If you have houseplants and have dealt with an aphid infestation you may want to re-use your potting soil. There are some things to consider about this practice.
Aphids are sucking insects that multiply in the soil rapidly. One aphid can produce 80 within a week, so the potential can be disastrous to your houseplants. Since they are also difficult to see, you can have a huge problem before you see them or their damage. They are also difficult to get rid of.
Since aphids lay eggs in the soil that are microscopic, they can re-infest any plant before you know they are there. If you have lost a plant due to an aphid infestation it is generally not a good idea to reuse the soil, but to start over with sterile soil and a pot and saucer that has been cleaned well.
You can sterilize the soil yourself by placing it on a cookie sheet in a hot oven for 15 minutes. Most people don't like this smell so you may wish to avoid doing it.
You can also treat the soil with systemic insecticide granules and store in a sealed container for at least a month before reusing it, to control aphids.