Food waste
From Wikipedia, the free encyclopedia
Food waste, kitchen waste, or garbage (North American English) is any form of waste derived from food materials. It typically consists of vegetable peelings, meat scraps, excess or spoiled prepared food, and other discards from domestic or commercial kitchens.
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[edit] Sources and quantities
The per capita annual food waste output in North America in 1918 was estimated as 100-200 pounds.[1] The largest source is from domestic properties.
In 2004, a University of Arizona study indicates that forty to fifty per cent of US edible food never gets eaten. Every year $43 billion worth of edible food is estimated to be thrown away in the US.[2]
[edit] Collection
In areas where waste collection is a public function, food waste is usually managed by the same governmental organization as other waste collection. Most food waste is combined with general waste at the source. Separate collections have the advantage that food wastes can be disposed of in ways not applicable to other wastes.
From the end of the 19th century through the middle of the twentieth century, many municipalities collected food waste separately. Separate kerbside collection of food waste is now being revived in some areas. To keep collection costs down and raise the rate of food waste segregation, some local authorities, especially in Europe, have introduced "alternate weekly collections" of biodigradable waste (including eg. garden waste), which enable a wider range of recyclable materials to be collected at reasonable cost, and improve their collection rates. However, they result in a two week wait before the waste will be collected. So there is criticism that, particularly during hot weather, food waste rots and stinks, and attracts vermin.
Much kitchen waste also leaves the home through garbage disposal units.
[edit] Disposal
Like other waste, food waste can be dumped or incinerated. But food waste can also be fed to animals, typically swine; or it can be biodegraded by composting or anaerobic digestion, and reused to enrich soil.
Dumping food waste in a landfill causes environmental damage. By volume, it is the largest contributor to methane gas production.[1] It causes odour as it decomposes, attracts flies and vermin, and has the highest potential to add Chemical Oxygen Demand (COD) to the leachate. The EU Landfill Directive and Waste Regulations, like regulations in other countries, enjoin diverting organic wastes away from landfill disposal for these reasons.
Food waste can be composted at home, avoiding central collection entirely, and many local authorities have schemes to provide subsidised composting bin systems. However, the proportion of the population willing to dispose of their food waste in that way is limited.
In the past, many municipalities collected food waste separately, steamed it to disinfect it, and fed it to pigs, either on private farms or in municipal piggeries:
- Most of the smaller cities in this country dispose of a part or all their garbage by feeding to swine, but ... only four maintain municipal piggeries. (1918)[3]
Anaerobic digestion produces both useful fertilising liquid products and a solid fibrous "compost" (soil making) type of material. Anaerobic digestion plants can provide energy from waste by burning the methane created from food and other organic wastes to generate electricity, defraying the plant's costs and reducing greenhouse gas emissions.
Food waste coming through the sanitary sewers from garbage disposal units is treated along with other sewage and contributes to sludge.
[edit] See also
[edit] Notes
[edit] References
- William Parr Capes, Jeanne Daniels Carpenter. Municipal Housecleaning: The Methods and Experiences of American Cities in Collecting and Disposing of their Municipal Wastes--Ashes, Rubbish, Garbage, Manure, Sewage, and Street Refuse, New York: Dutton, 1918. full text at Google Books
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