Bio-, Biodegradable and Compostable Plastics - explained

Bioplastics are currently used in disposable items that we make use of in our everyday lives including packaging, containers, straws, bags and bottles, and in non-disposable carpet, plastic piping, phone casings, 3D printing, car insulation and medical implants, the list goes on! The global bioplastic market is projected to grow from $17 billion in 2017, to almost $44 billion in 2022. Plastic is what the terms bio-, biodegradable and compostable have in common here, but what exactly makes them different? Are there any benefits? ––are they a solution towards a zero waste world?
Bioplasts

We often read these terms, but their names can be misleading, so let’s get a brief overview:


Bioplastic is not just one single material, they make up a whole family of materials with different properties and applications. According to European Bioplastics, a plastic material is defined as a bioplastic if it is either biobased, biodegradable, or features both properties–this means bioplastic is not automatically biodegradable. A common misconception is that bioplastic is always 100% made from plant based materials. According to Zero Waste Europe, most bio-based plastics available on the market are actually a combination of plant or animal organic matter, and fossil fuels. At the moment there is no label to qualify a product as bioplastic in Europe. There is also no obligation to display how much of a product is plant based.

 

Biodegradable plastic can be broken down completely into water, carbon dioxide and compost by microorganisms under the right conditions. Biodegradable implies that the decomposition happens in weeks to months––the process of biodegradation depends on the surrounding environmental conditions, for example, temperature. Everything is biodegradable given time (thousands, to millions of years), so it’s important to check the condition of biodegradability of each product. There is no European certification for biodegradable products, and there is no obligation to state the condition of biodegradability in products. While the biodegradability of bioplastics can be seen as an advantage, most need high temperature industrial composting facilities to break down and currently there is no infrastructure to properly manage them. As a result, bioplastics often end up in landfills where, deprived of oxygen, they may release methane, a greenhouse gas 23 times more potent than carbon dioxide––or they will continue to float around our oceans. In this case, are biodegradable plastics truly a solution?

Compostable plastic will biodegrade in a compost site––microorganisms break it down into carbon dioxide, water, inorganic compounds and biomass at the same rate as other organic materials in a compost pile, leaving no toxic residue. The International Organization for Standardization (ISO) states that there are four main characteristics to assess the compostability of plastics including:

 

  1. disintegration during composting
  2. ultimate aerobic biodegradation (breakdown of organic contaminants by microorganisms when oxygen is present) 
  3. no adverse effects of compost on terrestrial organisms
  4. control of organic and chemical constituents (carbon covalently linked to other carbon atoms and to other elements, most commonly hydrogen, oxygen or nitrogen)

 

It is important to note that biodegradable material is not necessarily compostable because it must also break up during one composting cycle. On the other hand, a material that breaks up, over one composting cycle, into microscopic pieces that are not 100% biodegradable, are not considered compostable. Compostable plastics are also typically certified for industrial composters only. In rare cases there are products that can be composted at home. Again, the issue with this is that there are not always systems in place to properly collect and dispose of compostable plastics, therefore they end up thrown in the wrong bin and possibly mixed with other plastics. When bioplastics are discarded improperly, they contaminate batches of recycled plastic (such as PET, the most common single-use plastic) therefore harming recycling infrastructure. This can lead to entire batches of recyclable plastic to end up in landfill, contributing to the issue of only 9% of plastics actually being recycled

So, are bioplastics truly more eco-friendly?

A 2010 study from the University of Pittsburgh found that bioplastics aren’t necessarily more environmentally friendly when their entire life-cycle is taken into consideration. The study compared seven traditional plastics, four bioplastics, and one made from both fossil fuel and renewable sources. The researchers determined that bioplastics production resulted in greater amounts of pollutants, due to the fertilizers and pesticides used in growing the crops and the chemical processing needed to turn organic material into plastic, and required extensive land use––biobased plastics that are predominantly made from corn and/or sugarcane are monoculture with a high impact on the environment (deforestation, loss of biodiversity and habitat, as well as increased pressure on limited water reserves). Food security is a global issue––climate change and  biofuel are taking up much needed land that could be used for food production or reforestation. In addition, according to the study, bioplastics also contributed more to ozone depletion than the traditional plastics. B-PET, the hybrid plastic, was found to have the highest potential for toxic effects on ecosystems and the most carcinogens, and scored the worst in the life cycle analysis because it combined the negative impacts of both agriculture and chemical processing. With all of that said, bioplastics do produce significantly fewer greenhouse gas emissions than traditional plastics over their lifetime. There is no net increase in carbon dioxide when bioplastics break down because the plants that they are made from absorb that same amount of carbon dioxide as they grew.

Future Solutions

Research is ongoing to create biobased plastics from food waste, and other innovative materials, however there is not currently a fully developed solution when you look at entire infrastructures. We need to work to find solutions that limit typical plastic production, and find better, alternative solutions to the biobased plastics that are currently on the market. Here are some interesting examples:

 

  • Full Cycle Bioplastics in California are also producing PHA from organic waste such as food waste, crop residue such as stalks and inedible leaves, garden waste, and un-recycled/leftover paper or cardboard. Used to make bags, containers, cutlery, water and shampoo bottles, this bioplastic is compostable, marine degradable (meaning that if it ends up in the ocean, it can serve as fish or bacteria food) and has no toxic effects!
  • Renmatix is utilizing woody biomass, energy grasses and crop residue instead of costlier food crops. 
  • Michigan State University scientists are trying to cut production costs for bioplastic through the use of cyanobacteria, also known as blue-green algae, that use sunlight to produce chemical compounds through photosynthesis.
  • Stanford University researchers and Mango Materials are transforming methane gas from wastewater treatment plants or landfills into bioplastic.
  • The Centre for Sustainable Technologies at the University of Bath in England is making polycarbonate from sugars and carbon dioxide for use in bottles, lenses and coatings for phones and DVDs. 
  • Japanese design company AMAM is producing packaging materials made from the agar in red marine algae.
  • The U.S. Department of Agriculture is developing a biodegradable and edible film from the milk protein casein to wrap food in, which is 500 times better at keeping food fresh than traditional plastic film.
  • Ecovative is using mycelium, the vegetative branching part of a fungus, to make Mushroom Materials, for biodegradable packaging material, tiles, planters and more.

Canadian company Pela Case, and Swedish, A Good Company, have utilized plants and plant-waste, including hemp and linseed, to make phone cases and other items that are fully compostable at home.

Looking ahead

So now what? Bio-, biodegradable and compostable plastics may be creeping their way into the market, but are they currently a feasible solution? When you take into account the complete lifecycle of different biobased plastics, you must consider land use, pesticides/herbicides, energy consumption, water use, greenhouse gas and methane emissions, biodegradability, recyclability, and lack of proper disposal infrastructure. In the future, it is possible that bioplastics will truly be more environmentally friendly, however, in the meantime, is avoiding single-use plastics still the best option? At the basic level, the answer is yes. On a day to day basis it is easier to avoid all single-use plastics, biobased or not, rather than determine the recyclability of a product based on what it is made of, if it is biodegradable vs compostable, the overall impact of its lifecycle, and ensuring proper disposal––too many variables. It comes down to making educated decisions, and mindful purchases in your everyday life; Let’s continue towards a plastic free future.



Special thanks to Jeremy for helping with research on this piece.

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References: 

 

Europeans Bioplastic - What are bioplastics?

https://www.european-bioplastics.org/bioplastics/

 

Zero Waste Europe - So-called “bioplastics” won’t solve the plastic pollution problem

https://zerowasteeurope.eu/2018/08/so-called-bioplastics-wont-solve-the-plastic-pollution-problem/

 

Bioplastic news - Are Bioplastics Better for the Environment or a Waste of Time?

https://bioplasticsnews.com/2019/08/22/are-bioplastics-better-for-the-environment-or-a-waste-of-time/

 

Plymouth University - Biodegradable bags can hold a full load of shopping three years after being discarded in the environment

https://www.plymouth.ac.uk/news/biodegradable-bags-can-hold-a-full-load-of-shopping-three-years-after-being-discarded-in-the-environment

 

Packaging gateway - Compostable packaging: the myths, realities and future possibilities

https://www.packaging-gateway.com/features/compostable-packaging/

 

BBC - Why biodegradables won’t solve the plastic crisis

https://www.bbc.com/future/article/20191030-why-biodegradables-wont-solve-the-plastic-crisis

 

The Truth About Bioplastics | Columbia University

https://blogs.ei.columbia.edu/2017/12/13/the-truth-about-bioplastics/

 

International Organization for Standardization

https://www.iso.org/obp/ui#iso:std:iso:17088:dis:ed-3:v1:en