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By-product
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<h2 id="in-economics">In economics</h2> <p>In the context of production, a by-product is the "output from a <a href="/facts/Joint_production_process/D7uMpxhU">joint production process</a> that is minor in quantity and/or <a href="/facts/Net_realizable_value/kVF077z2">net realizable value</a> (NRV) when compared with the <a href="/facts/Main_products/ducuBvbx">main products</a>".<a class="footnote-ref" id="fnref:2" href="#fn:2"><sup>2</sup></a> Because they are deemed to have no influence on reported financial results, by-products do not receive allocations of <a href="/facts/Joint_cost/ktKIzkTn">joint costs</a>. 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 <a href="/facts/Joint_production_process/D7uMpxhU">joint production processing</a> costs when the by-product is produced.<a class="footnote-ref" id="fnref:3" href="#fn:3"><sup>3</sup></a> </p><p>The <a href="/facts/International_Energy_Agency/HErEraSy">International Energy Agency</a> (IEA) defines <i>by-product</i> in the context of <a href="/facts/Life-cycle_assessment/vGKCvfYf">life-cycle assessment</a> 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 <a href="/facts/Waste_products/qLmtkUQ4">waste products</a> (which provide little or no revenue)."<a class="footnote-ref" id="fnref:4" href="#fn:4"><sup>4</sup></a> </p> <h2 id="in-chemistry">In chemistry</h2> <p>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 <a href="/facts/Reagents/c3GLInCu">reagents</a> that are not incorporated into the <i>desired product</i>, as a consequence of <a href="/facts/Conservation_of_mass/fRu05SS1">conservation of mass</a>; 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.<a class="footnote-ref" id="fnref:5" href="#fn:5"><sup>5</sup></a> </p> <h2 id="common-byproducts">Common byproducts</h2> <ul><li><a href="/facts/Bagasse/rXFNWeyU">bagasse</a> and <a href="/facts/Molasses/N8kE2HfI">molasses</a> from sugar production</li> <li><a href="/facts/Bran/BIdpgSwl">bran</a> and <a href="/facts/Cereal_germ/FREfnHBx">germ</a> from flour milling</li> <li><a href="/facts/Buttermilk/hJxJb6SM">buttermilk</a> from butter production</li> <li><a href="/facts/Distillers_grains/Jq4z6Qvz">distillers grains</a> from ethanol production</li> <li><a href="/facts/Fly_ash/RrPNlq9t">fly ash</a> and <a href="/facts/Bottom_ash/dWK680cU">bottom ash</a> from coal combustion</li> <li><a href="/facts/Glycerol/sRQ6NBQQ">glycerol</a> from soap or biodiesel production</li> <li><a href="/facts/Lanolin/VyKnaor3">lanolin</a> from wool processing</li> <li><a href="/facts/Lees_(fermentation)/yDwslU1l">lees</a> from wine fermentation</li> <li><a href="/facts/Pomace/LwuP013p">pomace</a> from fruit juice or olive oil production</li> <li><a href="/facts/Saw_dust/lVFHgXxK">saw dust</a> from lumber production</li> <li><a href="/facts/Slag/LD3qEAlV">slag</a> from smelting ore</li> <li><a href="/facts/Straw/hqULAcwx">straw</a> from grain harvesting</li> <li><a href="/facts/Trub_(brewing)/4VLaFfKM">trub</a> from beer fermentation</li> <li><a href="/facts/Vinasse/F0sj6Uuh">vinasse</a> from sugar or ethanol production</li> <li><a href="/facts/Whey/sTKcoxRq">whey</a> from cheese production</li></ul> <h2 id="see-also">See also</h2> <ul><li><a href="/facts/Main_product/ducuBvbx">Main product</a></li> <li><a href="/facts/By-product_synergy/x9X7GAzz">By-product synergy</a></li> <li><a href="/facts/Circular_economy/13UFemv7">Circular economy</a></li> <li><a href="/facts/Side_reaction/HMJ8CYxH">Side reaction</a></li></ul> <h2 id="references">References</h2> <ol> <li id="fn:1"><p>Muthu, Subramanian Senthilkannan; Li, Yi (2013). "Manufacturing Processes of Grocery Shopping Bags". Assessment of Environmental Impact by Grocery Shopping Bags: An Eco-Functional Approach. Environmental Issues in Logistics and Manufacturing. Singapore: Springer Science & Business Media. p. 7. ISBN 9789814560207. Retrieved 27 July 2019. Plastic is obtained as a by-product from the oil refining process [...] <a href="9789814560207" target="_blank">9789814560207</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li> <li id="fn:2"><p>Wouters, Mark; Selto, Frank H.; Hilton, Ronald W.; Maher, Michael W. (2012): Cost Management: Strategies for Business Decisions, International Edition, McGraw-Hill, p. 535. <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li> <li id="fn:3"><p>World Trade Organization (2004): United States – Final dumping determination on softwood lumber from Canada, WT/DS264/AB/R, 11 August 2004. <a href="/wiki/World_Trade_Organization" target="_blank">/wiki/World_Trade_Organization</a> <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li> <li id="fn:4"><p>"BIOMITRE Technical Manual, Horne, R. E. and Matthews, R., November 2004" (PDF). Archived from the original (PDF) on 2011-07-26. Retrieved 2011-02-16. <a href="https://web.archive.org/web/20110726171133/http://www.ieabioenergy-task38.org/systemdefining/biomitre_technical_manual.pdf#" target="_blank">https://web.archive.org/web/20110726171133/http://www.ieabioenergy-task38.org/systemdefining/biomitre_technical_manual.pdf#</a> <a href="#fnref:4" class="footnote-back-ref">↩</a></p></li> <li id="fn:5"><p>Watson, Will (2012). "On Byproducts and Side Products". Org. Process Res. Dev. 16 (12): 1877–1877. doi:10.1021/op300317g. <a href="https://doi.org/10.1021%2Fop300317g" target="_blank">https://doi.org/10.1021%2Fop300317g</a> <a href="#fnref:5" class="footnote-back-ref">↩</a></p></li> </ol>