Alternative Plastics: Degradable vs. Biodegradable vs. Compostable

By Meghan Ibach

In this age of plastic, trying to discern what is recyclable, compostable, or just plain trash is confusing! Companies with misleading marketing schemes claiming false “greenness” further confuse the issue. Referring to biodegradable, compostable containers as ‘plastic’ creates confusion. 

People tend to conflate compostable “plastics” with actual plastic. That’s why, in this blog post, I’ll use the term ‘bioplastics.’ Bioplastics look and act very similar to plastic, but they aren’t the same. You may remember a time you left a ‘plastic’ cup in your car on a hot day, only to find it melted in your cup holder! That was a bioplastic.

There are a few different kinds of bioplastic:

Degradable – All plastic is degradable, even traditional plastic. However, breaking down into tiny fragments or powder does not mean the materials will ever return to nature. Some additives to traditional plastics make them degrade more quickly. Plastic debris erodes and becomes microscopic fragments that accumulate in oceans, are eaten by marine life, and make their way up the food chain.  

Biodegradable – Biodegradable bioplastic can be broken down completely into water, carbon dioxide, and compost. However, it can only be composted under the right conditions, with the right microorganisms. “Biodegradable” generally implies decomposition will happen in weeks to months. The true definition of biodegradable does not have an implicit time limit, so these plastics can actually take years to break down. 

Compostable – Compostable bioplastic will biodegrade at an industrial compost site. You can’t put them in your backyard bin, but you could send them to Danny’s Dumpsters. During the composting process, microorganisms break down the bioplastic into carbon dioxide, water, inorganic compounds, and biomass at the same rate as other organic materials in the compost pile, leaving no toxic residue. Most containers that are commercially compostable state it on their packaging. 
The terms ‘degradable’ and ‘biodegradable’ plastic are somewhat misleading. People tend to wrongly believe these items will degrade and disappear from the environment. However, ‘biodegradable’ and ‘compostable’ items need specific environments to truly disappear. 

Here’s one very common misconception: trash will decompose in the landfill. This isn’t true! Due to the lack of microbes in an anaerobic (without oxygen) environment, most of our waste (whether it’s food scraps or bioplastics) practically mummifies. Although bioplastics don’t release as many toxic chemicals as traditional plastics, they won’t decompose in the landfill, and their potential to be repurposed into compost will be wasted.

Hot tip: Look out for #7 plastics. 

This is an ‘other’ category. Think of it as your miscellaneous junk drawer. So many different plastic-type products have a #7 recycling symbol stamped on them, the label is pretty much devoid of meaning. Commercially compostable products are frequently stamped with a #7, but they cannot go to the recycling center! Not all #7 stamped products are compostable, so be sure to read any extra language printed on the package. If you determine that your #7 package is compostable, send it to a commercial composting company. If not, it is destined for the landfill.
 
Bioplastics have their advantages, but they require high temperatures at commercial composting facilities to break down. Very few cities have the infrastructure needed to process them. Commercial composting companies like Danny’s Dumpster (Asheville, NC) and Atlas Organics (Greenville, SC) divert enormous amounts of food waste from our landfill. Unfortunately, we create more food waste than either company has the capacity to process. 

Many bioplastics end up in the landfill, where they slowly break down - producing high levels of methane and taking up landfill space. Some bioplastics end up at the recycling center, contaminating the recycling stream. When bioplastics are mixed with recyclable plastics like PET (commonly used for water and soda bottles), the entire lot could be rejected. A lot rejected due to contamination ends up in the landfill, because it is no longer reusable. 

Bioplastics require a lot of plant matter to create. In fact, 1 kg of the most common bioplastic, PLA (polylactic acid), requires 2.65 kg of corn to produce. Bioplastic industries compete for land that could be used for food production, growing crops to feed the packaging industry instead of feeding people. 

The Plastic Pollution Coalition projects meeting the growing global demand of bioplastics will require more than 3.4 million acres of land - an area larger than Belgium, the Netherlands, and Denmark combined. 

Bioplastics are also relatively expensive to make. This cost is passed onto retailers and consumers through high prices. The price is decreasing as technology adapts and more efficient systems are created. Several companies and clever scientists are looking more at food waste and other inedible parts of plants to create totally biodegradable containers, bags, cutlery, etc. If they succeed, bioplastics can be grown symbiotically with food crops.
​
Currently, bioplastics take a lot of resources and energy to create. When they aren’t disposed of properly, they make more trash. Thankfully, we can see trends of human ingenuity aiming to utilize our resources- including our food waste- to create economical and environmentally-friendly packaging, to-go ware, and much more. 





​








​Meghan Ibach is the Sustainability and Marketing Manager for UNC Asheville Dining Services. She believes in collective power to radically change systems, and that we vote with our purchases and choices every day. She’s part of the Plastic Reduction Task Force to help reduce plastic waste in our community, hoping we can all make a greener, brighter future together.

Sources:
https://blogs.ei.columbia.edu/2017/12/13/the-truth-about-bioplastics/
https://en.wikipedia.org/wiki/Biodegradable_plastic
​http://www.youngscientist.com.au/wp-content/uploads/2017/02/degradablevsbiodegradable.pdf

---