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An alternative name for a UDDT is "urine diversion dehydration toilet", or "urine diversion desiccation toilet", 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<ref name=":1" /> or for UDDTs that have an in-built electrical fan.
An alternative name for a UDDT is "urine diversion dehydration toilet", or "urine diversion desiccation toilet", 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<ref name=":1" /> or for UDDTs that have an in-built electrical fan.


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 an "[[ecosan]] toilet" as this name is quite easy to communicate at the local level with potential users. However, the term [[ecosan]] is in fact much broaded and not limited to this type of toilet.


UDDTs can 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.
UDDTs can 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.
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== Challenges ==
== Challenges ==
[[File:Urine Diversion Dehydration Toilet at Mwijo Primary School (4460239832).jpg|thumb|School UDDT in rural areas of Western Kenya; the steep stairs are not recommended (due to potential users with disabilities)]]
[[File:Urine Diversion Dehydration Toilet at Mwijo Primary School (4460239832).jpg|thumb|School UDDT in rural areas of Western Kenya; the steep stairs are not recommended (due to potential users with disabilities)]]
Significant barriers to more universal acceptance of this technology remain. These include in the case of developing countries: lack of awareness, a limited supply of prefabricated UDDT components and a low interest in financing sanitation services for non-sewered areas of settlements.
It is important that the sanitation system selected not only has legal acceptability but support at the local policy level amongst the various government departments affected.<ref name=":3">Flores, A. (2010). [http://www.susana.org/en/resources/library/details/1172 Towards sustainable sanitation: evaluating the sustainability of resource-oriented sanitation]. PhD Thesis, University of Cambridge, UK</ref> Significant barriers to more universal acceptance of this technology remain. These include in the case of developing countries: lack of awareness, a limited supply of prefabricated UDDT components and a low interest in financing sanitation services for non-sewered areas of settlements.


Many users do not have an interest in handling their excreta which is understandable.  Therefore, provisions should be made for door-to-door/curbside collection of these materials, similar to how existing municipal or private schemes collect household organic waste (from kitchens and gardens, etc.) and transport it to a centralised facility for composting or biogas generation.
Many users do not have an interest in handling their excreta which is understandable. Therefore, provisions should be made for door-to-door/curbside collection of these materials, similar to how existing municipal or private schemes collect household organic waste (from kitchens and gardens, etc.) and transport it to a centralised facility for composting or biogas generation.


UDDTs are sometimes built with very steep stairs without handrails which is not recommended as it could leave people with disabilities struggling to access even the door of the toilet. The needs of people with disabilities should always be considered and less steep stairs or ramps should be used. The bench design UDDT can even completely overcome the need for stairs (see below).
UDDTs are sometimes built with very steep stairs without handrails which is not recommended as it could leave people with disabilities struggling to access even the door of the toilet. The needs of people with disabilities should always be considered and less steep stairs or ramps should be used. The bench design UDDT can even completely overcome the need for stairs (see below).
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Sewer-based excreta management is in any case impractical in many regions due to limited water supplies and the high cost of sewer systems and wastewater treatment plants.<ref name=":1" /> Furthermore, water-based sanitation systems (flush toilets) dilute excreta and create larger wastewater streams which UDDTs do not.
Sewer-based excreta management is in any case impractical in many regions due to limited water supplies and the high cost of sewer systems and wastewater treatment plants.<ref name=":1" /> Furthermore, water-based sanitation systems (flush toilets) dilute excreta and create larger wastewater streams which UDDTs do not.

Decentralised sanitation systems which employ UDDTs offer the potential advantages of quick deployment (especially where there is no capable centralized institutional infrastructure in place or no financial ability to implement larger centralized systems) as well as greater local control. Such a sanitation system that uses UDDTs - and perhaps even aims at [[resource recovery]] in agriculture - differs however from a conventional sewer-based system in that it requires greater coordination and cooperation amongst different sectors.<ref name=":3" /> Policies could encourage their development through: financial support of research programmes, enactment of regulations that require the recovery of resources from wastewater and adequately account for the reduced contaminant loading and incentives for resource recovery.<ref name=":3" />


=== Pharmaceutical residues ===
=== Pharmaceutical residues ===

Revision as of 21:17, 4 November 2014

Double-vault UDDT, waterless urinal and shower integrated into a household's bathroom in non-sewered area of Lima, Peru
Double vault UDDT used in squatting position in Ouagadougou, Burkina Faso
UDDT with single vault and exchangeable container: Separett toilet at a household in Germany; As the user sits on the seat, the blue view gard that covers the faeces buckets opens up.
Back view of UDDT toilet building at school in low-income aread of Lusaka, Uganda, showing vault doors and vent pipes

A urine-diverting dry toilet (UDDT) is a type of dry toilet with urine diversion that can be used to provide sustainable sanitation in a variety of contexts worldwide. It can be configured as a sitting toilet (with a urine diversion pedestal or bench) or as a squatting toilet (with a urine diversion squatting pan). The most important design elements of the UDDT are: source separation of urine and faeces (feces); waterless operation; and ventilated vaults (also called "chambers") or movable containers for faeces storage and treatment. UDDTs may be constructed with two dehydration vaults that are used alternately or one single vault into which interchangeable containers are placed.[1] The UDDT is a dry excreta management system (or "dry sanitation" system) known since the late-1990s and can be an alternative to pit latrines and flush toilets in certain contexts where they are particularly suitable.

An alternative name for a UDDT is "urine diversion dehydration toilet", or "urine diversion desiccation toilet", 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] or for UDDTs that have an in-built electrical fan.

This type of toilet is also called by many people an "ecosan toilet" as this name is quite easy to communicate at the local level with potential users. However, the term ecosan is in fact much broaded and not limited to this type of toilet.

UDDTs can 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.

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.

A UDDT consists of eight basic functional elements:[1]

  1. Urine diversion toilet seat or squatting pan;
  2. One or two faeces vaults (also called "chambers"; with or without removable containers), usually above ground, or one shallow pit for faeces collection and storage;
  3. Urine piping system leading from the user interface to an infiltration or collection system;
  4. Ventilation pipe to exhaust moisture and odours from the vault or pit; 
  5. If required: An anal cleansing area with mechanisms for the separate collection and drainage of anal wash water; 
  6. Toilet super-structure, unless the toilet is installed inside an existing house or is of the standalone or portable variety;
  7. Bucket with dry cover material (see below);
  8. Hand washing facility with soap and water - like any other toilet should have. 

Various types of cover material, such as ash, sawdust, soil, sand, shredded coconut husk (coir), dried leaves, dried peat moss etc. or lime is added to the faeces chamber of a UDDT to reduce odour and speed up the drying process (or to raise the pH in the case of lime).

Waterless urinals

UDDTs are often installed alongside waterless urinals particularly in lavatories or bathrooms frequented by male users. This is done for the convenience of male users and to address the problem of male users standing over the UDDT to urinate and inadvertently directing urine into the wrong opening i.e. the faeces vault or faeces container.

Suitability

UDDTs are particularly suitable in situations where:[1]

  1. Water is scarce or costly, such as in arid or semi-arid climates; 
  2. Sewerage infrastructure costs are prohibitive, such as instances of unfavourable terrain, sprawling settlement patterns or poverty;
  3. Frequent flooding would impact pit latrines and septic tank systems, resulting in inoperable toilet systems and the contamination of water resources;
  4. Unfavourable soil conditions, such as unstable or rocky soil and high water table, make pit-based sanitation difficult and expensive;
  5. Groundwater is the primary source of drinking water and is likely to be contaminated by pit-based sanitation;
  6. Limited land space restricts the excavation of new pits if full pit latrines are usually not emptied;
  7. Indoor installations are preferred as they provide greater comfort and security at night thus making them more accessible for all;
  8. Local agriculture and diminishing soil fertility create demand for affordable fertiliser and soil conditioner.

Furthermore, with a particular perspective of developed countries, UDDTs can be suitable in situations where:

  • An individual, family or community wants to increase the resiliency of their existing sanitation system in the face of natural disasters (i.e. climate change, earth quakes) and/or the looming low energy future; and
  • Following approval by local building inspectors and health department authorities, an individual or family seeks to reduce or perhaps eliminate the need for an onsite septic system (particularly when used in conjunction with an onsite greywater system) to reduce their environmental footprint.

Challenges

School UDDT in rural areas of Western Kenya; the steep stairs are not recommended (due to potential users with disabilities)

It is important that the sanitation system selected not only has legal acceptability but support at the local policy level amongst the various government departments affected.[2] Significant barriers to more universal acceptance of this technology remain. These include in the case of developing countries: lack of awareness, a limited supply of prefabricated UDDT components and a low interest in financing sanitation services for non-sewered areas of settlements.

Many users do not have an interest in handling their excreta which is understandable. Therefore, provisions should be made for door-to-door/curbside collection of these materials, similar to how existing municipal or private schemes collect household organic waste (from kitchens and gardens, etc.) and transport it to a centralised facility for composting or biogas generation.

UDDTs are sometimes built with very steep stairs without handrails which is not recommended as it could leave people with disabilities struggling to access even the door of the toilet. The needs of people with disabilities should always be considered and less steep stairs or ramps should be used. The bench design UDDT can even completely overcome the need for stairs (see below).

UDDTs can also be built for schools (many examples exist in Kenya, Rwanda and Uganda). However, they do suffer from the same issues as any other type of school toilets and this is related to the maintenance of the school toilets: If clear responsibilities and a dedicated budget for school toilets' maintenance is lacking, then the toilets may easily fall into disrepair, e.g. with blocked urine pipes or faeces vaults that are not being emptied.

Comparison with pit latrine

Very simple home made design for a UDDT with a bucket for faeces collection at a household in Addis Ababa, Ethiopia

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.

Advantages

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]

Disadvantages

Disadvantages compared to pit latrines include: higher capital costs (although whole-of -life costs might be lower, see below), more awareness required by the user who has to use it properly (no urination into faeces compartment) and react appropriately when the urine vessel is full (or there are problems with the urine soak pit), the urine pipe is blocked or the faeces vaults or containers are full.

Comparison with sewer-based sanitation

The comparison of UDDTs with sewer-based sanitation systems (sewerage and wastewater treatment plants) is not as straight forward as the comparison with pit latrines as a sewer does not only deal with excreta management like a UDDT does, but it also transports and treats greywater, municipal wastewater, stormwater and industrial wastewater. Obviously the installation of UDDTs in all households of a catchment would lead to reduced quantities of water, nutrients and organic matter arriving at the wastewater treatment plant.

Sewer-based excreta management is in any case impractical in many regions due to limited water supplies and the high cost of sewer systems and wastewater treatment plants.[1] Furthermore, water-based sanitation systems (flush toilets) dilute excreta and create larger wastewater streams which UDDTs do not.

Decentralised sanitation systems which employ UDDTs offer the potential advantages of quick deployment (especially where there is no capable centralized institutional infrastructure in place or no financial ability to implement larger centralized systems) as well as greater local control. Such a sanitation system that uses UDDTs - and perhaps even aims at resource recovery in agriculture - differs however from a conventional sewer-based system in that it requires greater coordination and cooperation amongst different sectors.[2] Policies could encourage their development through: financial support of research programmes, enactment of regulations that require the recovery of resources from wastewater and adequately account for the reduced contaminant loading and incentives for resource recovery.[2]

Pharmaceutical residues

The separate, waterless collection of urine and faeces in UDDTs would prevent hormones and pharmaceutical residues (micro-pollutants which are contained in human excreta) entering drinking water sources via household wastewater (sewage), as such substances are not fully removed in conventional wastewater treatment plants.[3] With sewer-based sanitation systems, the micro-pollutants hormones and pharmaceutical residues are not removed in conventional sewage treatment plants and are thus discharged into surface water bodies and can even reach the groundwater (detected concentrations of pharmaceutial residues in groundwater are in the order of 50 ng/L in several locations in Germany).[3] If the excreta from UDDTs is treated further and then used as fertiliser then the pharmaceutical residues in the excreta will be degraded better in the soil because "Terrestial systems (soil) are more suitable for natural degradation of pharmaceuticals than aquatic systems."[3] Therefore, UDDTs (or in fact all urine diversion systems) have a certain advantage over sewer-based sanitation systems in this respect.

Costs

UDDTs have been criticised for being too expensive compared to pit latrines. However, rather than looking only at the construction cost, the whole of life cost (or life-cycle cost) should be considered, as the regular emptying or re-building of pit latrines may add a significant expense to the households in the longer term.[4] When a period of for example 10 years is considered in the analysis, UDDTs may well be the more economical alternative as emptying the faeces vaults is very simple and therefore low cost, even if the households decide to user an external service provider for this activity (if such a service provider exists already).

Compared to flush toilets connected to sewer systems and wastewater treatment plants, UDDTs are often thought to be cheaper. However, this needs to be assessed on a case-by-case basis because the two systems provide a different level of service (the sewer system also treats greywater whereas the UDDT does not); an example calculation exists for the case of Lima, Peru.[5]

Reuse of treated excreta

Dried faecal matter from UDDTs after external composting, now ready for reuse (Addis Ababa, Ethiopia)

The World Health Organisation has issued in 2006 the “Guidelines for the safe use of wastewater, excreta and greywater in agriculture” containing guidelines for managing the health risks associated with the use of excreta, including excreta from UDDTs, in agriculture.[6] The key concept of these guidelines is the multiple barrier approach which can also be applied to reuse activities in connection with UDDTs.

The dried 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]

Urine from the UDDTs can safely be used as nitrogen-rich fertiliser after a recommended storage period for pathogen kill (or without storing if it is used in the garden or field of the same household where it was generated).[7] In cases where no reuse is possible or desired, urine is usually infiltrated in the soil unless this would cause groundwater pollution, for example with the UDDTs in eThekwini municipality in South Africa[8] or the UDDTs in Lima, Peru.

Design aspects

Bench design

UDDTs can also be built with a bench style user interface. This design has been standardised by the company Rotaria del Peru who have built by now 800 double vault bench UDDTs in and around Lima, Peru.[9] This type of toilet has a wide, spaceous bench or box, covering both faeces chambers, into which two urine diverstion toilet seats are integrated.

Users with disabilities can benefit from this kind of design as it is very sturdy (compared to the option of a chair or commode over a pit latrine). The wide bench provides space for an assistan if needed, and handrails can easily be fixed next to the toilet. This type of UDDT is accessible directly from the ground level and does not require access steps or ramps unlike conventional raised UDDTs.[10]

Source of UDDT components

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. Complete UDDT toilet solutions (with or without in-built electrical fans) made of plastic are also commercially available, see examples below.

History

Exchanging the faeces container for single vault UDDT at household in Addis Ababa, Ethiopia

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.[11]

Since the 1990s, modifications of this design such as addition of ventilation pipes to the faeces vault have been developed in many countries. Prefabricated 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.[1]

UDDTs have also been commercially produced in Sweden since the mid-1990s for example by the company Separett who have sold approximately 200,000 UDDTs between 1994 and 2010.[12] Such off-the shelf commercial products are now also available in Do-it-yourself shops and are used in locations where piped sewerage is not available, such as remote summer cottages in Sweden or for camping activities.

Examples

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 (this list does not include commercially sold units).[13]

Some examples are provided below:

  • The highest number of UDDTs in one area have been installed by the eThekwini Municipality in the non-sewered peri-urban areas of Durban, South Africa. To date, about 80,000 UDDTs are in operation in that area, serving about 500,000 residents (reuse of urine or excreta is not taking place).[8]
  • 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).[14]
  • The NGO SOIL in Haiti has built UDDTs and composting 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.[15] Their current design for households in Haiti is a small portable single vault unit made out of wood with a bucket for faeces collection.
  • For the boating community, it can also be an interesting alternative to convert from conventional nautical toilets that store waste in black water tanks, or immediate discharge overboard, to a UDDT. Such UDDTs for nautical use are for example marketed in the US under the names of Nature's Head and Air Head Toilet.[16]
  • 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 UDDTs available for example by the Swedish company Separett that allow feces to be collected and packed out.[17] 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.[18]
  • In Namibia, UDDTs are known under the name of Otji toilets.[19]
  • 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.[20]

References

  1. ^ a b c d e f g h i j 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. ^ a b c Flores, A. (2010). Towards sustainable sanitation: evaluating the sustainability of resource-oriented sanitation. PhD Thesis, University of Cambridge, UK
  3. ^ a b c von Münch, E., Winker, M. (2011). Technology review of urine diversion components - Overview on urine diversion components such as waterless urinals, urine diversion toilets, urine storage and reuse systems. Gesellschaft für Internationale Zusammenarbeit (GIZ) GmbH
  4. ^ McIntyre, P., Casella D., Fonseca, C. and Burr, P. Priceless! Uncovering the real costs of water and sanitation (PDF). The Hague: IRC. ISBN 978-90-6687-082-6.{{cite book}}: CS1 maint: multiple names: authors list (link)
  5. ^ Platzer, C., Hoffmann, H., Ticona, E. (2008). Alternatives to waterborne sanitation - a comparative study – limits and potentials. IRC Symposium: Sanitation for the urban poor - partnerships and governance, Delft, The Netherlands
  6. ^ WHO guidelines for the safe use of wastewater, excreta and greywater. Volume 4. Excreta and greywater use in agriculture. WHO, Geneva. ISBN 92 4 154685 9.
  7. ^ Richert, A., Gensch, R., Jönsson, H., Stenström, T., Dagerskog, L. (2010). Practical guidance on the use of urine in crop production. Stockholm Environment Institute (SEI), Sweden
  8. ^ a b Roma, E., Holzwarth, S., Buckley, C. (2011). Large-scale peri-urban and rural sanitation with UDDTs, eThekwini Municipality (Durban), South Africa - Case study of sustainable sanitation projects. Sustainable Sanitation Alliance (SuSanA)
  9. ^ "Video by AKUT on Sustainable Sanitation in Peru". October 2014. Retrieved October 2014. {{cite web}}: Check date values in: |accessdate= (help)
  10. ^ von Münch, E., Düring, I. (2011). Making sustainable sanitation inclusive for persons with disabilities - Factsheet. Deutsche Gesellschaft fuer Internationale Zusammenarbeit (GIZ) GmbH, Eschborn, Germany
  11. ^ Winblad, U., Simpson-Hebert, M. (2004). Ecological Sanitation - Revised and enlarged edition. Stockholm Environment Institute, Sweden
  12. ^ von Münch, E., Winker, M. (2011). Worldwide listing of suppliers for urine diversion pedestals/seats (for UDDTs or for UD flush toilets) - Appendix 3 of technology review of urine diversion components. Gesellschaft für Internationale Zusammenarbeit (GIZ) GmbH
  13. ^ GIZ (2012). Worldwide list of 324 documented ecosan projects by various organisations. Gesellschaft für internationale Zusammenarbeit (GIZ) GmbH, Eschborn, Germany
  14. ^ 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
  15. ^ Christine Dell'Amore, "Human Waste to Revive Haitian Farmland?", The National Geographic, October 26, 2011
  16. ^ http://forum.woodenboat.com/showthread.php?114077-Nature-s-Head-vs.-Air-Head-Toilet Wooden Boat Forum
  17. ^ http://www.flickr.com/photos/gtzecosan/2921708370/ Photo of Foldable camping UDD toilet by Separett (Sweden)
  18. ^ COMPUS Full Access dry toilet
  19. ^ 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
  20. ^ "UDDT case studies of the Sustainable Sanitation Alliance". Retrieved 19 October 2014.