<!{|style="float: left;"|{{Language-- table at top of page with logo, picture, Application level, Management level, and input-output tables -->box|english_link=Fossa_Alterna|french_link=Latrine_à_fosses_alternées_(Fossa_Alterna)|spanish_link=Fossa Alterna (Español)|hindi_link=coming soon|malayalam_link=coming soon|tamil_link=coming soon | korean_link=coming soon | chinese_link=Coming soon | indonesian_link=Coming soon | japanese_link=Coming soon}}|}{|width="100%"|style="width:50%;"|{{santablesantable_new|
sys1=[[Waterless System with Alternating Pits|2]] |
sys2=|
sys7=|
sys8=|
sys9=|
pic=Fossa_alterna.png|
ApplHousehold=XX|
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=
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|[[Image:Fossa_alterna.png |right|500px]]
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[[Image:Icon_fossa_alterna.png |right|95px80px]]'''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 is fullAlso, the concrete slab and portable superstructure are placed on the second pit. The full pit degrades during the period of time that the second pit pore space is fillingincreased, whichallows for aerobic conditions. Additionally, ideallyash helps to control flies, should take one year. The material in reduces odours and makes the full pit will degrade into a dry, earth-like mixture that can be easily removed manuallymix slightly more alkaline.
[[Image:Fossa_alternaThe full pit degrades while the second pit is filling, which, ideally, should take one year.PNG|thumb|right|150px|[[Fossa alterna |Fossa alterna]]The material in the full pit will degrade into a dry, in Epworth (for creditsearth-like mixture that can be easily removed manually. Because of the added carbon-rich bulking material, the degradation process is accelerated, click and the picture)]]content is ready for excavation and use much faster than in a Double VIP.
Soil, ash, and/or leaves should be added to the pit after defecation (not urination)[[Image:Fossa_alterna. The soil and leaves introduce a variety of organisms like wormsPNG|thumb|right|200px|[[Fossa alterna |Fossa alterna]], fungi and bacteria which help in the degradation process. Also, the pore space is increased, which allows Epworth (for anaerobic conditions. Additionallycredits, click the ash helps to control flies, reduce odours and make the mix slightly more alkaline.picture)]]
The ===Design Considerations=== A Fossa Alterna should be used for urinepit would fill over a period of 12 to 24 months depending on its size and the number of users. Even though the pits are shallow (1 to 1.5 m), but water should not be added (small amounts each of anal cleansing water them can be tolerated). Water encourages the development used by a family of vectors and pathogens but it also fills the porespaces and deprives the aerobic bacteria of the oxygen that is required six for degradationone year. The choice of User Interface Fossa Alterna technology will determine only work properly if the material that enters the pittwo pits are used sequentially and not concurrently. Since bulking material is used to continuously Therefore, an adequate cover for the excreta, smells are reduced but the addition out of a ventilation pipe can reduce the smells even furtherservice pit is required.
The Fossa Alterna pits are relatively shallow with a depth of 1.5m. Even though the pits are shallowshould be used for urine, this but water should not be more than enough space to accommodate a family added (small amounts of 6 for one yearanal cleansing water can be tolerated). To optimize Water encourages the spacedevelopment of vectors and pathogens, but it also fills the material that mounds in pore spaces and deprives the centre aerobic bacteria of the pit oxygen that is required for degradation. A UDDT (underneath the toiletU.2) should can be pushed to the sides periodically. Unlike a simple or ventilated pit which will be covered or emptied, the material in used with the Fossa Alterna is meant to be reused. Therefore, it is extremely important that no garbage is put into but only in circumstances when the pit as it will reduce soil cannot sufficiently absorb the quality of urine or when the material recovered, and may even make it unusableurine is highly valued for application.
After compostingSince cover material is used to continuously cover the excreta, smells are reduced. To reduce the content of the first pit smells even further, a ventilation pipe can be used as fertiliseradded. The best compost time In flood-prone areas and where the groundwater table is more than 12 months. The material can be excavated earlier at 6 monthstoo high, but is best transferred at this stage to a pit in which a tree will be planted. Emptying the Fossa Alterna is easier than emptying other pits: could be raised or built entirely above ground to avoid water intrusion and groundwater pollution. Raising the pits are shallower could also be an option for rocky ground and the addition of soil means compacted soils that the material is less compactare difficult to dig. The material that is removed If space is abundant and emptying not offensive desired, the [[Fill and presents a reduced threat of contaminationCover - Arborloo | Arborloo]] (D.1) can be an alternative Disposal option. Pits should not be 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
}}
===Appropriateness===
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.
==Adequacy== The Fossa Alterna is not suited for rocky or compacted soils (that are difficult to dig) or for areas that flood frequently, except if the pits are raised.
The ===Health Aspects/Acceptance=== By covering faeces with soil, ash, and/or leaves, flies and odours are kept to a minimum. Users may not understand the difference between the Fossa Alterna is appropriate for rural and peri-urban areasa Double VIP, although if given the opportunity to use one, people should have a good appreciation of the advantages. It is especially adapted Demonstration units can be used to waterscarce environments. It is show how easily one can empty a useful solution for areas that have poor soil and could benefit from the composted humic material as Fossa Alterna in comparison to emptying a soil amendment. A constant source of soil, ash and/or leaves is requireddouble pit.
Not applicable Keeping the contents sealed in areas with a high water table, with very loose soil (which could collapse), or very solid soil which would prevent drainage. In order to prevent water tables penetrating the pits and contaminating pit for the water, pits should be shallow. The conversion duration of excreta into humus will not take place if at least one year makes the pit is flooded with watermaterial safer and easier to handle. Therefore, the pit The same precautions that are taken when handling compost should not be sealed and water used for anal cleaning should not enter taken with the humus derived from the pitFossa Alterna.
The Fossa Alterna ===Operation & Maintenance=== When the first pit is not appropriate for greywater as put into use, a layer of leaves should be put onto the bottom of the pit is shallow . Periodically, more leaves should be added to increase the porosity and oxygen availability. Following the addition of faeces to the conditions must remain aerobic for degradation. Another greywater treatment system must pit, a small amount of soil, ash, and/or leaves should be used in paralleladded. A [[Urine Diverting Dry Toilet]] can Occasionally, the mounded material beneath the toilet hole should be used with pushed to the Fossa Alterna, but only sides of the pit in circumstances when order to optimise the soil cannot sufficiently absorb the urine or when urine is highly valued for applicationuse of space.
The Unlike a [[Single Pit | Single]] or [[Single Ventilated Improved Pit | Ventilated]] Pit (S.2, S.3) which will be covered or emptied, the material is manually emptied from in the Fossa Alterna (is meant to be used as a soil conditioner. Therefore, it is dug out, not pumped out), so vacuum truck access to extremely important that no garbage is put into the pits is not necessarypit. The Emptying the Fossa Alterna technology will only work properly if is easier than emptying other pits; the two pits are used sequentially shallower and not concurrently. Thereforethe addition of soil, ash, an adequate cover for and/or leaves means that the out of service pit is requiredcontents are less compact. The Fossa Alterna is especially appropriate when water material that is scarce. It removed is not suited for rocky or compacted soils (that are difficult to dig) or for areas that flood frequentlyoffensive and presents a reduced threat of contamination.
As with many sanitation systemsDepending on the dimensions of the pits, household members need to understand the key principles for efficient operation and maintenance and discipline is required for adding soil after each defecationcontents should not be emptied more often than once a year.
==Health Aspects/Acceptance=Field experiences=== By covering faeces with soil/ash, flies and odours are kept to a minimumThe following project(s) utilize fossa alterna. Users may not understand the difference between the Fossa Alterna and a <br>{|style="border: 2px solid #e0e0e0; width: 20%; text-align: justify; background-color: #e9f5fd;" cellpadding="2"|- style="vertical-align: top"|[[Double Ventilated Improved PitImage:akvorsr logo_lite.png|center|60px|Double VIPlink=http://akvo.org/products/rsr/]], although if given the opportunity to use one, people should have a good appreciation of the advantages|- style="vertical-align: bottom"|[[Image:project 644. Demonstration units can be used to show how easily one can empty a Fossa Alterna in comparison to emptying a Double Pitjpg |thumb|center|140px|<font size="2"><center>[http://rsr. Keeping the contents sealed in the pit for the duration of at least one year makes the material safer and easy to handleakvo. The same precautions that are taken when handling compost should be taken with the humus derived from the Fossa Alternaorg/project/644/ RSR Project 644]<br>Rwenzori Integrated School WASH Project</center></font>|link=http://rsr.akvo.org/project/644/ ]] |}
<br>==Maintenance=Manuals, videos, and links= ==This [https://sswm.info/taxonomy/term/3916/fossa-alterna document] contains a lot of information about building, maintaining a fossa alterna.
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 ===References 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. external links===
Occasionally* Morgan, the mounded material beneath the toilet hole should be pushed to the sides of the pit P. R. (2007). [http://www.ecosanres.org/pdf_files/ToiletsThatMakeCompost.pdf Toilets That Make Compost. Low-Cost, Sanitary Toilets That Produce Valuable Compost for Crops in an even distribution of materialsAfrican Context]. Depending on the dimensions of the pitsStockholm Environment Institute, Stockholm, materials should be emptied every yearSE.
==Manual==This * Morgan, P. R. (2009). [http://www.bvsde.pahoecosanres.org/bvsacd/cd66pdf_files/ToiletsCompost/cap4EcologicalToilets-PeterMorgan-Mar2009.pdf documentEcological Toilets. Start Simple and Upgrade from Arborloo to VIP] contains a lot of information about building. Stockholm Environment Institute, Stockholm, maintaining a fossa alternaSE.
===Acknowledgements===
{{:Acknowledgements Sanitation}}
==References and external links==
* Morgan, P. (2007) Toilets That Make Compost: Low-cost, sanitary toilets that produce valuable compost for crops in an African context. Stockholm Environment Institute, Sweden. Available: http://www.ecosanres.org (Step-by-step guide for building a Fossa Alterna.)