By-products

Aluminium dross|right|thumb Dross is a mass of solid impurities floating on a molten metal or dispersed in the metal, such as in wrought iron. It forms on the surface of low-melting-point metals such as tin, lead, zinc or aluminium or alloys by oxidation of the metal. For higher melting point metals and alloys such as steel and silver, oxidized impurities melt and float making them easy to pour off.

informal term for the white solid that results from the addition of soap to hard water

thumb|Piles of scrap metal collected for the World War II effort, thumb|Collection of leftover scrap metal items

thumb|right|Barkdust being used as mulch. In agriculture, gardening, and landscaping, barkdust (also bark dust, bark chips, bark mulch, beauty bark, tanbark, tan bark, or simply bark) is a form of mulch produced out of chipped or shredded tree bark. Coarser forms of barkdust may be known as bark nuggets. Trees typically used in the production of barkdust include the Douglas fir and the western hemlock.

maize plant parts left in field after harvest

feces of chickens used as an organic fertilizer, especially for soil low in nitrogen

Dunder is the liquid left in a boiler after distilling a batch of rum. It is a traditional flavor source used in the fermentation of the wash of Jamaican rum. Similar in process to sour mash in Bourbon whiskey, it is a crucial step in achieving an authentic rum flavor. In Europe, waste liquors from alcohol distillation are referred to as vinasse.