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(took over a section from the wikipedia on greywater I wrote myself) |
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Redirecting the water we use for tasks such as showering allows us to reclaim some of that value to grow plants and recharge the [[water table]]. It may be necessary to choose our [[soap]]s and [[detergent]]s more carefully, if we use the greywater for watering and fertilizing plants. | Redirecting the water we use for tasks such as showering allows us to reclaim some of that value to grow plants and recharge the [[water table]]. It may be necessary to choose our [[soap]]s and [[detergent]]s more carefully, if we use the greywater for watering and fertilizing plants. | ||
==Recycling== | |||
===Systems=== | |||
{{See also|Water purification|Ecological sanitation}} | |||
At present, several water recycling systems exist which can be used to: | |||
* recycle the water without purifying it | |||
* recycle the water while [[Water purification|purifying]] or decontaminating it | |||
====Water recycling systems without purification==== | |||
Water recycling without purification is used in certain agricultural companies (e.g., tree nurseries) and [[dwellings]] for applications where potable water is not required (e.g., garden and land irrigation, toilet flushing). It may also be used in dwellings when the greywater (e.g., from [[Rainwater harvesting|rainwater]]) is already fairly clean to begin with and/or has not been polluted with non-degradable chemicals such as non-natural soaps (thus using natural cleaning products instead). | |||
This water system also needs a supply of water to recycle and reuses water as well. It is also not recommended to use water that has been in the greywater filtration system for more than 24 hours or bacteria builds up affecting the water that is being reused. | |||
Water purification/decontamination systems then again are used for applications where potable water ''is'' required (e.g., to allow [[drinking]], and/or for other [[Home|domestic]] tasks as [[washing]], [[showering]]). | |||
====Water recycling with purification==== | |||
For filtering the water to become potable (or near-potable), there are numerous systems based on ''soft'' processes. These include [[Biofilter|natural biological principles]] such as | |||
* mechanical systems ([[sand filter|sand filtration]], [[lava filter|lava filter systems]] and systems based on [[UV]] radiation) | |||
* biological systems (plant systems as [[treatment pond]]s, [[constructed wetlands]], [[living wall]]s) and Bio reactors or compact systems as [[Activated sludge|activated sludge systems]], biorotors, [[aerobic biofilter|aerobic]] and [[anaerobic biofilters]], submerged aerated filters, biorolls{{Vague|date=January 2010}}<!-- what are these? products no-one has heard of --> <ref>[http://www.oost-vlaanderen.be/docs/nl/gc/35447.%20afvalwaterzuivering%20op%20landbouwbedrijven.pdf Overview of biological systems with pictures]</ref> | |||
Finally, "hard", direct processes, such as [[distillation]] (evaporation) or mechanical processes such as [[Membrane technology|membrane filtration]], (typically [[ultrafiltration]] and [[reverse osmosis]], which are capable of treating high volumes of grey water) can create potable, or near-potable water. There seem to be no commercially available "hard" greywater recovery devices suitable for on-site use in the individual household, even though a number of such technologies exist. | |||
In order to purify the potable water adequately, several of these systems are usually combined to work as a whole. Combination of the systems is done in two to three stages, using a [[Primary water purification|primary]] and a [[Secondary water purification|secondary purification]]. Sometimes a tertiary purification is also added. | |||
Some municipal sewage systems recycle a certain amount of grey and blackwater using a high standard of treatment, providing [[reclaimed water]] for irrigation and other uses. | |||
== Minimizing health risks from greywater== | == Minimizing health risks from greywater== | ||
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*The old [http://www.humboldt.edu/~ccat/waterconservation/marsh/index.html greywater] system at [[:Category:CCAT|CCAT]] | *The old [http://www.humboldt.edu/~ccat/waterconservation/marsh/index.html greywater] system at [[:Category:CCAT|CCAT]] | ||
== | ==External links== | ||
* [[Greenlivingpedia:Knoxfield house#Greywater System|Knoxfield greywater system]] - application of greywater treatment in a house in Knoxfield, in the suburbs of [[Melbourne]], [[Australia]]. - ''Greenlivingpedia'' | * [[Greenlivingpedia:Knoxfield house#Greywater System|Knoxfield greywater system]] - application of greywater treatment in a house in Knoxfield, in the suburbs of [[Melbourne]], [[Australia]]. - ''Greenlivingpedia'' | ||
* [[Wikipedia:Greywater]] | * [[Wikipedia:Greywater]] | ||
*[http://www.graywater.net/ Oasis Designs] - The best [http://www.oasisdesign.net/greywater/misinfo/index.htm common errors and best practices] section ever. | *[http://www.graywater.net/ Oasis Designs] - The best [http://www.oasisdesign.net/greywater/misinfo/index.htm common errors and best practices] section ever. | ||
*The [http://epa.gov/water/ EPA] on water. | *The [http://epa.gov/water/ EPA] on water. | ||
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{{Stub}} | {{Stub}} | ||
{{Topicadmin|Lonny}} | {{Topicadmin|Lonny}} | ||
[[Category:Greywater]] | [[Category:Greywater]] | ||
[[Category:Wastewater]] | [[Category:Wastewater]] | ||
[[Category:Sewage]] | [[Category:Sewage]] |
Revision as of 10:17, 1 October 2012
Template:Topic with portal header
Greywater, sometimes also spelled as graywater, grey water or gray water, is all of the effluent water from a household, except that from the toilets, which is sometimes called "blackwater". In addition, if greywater is held for too long (>24 hours in temperate climates), it will become blackwater.[verification needed]
The water leaving our homes carries nutrients. The water itself is also of value, an increasingly limited resource especially in dry climates. It may also contain pathogens, and/or harsh chemicals and care should be taken with it; although it is not as great a health risk as blackwater (sewage), it should be handled with great care and human exposure to greywater should be avoided.
Redirecting the water we use for tasks such as showering allows us to reclaim some of that value to grow plants and recharge the water table. It may be necessary to choose our soaps and detergents more carefully, if we use the greywater for watering and fertilizing plants.
Recycling
Systems
At present, several water recycling systems exist which can be used to:
- recycle the water without purifying it
- recycle the water while purifying or decontaminating it
Water recycling systems without purification
Water recycling without purification is used in certain agricultural companies (e.g., tree nurseries) and dwellings for applications where potable water is not required (e.g., garden and land irrigation, toilet flushing). It may also be used in dwellings when the greywater (e.g., from rainwater) is already fairly clean to begin with and/or has not been polluted with non-degradable chemicals such as non-natural soaps (thus using natural cleaning products instead). This water system also needs a supply of water to recycle and reuses water as well. It is also not recommended to use water that has been in the greywater filtration system for more than 24 hours or bacteria builds up affecting the water that is being reused. Water purification/decontamination systems then again are used for applications where potable water is required (e.g., to allow drinking, and/or for other domestic tasks as washing, showering).
Water recycling with purification
For filtering the water to become potable (or near-potable), there are numerous systems based on soft processes. These include natural biological principles such as
- mechanical systems (sand filtration, lava filter systems and systems based on UV radiation)
- biological systems (plant systems as treatment ponds, constructed wetlands, living walls) and Bio reactors or compact systems as activated sludge systems, biorotors, aerobic and anaerobic biofilters, submerged aerated filters, biorollsTemplate:Vague [1]
Finally, "hard", direct processes, such as distillation (evaporation) or mechanical processes such as membrane filtration, (typically ultrafiltration and reverse osmosis, which are capable of treating high volumes of grey water) can create potable, or near-potable water. There seem to be no commercially available "hard" greywater recovery devices suitable for on-site use in the individual household, even though a number of such technologies exist.
In order to purify the potable water adequately, several of these systems are usually combined to work as a whole. Combination of the systems is done in two to three stages, using a primary and a secondary purification. Sometimes a tertiary purification is also added.
Some municipal sewage systems recycle a certain amount of grey and blackwater using a high standard of treatment, providing reclaimed water for irrigation and other uses.
Minimizing health risks from greywater
- Wash yourself after contacting greywater.
- Install signage around greywater irrigation systems or areas.
- Do not drink or play with greywater.
- Do not allow anything that may be eaten to come into contact with greywater.
- Do not allow greywater to pond or run off the property.
- Do not wash domestic pets in greywater or allow pets to drink greywater.
- Do not use greywater in public places such as children's play areas or playgrounds, BBQ areas or recreation facilities.
Suggested projects
- What is the effect of various detergents and soaps in a greywater system? Consider the receiving soil and plant types - the answer may vary.[expansion needed]
Organizations
Projects
External links
- Knoxfield greywater system - application of greywater treatment in a house in Knoxfield, in the suburbs of Melbourne, Australia. - Greenlivingpedia
- Wikipedia:Greywater
- Oasis Designs - The best common errors and best practices section ever.
- The EPA on water.
- Agroforestry on greywater for Trees and Landscape.
- http://www.greywater.com/ - Check out their pollution page.
- College of Agriculture and Home Economics New Mexico State University
- 3/29/07 LA Times article on Grey water's red tape
- The graywater guide book from January 1995 (pdf)
- Focuses on Subsurface Drip Irrigation and Mini-Leachfield in California
- 1997 Revised California Graywater Standards (pdf)
- Main changes:
- Use in commercial, industrial and multifamily projects is now acceptable (and procedures for estimating discharge in those environments are now included). Whereas before only single family homes were allowed.
- One irrigation zone is now acceptable. Whereas before two were required.
- Filters are now sized based on filtration rate. Whereas before a 1 inch filter was prescribed.
- California Revised Greywater Code (html)
- Colorado State University - Greywater information
- Chapter 9 of the Humanure Handbook
- Guide to Greywater
- Excellent resource. Punchline: 1 of Constructed Wetland for every 1 gallon of graywater per day. This must be with a maximum two foot depth, especially considering that Oasis Design states 1/2 to 1 square foot for every 1 gallon of graywater per day.
- Texas A&M Greywater
- Great pictures