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Anaerobic Digestion

Anaerobic digestion is when tiny living things break down waste in a space with no air, making gas.

Think of it this way

A sealed jar of food scraps sits on a shelf with no air inside. Tiny living things in the scraps start to eat and break down the waste. Over time, they release bubbles of gas that collect at the top. The solid waste shrinks and gas fills the space above it.

Explaining anaerobic digestion by grade level

When you seal cow manure in a warm jar, germs eat the waste. They make a gas you can not see or smell at first. The jar gets warm and the gas builds up. This happens best when the jar stays at body heat.

Projects that explore anaerobic digestion

Temperature and Methane from Cow Manure

Anaerobic digestion happens when tiny living things break down waste in a sealed space with no air. In this experiment, sealed flasks hold manure and water while bacteria break down the manure without oxygen, releasing methane gas that pushes water out of an inverted measuring cylinder. The flask at 34 degrees Celsius produced the most methane, showing that warmer conditions speed up the digestion process.

Medium