The Science of Recycling 2

From the bin to the processing plant, recycling is no simple process. CEM does the dirty work for you and goes in-depth to find out how they do it!

The University of Colorado and the city of Boulder have both been leading pioneers in sustainable living by implementing zero-waste sports events, pushing for renewable power and creating an accessible public transport system. On top of all these environmental successes, sits the most impactful factor in minimizing our ecological footprint: the recycling system. With the city of Boulder requiring trash companies to provide free recycling, minimizing waste is at residentsí fingertips. But how much do we really know about the whole recycling process? With  the further simplification of single stream recycling, we are as disconnected with the fate of our plastic bottles as we are with the future of everything we toss in the dumpster. The story of recycled materials after they leave the bin feeds into an intricate network of transport, sorting, processing and more sorting after that. Next time you toss an item that is embossed with a numbered triangle, youíll be able to picture the future journey it is about to take, or even reflect of the hundreds of miles it has already traveled.


The first, and most important, step of recycling after it has left the curb is sorting. Sorting separates out contaminants and various different materials, combined through the single stream system for convenience, so that they can be processed correctly. This step is critical as some materials, such as glass, cannot be recycled properly if not isolated correctly. Eco-Cycle, a non-profit organization that manages recycling facilities in Boulder, has a wide variety of equipment and screens to make sure that everything is in the right place. This equipment can range from very simple techniques, such as filters that separate large paper objects from smaller recyclables, to advanced technologies, like the KSP unit that removes glass particles from paper particles through testing the transparency of the material using cameras, light and air jets. Once everything is separated, then they are transported to other facilities that can turn the materials back into products.


Glass is a high-demand recyclable due to the large energy costs associated with making virgin glass from sand.  When there are no contaminants, the quality of the glass does not deteriorate during the recycling process and it can be recycled many times. To recycle glass, the glass is simply melted down and flowed into new molds to create bottles, containers or anything else the glass could be used for. A chemical process can also be applied to color or decolor the glass, but the glass that flows through the boulder recycling center is able to skip this process as the majority of it is sent to Coors, in Golden,  who uses brown glass for its bottles. When done correctly, recycling glass is a very cost-effective and energy-saving process compared to creating new glass, but when contaminants are accidentally included, mainly because of negligence or lack of education about recyclables, entire batches must be thrown away. “My first week on the job, I had to deal with a batch of glass being rejected from Coors”, says Jack DeBell, the director of CU’s recycling services, “someone had put some lab glass into the recycling bin and we were given the option to throw it all away or somehow get the lab glass fragments out of it”. Mixed grades of glass are not recyclable due to the varying melting points of different kinds of glass. If the glass does not melt evenly then it might not flow into the molds or it could cause weaknesses in the finished product.


Metals, much like glass, also go through a process of melting and re-molding and does not become less valuable during the recycling process. Unlike glass, however, recycling metal actually results in a higher quality of metal. As the metal melts, the different kinds of metals can be separated from each other, due to different melting points, resulting in a purer form of each metal. The most interesting part about metal recycling is not the process itself, but where it goes once it leaves the Boulder sorting facility. With the increase of Chinese goods entering the U.S. market, with little flowing back to China, so have the number of ships bringing those goods to the U.S.,which make the trip back empty. In order to decrease the waste of the return trip, the Chinese have started buying almost all of the recycled metals at a price higher than the market to outbid other buyers. Bringing goods to America, and then returning with a full load of recycled metal to feed China’s rapidly growing industry.

2 thoughts on “The Science of Recycling

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    Ted Peterson

    The only metal supplier my company uses is Avion Alloys. We never had the cause to postpone any projects due to the fact that they provide a wide variety of high performance metals, and customize to required specification and orders delivered on time. If you are looking for hard to find metals, you should check their website or call 1 (866) 610-1660.

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