our recyclables and putting only those materials that our area recycles into our recycling containers.

Currently, there are insufficient markets for products made with recycled plastic. This is a circular problem. Both the capacity to process post-consumer plastics and the market demand for recovered plastic resin exceed the amount of post-consumer plastics recovered from the waste stream. This leaves manufacturers waiting for recycled plastic feedstock to manufacture their products.

We are all involved; manufacturers, recyclers, and consumers. Generating a consistent post consumer recyclable plastic requires all participants to engage. Sorting and purity requirements can be so restrictive that it is not uncommon for plastics bound for recycling to be rejected by the processor and ultimately disposed at the expense of the collector.

This is where recycling becomes personal.

We can choose to eliminate plastic from our lives; it's difficult, but possible to avoid plastic altogether. We can also look for and purchase those products made from recycled plastic or bio-plastic whenever it make sense in our lives. Using plastic lumber for the deck you plan to build. Buy recycled plastic toys for the children in our lives–or toothbrushes, or shaving razors. Or we can make purchasing decisions based upon what we are able to recycle. Check out what your city recycles and limit yourself to only those plastics. That takes awareness and commitment.

There are many recycling references for plastic available and I've put a few together on the Sustainability Resources page. Let me know how you engage plastic, plastic recycling, or bioplastic choices. If you have a favorite informative reference you'd like to see added to the resources list, I'd like to add it. I can be contacted via the contacts page. (Click on "Contact Us" at the bottom of this page, and select "Sustainability" from the drop-down menu.)