Methane forms in landfills due to decomposing foods, so people are encouraged to compost food. Why is composting (i.e. separating food from other garbage to decompose in dirt) any better?
In: Chemistry
Composting does not create methan the way organic waste in a landfill does. The difference is air.
Composting allows plenty of oxygen into the process and oxygen loving bacteria can break the waste down without creating methane.
Decomposition works differently in low oxygen environments such as buried deep in a landfill inside a plastic bag. Without oxygen only anarobic bacteria can flourish and release methan as they break down food.
Similar to yeast. In the presence of air, like in bread dough, they are able to flourish without making alcohol. Take away the oxygen by trapping them in a tank, and they switch to an anaerobic process and create alcohol as a biproduct.
There is no methan from composting just like there is no alcohol in your bread. Because of plenty of air.
You are correct methane is the result of decomposition of organic matter.
Composting keeps the organic matter from going to a landfill and uses the material as fertilizer for home use in your garden.
This removes the organic matter from the land fill where it would eventually decompose but in the meanwhile occupies a lot of space.
It removes the greenhouse gases produced by the waste stream machines that move it from place to place.
So it is better for the planet. It will produce those gases either way but it becomes useful and doesn’t require space for storage or fuel to relocate it.
Compost is useful stuff, for gardening and landscaping. Garbage in landfills just takes up space. And costs money.
It’s the plastic trash bags that prevent the food waste from airflow that cause the methane production to occur if I’m not mistaken. With composting there is a more specific process of layering food waste and yard waste (hay, leaves, lawn clippings) and stirring that allow the food to decompose into dirt without the off gassing
In some cases, it is better off in a landfill. I work at a “class A landfill” where it is encouraged that organic waste is disposed of here. There is a sophisticated underground network of gas capturing pipelines that feed the methane to a plant where it is burnt for the production of dried lime fertilizer. This has eliminated the need to burn coal at our facility.
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