Though they may not be the first thing that comes to mind when you think of trash, carpets make up over 4 billion pounds of waste in American landfills — that’s 3.5 percent of all landfill waste in the entire country.
Whether they end up in landfills or burned at the end of their life, carpets pose significant environmental hazards, especially if they’re made from synthetic materials which contribute to greenhouse gas emissions and can take hundreds of years to degrade.
Soon, however, we may be able to recover high-grade polypropylene from synthetic carpets and thus prevent this material from polluting the environment. That’s thanks to scientists at Germany’s Fraunhofer Institute for Building Physics, who have developed an innovative carpet recycling process.
The first step in the process involves cleaning the carpet and removing the backing as much as possible. Next, the material is shredded, mixed with liquified salt, and placed inside a reactor chamber. Within that reactor, the polypropylene is dissolved out of the carpet fibers and into the solvent, leaving out impurities such as dyes.
The polypropylene is then separated from the solvent, most of which can be reused. The great thing about this entire process is that the harvested plastic is “virgin-standard,” which means it can be recycled into high-quality products.
Currently, scientists are working on maximizing the amount of solvent that can be reused in order to make the process more cost-effective and energy-efficient. “If loss rates can be kept to one percent or less, there is potential for the costs of the process to rival those of producing new polypropylene,” says Fraunhofer researcher Maike Illner.
The scientists expect to trial the process next March at a pilot plant capable of recycling one ton of carpet waste per day. The novel process could eventually also recycle other types of waste materials containing polypropylene.
