quarta-feira, 6 de maio de 2009

Do you know what compostable means?

I realize, in this 1st day, that many places like coffee shop, bars, supermarket and restaurants have compostable trash.
Compostable? What it exactly means?
And what the difference between Degradable, Biodegradable and Compostable?

I got in this site, the exaclty answer for what we need.
check this out:

Biodegradable Plastics

Biodegradable products break down through the action of a naturally occurring microorganism, such as bacteria, fungi etc. over a period of time. These products are usually made from plant or animal sources. Examples of biodegradable include paper, vegetable scraps and some forms of plastics made from ingredients such as corn starch.

There are some disadvantages to biodegradable waste. When dumped in landfills, it's often dug under where the "good" bacteria can't survive in the oxygen depleted environment. It then breaks down under anaerobic conditions which creates methane, a greenhouse gas with over 62 times the GWP (Global Warming Potential) of carbon dioxide. Also, biodegrable waste can contain toxins. For example, human and animal waste, which is considered biodegradable may contain traces of all sorts of toxins such as heavy metals and pesticides depending on the person/animal's diet.

Degradable Plastics

Degradable plastics are oil based and break down through chemical reactions rather than the activity of micro-organisms, so they can degrade in an anaerobic environment into water, CO2, biomass and trace elements.

Compostable Plastic

This is pretty close to biodegrable plastic but "greener". According to the American Society for Testing & Materials, for plastic to be considered as compostable, it must be able to break down into carbon dioxide, water and biomass at the same rate as paper. It 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.

So, just to resume:

Biodegradable - green, but can leave traces of toxins
Degradable - made from oil, but breaks down into harmless materials
Compostable - green from start to finish.. perhaps

So, let's get compostable stuffs now! :)

Um comentário:

  1. Hi! I am Anna and I am a graduate at Tech. Universtity in Delft. My research is on bioBASED plastics. I would like to point out that DEGRADABLE does not, at all, mean that the plastics break down into harmless elements! As you write: they degreade into water, co2 and TRACE ELEMENTS. It is these elements that can be very toxic when released into nature. Chemical additives put into plastics to enhance properties. Another thing is that degradable petroleum based plastics do not fully degrade in nature, but fall apart in invisibly small pieces of plastic. These peices end up in our rainwater and eventually in the ocean. Here, they float around as hydrophobic islands, that work as magnets to other toxic elements, already dissolved in the water. Fish confuse these tiny plastic toxic-bombs with food, eat them and that's how we spoil our foodchain. So, to conclude: DON'T BUY DEGRADABLE PETRO BASED PLASTICS!! Rather recycle your old plastic and buy compostable, or BIO BASED plastics. I rest my case...