scavenger

An animal, such as a vulture or housefly, that feeds on dead or decaying matter.

One that scavenges, as a person who searches through refuse for useful items.

A substance added to a mixture to remove or inactivate impurities.

An officer whose duty it was to take custom upon the inspection of imported goods, and later also to see that the streets were kept clean. Also scavager.

Hence A person whose employment is to clean the streets, etc., of a city or the like, by scraping or sweeping together and carrying off the filth.