S.9 Double Vault UDDT (Urine Diversion Dry Toilet)

Double Vault UDDTs operate without water. Urine and faeces are diverted using a Urine Diverting Dry Toilet (U.2) and are collected separately. While urine goes into a container (or is drained away), faeces are collected in vaults underneath, where they are stored and dried. Alternating vaults allow for prolonged storage and thereby treatment of collected faeces in the unused vault.Refers to (semi-solid) excrement that is not mixed with urine or water. Depending on diet, each person produces approximately 50–150 L per year of faecal matter of which about 80 % is water and the remaining solid fraction is mostly composed of organic material. Of the total essential plant nutrients excreted by the human body, faeces contain around 39 % of the phosphorus (P), 26 % of the potassium (K) and 12 % of the nitrogen (N). Faeces also contain the vast majority of the pathogens excreted by the body, as well as energy and carbon rich, fibrous material.The liquid produced by the body to rid itself of nitrogen in the form of urea and other waste products. In this context, the urine product refers to pure urine that is not mixed with faeces or water. Depending on diet, human urine collected from one person during one year (approx. 300 to 550 L) contains 2 to 4 kg of nitrogen. The urine of healthy individuals is sterile when it leaves the body but is often immediately contaminated by coming into contact with faeces.Any substance that is used for growth. Nitrogen (N), phosphorus (P) and potassium (K) are the main nutrients contained in agricultural fertilisers. N and P are also primarily responsible for the eutrophication of water bodies.
An organism or other agent that causes disease.The organic molecule (NH2)2CO that is excreted in urine and that contains the nutrient nitrogen. Over time, urea breaks down into carbon dioxide and ammonium, which is readily used by organisms in soil. It can also be used for on-site faecal sludge treatment. See. S.18

When faeces are not mixed with urine and other liquids, they dry quickly. In absence of moisture, pathogens are destroyed and smell minimised. Use of alternating vaults allow faeces to dehydrate in one vault while the other fills. When one vault is full, the urine-diverting device is moved to the second vault. While the second vault fills up, faeces in the first vault dry and decrease in volume. When the second vault is full, the first one is emptied and put back into service. To encourage drying, a small amount of ash, lime, dry soil or sawdust is used to cover faeces after each use.

Refers to (semi-solid) excrement that is not mixed with urine or water. Depending on diet, each person produces approximately 50–150 L per year of faecal matter of which about 80 % is water and the remaining solid fraction is mostly composed of organic material. Of the total essential plant nutrients excreted by the human body, faeces contain around 39 % of the phosphorus (P), 26 % of the potassium (K) and 12 % of the nitrogen (N). Faeces also contain the vast majority of the pathogens excreted by the body, as well as energy and carbon rich, fibrous material.The liquid produced by the body to rid itself of nitrogen in the form of urea and other waste products. In this context, the urine product refers to pure urine that is not mixed with faeces or water. Depending on diet, human urine collected from one person during one year (approx. 300 to 550 L) contains 2 to 4 kg of nitrogen. The urine of healthy individuals is sterile when it leaves the body but is often immediately contaminated by coming into contact with faeces.The common name for calcium oxide (quicklime, CaO) or calcium hydroxide (slaked or hydrated lime, Ca(OH)2). It is a white, caustic and alkaline powder produced by heating limestone. Slaked lime is less caustic than quicklime and is widely used in water/wastewater treatment and construction (for mortars and plasters). It can also be used for on-site treatment of faecal sludge. See S.17Any substance that is used for growth. Nitrogen (N), phosphorus (P) and potassium (K) are the main nutrients contained in agricultural fertilisers. N and P are also primarily responsible for the eutrophication of water bodies.
An organism or other agent that causes disease.The organic molecule (NH2)2CO that is excreted in urine and that contains the nutrient nitrogen. Over time, urea breaks down into carbon dioxide and ammonium, which is readily used by organisms in soil. It can also be used for on-site faecal sludge treatment. See. S.18Used water from any combination of domestic, industrial, commercial or agricultural activities, surface runoff/stormwater, and any sewer inflow/infiltration.

Design Considerations

The vault size must be chosen according to anticipated number of users (around 100 L/person/ year) and to allow for a storage time between 6–24 months. WHO recommends a minimum storage period of 6 months if ash or lime are used as cover material (alkaline treatment), otherwise storage should be for at least 1 year for warm climates and 1.5 to 2 years for colder climates. Vault dimensions should account for cover material, airflow and non-even distribution of faeces. Urine piping should not go directly through vaults to avoid potential leaking. A vent pipe is required to remove humidity from vaults and control flies and odours. Water from the handwashing facility and anal cleansing water (if applicable) must be drained separately D.10 . If dry anal cleansing material is used a separate trash bin should be provided. Connection pipes should be as short as possible without sharp bends and installed with > 1 % slope. An odour seal should be installed at the urine drain.

Water used to cleanse the body after defecating and/or urinating; it is generated by those who use water, rather than dry material, for anal cleansing. The volume of water used per cleaning typically ranges from 0.5–3 litres (but can be more in developed urban areas).Refers to (semi-solid) excrement that is not mixed with urine or water. Depending on diet, each person produces approximately 50–150 L per year of faecal matter of which about 80 % is water and the remaining solid fraction is mostly composed of organic material. Of the total essential plant nutrients excreted by the human body, faeces contain around 39 % of the phosphorus (P), 26 % of the potassium (K) and 12 % of the nitrogen (N). Faeces also contain the vast majority of the pathogens excreted by the body, as well as energy and carbon rich, fibrous material.The liquid produced by the body to rid itself of nitrogen in the form of urea and other waste products. In this context, the urine product refers to pure urine that is not mixed with faeces or water. Depending on diet, human urine collected from one person during one year (approx. 300 to 550 L) contains 2 to 4 kg of nitrogen. The urine of healthy individuals is sterile when it leaves the body but is often immediately contaminated by coming into contact with faeces.The common name for calcium oxide (quicklime, CaO) or calcium hydroxide (slaked or hydrated lime, Ca(OH)2). It is a white, caustic and alkaline powder produced by heating limestone. Slaked lime is less caustic than quicklime and is widely used in water/wastewater treatment and construction (for mortars and plasters). It can also be used for on-site treatment of faecal sludge. See S.17Any substance that is used for growth. Nitrogen (N), phosphorus (P) and potassium (K) are the main nutrients contained in agricultural fertilisers. N and P are also primarily responsible for the eutrophication of water bodies.
An organism or other agent that causes disease.The organic molecule (NH2)2CO that is excreted in urine and that contains the nutrient nitrogen. Over time, urea breaks down into carbon dioxide and ammonium, which is readily used by organisms in soil. It can also be used for on-site faecal sludge treatment. See. S.18Used water from any combination of domestic, industrial, commercial or agricultural activities, surface runoff/stormwater, and any sewer inflow/infiltration.

Materials

Double Vault UDDTs can be constructed with materials such as bamboo, wood, concrete, corrugated iron and bricks. Potential cover/drying material that can be used include ash, lime, sawdust, dried soil or dried agricultural waste products. Urine diversion toilet seats or squatting pans can be obtained or produced locally. Vaults should be made of sealed brickwork or concrete to ensure surface runoff cannot enter.

The common name for calcium oxide (quicklime, CaO) or calcium hydroxide (slaked or hydrated lime, Ca(OH)2). It is a white, caustic and alkaline powder produced by heating limestone. Slaked lime is less caustic than quicklime and is widely used in water/wastewater treatment and construction (for mortars and plasters). It can also be used for on-site treatment of faecal sludge. See S.17The portion of precipitation that does not infiltrate the ground and runs
overland.
User interface used for urination and defecation. Used water from any combination of domestic, industrial, commercial or agricultural activities, surface runoff/stormwater, and any sewer inflow/infiltration.

Applicability

Double Vault UDDTs can be considered an appropriate solution in the stabilisation and recovery phases, provided the technology is acceptable to the users and space is available. If used in urban contexts, they rely on a transport service since urban users usually do not have an interest and/or opportunity to use (or dispose of) urine and dried faeces locally. They are appropriate for water-scarce, rocky, high groundwater or frequently flooded areas. In flood-prone areas special care should be taken to ensure that vaults are watertight. UDDTs might not be appropriate in the acute response due to time needed to educate and train users and to construct. The design can be adjusted to the needs of specific target groups and cultural settings, e.g. smaller for children, sitting/squatting. Depending on context and acceptability collected resources can be used as fertilizer and soil conditioner in agriculture.

Refers to (semi-solid) excrement that is not mixed with urine or water. Depending on diet, each person produces approximately 50–150 L per year of faecal matter of which about 80 % is water and the remaining solid fraction is mostly composed of organic material. Of the total essential plant nutrients excreted by the human body, faeces contain around 39 % of the phosphorus (P), 26 % of the potassium (K) and 12 % of the nitrogen (N). Faeces also contain the vast majority of the pathogens excreted by the body, as well as energy and carbon rich, fibrous material.The liquid produced by the body to rid itself of nitrogen in the form of urea and other waste products. In this context, the urine product refers to pure urine that is not mixed with faeces or water. Depending on diet, human urine collected from one person during one year (approx. 300 to 550 L) contains 2 to 4 kg of nitrogen. The urine of healthy individuals is sterile when it leaves the body but is often immediately contaminated by coming into contact with faeces.Water that is located beneath the earth’s surface.
Any substance that is used for growth. Nitrogen (N), phosphorus (P) and potassium (K) are the main nutrients contained in agricultural fertilisers. N and P are also primarily responsible for the eutrophication of water bodies.
An organism or other agent that causes disease.A product that enhances the water and nutrient retaining properties of soil.
The degradation of organic matter with the goal of reducing readily biodegradable compounds to lessen environmental impacts (e.g., oxygen depletion, nutrient leaching).
The organic molecule (NH2)2CO that is excreted in urine and that contains the nutrient nitrogen. Over time, urea breaks down into carbon dioxide and ammonium, which is readily used by organisms in soil. It can also be used for on-site faecal sludge treatment. See. S.18

Operation and Maintenance

Key operation and maintenance tasks include regular emptying and replacing of urine collection containers (if urine is not drained away), cleaning, checking availability of hygiene items, water and dry cleansing materials, conducting minor repairs and advising on proper use. Ample supply of cover material must be secured. Accumulated faeces beneath the toilet should occasionally be pushed to the sides of the chamber. Water or urine should not get into the dehydration vault. If it happens, extra drying material can be added to help absorb the liquid. For vault emptying, personal protective equipment should be used to avoid contact with dried faeces.

Refers to (semi-solid) excrement that is not mixed with urine or water. Depending on diet, each person produces approximately 50–150 L per year of faecal matter of which about 80 % is water and the remaining solid fraction is mostly composed of organic material. Of the total essential plant nutrients excreted by the human body, faeces contain around 39 % of the phosphorus (P), 26 % of the potassium (K) and 12 % of the nitrogen (N). Faeces also contain the vast majority of the pathogens excreted by the body, as well as energy and carbon rich, fibrous material.The liquid produced by the body to rid itself of nitrogen in the form of urea and other waste products. In this context, the urine product refers to pure urine that is not mixed with faeces or water. Depending on diet, human urine collected from one person during one year (approx. 300 to 550 L) contains 2 to 4 kg of nitrogen. The urine of healthy individuals is sterile when it leaves the body but is often immediately contaminated by coming into contact with faeces.Any substance that is used for growth. Nitrogen (N), phosphorus (P) and potassium (K) are the main nutrients contained in agricultural fertilisers. N and P are also primarily responsible for the eutrophication of water bodies.
An organism or other agent that causes disease.User interface used for urination and defecation. The organic molecule (NH2)2CO that is excreted in urine and that contains the nutrient nitrogen. Over time, urea breaks down into carbon dioxide and ammonium, which is readily used by organisms in soil. It can also be used for on-site faecal sludge treatment. See. S.18

Health and Safety

If used and managed well, Double Vault UDDTs are a safe excreta containment and treatment technology. They need to be equipped with Handwashing Facilities U.7 and proper handwashing with soap after toilet use needs to be addressed as part of hygiene promotion activities X.12. Users need to be trained to understand how the technology works and appreciate its benefits. Although human urine can generally be considered pathogen-free, there is a remaining risk of urine cross-contamination (faecal material entering urine compartment). It is therefore recommended to store urine for 1–6 months (depending on system size) prior to any potential use as liquid fertiliser in agriculture D.1 to allow for respective treatment. When vaults are kept dry, problems with flies or odours are low. As a result of faeces drying there is a significant pathogen reduction. After recommended storage time (6–24 months), faeces should be safe to handle. However, some pathogens (e.g. Ascaris) might remain viable even after longer storage intervals. If reuse is foreseen, e.g. as soil conditioner for use with ornamental plants, trees, or low-risk crops D.2 , it is recommended that dried faeces should undergo secondary treatment (e.g. T.11 or T.12 ). If reuse is not intended dried faeces can be safely buried or brought to a final disposal site.

Decomposed organic matter that results from a controlled aerobic degradation process. In this biological process, microorganisms (mainly bacteria and fungi) decompose the biodegradable waste components and produce an earth-like, odourless, brown/black material. Compost has excellent soil-conditioning properties and a variable nutrient content. Because of leaching and volatilisation, some of the nutrients may be lost, but the material remains rich in nutrients and organic matter. Generally, excreta or sludge should be composted long enough (2 to 4 months) under thermophilic conditions (55 to 60 °C) in order to be sanitised sufficiently for safe agricultural use.Consists of urine and faeces that are not mixed with any flushwater. Excreta is relatively small in volume, but concentrated in both nutrients and pathogens. Depending on the characteristics of the faeces and the urine content, it can have a soft or runny consistency.Refers to (semi-solid) excrement that is not mixed with urine or water. Depending on diet, each person produces approximately 50–150 L per year of faecal matter of which about 80 % is water and the remaining solid fraction is mostly composed of organic material. Of the total essential plant nutrients excreted by the human body, faeces contain around 39 % of the phosphorus (P), 26 % of the potassium (K) and 12 % of the nitrogen (N). Faeces also contain the vast majority of the pathogens excreted by the body, as well as energy and carbon rich, fibrous material.Mixture of solids and liquids, containing mostly excreta and water, in combination with sand, grit, metals, trash and/or various chemical compounds. A distinction can be made between faecal sludge and wastewater sludge. Faecal sludge comes from on-site sanitation technologies, i.e. it has not been transported through a sewer. It can be raw or partially digested, a slurry or semisolid, and results from the collection and storage/treatment of excreta or blackwater, with or without greywater. Wastewater sludge (also referred to as sewage sludge) originates from sewer-based wastewater collection and (semi-)centralised treatment processes. The sludge composition will determine the type of treatment that is required and the end-use possibilities.The liquid produced by the body to rid itself of nitrogen in the form of urea and other waste products. In this context, the urine product refers to pure urine that is not mixed with faeces or water. Depending on diet, human urine collected from one person during one year (approx. 300 to 550 L) contains 2 to 4 kg of nitrogen. The urine of healthy individuals is sterile when it leaves the body but is often immediately contaminated by coming into contact with faeces.Describes technologies for on-site collection, storage, and sometimes (pre-) treatment of the products generated at the user interface. The treatment provided by these technologies is often a function of storage and is usually passive (i.e. requires no energy input), except a few emerging technologies where additives are needed. Thus, products that are ‘treated’ by these technologies often require subsequent treatment before use and/or disposal. In the technology overview graphic, this functional group is subdivided into the two subgroups: “Collection/Storage” and “(Pre-)Treatment”. This allows a further classification for each of the listed technologies with regard to their function: collection and storage, (pre-) treatment only or both.Refers to the methods through which products are returned to the environment, either as useful resources or reduced-risk materials. Some products can also be cycled back into a system (e.g. by using treated greywater for flushing).A functional group is a grouping of technologies that have similar functions. The compendium proposes five different functional groups from which technologies can be chosen to build a sanitation system:
User interface (U), Collection and Storage/Treatment (S), Conveyance (C), (Semi-) Centralised Treatment (T), Use and/or Disposal (U).
A sanitation system is a multi-step process in which sanitation products such as human excreta and wastewater are managed from the point of generation to the point of use or ultimate disposal. It is a context-specific series of technologies and services for the management of these sanitation products, i.e. for their collection, containment, transport, treatment, transformation, use or disposal. A sanitation system comprises functional groups of technologies that can be selected according to context. By selecting technologies from each applicable functional group, considering the incoming and outgoing products, and the suitability of the technologies in a particular context, a logical, modular sanitation system can be designed. A sanitation system also includes the management and operation and maintenance (O & M) required to ensure that the system functions safely and sustainably. Simple, single cell organisms that are found everywhere on earth. They are essential for maintaining life and performing essential “services”, such as composting, aerobic degradation
of waste, and digesting food in our intestines. Some types, however, can be pathogenic and cause mild to severe illnesses. Bacteria obtain nutrients from their environment by excreting enzymes that dissolve complex molecules into more simple ones which can then pass through the cell membrane.

The process by which biodegradable components are biologically decomposed by microorganisms (mainly bacteria and fungi) under controlled aerobic conditions.
The utilisation of products derived from a sanitation system.
A mechanical separation process using a porous medium (e.g., cloth, paper, sand bed, or mixed media bed) that captures particulate material and permits the liquid or gaseous fraction to pass through. The size of the pores of the medium determines what is captured and what passes through.Any cellular or non-cellular microbiological entity capable of replication or of transferring genetic material (e.g. bacteria, viruses, protozoa, algae or fungi).
Any substance that is used for growth. Nitrogen (N), phosphorus (P) and potassium (K) are the main nutrients contained in agricultural fertilisers. N and P are also primarily responsible for the eutrophication of water bodies.
A sanitation system in which excreta and wastewater are collected and stored or treated on the plot where they are generated.
An organism or other agent that causes disease.A diverse group of unicellular eukaryotic organisms, including amoeba, ciliates, and flagellates. Some can be pathogenic and cause mild to severe illnesses.
Use of recycled water or other sanitation products.
The means of safely collecting and hygienically disposing of excreta and liquid
wastes for the protection of public health and the preservation of the quality of public water bodies and, more generally, of the environment.

Follows primary treatment to achieve the removal of biodegradable organic matter and suspended solids from effluent. Nutrient removal (e.g., phosphorus) and disinfection can be included in the definition of secondary treatment or tertiary treatment, depending on the configuration.
Waste matter that is transported through the sewer.
An open channel or closed pipe used to convey sewage. See C.3 and C.4
A product that enhances the water and nutrient retaining properties of soil.
Follows secondary treatment to achieve enhanced removal of pollutants from effluent. Nutrient removal (e.g., phosphorus) and disinfection can be included in the definition of secondary treatment or tertiary treatment, depending on the configuration. See POST
User interface used for urination and defecation. The organic molecule (NH2)2CO that is excreted in urine and that contains the nutrient nitrogen. Over time, urea breaks down into carbon dioxide and ammonium, which is readily used by organisms in soil. It can also be used for on-site faecal sludge treatment. See. S.18An infectious agent consisting of a nucleic acid (DNA or RNA) and a protein coat. Viruses can only replicate in the cells of a living host. Some pathogenic viruses are known to be waterborne (e.g., the rotavirus that can cause diarrheal disease).
Used water from any combination of domestic, industrial, commercial or agricultural activities, surface runoff/stormwater, and any sewer inflow/infiltration.

Costs

The capital costs for constructing a Double Vault UDDT may vary depending on availability and costs of local materials and prefabricated slabs/ toilet seats but are generally low to moderate. The operating costs are very low if self-managed.

Funds spent for the acquisition of a fixed asset, such as sanitation infrastructure.
The means of safely collecting and hygienically disposing of excreta and liquid
wastes for the protection of public health and the preservation of the quality of public water bodies and, more generally, of the environment.

User interface used for urination and defecation.

Social Considerations

The technology should be discussed with the community beforehand as the use of a urine diversion facility might have considerable acceptability and behavior change implications. Training might be needed to support acceptance, ensure proper use and maintenance and to avoid accidental misuse. It should reflect local user preferences ( sitter vs. squatter, anal cleansing practices, direction, positioning etc.) and should account for the accessibility and safety of all users, including men, women, children, elderly and disabled people X.10. If reuse is not intended and soil conditions allow, urine can be drained away in a Soak Pit D.10 . This avoids regular urine management and might increase acceptance

The liquid produced by the body to rid itself of nitrogen in the form of urea and other waste products. In this context, the urine product refers to pure urine that is not mixed with faeces or water. Depending on diet, human urine collected from one person during one year (approx. 300 to 550 L) contains 2 to 4 kg of nitrogen. The urine of healthy individuals is sterile when it leaves the body but is often immediately contaminated by coming into contact with faeces.Use of recycled water or other sanitation products.
The means of safely collecting and hygienically disposing of excreta and liquid
wastes for the protection of public health and the preservation of the quality of public water bodies and, more generally, of the environment.

A person who prefers to sit on the toilet.A person who prefers to squat over the toilet.
User interface used for urination and defecation. The organic molecule (NH2)2CO that is excreted in urine and that contains the nutrient nitrogen. Over time, urea breaks down into carbon dioxide and ammonium, which is readily used by organisms in soil. It can also be used for on-site faecal sludge treatment. See. S.18

Fact Sheet Overview

Input Products

Faeces
Urine

Output Products

Dried Faeces
Stored Urine

Emergency Phase

Stabilisation + +
Recovery + +

Challenging Ground Conditions

Suitable

Application Level / Scale

Household + +
Neighbourhood + +

Water-based and Dry Technologies

Dry

Management Level

Household + +
Shared + +
Public +

Technical Complexity

Space Required

Objectives & Key Features

• Excreta containment
• Alternative for challenging ground conditions
• Pathogen removal and nutrient recovery

Strength & Weakness

  • Long lifespan and low/no operating costs if self- emptied
  • Requires water only for handwashing and possibly anal cleansing
  • Significant pathogen reduction
  • Potential use of urine and faeces as fertilizer and soil conditioner
  • Requires training and acceptance
  • Requires constant source of cover material
  • Manual removal of dried faeces required
  • Capacity limited by vault size
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