By-product
A by-product is a secondary or incidental product deriving from a manufacturing process or chemical reaction, and is not the primary product or service being produced. A by-product can be useful and marketable, or it can have severe ecological consequences.
Major by-products
Animal sources
- dried blood and blood meal - from slaughterhouse operations
- chicken by-product meal - clean parts of the carcass of slaughtered chicken, such as necks, feet, undeveloped eggs, and intestines.
- chrome shavings - from a stage of leather manufacture
- collagen and gelatin - from the boiled skin and other parts of slaughtered livestock
- feathers - from poultry processing
- lanolin - from the cleaning of [[wool]
- manure - from animal husbandry
- meat and bone meal - from the rendering of animal bones and offal
- poultry byproduct and poultry meal - made from unmarketable poultry bones and offal
- poultry litter - swept from the floors of chicken coops]
- whey - from cheese manufacturing
Vegetation
- acidulated soap stock - from the refining of vegetable oil
- bran and germ - from the milling of whole grains into refined grains
- brewer's yeast - from ethanol fermentation
- corn stover - residual plant matter after harvesting of cereals
- dried distiller's grain - from ethanol fermentation
- glycerol - from the production of biodiesel
- grape seed oil - recovered from leftovers of the winemaking process
- molasses - from sugar refining
- orange oil and other citrus oils - recovered from the peels of processed fruit
- pectin - recovered from the remains of processed fruit
- sawdust and bark- from the processing of logs into lumber
- straw- from grain harvesting
Minerals and petro chemicals
- asphalt - from the refining of crude oil
- slag - from ore refining
- gypsum - from Flue gas desulfurization
- ash and smoke - from the combustion of fuel
- mineral oil - from refining crude oil to produce gasoline
Other
- sludge - from wastewater treatment