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Yowzers – according to the U.S. EPA, about four billion, yes billion pounds of carpet go into the waste stream every year – much of it is used, some is new carpet left over from building construction. A lot of that carpet (and carpet backing) is made of cheap, durable polypropylene fiber, which makes up about 80% of the sales for commercial carpet.
Polypropylene, aka olefin, may be familiar to recycling addicts through its #5 plastic recycling designation, a number that can spell trouble. Until now, recyclers have been slow to adopt #5, partly due to the expense of separating it from other materials. Used polypropylene carpets on the other hand offer good potential for cost effective processing due to their sheer bulk and availability.
Because of its relatively low cost and high durability, polypropylene has a few other uses aside from carpets including ropes, plastic containers (margarine, yogurt, etc.), bottle tops and “living” hinges (think Tic-Tacs), lab equipment, auto parts, piping, furniture, consumer electronics and toys (cell phones, loudspeakers and Rubik’s Cube), lampshades, kettles, surgical materials, buckets, pitchers, model aircraft (in its foam form), car batteries, jewelry, stationery folders and storage boxes, coolers, air filters, insulated cable, diapers (disposable, natch), and activity wear (Under Armour). There is even polypropylene currency, if you can believe it. The annual global market for polypropylene adds up to about 45 million tons – a recycling gold mine ripe for the picking.
Axion Polymers is a recycling specialist in the U.K. that has just announced it is ready to do some polypropylene picking, working with Carpet Recycling UK Ltd. and the public organization Envirolink Northwest. The company has developed a method for recovering polypropylene from used carpets and converting it into pellets. In this form the material is not suitable for manufacturing sensitive products such as lab equipment or food containers, but it could be reformed through injection molding into things like plant pots, compost bins and buckets. Last year Axion undertook trial runs on a small scale that showed promise, and now it’s ready to embark on larger trials to demonstrate cost-effectiveness.
Axion has found that the key to cost-effective recycling of polypropylene carpets starts at the beginning, by selectively targeting “pure” polypropylene carpets for the process. Carpets that contain mixed fibers are not suitable for this form of recycling, but at least it’s a start toward getting more #5 plastic out of the waste stream. In the U.S., carpet recycling is starting to take off in San Francisco among other places, and companies like Aveda, Organic Valley and Stoneyfield Farms are focusing on small #5 plastic items like bottle caps and yogurt containers.
Image: Carpets by ishane on flickr.com.
Tina Casey specializes in military and corporate sustainability, advanced technology, emerging materials, biofuels, and water and wastewater issues. Tina’s articles are reposted frequently on Reuters, Scientific American, and many other sites. You can also follow her on Twitter @TinaMCasey and Google+.