scavenge

To collect and remove refuse, or to search through refuse, carrion, or abandoned items for useful material.

We scavenged a couple of old beer cans for our art project.

They had to scavenge the forest for firewood.

To remove unwanted material from something, especially to purify molten metal by removing impurities.

To expel the exhaust gases from the cylinder of an internal combustion engine, and draw in air for the next cycle.

To feed on carrion or refuse.