绿色地球

The Myth of Biodegredation

Myth: Waste simply biodegrades in the landfill.
Biodegredation

biodegrades Reality: Nothing biodegrades in a landfill because nothing is supposed to.Biodegredation
Biodegradation 101

Organic matter “biodegrades” when it is broken down by other living organisms (such as enzymes and microbes) into its basic components, and in turn, these molecules are recycled by nature into the building blocks for new life.

This process can occur aerobically (with the aid of oxygen) or anaerobically (without oxygen). Substances break down much faster under aerobic conditions because oxygen helps break the molecules apart.


Landfills excavations have uncovered some startling facts:

Modern landfills are designed to entomb municipal garbage safely and securely. Most landfills are anaerobic, because they are compacted so tightly that air cannot get in. Because of this, any biodegradation that does take place does so very, very, very slowly. Trash entering landfills essentially retains its original weight, volume and form for the entire active life of the landfill.

Newspapers are still readable after almost 40 years; ten-year-old carrots are brown on the outside but bright orange on the inside; and 20-year-old steaks still have meat on the bones.

Why aren’t materials – even raw organic debris – rapidly biodegrading in landfills?


The answer is simple: Many people believe that landfills are just big, carefully controlled
compost piles. They are not!


Micro-organisms in a compost heap are aerobic
and they biodegrade organic matter quickly and
efficiently outside. In compost piles, the garbage is
chopped, kept moist, oxygenated, and stirred.

The anaerobic microorganisms in a landfill just don’t receive the proper balance of moisture, nutrients,
and temperature to biodegrade organic matter. No
one chops garbage in a landfill or stirs it, and no one
adds fluids or oxygen- it is stable.


The dry and oxygen-poor conditions found in modern landfills cause organic matter to mummify rather than decompose. The result is very little biodegradation in a landfill.


But what about methane from landfills?

Landfills are the third-largest source of human-related methane emissions in the United States, accounting for approximately 17% of these emissions in 2009. Methane is a potent greenhouse gas.

Uncontrolled biodegradation in a landfill can cause methane gas emissions, ground water pollution, and unstable sub-soil conditions. As a result, modern landfills are kept dry and air-tight to try to prevent biodegradation.

Really old organic materials in landfills are slowly releasing methane today as they anaerobically degrade, but since we have started managing landfills more responsibly, we are learning that the legacy of poorly managed landfills is not sustainable. Even more importantly, we can capture the methane emissions from landfills and use them as a
significant energy resource.

This is why we encourage everyone to divert as much organic waste from landfills today.

All the plastic that has ever been created is still around today. Biodegredation

Petroleum biodegrades easily and quickly in its original form of crude oil. But when petroleum is processed into plastic, it is no longer biodegradable, and will remain in the landfill indefinitely.

Most plastics are stable in the landfill. The industrial processing they went through prior to their useful days converted them into forms unrecognizable to many microbes and enzymes.

Bioplastics like PLA are also stable in the landfill, even though they are made from renewable resources like corn.

Once PLA has been created, it is strong and rigid – and is designed to break down aerobically in a compost pile. So PLA will remain stable in a landfill and as far as we know, it does not contribute to landfill methane. Biodegredation

Composting Biodegredation

Composting, on the other hand, is the process of controlled biodegradation outside a landfill in an aerobic, outdoor compost site.

Compost can be used in farming, landscaping, gardening and soil conservation and is one the simplest and most effective ways to return carbon and structure to soils.

By carefully controlling compost inputs such as organics materials, wood chips, yard waste, food scraps, foodservice items, etc., and controlling the moisture content and oxygen levels at the site, composters transform biogegradable materials into useful compost.

Today, despite national progress on yard waste composting, more than 60 million tons of biodegradable materials (food scraps, wet & soiled paper, leaves and grass) are still being sent to landfills where they will sit in an airless, dry environment to be mummified. Biodegredation

Biodegradable ≠ Compostable ≠ Recyclable

“Compostable” products are biodegradable, but with an added benefit: when they break down in a compost pile, they release valuable nutrients into the soil, aiding the growth of trees and plants. These products degrade within several months in an industrial composting facility and produce no toxic residues. Biodegredation

Reduce, Reuse, Recycle is Best Solution for Landfills

Getting people to sort their trash accordingly is the new challenge. Plastics need to stay out of the compost and organic matter (and recyclables) need to stay out of the landfills. With landfills around the world reaching capacity, it’s time to think about where things go when we throw them “away”. Biodegredation

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