MadSci Network: Environment

Re: What things cause an object to biodegrade faster?

Date: Mon Feb 5 17:15:20 2001
Posted By: Steve Williams, Staff, Science Demonstrator, Pacific Science Center
Area of science: Environment
ID: 975804064.En

Hi there!

In order to figure out what makes things biodegrade faster, we need to figure out what makes things biodegrade.

When something is biodegrading, it is changing from one form to another. It's important to remember that nothing can be completely destroyed, it can only be changed from one form to another.

One thing that something can be is good food. If an object (like an apple core) is food for a plant or animal, it is consumed and converted into energy and waste products. Many people do not make the connection between these waste products and the food they came from. Luckily, nature is good at getting rid of animal and plant waste products, so if something is made of food for something else, it probably won't be a pollutant. This kind of object will biodegrade faster the closer it is to food. Let's take an apple core for example. Apple cores biodegrade quickly into nutrients for plants because a lot of things can eat them. Paper degrades more slowly, because only certain things can eat them. If those plants and animals are not there, it doesn't get eaten. An aluminum can may never biodegrade because there's very very few things that eat raw metal and use it.

Another thing that an object can be is unstable. If the sun shines on some things (like some plastics) then they change into another form. The energy from the sun breaks down the structure of the plastic and converts it into another form. It is no longer the plastic we use, but they still are hangin around. Many of these changes give off gases we cannot see, and turn the remainder into a type of food for plants and animals. If the plastic gets the sun in the first place, then it can biodegrade. If it does not get sunlight, it won't be able to broken down into food.

The last thing that can make something biodegrade faster is what it is made of. Some things are made of chemicals that mix easily with other chemicals to turn them into food. If it can mix with these chemicals it will biodegrade faster. Sunlight sometimes hinders things from biodegrading for this reason. It prevents these chemicals from getting together. When things are dumped into a landfill, they often fall into all three of these categories. As they sit in the landfill, however, they may not be able to mix with the right chemicals, they may get too much (or too little) sun, and they may not be in the right place to be eaten. For this reason, many things that are biodegradable (or can become biodegradable) do not degrade. Composting is an example of this. If you send your food remains to a landfill, they will not be in the right environment to degrade quickly. Composting properly makes your food remains into useful parts of the environment more quickly for the reasons above. It lets the food remains get the right ingredients to be broken down: little sunlight, the right chemicals, and the best place to put the degraded materials: in your garden.

Take Care and Be Safe,

Steve E. Williams
Rock Star and Science Demonstrator
Pacific Science

Admin note:

The speed of biodegradation will depend on factors such as surface area/volume ratio, temperature, acidity and availability of oxygen. Bacteria need surface area to attack a substance. If S.A. is increased, then the breakdown occurs at a faster rate; therefore, shredded food will decompose faster than uncut food. The rate of breakdown will slow if it is too hot or too cold. Breakdown will occur without oxygen, but generally it is much faster is oxygen is available. If you compost food outside, you should turn over the compost on a regular basis to increase the oxygen supply.

Richard Kingsley

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