What happens to ash from burning trash?
I was talking with my son about how garbage trucks take our trash away to be burned, and he asked me what happens to the ash that is left over (another garbage trucks picks it up and takes it away?).
There are two kinds of ash that are left over – very fine ash (called Fly Ash) that is in the air, and heavier ash that is left sitting at the bottom.
Fly Ash is carefully taken out of the air, by giving it multiple chances to settle. Since this ash can be harmful to the environment, it is treated with various chemicals to reduce its toxicity. After treatment, you are left with a pile of mostly safe, very fine ash.
The heavier ash tends to have useful materials left inside. Magnets are used to pull out metals, and non-magnetic metals are given a charge by creating an electric current with spinning magnets. These metals are extracted and recycled.
The two kinds of left over ash may be taken to a landfill, or they can be used as a filling agent for things like asphalt, cement, and lightweight blocks.