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This type of toilet is also called by many people [[ecosan]] toilet, although this is not recommended as [[ecosan]] is not limited to this type of toilet.
This type of toilet is also called by many people [[ecosan]] toilet, although this is not recommended as [[ecosan]] is not limited to this type of toilet.

UDDTs can also accommodate users who prefer anal cleansing with water by including a separate anal cleansing pan with a drain to divert wash water into a dedicated disposal or treatment system. In many cases, UDDTs are offered together with waterless [[urinal|urinals]] to prevent male users from standing over the UDDT and aiming by mistake for the wrong hole, i.e. the faeces hole.


== Principle ==
== Principle ==
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== Historical development ==
== Historical development ==
The UDDTs with double dehydration vaults that we know today were originally designed around 1950 in Japan and further developed in Vietnam in the 1960s as a means of increasing the hygienic safety of excreta reused in agriculture.<ref>Winblad, U., Simpson-Hebert, M. (2004). [http://www.susana.org/en/resources/library/details/487 Ecological Sanitation - Revised and enlarged edition.] Stockholm Environment Institute, Sweden</ref>
The UDDTs with double dehydration vaults that we know today were originally designed around 1950 in Japan and further developed in Vietnam in the 1960s as a means of increasing the hygienic safety of excreta reused in agriculture.<ref>Winblad, U., Simpson-Hebert, M. (2004). [http://www.susana.org/en/resources/library/details/487 Ecological Sanitation - Revised and enlarged edition.] Stockholm Environment Institute, Sweden</ref>

Since the 1990s, modifications of this design such as addition of ventilation pipes to the faeces vault have been developed in many countries. TPrefabricated ceramic or plastic urine diversion squatting pans and pedestals have become available on the market, generally increasing the durability and perceived prestige associated with the system.
== Examples of UDDT installations ==
== Examples of UDDT installations ==
The exact number of UDDT users worlwide is impossible to determine, but a rough estimate by GIZ in 2012 based on known projects in 84 countries put the number at approximately 2 million users worldwide.<ref>GIZ (2012). [[Worldwide list of 324 documented ecosan projects by various organisations]]. Gesellschaft für internationale Zusammenarbeit (GIZ) GmbH, Eschborn, Germany</ref>
The exact number of UDDT users worlwide is impossible to determine, but a rough estimate by GIZ in 2012 based on known projects in 84 countries put the number at approximately 2 million users worldwide.<ref>GIZ (2012). [[Worldwide list of 324 documented ecosan projects by various organisations]]. Gesellschaft für internationale Zusammenarbeit (GIZ) GmbH, Eschborn, Germany</ref>

Revision as of 22:50, 25 October 2014

A urine-diverting dry toilet (UDDT) is a type of dry toilet with urine diversion. The functional design elements of the UDDT are: source separation of urine and faeces; waterless operation; and ventilated vaults or containers for faeces storage and treatment. UDDTs may be constructed with two dehydration vaults that are used alternately or one single vault with interchangeable containers.[1] The UDDT is a dry excreta management system that since the late-1990s is seen as an alternative to pit latrines and flush toilets.

An alternative name of it is urine diversion dehydration toilet (also abbreviated as UDDT), although with this term more emphasis is placed on the process of dehydration in the vault of the toilet and it should only be used for UDDTs with two vaults.[1]

This type of toilet is also called by many people ecosan toilet, although this is not recommended as ecosan is not limited to this type of toilet.

UDDTs can also accommodate users who prefer anal cleansing with water by including a separate anal cleansing pan with a drain to divert wash water into a dedicated disposal or treatment system. In many cases, UDDTs are offered together with waterless urinals to prevent male users from standing over the UDDT and aiming by mistake for the wrong hole, i.e. the faeces hole.

Principle

Urine diversion takes advantage of the anatomy of the human body, which excretes urine and faeces separately.[1] In a UDDT, the urine is drained via a basin with a small hole near the front of the user interface, while faeces fall through a larger drop-hole at the rear. This separate collection – or ‘source separation’ – does not require the user to change positions between urinating and defecating, although some care is needed to ensure the right position over the user interface. Female users may find that some urine may enter the vault during normal operation. This is typically a small amount and does not significantly affect the function of the toilet.

Ash and/or sawdust are usually added to the faeces chamber of a UDDT to speed the composting process. Of the two, ash decreases microbial activity faster.[2] Dehydration and conversion into a biofuel is typically accomplished by exposure to dry air and/or solar heat.

Challenges

Significant barriers to more universal acceptance of this technology remain. These include: lack of awareness, a limited supply of prefabricated UDDT components and a low interest in financing sanitation services for non-sewered areas of settlements.

Comparison with pit latrine

The advantage of UDDTs compared to pit latrines is the conversion of faeces into a dry odourless material and therefore a complete avoidance of the issues surrounding faecal sludge management. A well-maintained UDDT is an odour and insect free toilet which is appreciated by users and allows simple removal and less offensive and safer handling of the faecal material once the faeces vault has filled up. Moreover, the risk of water pollution is minimised through the safe containment of faces in aboveground vaults and this allows the toilets to be constructed in locations where pit-based systems are not appropriate.[1]

Reasons for keeping urine and feces separate in a UDDT compared to a pit latrine can be to:[1]

  1. reduce odour (a mix of urine and faeces causes substantial odour);
  2. avoid production of wet, odorous faecal sludge, which has to be removed by someone when the pit latrine is full;
  3. enable fast drying of faeces which makes handling of faeces more simple and hygienic;
  4. reduce environmental impacts;
  5. allow for the recovery of urine, which can be reused as fertiliser.

Reuse of dried faeces

The faeces are in almost all cases not entirely sanitised when removed from the vaults of the UDDT, so careful handling is obligatory. In scenarios with reuse of excreta in agriculture, a post-treatment of faecal matter and storage of urine is advisable to ensure adequate sanitisation.[1]

Source of bowl or squatting pan

The toilet bowls or squatting pans for UDDTs can be commercially manufactured from plastic or ceramic and transported to the user or built locally by local NGOs or artisans, for example made of concrete.

Historical development

The UDDTs with double dehydration vaults that we know today were originally designed around 1950 in Japan and further developed in Vietnam in the 1960s as a means of increasing the hygienic safety of excreta reused in agriculture.[3]

Since the 1990s, modifications of this design such as addition of ventilation pipes to the faeces vault have been developed in many countries. TPrefabricated ceramic or plastic urine diversion squatting pans and pedestals have become available on the market, generally increasing the durability and perceived prestige associated with the system.

Examples of UDDT installations

The exact number of UDDT users worlwide is impossible to determine, but a rough estimate by GIZ in 2012 based on known projects in 84 countries put the number at approximately 2 million users worldwide.[4]

Some examples are provided below:

  • The NGO Women in Europe for a Common Future (WECF) and local partners have built built many urine-diverting dry toilets for schools in Eastern Europe, Caucasus and Central Asia (EECCA region).[5]
  • Haiti - SOIL has built urine-diversion toilets and composting waste treatment plants in Port-au-Prince as part of the 2010 Haiti earthquake emergency relief effort and in northern Haiti. There are currently 20,000 people using these units and more than 400,000 liters of compost have been produced as a result.[6]
  • Cambodia - Lien Aid has assisted with the development and implementation of floating toilets that utilize UDD in a project called “River of life”[7]
  • Boating - Chris Melo, sailboat resident and nautical engineer, cites 9 reasons to convert from conventional nautical toilets that store waste in black water tanks, or immediate discharge it overboard, to a UDD composting toilet[8] Two competing manufactures for nautical use call their products Nature's Head and the Air Head Toilet.[9]
  • Camping - Leave no trace is not only a philosophy but a necessity in areas where human waste left behind would not decay naturally. There are now portable UDD toilets for example by the Swedish company Separett that allow feces to be collected and packed out.[10] Only urine is left behind which is of less concern as urine is nearly pathogen free.
  • NatSol, a UK company that specialises in urine diverting dry toilets, has developed a solution that avoids the usual problems of blockage and fouling of urine separating bowls. It uses the Coandă effect to divert and send urine to a soakaway, rather than rely on evaporation.[11]
  • Owing to limited water supplies in outer space, NASA started in May 2009 to utilize a UDD toilet to recycle urine into drinking water.[12]
  • In Namibia, UDDTs are known under the name of Otji toilets.[13]
  • More examples of installations of UDDTs in developing countries is available in 45 case studies of the Sustainable Sanitation Alliance that describe projects with UDDTs.[14]

References

  1. ^ a b c d e f Rieck, C., von Münch, E., Hoffmann, H. (2012). Technology review of urine-diverting dry toilets (UDDTs) - Overview on design, management, maintenance and costs. Deutsche Gesellschaft fuer Internationale Zusammenarbeit (GIZ) GmbH, Eschborn, Germany
  2. ^ http://www.ncbi.nlm.nih.gov/pubmed/19303763 Comparing microbial die-off in separately collected faeces with ash and sawdust additives, Author Niwagaba C et al, 2009
  3. ^ Winblad, U., Simpson-Hebert, M. (2004). Ecological Sanitation - Revised and enlarged edition. Stockholm Environment Institute, Sweden
  4. ^ GIZ (2012). Worldwide list of 324 documented ecosan projects by various organisations. Gesellschaft für internationale Zusammenarbeit (GIZ) GmbH, Eschborn, Germany
  5. ^ Deegener, S., Wendland, C., Samwel, A., Samwel, M. (2009). Sustainable and safe school sanitation - How to provide hygienic and affordable sanitation in areas without a functioning wastewater system. Examples from Eastern Europe, Caucasus and Central Asia. Women in Europe for a Common Future (WECF), The Netherlands, Germany, France
  6. ^ Christine Dell'Amore, "Human Waste to Revive Haitian Farmland?", The National Geographic, October 26, 2011
  7. ^ http://washasia.wordpress.com/category/regions/east-asia/cambodia/ UDD and floating toilets in Cambodia
  8. ^ http://ecovita.net/news/wp-content/uploads/2009/07/NaturesheadOnBoat2.pdf
  9. ^ http://forum.woodenboat.com/showthread.php?114077-Nature-s-Head-vs.-Air-Head-Toilet Wooden Boat Forum
  10. ^ http://www.flickr.com/photos/gtzecosan/2921708370/ Photo of Foldable camping UDD toilet by Separett (Sweden)
  11. ^ COMPUS Full Access dry toilet
  12. ^ http://www.nasa.gov/home/hqnews/2009/may/HQ_09-096_Recycled_Water_Go.html NASA Gives Space Station Crew 'Go' to Drink Recycled Water, May 2009
  13. ^ Ingle, R., Berdau, S., Kleemann, F., Arndt, P. (2012). What does it take to convince decision makers in Omaruru, Namibia to scale up urine diversion dehydration “Otji toilets”? 4th International Dry Toilet Conference, Tampere, Finland
  14. ^ "UDDT case studies of the Sustainable Sanitation Alliance". Retrieved 19 October 2014.