Editing Dairy (section)

==Waste disposal and wastewater management==
[[File:Manure spreader 8685.jpg|thumb|Manure spreader going to the field from a dairy farm, [[Elba, New York]]]]
In countries where cows are grazed outside year-round, waste disposal issues need to be dealt with. The most concentrated waste is at the milking shed, where the animal waste may be liquefied (during the water-washing process) or left in a more solid form, either to be returned to be used on farm ground as organic fertiliser.<ref>{{cite web|url=http://www.extension.umn.edu/agriculture/dairy/manure/surface-irrigation-systems-for-wastewater/|title=Surface irrigation systems for treating milk house wastewater : Dairy Extension : University of Minnesota Extension|website=Extension.umn.edu|access-date=20 November 2017|url-status=dead|archive-url=https://web.archive.org/web/20170915004140/http://www.extension.umn.edu/agriculture/dairy/manure/surface-irrigation-systems-for-wastewater/|archive-date=15 September 2017}}</ref>

In the associated milk processing factories, most of the waste is washing water that is treated, usually by composting, and spread on farm fields in either liquid or solid form. This is much different from half a century ago, when the main products were butter, cheese and casein, and the rest of the milk had to be disposed of as waste (sometimes as animal feed).<ref>{{cite journal|jstor=25030895|title=Milk Waste Disposal|first=Don E.|last=Bloodgood|date=20 November 2017|journal=Sewage Works Journal|volume=20|issue=4|pages=695–706}}</ref>

In the dairy industries, there are two main types of wastewater produced: dairy wastewater and cheese whey. Dairy wastewater consists of material losses from the dairy products, effluents from the washing of tanks and equipment, and sanitary wastewater from toilets and sinks.<ref>Slavov AK, General characteristics and treatment possibilities of dairy wastewater – a review. Food Technol Biotechnol 53:237–242 (2017). https://doi {{Webarchive|url=https://web.archive.org/web/20130711094433/https://doi/ |date=11 July 2013 }}: 10.17113/ftb.55.01.17.4520</ref> The typical concentrations of BOD and total Kjeldahl nitrogen for dairy wastewater range from 1200 to 5000&nbsp;mg/L and 30 to 200&nbsp;mg/L, respectively.<ref name="SCV21">Stasinakis AS, Charalambous P and Vyrides I, Dairy wastewater management in EU: produced amounts, existing legislation, applied treatment processes and future challenges. J Environ Manage 303:114–152 (2021). https://doi.org/10.1016/j.jenvman.2021.114152 {{Webarchive|url=https://web.archive.org/web/20221228063418/https://www.sciencedirect.com/science/article/pii/S0301479721022143?via%3Dihub |date=28 December 2022 }}</ref> Cheese whey is the liquid remaining after the formation of curds. It contains important amounts of carbohydrates, proteins, lactic acid, fats, and salts and its BOD value can exceed 40,000&nbsp;mg/L.<ref>[4]	Flores-Mendoza AP, Hernández-García H, Cocotle-Ronzón Y and Hernandez-Martinez E, Methanogenesis of raw cheese whey: pH and substrate–inoculum ratio evaluation at mesophyll temperature range. J Chem Technol Biotechnol 95:1946–1952 (2020),  https://doi.org/10.1002/jctb.6391</ref> Dairy wastewater management usually includes equalisation, neutralisation and physical separation followed by biological treatment, while cheese whey is treated in anaerobic digesters or passes through membranes for protein recovery.<ref name="SCV21" />

In dairy-intensive areas, various methods have been proposed for disposing of large quantities of milk. Large application rates of milk on the land, or disposing in a hole, is problematic as the residue from the decomposing milk will block the soil pores and thereby reduce the water infiltration rate through the soil profile. As recovery of this effect can take time, any land-based application needs to be well managed and considered.<ref>{{cite book | url=http://www.ecohydrology.uwa.edu.au/__data/page/142432/Waste_Management.pdf | title=Environmental Best Practice Guidelines | chapter=Waste Management | publisher=Dairy Catch | url-status=dead | archive-url=https://web.archive.org/web/20110220180710/http://www.ecohydrology.uwa.edu.au/__data/page/142432/Waste_Management.pdf | archive-date=20 February 2011 | access-date=7 October 2010 }}</ref> Other waste milk disposal methods commonly employed include solidification and disposal at a solid waste landfill, disposal at a wastewater treatment plant, or discharge into a sanitary sewer.<ref>{{cite web | title=Fact Sheet: Proper Disposal of Milk Waste | url=http://www.in.gov/idem/files/landcomp_dairyfactsheet.pdf | publisher=Indiana Department of Environmental Management | access-date=7 June 2014 | url-status=dead | archive-url=https://web.archive.org/web/20150924050110/http://www.in.gov/idem/files/landcomp_dairyfactsheet.pdf | archive-date=24 September 2015 }}</ref>