Plastics in the Environment: The Complex Recycling Landscape


By Dan Barbin

Climate change is very real and is a growing concern for the entire planet.  One major cause that has no single solution involves greenhouse gas emissions.  The largest greenhouse gas emitted is carbon dioxide which is dominated by fossil fuels and industrial processes. It has become clear that the world must wean itself off its dependency on non-renewable fossil resources.  The plastics industry is inextricably linked to the fossil fuel industry not only because 4% of the world’s natural gas and oil are used to make plastics, but also since lightweight plastic packaging drastically reduces CO2 emissions from transportation of goods. The lifecycle of a plastic has dangerous implications for the planet since society throws plastics away and wastes the energy and resources invested into forming them.

              Let us assume you live in a Massachusetts household and recycle 100% of your plastic.  What does that mean to you?  Does your supermarket have a bottle depository, and do you bring your bottles back?  Massachusetts incentivized recycling where those 500 mL bottles (carbonated soft drink, beer, malt beverage, and water) are worth 5 cents each when returned to a collection machine.  Let’s run some calculations quickly.  If you purchased a 24-pack of Poland Spring sparkling water from Market Basket while it was on sale, it will cost you $2.99; so, if you bring those 24 empty water bottles back to Market Basket in MA, then your $0.05 per bottle will yield $1.20.  This effectively means that depositing your water bottles will save you 40% on your water cost at the supermarket, a pretty attractive deal.  Perhaps you prefer still water and a local recycling company collects your plastic every other week from your curbside.  What does it mean for your household to recycle?  You put your plastic in the recycling bin, and you wheel it to the curb, and the collectors come by and take your materials away, and your material gets recycled and your family contributes less to the global carbon footprint.  But instead of making money for your recycling work, you pay for a service to come collect that material to do the same thing.

              While PET bottles have high potential for recyclability, other plastic materials do not.  Did you know that recycling municipalities used to ship their curbside recycling to China for processing?  China has since announced that it no longer wants to be importing the globe’s waste, and they have tightened their standards for what material they will accept.  The impact of this is hugely significant because other countries have to find a way to adapt to the Chinese market closing its doors on accepting material due to the larger percentage of contamination.  For America, the value of plastic scrap has decreased 90% from 2015 to 2018, and some waste managers believe the new contamination percentage is impossible for the country to achieve.  Other countries have stepped into the recycling market to help with the problem, but the total exports are still 40% lower from 2015 to 2018.  This challenge requires a better understanding of the recycling process and how we can reduce our contamination.

              So how does a Material Recovery Facility (MRF) work? We’ll explain, but it might be more entertaining to you to check out this YouTube video or this article instead. At a typical MRF, commingled materials are fed onto a conveyor at a steady rate.  The materials are pre-sorted manually where workers remove any trash, plastic bags, and other miscellaneous materials that do not belong in the feedstock.  Large pieces of cardboard are then removed from the stream via sorting disks, and the heavier material stays beneath.  From here, magnets are used to pull the steel and tin materials off the conveying system, and the aluminum cans and non-ferrous metals are removed using an eddy current separator.  With the metals removed, glass and plastic remain; glass can be separated by a density blower where it is then crushed.  The remaining plastic is separated by material type, and optical sorters and air classification systems can be used to divert streams of PET and HDPE; optical sorters identify the quality and composition of plastics, allowing removal of contaminated plastics that compromise recyclability. Not all MRFs have the same material identification technology available, which influences the final sorting quality. Humans also work on these lines to divert streams of materials that they recognize, but the material that remains is typically sent to a landfill.  It is an unfortunate reality that materials are thrown away when they have the potential to be recycled.  However, facilities do not have all of the necessary resources at their disposal, so they have to make cost-effective decisions to keep their companies in business.

              In order to increase the fraction of plastics waste that can be recycled, one option is to design plastic parts that can be recycled utilizing the currently available MRF infrastructure.  Plastic part designers should be developing parts that are made of a single material (i.e. do not use multiple over-molded plastics or metal inserts) in applications where this is feasible.  The primary materials being selected should be PET, HDPE, or PP because these materials are currently recycled at the highest rates and have the largest market for granulated flake; if you are curious how much recycled plastic is sold for within the plastics industry, then check out Plastics News resin pricing.  Manufacturers need to be held responsible for the full lifecycle of their parts because single-use plastics that do not get recycled are steadily increasing the globe’s carbon footprint.  There is no single solution for the world’s recycling problems, and it will not be solved overnight.  Trying to change the design landscape for plastics is an ambitious goal and might be improbable.  Perhaps regulations can drive change in the U.S. economy, but we need to start doing something now before it is too late and irreversible environmental damage occurs.  The place to start is at the manufacturing level where we can use more environmentally conscientious materials to show recyclers that businesses are making an effort to fix the problem that they are contributing to.  If businesses will show that they are willing to help and can produce more potentially recyclable materials, then recycling companies can invest in technology to recycle those materials since the input volume will increase enough to justify their investments.  There simply is not enough time to wait for a new technology to emerge to solve every problem.  As a society, we need to start making changes to embrace our reality, and we have to start somewhere.  Perhaps this approach will make the overall problem more manageable.  Perhaps it will buy some time and give the planet an opportunity to survive.