A by-product or byproduct is a secondary product derived from a production process,

manufacturing Manufacturing is the creation or production of goods with the help of equipment, labor, machines, tools, and chemical or biological processing or formulation. It is the essence of the secondary sector of the economy. The term may refer ...

process or

chemical reaction A chemical reaction is a process that leads to the chemistry, chemical transformation of one set of chemical substances to another. When chemical reactions occur, the atoms are rearranged and the reaction is accompanied by an Gibbs free energy, ...

; it is not the primary product or service being produced. A by-product can be useful and marketable or it can be considered waste: for example,

bran Bran, also known as miller's bran, is the component of a Cereal, cereal grain consisting of the hard layersthe combined aleurone and Fruit anatomy#Pericarp layers, pericarpsurrounding the endosperm. Maize, Corn (maize) bran also includes the p ...

, which is a byproduct of the

milling Milling may refer to: * Milling (minting), forming narrow ridges around the edge of a coin * Milling (grinding), breaking solid materials into smaller pieces by grinding, crushing, or cutting in a mill * Milling (machining), a process of using ro ...

wheat Wheat is a group of wild and crop domestication, domesticated Poaceae, grasses of the genus ''Triticum'' (). They are Agriculture, cultivated for their cereal grains, which are staple foods around the world. Well-known Taxonomy of wheat, whe ...

into refined

flour Flour is a powder made by Mill (grinding), grinding raw grains, List of root vegetables, roots, beans, Nut (fruit), nuts, or seeds. Flours are used to make many different foods. Cereal flour, particularly wheat flour, is the main ingredie ...

, is sometimes

compost Compost is a mixture of ingredients used as plant fertilizer and to improve soil's physical, chemical, and biological properties. It is commonly prepared by Decomposition, decomposing plant and food waste, recycling organic materials, and man ...

ed or burned for disposal, but in other cases, it can be used as a nutritious ingredient in

human food Human food is food which is fit for human consumption, and which humans willingly eating, eat. Food is a basic necessity of life, and humans typically seek food out as an instinctual response to hunger (physiology), hunger; however, not all thing ...

or animal feed.

Gasoline Gasoline ( North American English) or petrol ( Commonwealth English) is a petrochemical product characterized as a transparent, yellowish, and flammable liquid normally used as a fuel for spark-ignited internal combustion engines. When for ...

was once a byproduct of oil refining that later became a desirable commercial product as motor fuel. The plastic used in

plastic shopping bag In use by consumers worldwide since the 1960s, shopping bags made from various kinds of plastic, are variously called plastic shopping bags, carrier bags, or plastic grocery bags. They are sometimes referred to as single-use bags—referring to c ...

s also started as a by-product of oil refining. By-products are sometimes called co-products to indicate that although they are secondary, they are desired products. For example, hides and leather may be called co-products of beef production. There is no strict distinction between by-products and co-products.

In economics

In the context of production, a by-product is the "output from a joint production process that is minor in quantity and/or net realizable value (NRV) when compared with the main products". Because they are deemed to have no influence on reported financial results, by-products do not receive allocations of joint costs. By-products also, by convention, are not inventoried, but the NRV from by-products is typically recognized as "other income", or as a reduction of joint production processing costs when the by-product is produced. The

International Energy Agency The International Energy Agency (IEA) is a Paris-based autonomous intergovernmental organization, established in 1974, that provides policy recommendations, analysis and data on the global energy sector. The 31 member countries and 13 associatio ...

(IEA) defines ''by-product'' in the context of life-cycle assessment by defining four different product types: "main products, co-products (which involve similar revenues to the main product), by-products (which result in smaller revenues), and waste products (which provide little or no revenue)."

In chemistry

While some chemists treat "by-product" and "side-product" as synonyms in the above sense of a generic secondary (untargeted) product, others find it useful to distinguish between the two. When the two terms are distinguished, "by-product" is used to refer to a product that is not desired but inevitably results from molecular fragments of starting materials and/or reagents that are not incorporated into the ''desired product'', as a consequence of

conservation of mass In physics and chemistry, the law of conservation of mass or principle of mass conservation states that for any system closed to all transfers of matter the mass of the system must remain constant over time. The law implies that mass can neith ...

; in contrast, "side-product" is used to refer to a product that is formed from a competitive process that could, in principle, be suppressed by an optimization of reaction conditions.

Common byproducts

* bagasse and molasses from sugar production *

and germ from flour milling * buttermilk from butter production * distillers grains from ethanol production *

fly ash Coal combustion products (CCPs), also called coal combustion wastes (CCWs) or coal combustion residuals (CCRs), are byproducts of burning coal. They are categorized in four groups, each based on physical and chemical forms derived from coal combust ...

and

bottom ash Bottom ash is part of the non- combustible residue of combustion in a power plant, boiler, furnace, or incinerator. In an industrial context, it has traditionally referred to coal combustion and comprises traces of combustibles embedded in for ...

from coal combustion *

glycerol Glycerol () is a simple triol compound. It is a colorless, odorless, sweet-tasting, viscous liquid. The glycerol backbone is found in lipids known as glycerides. It is also widely used as a sweetener in the food industry and as a humectant in pha ...

from soap or biodiesel production * lanolin from wool processing * lees from wine fermentation *

pomace Pomace ( ), or marc (; from French ''marc'' ), is the solid remains of grapes, olives, or other fruit after pressing (wine), pressing for juice or Vegetable oil, oil. It contains the skins, pulp, seeds, and stems of the fruit. Grape pomace has ...

from fruit juice or olive oil production * saw dust from lumber production * slag from smelting ore *

straw Straw is an agricultural byproduct consisting of the dry wikt:stalk, stalks of cereal plants after the grain and chaff have been removed. It makes up about half of the crop yield, yield by weight of cereal crops such as barley, oats, rice, ry ...

from grain harvesting * trub from beer fermentation * vinasse from sugar or ethanol production * whey from cheese production

References

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In economics

In chemistry

Common byproducts

See also

References

References