Difference between revisions of "Waterless System with Urine Diversion"

Revision as of 11:37, 4 March 2009

This system is designed to separate Urine and Faeces to allow Faeces to dehydrate and/or recover the Urine for beneficial use. This system can be used anywhere, but it is especially appropriate for rocky areas where digging is difficult, where there is a high groundwater table, or in water-scarce regions.

The inputs to the system can include Faeces, Urine, Anal Cleansing Water and Dry Cleansing Materials.

There are two User Interface Technologies for this system; a Urine Diverting Dry Toilet (UDDT) or a Urinal. UDDTs with a third diversion for Anal Cleansing Water are not common, but can be manufactured locally or ordered depending on local washing customs. Dry cleansing materials will not harm the system, but they should be collected separately from the UDDT and directly transferred for Surface Disposal.

Double Dehydration Vaults are used for the Collection and Storage/Treatment Technology for Faeces. Anal Cleansing Water should never be put into Dehydration Vaults, but it can be diverted and put into a Soak Pit. When storing the Faeces in chambers, they should be kept as dry as possible to encourage dehydration and hygienization. Therefore, the chambers should be watertight and care should be taken to ensure that no water is introduced during cleaning.

Also important is a constant supply of ash, lime, or dry earth to cover the Faeces to minimize odours and provide a barrier between the Faeces and potential vectors (flies). The pH increase will also help to kill organisms. A separate Greywater system is required since it should not be introduced into the Dehydration Vaults and preferably not into the pits.

Urine can be disposed of easily and without risk to the environment because it is generated in relatively small volumes and is nearly sterile. The Urine can be diverted directly to the ground for Use and/or Disposal as Land Application, Irrigation or soil infiltration through a Soak Pit. Storage Tanks can be used for the Collection Storage/Treatment of Urine.

The Dried Faeces that are generated from the Collection and Storage/Treatment Technology can be removed and transported for Use and/or Disposal. The Conveyance Technology that can be used is Human Powered E&T. The Dried Faeces pose little human health risk. Stored Urine can be transported for Use and/ or Disposal using either the Jerrycan or Motorized E&T Technologies.

Guidelines for the safe use of Excreta, Faecal Sludge and Urine have been published by the World Health Organization (WHO) and are referenced on the relevant Technology Information Sheets.

Considerations

The success of this system depends on the efficient separation of urine and faeces as well as the use of a suitable drying agent; a dry, hot climate can also contribute considerably to the rapid dehydration of the faeces. The system can be used regardless of the users’ acceptance to Urine use; it can be adapted to suit the agricultural and cultural needs of the users.

All types of solid cleansing materials can be used, although they should be discarded separately. Anal Cleansing Water must be separated from the Faeces although it can be mixed with the Urine before it is transferred to the Soak Pit (not shown in the System Template). If Urine is used in agriculture, Anal Cleansing Water should be kept separate and treated along with Greywater.

References

• Elizabeth Tilley et.al (2008). Compendium of Sanitation Systems and Technologies (low res version). Department of Water and Sanitation in Development Countries (Sandec) at the Swiss Federal Institute of Aquatic Science and Technology (Eawag). (Provides a full overview of sanitation systems.)