There are 3 main processes that carbon dioxide (co2) must go through :
Respiration - All plants and animals are able to release energy from their food using respiration. This can also include any other living organism out there.
Combustion - This is the process of burning fuel. This releases carbon dioxide into the open space.
Photosynthesis- Any sort of green plant, such as flowers, can remove carbon dioxide from the atmosphere by using photosynthesis.