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<!{|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|

Input1=Excreta|Input2=Faeces |Input3=Organics | Input4=Anal cleansing water| Input4= |Input5=Dry Cleansing Materials|Output1=Compost - EcoHumusPit Humus| Output2= | Output3= | Output4= | Output5=

Two shallow pits are dug next to each other (0.5 ­ 1.5 metre deep). One of the Fossa Alterna pits should fill over a period of 12–24 months depending on the size of the pit and the number of users. When a pit is full, the concrete slab and portable superstructure are placed on the second pit. 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|150px200px|[[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.

- 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

==Adequacy==  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 the composted humic material as a soil amendment. A constant source of soilflood frequently, ash and/or leaves is required. Not applicable 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 except if the pits and contaminating the water, pits should be shallow. The conversion of excreta into humus will not take place if the pit is flooded with water. Therefore, the pit should not be sealed and water used for anal cleaning should not enter the pit. The Fossa Alterna is not appropriate for greywater as the pit is shallow and the conditions must remain aerobic for degradation. Another greywater treatment system must be used in parallel. A [[Urine Diverting Dry Toilet]] can be used with the Fossa Alterna, but only in circumstances when the soil cannot sufficiently absorb the urine or when urine is highly valued for applicationare raised.

The material is manually emptied from the Fossa Alterna (it is dug out===Health Aspects/Acceptance=== By covering faeces with soil, ash, not pumped out)and/or leaves, so vacuum truck access flies and odours are kept to a minimum. Users may not understand the difference between the pits is not necessary. The Fossa Alterna technology will only work properly and a Double VIP, although if given the two pits are used sequentially and not concurrently. Thereforeopportunity to use one, an adequate cover for people should have a good appreciation of the out of service pit is requiredadvantages. The Demonstration units can be used to show how easily one can empty a Fossa Alterna is especially appropriate when water is scarce. It is not suited for rocky or compacted soils (that are difficult in comparison to dig) or for areas that flood frequentlyemptying a double pit.

As with many sanitation systems, household members need to understand Keeping the contents sealed in the key principles pit for efficient operation the duration of at least one year makes the material safer and maintenance and discipline is required for adding soil after each defecationeasier to handle. The same precautions that are taken when handling compost should be taken with the humus derived from the Fossa Alterna.

==Health Aspects/Acceptance=Operation & Maintenance=== By covering faeces with soil/ash, flies and odours are kept to a minimum. Users may not understand When the difference between the Fossa Alterna and a [[Double Ventilated Improved Pit|Double VIP]], although if given the opportunity to first pit is put into use one, people a layer of leaves should have a good appreciation be put onto the bottom of the advantagespit. Demonstration units can Periodically, more leaves should be used added to show how easily one can empty a Fossa Alterna in comparison to emptying a Double Pitincrease the porosity and oxygen availability. Keeping Following the contents sealed in addition of faeces to the pit for the duration , a small amount of at least one year makes soil, ash, and/or leaves should be added. Occasionally, the mounded material safer and easy to handle. The same precautions that are taken when handling compost beneath the toilet hole should be taken with pushed to the humus derived from sides of the Fossa Alternapit in order to optimise the use of space.

When the first pit is put into use, a layer of leaves should be put into the ===Field experiences===The following project(s) utilize fossa alterna.<br>{|style="border: 2px solid #e0e0e0; width: 20%; text-align: justify; background-color: #e9f5fd;" cellpadding="2"|- style="vertical-align: top"|[[Image:akvorsr logo_lite.png|center|60px|link=http://akvo.org/products/rsr/]]|- style="vertical-align: bottom of the pit"|[[Image:project 644. Periodically, more leaves should be added to increase the porosity and oxygen availabilityjpg |thumb|center|140px|<font size="2"><center>[http://rsr. Following the addition of faeces to the pit, a small amount of soil or ash should be addedakvo. To lengthen the filling time of the pit soil is not added to the pit following urinationorg/project/644/ RSR Project 644]<br>Rwenzori Integrated School WASH Project</center></font>|link=http://rsr.akvo. org/project/644/ ]] |}

Occasionally<br>===Manuals, the mounded material beneath the toilet hole should be pushed to the sides of the pit for an even distribution of materialsvideos, and links===This [https://sswm. Depending on the dimensions info/taxonomy/term/3916/fossa-alterna document] contains a lot of the pitsinformation about building, materials should be emptied every yearmaintaining a fossa alterna.

==Manual=References and external 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==* Elizabeth Tilley etMorgan, P. R.al (20082009). [http://www.eawagecosanres.ch/organisation/abteilungen/sandec/publikationen/publications_sesporg/downloads_sesppdf_files/compendium_highEcologicalToilets-PeterMorgan-Mar2009.pdf Compendium of Sanitation Systems Ecological Toilets. Start Simple and Technologies] ([http://www.eawag.ch/organisation/abteilungen/sandec/publikationen/publications_sesp/downloads_sesp/compendium_low.pdf low res versionUpgrade from Arborloo to VIP]). Department of Water and Sanitation in Development Countries ([http://www.sandec.ch/ Sandec]) at the Swiss Federal Stockholm Environment Institute of Aquatic Science and Technology (Eawag), Stockholm, SE. (Provides a full overview of sanitation systems.)

* Morgan, P. (2007) Toilets That Make Compost===Acknowledgements==={{: 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.)Acknowledgements Sanitation}}