In Layman’s Terms: In Search of Treasure from Trash

contributed by Priscilla Carrillo-Barragán

It’s not rocket science: with waste, as with fashion, less is more. But what is it that we human beings, creatures of diverse opinions, consider waste? How can we define this common term?

Remember that bottle of water you bought last summer? It was a hot, sunny day, and heat means getting thirsty. The water was so refreshing that you drank it all, and suddenly there you were, with an empty plastic bottle on your hands and only one question in mind: how do I get rid of this? The bottle, valuable when it had water in it, was now waste, and the only place you wanted it was away from you.

So, simply put, waste is an unwanted material which no longer has value.

As a responsible citizen, you probably tossed the water bottle into the nearest recycling bin as plastic waste. But what if a drinking fountain had crossed your way? You could have refilled the bottle, and it would have held value for you again.

The difference between these actions might not be immediately obvious. Reusing, recycling—aren’t they equivalent? Either way, the bottle escapes the landfill. Aren’t you doing your bit by doing either of these?

The answers: No, and maybe.

Let me introduce you to the Waste Hierarchy, a ranking of the waste management options according to what is best for the environment (Fig. 1).



Waste hierarchy. Source: Welsh Government 2015

The top priority is given to the elimination of waste in the first place. Elimination is particularly important with hazardous materials, due to their inherent toxicity like mercury in thermometers and asbestos in buildings. If the waste cannot be avoided, then it should be reduced.

Before an item becomes waste, it should be reused. Remember the plastic water bottle? In addition to reusing it by filling it again, you could reuse it as a planter, a chandelier, a trinket organizer…your creativity is the limit. Similarly, a printed paper could be used to scribble notes on, folded into decorative origami, or shredded to create packing material. Once the reused item becomes unusable, it should be recycled.

The recycling company will have to process it, investing energy and generating waste in the process. The company may be able to recover some energy from the process, but in the end there will always be waste to be disposed of. Frequently, the recycled product will be of lower quality, or “downcycled”, as is the case in plastics recycling.

So here is the answer: reusing and recycling are not the same thing. When you reuse a material, you are using it again for the same or another purpose without it requiring further processing. But to recycle, you change the material physically and/or chemically, consuming more materials and energy. That is why reusing is preferred over recycling.

The last two levels of the waste hierarchy are the least preferred—recovery and disposal. Recovery refers to turning waste into usable energy, which can be difficult and inefficient. Finally, when all other options are exhausted, waste can be disposed of in a landfill.

Unfortunately, not all materials can go through every level of the waste hierarchy. Consider agriculture and food waste. An activity as common and necessary as eating unavoidably produces waste every day, starting with agricultural waste, which cannot be reused or recycled, and often is disposed by burning it in site without energy recovery. Composting is an option, but there is only so much compost that can be usefully applied, and the remainder of food waste is landfilled in many countries, as the U.S., where about 30 million tons of food waste are sent to landfills every year (U.S. Waste Characterization, U.S. EPA, 2007).


Landfill receiving a painful lot of food waste that could have been diverted. Source: Cheaperwaste 2013

In an ideal world, this waste would be turned into value. Can you imagine fueling your car with ethanol that comes from organic waste, and not from crops that could have been eaten? Or food industries using their waste to generate energy which could be applied at their own facilities? And what if the plastic for food packaging were made of agricultural waste, such as corn husks?

Well, all these possibilities are being studied and developed by researchers around the world, some of whom are NESSE members! Stay tuned for the details in upcoming posts.

In the meantime, remember: waste is in the eye of the beholder. What do you see?