How Are Materials Recycled?
By: Nathaniel Bevins, KIBCU Intern
The Process for Recycling Plastic
Once plastic has been delivered to the plastic recycling facility, it must be sorted by resin type (polyethylene, polyvinyl chloride, polypropylene and polystyrene) to ensure it can be reused. This can be done manually or mechanically.
These newly sorted plastics are then shredded into small fragments.
The fragments must be washed or undergo some other cleaning process to remove impurities like labels Blocks of plastic about to be sorted
After being cleaned the plastic is melted and then poured into a mold to form small pellets that can be sold and used for other products.
In this method unsorted but cleaned plastic is placed in tumblers. Tumblers are large rotating drums that rotate and melt plastic down. This method is good because it means that plastic not in matching forms can be recycled at once. A disadvantage of the tumblers is they require a large quantity of energy.
Challenges for Recycling Plastic
A challenge for recycling plastic is that when polymer blends of plastic are melted together, they phase separately. This means that the different parts of the combined plastics form layers like oil and water. As a result, the material is weaker and isn’t really useful. In order to be reused, new and unused plastic must be added into the mixture to stabilize the end result. The two most common types of plastic used and thus recycled are polypropylene and polyethylene, which are both polymer blends and unfortunately have this issue. Overall, this means that most recycled plastics must have new or unused plastic added before it can be successfully recycled. This makes the process less efficient.
Why Recycle Plastic?
In 2008 the US post-consumer plastic waste was estimated to be 33.6 million tons. Only 2.2 million tons were recycled, which is only (6.5%). However, 28.9 million tons (86%) were sent to landfills. This plastic will be around for over 500 years before it degrades. In addition, it is estimated that 8 million metric tons of plastic enter the oceans every year. Microplastics in particular have become a huge problem, harming marine life and even finding their way into human bodies. Thus efforts to recycle plastic can have a huge impact on keeping the earth clean and protecting the delicate balance of our ecosystems.
The Process for Recycling Paper
Once paper is delivered to the recycling plant it is separated by different types and grades.
The paper is washed in a mixture of water and chemicals such as surfactants, hydrogen peroxide, sodium hydrosulfite and/or chlorine, to remove ink, plastic, staples, and other possible contaminants and to break down the paper.
Next, the paper is put into a large container where it is chopped and heated in order to reduce it to cellulose strands. The resulting mixture is called pulp or slurry.
The pulp is strained to remove any excess material still in the mixture.
Then depending on the type and grade of paper wanting to be created different elements can be added.
The final mixture is spread into long sheets via large rollers and left to dry.
Once dry, it is cut into sheets and sold for future use.
Why Recycle Paper?
Today making new paper accounts for about 35% of all felled trees. In addition, pulp mills can produce high amounts of air and water pollution. Both of these can be harmful to ecosystems in the surrounding area. The EPA has found that just recycling can lead to a 34% decrease in water pollution and a 74% decrease in air pollution. And while the process of recycling itself can require the use of certain harmful chemicals, the end impact on the environment is still in favor of reusing paper.
The Process for Recycling Glass
Once recycled glass is delivered to a glass treatment plant, it is separated by color and any contaminants such as plastic must be removed. This can be done mechanically or manually.
Next, the glass is washed to remove impurities such as labels.
After being cleaned, it is crushed and melted down.
Finally, the recycled glass is molded into a new form and sent to be used again.
Why Recycle Glass?
The great thing about glass is that it can be 100% recycled, none of the glass is lost through the recycling process. This means that if more glass is recycled less has to be made. Less glass being made reduces air pollution by about 20% and water pollution by 40%. In addition, it reduces the amount of energy being used, as recycling glass takes less energy than making new glass. Finally, it means that less glass is polluting and harming ecosystems.