By-product

A by-product is a secondary or incidental product deriving from a manufacturing process, a chemical reaction or a biochemical pathway, 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
fetal pigs

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
distillers grains – 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
fly ash – from the combustion of coal
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
salt – from desalination

Other

sludge – from wastewater treatment