Dec
02
2010
what is that meaning the word ” biodegradable” ?
Posted by admin in Question & Answers, tags: Biodegradable, meaning, wordAlthough the paper and food scraps people throw away are BIODEGRADABLE, plastic and glass items remain unchanged for thousands of years.
Thanks!!
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it degrades after a period of time naturally
A “biodegradable” product has the ability to break down, safely and relatively quickly, by biological means, into the raw materials of nature and disappear into the environment. These products can be solids biodegrading into the soil (which we also refer to as compostable), or liquids biodegrading into water. Biodegradable plastic is intended to break up when exposed to microorganisms (a natural ingredient such as cornstarch or vegetable oil is added to achieve this result).
Sustainable disposal of any product requires that its wastes return to the earth and are able to biodegrade. Nature biodegrades everything it makes back into basic building blocks, so that new living things can be made from the old. Every resource made by nature returns to nature-plants and animals biodegrade, even raw crude oil will degrade when exposed to water, air, and the necessary salts. Nature has perfected this system-we just need to learn how to participate in it.
By the time many resources are turned into products, however, they have been altered by industry in such a way that they are unrecognizable to the microorganisms and enzymes that return natural materials to their basic building blocks. Crude oil, for example, will biodegrade in its natural state, but once it is turned into plastic, it becomes an unsustainable pollution problem. Instead of returning to the cycle of life, these products simply pollute and litter our land, air, and water.
Of all the environmental buzzwords, “biodegradable” has perhaps been the most misused and is perhaps the most difficult to understand. Because in the past there have been no guidelines or regulations, many products have called themselves biodegradable without any real justification. Unfortunately, the word biodegradable has frequently been applied to products that generally aren’t (such as detergents or plastics) and almost never used for products that really are (such as soap or paper).
A leaf is a perfect example of a biodegradable product: it is made in the spring, used by the plant for photosynthesis in the summer, drops to the ground in autumn, and assimilated into the soil to nourish the plant for the next season. The basic concept seems straightforward enough, however, there are several factors to consider in determining the biodegradability of a product or material.
The first is the question of the inherent biodegradability of the material. Any material that comes from nature will return to nature, as long as it is still in a relatively natural form. Therefore any plant-based, animal-based, or natural mineral-based product has the capability to biodegrade, but products made from man-made petrochemical compounds generally do not. When a manmade compound is formulated in a laboratory, combinations of elements are made that do not exist in nature, and there are no corresponding microorganisms to break them down.
The next issue is how long it takes for the material to actually break down. In nature, different materials biodegrade at different rates. A leaf takes approximately a year to become part of the forest floor. An iron shovel, on the other hand can take years to rust away to nothing, and a large tree can take decades to completely break down. Common sense tells us that any material will ultimately biodegrade, even if it takes centuries.
So what is the proper rate for a material to be biodegradable? It really depends on the material itself. The leaf example suggests that the proper rate is that which is appropriate to the ecosystem. A liquid going into a waterway should biodegrade fairly quickly, whereas there’s no harm done if it takes a while for a newspaper to break down. Plastics, on the other hand, will not biodegrade in anyone’s lifetime, and certainly will never break back down into the petroleum from which it was made.
And then there is the question of what exactly does the product or material break down into, and are there any toxic substances formed along the way or as the end result. In his book The Closing Circle, ecologist Barry Commoner gives the example of the benzene unit in synthetic detergents being converted as it biodegrades into phenol (carbolic acid), a substance toxic to fish. To be truly biodegradable, a substance or material should break down into carbon dioxide (a nutrient for plants), water, and naturally occurring minerals that do not cause harm to the ecosystem (salt or baking soda, for example, are already in their natural mineral state and do not need to biodegrade).
The characteristics of the environment that the substance or material is in can also affect its ability to biodegrade. Detergents, for example, might break down in a natural freshwater “aerobic” (having oxygen) environment, but not in an “anaerobic” (lacking oxygen) environment such as sewage treatment plant digestors, or natural ecosystems such as swamps, flooded soils, or surface water sediments.
Many products that are inherently biodegradable in soil-
Biodegradable matter is generally organic material such as plant and animal matter and other substances originating from living organisms, or artificial materials that are similar enough to plant and animal matter to be put to use by microorganisms.
It simply means that it has properties that enable it to breakdown over time :0
Plastic and glass don’t grow mold or get mushy when you pour water on it :3
Hope that answers your question :-D