The world of “Green” (as in other industries) has its own terms and terminologies. For the person trying to make some sense of these and wishing to make positive environmental lifestyle changes it can get awfully confusing. Take for instance the terms degradable, biodegradable, and compostable when used in relation to plastics. There are major differences between the three and they will probably play a role in your purchasing decisions.
Degradable
Degradable plastics are oil based and break down through chemical reactions rather than the activity of micro-organisms and as a result they can degrade in an anaerobic environment into water, CO2, biomass and trace elements.
Most degradable plastics leave some form of residual particulates that are not environmentally friendly.
Biodegradable
Biodegradable plastics are made from vegetable starch in most cases and break down through the actions of naturally occurring microorganisms such as bacteria, fungi, algae, etc. over a period of time. The time period varies and depends on diverse factors.
There are many advantages to products being biodegradable, most of which are obvious. However, there are some disadvantages. When dumped in landfills, they are often dug under where the "good" bacteria can't survive in an oxygen depleted (anaerobic) environments. As a result, when they break down they create methane, a greenhouse gas.
Note: There are products which can fully biodegradable under anaerobic conditions without adverse effect to the environment.
Compostable
According to the American Society for Testing & Materials (ASTM), in order for plastics to be considered compostable, they must be able to break down into carbon dioxide, water and biomass at the same rate as paper. The resulting product also needs to look like compost, should not produce any toxic material, and should be able to support plant life. Compostable items are made from plant materials such as corn, potato, cellulose, soy and sugar.
The downside is that in order for these products to compost they need to be disposed of in composting facilities where strict environmental conditions are continuously maintained i.e. heat, moisture, etc. unfortunately, there are very few industrial capacity composting facilities in the US so it is likely your compostable plastics will just wind up in a landfill, which sort of defeats the purpose.
In Conclusion
Whether you choose any of the three types of plastics over standard plastic products you are benefiting the cause and demonstrating environmental responsibility. As with any emerging technology, biodegradable plastics will continue to improve and someday there may only be upsides to using the products. Until then, the choice is yours.
Portions of this article are courtesy of Green Living Tips. We encourage you to visit their site: www.greenlivingtips.com
2 comments:
Compostable plastics such as PLA (corn derived) are a niche plastic. It will prove to have limited use even though PLA marketers are attempting to sell us on the idea that PLA is the final answer for solving plastic pollution. The only proper way to dispose of PLA type plastics is to send it to a commercial composting site for processing. Here in the U.S. commercial composting sites are few and far between and many of those won’t accept PLA because is made from genetically altered corn and they (composters) feel that mixing in genetically altered corn plastic will infect the other compost.
Plastic has become an important aspect in our lives, however, plastic has demonstrated some negative side effects and there isn’t any one perfect answer for solving plastic pollution.
Here in the U.S. recycling rates for plastic is horrible and it won’t get any better until the recycling industry finds a market where they can sell the plastics that now end up in the garbage. Most of the plastic we put in our recycle bins or trash can (somewhere between 70-80 percent of plastic) is ending up in a landfill. If PLA were to be manufactured in the same quantities as current plastics we could assume that like today’s plastics, a majority of PLA would end up in a landfill. That won’t solve the problem because PLA doesn’t biodegrade in a landfill.
There are basically three types of plastics; compostable, degradable and biodegradable. PLA is compostable but only in a commercial facility, PLA doesn’t biodegrade. Degradable plastics such as oxodegradable plastics, break down (degrade) into smaller and smaller pieces until they are too small to see. Degraded polymers don’t biodegrade they just get to small to see and that isn’t good for the environment either.
I would like to add that there is a third option which is a truly biodegradable PET plastic bottle like the ENSO biodegradable plastic bottle. The Enso bottle is plastic that has an additive which attracts microbes which consume plastic in an anaerobic or aerobic environment leaving behind biogases and humus.
Most landfills here in the U.S. are the dry tomb type where the trash is compacted and covered limiting oxygen and moisture within the trash. There is however, microbial activity within the anaerobic conditions of a dry tomb landfill. Microbes consuming trash in a landfill produce landfill gases (LFG). Landfill gases are now being captured and used to produce clean energy. There are new landfills coming on line called bioreactor landfills. Bioreactor landfills are landfills that are designed to enhance microbial action and are designed to capture all the LFG produced. Our company supports recycling and the development of bioreactor landfills. Ultimately, most thing end up in a landfill, biodegradable plastics and bioreactor landfills will be major factor toward improving our environment.
We know there isn’t any one perfect answer, but we are working toward a solution that will help.
Max
http://www.ensobottles.com
“Bottles for a Healthier Earth”
Thank you for your comments...what you said about fully biodegradable plastics using microbial additives is quite correct. We are in full support of those products.
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