Monte has several ideas and suggestions when it comes to the recycling conundrum:
- Landfill. A lot of plastic goes direct to landfill or it winds up in landfill after the cleaning and sorting process because there is no market. Landfills can range from garbage dumps to controlled environments, where moisture levels are maintained to help microbes do their work and the released methane gases are harnessed for energy.
- Organic recycling; composting/biodegradation. Microbes do the work of degradation and fall into five distinct classes from aerobic (oxygen loving) to anaerobic (oxygen hating). Microbes, corrosion and so forth are nature’s way of regenerating itself.
- Waste-to-energy/incineration. It works, but it’s not optimal in capturing the investment in technology needed to make a discarded plastic part.
- Chemical/depolymerization of select streams. This requires major capital investments to install the chemical plant and a supply infrastructure. It works for commodity plastics such as PET water and soda bottles that can be regenerated into rPET for bottle use. But if the rPET is made into carpet fiber, it needs pigments for color and about 40% CaCO3 for heft and wearability. When the carpet needs to be replaced, the CaCO3 is viewed as a contaminant and goes to landfill.
- Recycle sources, curbside or post-industrial. “I believe post-industrial recycling, such as car bumpers to produce materials for decking and large parts, will be the current market, with curbside recycling programs coming in time,” Monte said.
IDTechEx (Cambridge, UK) has just released a new report, "Green Technology and Polymer Recycling 2020-2030: Technology for a Sustainable Circular Economy in Plastic Waste," authored by Dr. Bryony Core. The report homes in on some of the same issues related to physical/mechanical recycling that Monte addressed. IDTechEx said that the “downsides of mechanical recycling are that sorting prior to melting is imprecise and prone to impurity inclusion.
“Although steps have been taken to increase impurity removal with new optical sorting techniques such as near infrared, the primary route to reducing contamination relies upon the individuals producing the waste to sort it correctly into constituent materials at the point of generation,” said the report. “Even if the input polymer is free from contamination, the very act of heating to melt the polymer can impair the properties of the recycled output polymer, as heat can break down the polymer backbone for certain polymer types.”
I’m assuming that means that consumers—the point of origin of much plastic waste—need to know what they’re throwing into the recycling bin. That requires a lot of education and, as Monte commented, “Can we really educate consumers enough so that they begin to care about what they put into the blue bins?”
These issues, along with the economic considerations cited by Monte, have “acted as barriers to widespread recycling implementation,” notes the IDTechEx report. And, I might add, they have impacted the decision of many municipalities to curtail recycling programs. It’s no wonder so many are starting to see recycling as part of the problem rather than a solution.
IDTechEx said, however, that “innovations in the field of polymer recycling are helping to address the technical hurdles to increasing recycled polymer quality.” These new processes fall into three categories: Solvent extraction, a physical process, and plastic-to-fuel conversion or depolymerization, which are both chemical methods. “The more mature technology, plastic-to-fuel conversion, uses mixed polymer waste, which is otherwise very challenging to recycle, and outputs fuel fractions using chemical reactions such as pyrolysis or gasification,” said the report.
Monte believes that making recycled polymers compatible is key to the long-term success of recycling. There is already an extensive infrastructure in place and recycling companies have made huge investments in the latest and greatest machinery and sorting technology in place. “It’s important for recyclers to know these [compatibilizing] technologies because the more you compatibilize, the less you have to clean and sort, allowing for more favorable economics in producing a functional recycled plastic part,” Monte said.
Monte will show companies that have pledged to achieve “sustainability” goals how to “walk the walk after they’ve talked the talk” at an upcoming Plastics Recyclates Forum on March 3 and 4, 2020, in Darmstadt, Germany. “You pledged your company to sustainability goals, such as increasing plastic recycle content and reducing the carbon footprint, but how do you get there? There’s more to plastics technology innovation than Industry 4.0,” Monte said. “There’s just so much you can do with software and hardware. Optimization cannot be achieved without first making more efficient use of the materials in the products you make.”