Merriam-Webster Collegiate Dictionary - scavenge

 verb  (~d; scavenging)  Etymology: back-formation from ~r  Date: circa 1644  transitive verb  1.  a.  (1) to remove (as dirt or refuse) from an area  (2) to clean away dirt or refuse from ; cleanse ~ a street  b. to feed on (carrion or refuse)  2.  a. to remove (burned gases) from the cylinder of an internal combustion engine after a working stroke  b. to remove (as an undesirable constituent) from a substance or region by chemical or physical means  c. to clean and purify (molten metal) by taking up foreign elements in chemical union  3. to salvage from discarded or refuse material; also to salvage usable material from  intransitive verb to work or act as a ~r