ManShared=XX|
ManPublic=X|
Input1=Excreta|Input2=Faeces |Input3=Organics | Input4=Anal cleansing water| Input4= |Input5=Dry Cleansing Materials)|Output1=Compost - EcoHumusPit Humus| Output2= | Output3= | Output4= | Output5=
|english_link=Fossa_Alterna
|french_link=Latrine_à_fosses_alternées_(Fossa_Alterna)
[[Image:Icon_fossa_alterna.png |right|80px]]
'''The Fossa Alterna is an a short cycle alternating, waterless (dry) double pit technology. Compared to the [[Double Ventilated Improved Pit|Double VIP]] (S.4) which is just designed to collect, store and partially treat excreta, the Fossa Alterna is designed to make [[Sanitation Products#Compost an earth-like product that can be used as a nutrient- EcoHumus|EcoHumus]]rich soil conditioner. The Fossa Alterna is dug to a maximum depth of 1.5 m and requires a constant input of cover material (soil, ash, and/or leaves).'''
Two shallow pits are dug next Cover material should be added to each other the pit after defecation (0.5 1.5 metre deepnot urination). One of the Fossa Alterna pits should fill over The soil and leaves introduce a period variety of 12–24 months depending on the size of the pit organisms like worms, fungi and bacteria which help in the number of usersdegradation process. When a pit Also, the pore space is fullincreased, which allows for aerobic conditions. Additionally, ash helps to control flies, the concrete slab reduces odours and portable superstructure are placed on makes the second pitmix slightly more alkaline. The full pit degrades during the period of time that while the second pit is filling, which, ideally, should take one year. The material in the full pit will degrade into a dry, earth-like mixture that can be easily removed manually. Because of the added carbon-rich bulking material, the degradation process is accelerated, and the content is ready for excavation and use much faster than in a Double VIP.
[[Image:Fossa_alterna.PNG|thumb|right|200px|[[Fossa alterna |Fossa alterna]], in Epworth (for credits, click the picture)]]
Soil, ash, and/or leaves should be added to the ===Design Considerations=== A Fossa Alterna pit after defecation (not urination). The soil and leaves introduce would fill over a variety period of organisms like worms, fungi 12 to 24 months depending on its size and bacteria which help in the degradation processnumber of users. Also, Even though the pore space is increasedpits are shallow (1 to 1.5 m), which allows each of them can be used by a family of six for anaerobic conditionsone year. Additionally, The Fossa Alterna technology will only work properly if the ash helps to control fliestwo pits are used sequentially and not concurrently. Therefore, reduce odours and make an adequate cover for the mix slightly more alkalineout of service pit is required.
The Fossa Alterna should be used for urine, but water should not be added (small amounts of anal cleansing water can be tolerated). Water encourages the development of vectors and pathogens , but it also fills the porespaces pore spaces and deprives the aerobic bacteria of the oxygen that is required for degradation. The choice of User Interface will determine the material that enters the pitA UDDT (U. Since bulking material is 2) can be used to continuously cover with the excretaFossa Alterna, smells are reduced but only in circumstances when the addition of a ventilation pipe can reduce soil cannot sufficiently absorb the urine or when the smells even furtherurine is highly valued for application.
The Fossa Alterna pits are relatively shallow with a depth of 1.5m. Even though Since cover material is used to continuously cover the pits excreta, smells are shallow, this should be more than enough space to accommodate a family of 6 for one yearreduced. To optimize reduce the spacesmells even further, the material that mounds in the centre of the pit (underneath the toilet) should a ventilation pipe can be pushed to added. In flood-prone areas and where the sides periodically. Unlike a simple or ventilated pit which will be covered or emptiedgroundwater table is too high, the material in the Fossa Alterna is meant could be raised or built entirely above ground to be reused. Therefore, it is extremely important that no garbage is put into the pit as it will reduce the quality of the material recovered, avoid water intrusion and may even make it unusablegroundwater pollution. After composting, Raising the content of the first pit can pits could also be used as fertiliser. The best compost time is more than 12 months. The material can be excavated earlier at 6 months, but is best transferred at this stage an option for rocky ground and compacted soils that are difficult to a pit in which a tree will be planteddig. Emptying the Fossa Alterna If space is easier than abundant and emptying other pits: not desired, the pits are shallower [[Fill and the addition of soil means that the material is less compactCover - Arborloo | Arborloo]] (D.1) can be an alternative Disposal option. The material that is removed is Pits should not offensive and presents a reduced threat of contaminationbe lined if used as an Arborloo.
{{procontable | pro=
- Can be built and repaired with locally available materials. <br> - Because double pits are used alternately, their life is virtually unlimited. <br> - Excavation of humus is easier than faecal sludge <br> - Significant reduction in pathogens <br> - Generates nutrient- Potential rich humus with good potential for use of stored faecal material as soil conditioner. <br> - Flies and odours are significantly reduced (compared to non-ventilated pits). <br> - Does not require a constant source of water. <br> -Shallow depth of pit required Can be built and repaired with locally available materials <br>- Suitable for all types of user (sitters, squatters, washers and wipers). <br> - Low (but variable) capital costs depending on materials; no or low operating costs if self-emptied. <br> - Small land area required. <br> - Significant reduction in pathogens. | con=- Requires constant source of cover material (soil, ash, leaves, etc.) <br> - Manual removal of humus is required<br>- Garbage thrown in the pit may ruin reuse end-use opportunities of Compost/EcoHumus. the product
}}
===AdequacyAppropriateness=== The Fossa Alterna is appropriate for rural and peri-urban areas. It is especially suitable to water-scarce environments. It is a useful solution for areas that have poor soil and could benefit from the use of the stabilized humic material as a soil amendment. The Fossa Alterna is not appropriate for greywater as the pit is shallow and the conditions must remain aerobic for degradation. The material is manually emptied from the Fossa Alterna (it is dug out, not pumped out); thus, vacuum truck access to the pits is not necessary.
The Fossa Alterna is appropriate not suited for rural and peri-urban areas. It is especially adapted rocky or compacted soils (that are difficult to waterscarce environments. It is a useful solution dig) or for areas that have poor soil and could benefit from flood frequently, except if the composted humic material as a soil amendment. A constant source of soil, ash and/or leaves is requiredpits are raised.
Not applicable in areas ===Health Aspects/Acceptance=== By covering faeces with a high water tablesoil, with very loose soil (which could collapse)ash, and/or very solid soil which would prevent drainageleaves, flies and odours are kept to a minimum. In order to prevent water tables penetrating Users may not understand the difference between the pits Fossa Alterna and contaminating a Double VIP, although if given the wateropportunity to use one, pits people should be shallow. The conversion have a good appreciation of excreta into humus will not take place if the pit is flooded with wateradvantages. Therefore, the pit should not Demonstration units can be sealed and water used for anal cleaning should not enter the to show how easily one can empty a Fossa Alterna in comparison to emptying a double pit.
The Fossa Alterna is not appropriate Keeping the contents sealed in the pit for greywater as the pit is shallow duration of at least one year makes the material safer and the conditions must remain aerobic for degradationeasier to handle. Another greywater treatment system must be used in parallel. A [[Urine Diverting Dry Toilet]] can The same precautions that are taken when handling compost should be used taken with the humus derived from the Fossa Alterna, but only in circumstances when the soil cannot sufficiently absorb the urine or when urine is highly valued for application.
The material is manually emptied from ===Operation & Maintenance=== When the Fossa Alterna (it first pit is dug output into use, not pumped out)a layer of leaves should be put onto the bottom of the pit. Periodically, so vacuum truck access more leaves should be added to increase the pits is not necessaryporosity and oxygen availability. The Fossa Alterna technology will only work properly if Following the two pits are used sequentially addition of faeces to the pit, a small amount of soil, ash, and not concurrently/or leaves should be added. ThereforeOccasionally, an adequate cover for the out mounded material beneath the toilet hole should be pushed to the sides of service the pit is required. The Fossa Alterna is especially appropriate when water is scarce. It is not suited for rocky or compacted soils (that are difficult in order to dig) or for areas that flood frequentlyoptimise the use of space.
As with many sanitation systemsUnlike a [[Single Pit | Single]] or [[Single Ventilated Improved Pit | Ventilated]] Pit (S.2, household members need S.3) which will be covered or emptied, the material in the Fossa Alterna is meant to understand be used as a soil conditioner. Therefore, it is extremely important that no garbage is put into the key principles for efficient operation pit. Emptying the Fossa Alterna is easier than emptying other pits; the pits are shallower and maintenance the addition of soil, ash, and discipline /or leaves means that the contents are less compact. The material that is removed is required for adding soil after each defecationnot offensive and presents a reduced threat of contamination.
===Health Aspects/Acceptance=== By covering faeces with soil/ash, flies and odours are kept to a minimum. Users may not understand the difference between the Fossa Alterna and a [[Double Ventilated Improved Pit|Double VIP]], although if given the opportunity to use one, people should have a good appreciation of the advantages. Demonstration units can be used to show how easily one can empty a Fossa Alterna in comparison to emptying a Double Pit. Keeping the contents sealed in the pit for the duration of at least one year makes the material safer and easy to handle. The same precautions that are taken when handling compost should be taken with the humus derived from the Fossa Alterna. ===Maintenance=== When the first pit is put into use, a layer of leaves should be put into the bottom of the pit. Periodically, more leaves should be added to increase the porosity and oxygen availability. Following the addition of faeces to the pit, a small amount of soil or ash should be added. To lengthen the filling time of the pit soil is not added to the pit following urination. Occasionally, the mounded material beneath the toilet hole should be pushed to the sides of the pit for an even distribution of materials. Depending on the dimensions of the pits, materials the contents should not be emptied every more often than once a year.
===Field experiences===
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===Manuals, videos, and links===
This [http://www.bvsde.paho.org/bvsacd/cd66/ToiletsCompost/cap4.pdf document] contains a lot of information about building, maintaining a fossa alterna.
===References and external links===
* Morgan, P. R. (2007) [http://www.ecosanres.org Toilets That Make Compost: . Low-costCost, sanitary toilets that produce valuable compost Sanitary Toilets That Produce Valuable Compost for crops Crops in an African contextContext. Stockholm Environment Institute, Stockholm, SE.:Available at: [http://www.ecosanres.org ecosanres.org] * Morgan, P. R. (2009). Ecological Toilets. Start Simple and Upgrade from Arborloo to VIP. Stockholm Environment Institute, SwedenStockholm, SE. Step-by-step guide for building a Fossa Alterna:Available at: [http://www.ecosanres.org ecosanres.org]
===Acknowledgements===
{{:Acknowledgements Sanitation}}