Plastics have most commonly and in large quantities been derived from petrochemicals. We call them ‘petroplastics’ or ‘fossil fuel plastics’. Bioplastics on the other hand are plastics made from renewable biomass sources, such as cellulose.
Did you know? The first man-made plastic was manufactured from cellulose. It was called Parkesine.
Not all bioplastics are degradable though. Some are designed to be durable. Durability often translates into less biodegradability. But any plastic on this planet right now is biodegradable, it will eventually breakdown into CO2, water and energy. Just not in the way that helps us and our environment.
“The relative ease with which petroleum hydrocarbons will degrade as a result of biological metabolism. Although virtually all petroleum hydrocarbons are biodegradable, biodegradability is highly variable and dependent somewhat on the type of hydrocarbon. In general, biodegradability increases with increasing solubility; solubility is inversely proportional to molecular weight.” – U.S. Environmental Protection Agency, 2009
You may ask: ‘What do you mean by ‘Just not in the way that helps us and our environment.’?’ I’ll give you three words: degradable; biodegradable; and compostable. Confused? Don’t worry. Read on.
Biodegradable plastics are decomposed by bacteria or living organisms converting it into CO2, water and energy. A compostable plastic can be defined the same way but a biodegradable material may not always turn into beneficial humus that composting provides. Plants should be able to grow in this humus. Only then can a biodegradable plastic can be called compostable. Polylactic acid (PLA) is a biodegradable plastic that comes from corn. The bad news here is that in a landfill, it will sit alongside a petroplastic as long as this petroplastic wants to. In short, it behaves just like a petroplastic. This also means that PLA releases methane as it degrades without oxygen. It breaks down only in a particular set of conditions i.e. commercial composting facilities, where the emissions can be taken better care of too.
Degradable or Oxo-degradable are those that require us humans to design a process that can degrade a plastic. Do you know what happens to the plastic that lies in the ocean? It is naturally shredded into little pieces via photodegradation. This is not a good news though, since these pieces end up in the guts of creatures living in the ocean. A similar process can be adopted on industrial level for degradation. If not photodegradation, biodegradable additives can help. These additives catalyze the biodegradation of the polymers by allowing microorganisms to utilize the carbon within the polymer chain itself.
Are bioplastics the ultimate solution?
Bioplastics seem to have their fair share of twists in their story. A life cycle assessment can tell us about this twist. When considering energy returned on energy invested, the production of bioplastics can lose its dependence on oil for energy as companies embrace renewable energy resources such as wind and solar or bagasse.
With huge production of bioplastics and a consequent elimination of regular plastic, we can achieve 100 percent recyclability. Although this seems like a far fetched fantasy. The industry has been buzzing over concerns of bioplastics contaminating existing recycling streams and huge capital investment over bioplastic recycling projects. But recent studies have shown that this is not the case. Doris de Guzman explains these studies in her blog post ‘Study on compostables in recycling‘.
While the future of bioplastics is seeking a strong foothold in the market, discoveries such as that of a bacteria that can decompose regular plastic, found by a high school boy can offer some solace or plastic made from banana peels can help. Isolation of useful bacteria through trial and error may sound like a long process but it may be worth its wait.
Then there are bioplastics derived from GM crops because like anything prefixed ‘-bio’ this too wants the food we eat: food vs plastic debate. With GM crops still amidst a hot ongoing debate, I wonder what shape this will take.
I’m a little less confused with all the bioplastic lexicon floating around. I hope you are too.
So, what do you think? Can bioplastics take over the world?
A helpful reader (requested anonymity) suggested these articles:
Chowdhury, T., Ghosh, A., & Gupta, S. B. (2010). Isolation and selection of stress tolerant plastic loving bacteria isolates from old plastic wastes. World Journal of Agricultural Sciences, 2, 138-140.
Revista de Biología Tropical – Polythene and Plastics-degrading microbes from the mangrove soil