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{|width="100%"
|style="width:50%;"|{{santable_new|
sys7=|
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pic=Single_ventilated_improved_pit.png|
ApplHousehold=XX|
ManShared=XX|
ManPublic=X|
Input1=Excreta|Input2=Blackwater |Input3=Faeces |Input3Input4=Anal cleansing water| Input4= |Input5=Dry Cleansing Materials|Output1=Faecal sludgeSludge| Output2= | Output3= | Output4= | Output5=|english_link=Single_Ventilated_Improved_Pit|french_link=Latrine_VIP_à_fosse_unique|spanish_link=Pozo_Simple_Mejorado_Ventilado
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|[[Image:Single_ventilated_improved_pit.png |right|300px500px]]
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Despite their simplicity, well-designed single VIPs can be completely smell free, and more pleasant to use than some other water-based technologies. Flies that hatch in the pit are attracted to the light at the top of the ventilation pipe. When they fly towards the light and try to escape , they are trapped by the fly-screen flyscreen and die. The ventilation also allows odours to escape and minimizes the attraction for flies.
'''Design Considerations:''' The vent pipe should have an internal diameter of at least 110mm to a maximum of 150mm 110 mm and reach more than 300mm 300 mm above the highest point of the toilet superstructure. Wind passing over the top creates a suction pressure within the vent pipe and induces an air circulation. Air is drawn through the User Interface into the pit, moves up inside the vent pipe and escapes into the atmosphere. Care should be taken that objects, such as trees or houses, do not interfere with the air stream. The vent works better best in windy areas , but where there is little wind, its effectiveness can be improved by painting the pipe black; the . The heat difference between the pit (cool) and the vent (warm) creates an updraft that pulls the air and odours up and out of the pit. To test the efficacy of the ventilation, a small, smoky fire lit cigarette can be lit in held over the pitUser Interface; the smoke should be pulled down into the pit and up and out of into the vent pipe and not remain in the superstructure. The mesh size of the fly screen must be large enough to prevent clogging with dust and allow air to circulate freely. Aluminium screens, with a hole-size of 1.2 to 1.5 mm, have proven to be the most effective. Typically, the pit is at least 3 m deep and 1 to 1.5 m in diameter, depending on the number of users. Deep pits can last up to 20 or the superstructuremore years.
<br>{{procontable | pro=- Flies and odours are significantly reduced (compared to non-ventilated pits). <br> - Does not require a constant source of water. <br> - Suitable for all types of user (sitters, squatters, washers and wipers). <br> - Can be built and repaired with locally available materials <br> - Can be used immediately after construction. <br> - Low (but variable) capital costs depending on materialsand pit depth. <br> - Small land area required. <br> | con= - Sludge requires secondary treatment Low reduction in BOD and/or appropriate dischargepathogens with possible contamination of groundwater. <br> - Costs to empty may be significant compared to capital costs. <br> - Low reduction in BOD Sludge requires secondary treatment and pathogens/or appropriate discharge.
}}
==Adequacy=Appropriateness= ==Treatment processes in the single VIP (aerobic, anaerobic, dehydration, composting, or otherwise) are limited, and, therefore, pathogen reduction and organic degradation is not significant. However, since the excreta are contained, pathogen transmission to the user is limited. This technology is a significant improvement over Single Pits or open defecation.
===Health Aspects/Acceptance===
A Single VIP can be a very clean, comfortable, and well accepted sanitation option. However some health concerns exist:
* Latrine leachate can contaminate groundwater;
* Health risks from flies are not completely removed by ventilation.
===Upgrading===
A Single VIP toilet can be upgraded to a [[Double Ventilated Improved Pit|Double VIP]], a [[Urine Diverting Dry Toilet|Urine Diverting Dry Toilet (UDDT)]] if there is a use for urine, or a water-based [[Pour Flush Toilet|Pour Flush Toilet]] if water is available. A Double VIP has the addition of an extra pit so that while one pit is in use, the contents of the full pit are draining, maturing and undergoing degradation. Pathogens are destroyed much more thoroughly in a Double VIP and therefore, the contents are less hazardous to remove from the pit, although because the contents are so solid, the contents cannot be pumped, but rather, must be manually emptied.
===Operation & Maintenance===
To keep the Single VIP free of flies and odours, regular cleaning and maintenance is required. Dead flies, spider webs, dust and other debris should be removed from the ventilation screen to ensure a good flow of air.
===Origins===
The VIP latrine was developed in the 1970s at the Blair Research Laboratory in Zimbabwe.
==Acknowledgements=Field experiences==={{RSR_table|1image= rsr 476.jpg|1link=http:Acknowledgements //rsr.akvo.org/project/476/ |1project#=476 |1project name=Ensure access to safe water and sanitation ||2image= rsr 474.jpg|2link=http://rsr.akvo.org/project/474/ |2project#=474 |2project name=Health & Sanitationproject||3image= rsr 360.jpg|3link=http://rsr.akvo.org/project/360/ |3project#= 360|3project name= WASH Facilities at Kajiado Schools||4image= rsr 727.jpg|4link=http://rsr.akvo.org/project/727/ |4project#= 727|4project name=ESO North School and Community WASH Project ||5image= rsr 467.jpg|5link=http://rsr.akvo.org/project/467/ |5project#=467 |5project name=Community Water and Sanitation Project |}}
===References and external links===* Mara, D. D. (1984). [https://www.pseau.org/outils/ouvrages/world_bank_the_design_of_ventilated_lmproved_pit_latrines_1984.pdf The Design of Ventilated Improved Pit Latrines]. UNDP Interregional Project INT/81/047, The World Bank and UNDP, Washington, D.C., US.
* Mara, DDD. D. (1996). Low-Cost Urban Sanitation. Wiley, Chichester, UK. (Provides Book; provides detailed design information.)
* Mara DDMorgan, P. R. (19842009). The Design of Ventilated Improved Pit Latrines (UNDP Interreg[http://www.ecosanres. Project INTorg/81pdf_files/047)EcologicalToilets-PeterMorgan-Mar2009.pdf Ecological Toilets. Start Simple and Upgrade from Arborloo to VIP]. The World Bank + UNDPStockholm Environment Institute, Stockholm, WashingtonSE.
* Morgan, PRP. R. (19772011). [http://www.ecosanres.org/pdf_files/Builders_Detailed_Manual_Upgradeable_%20Blair_VIP.pdf The Pit Latrine – RevivedBlair VIP toilet]. Manual for Upgradeable BVIP Model with Spiral Superstructure and Tubular Vent. Central African Journal of MedicineStockholm Environment Institute, Stockholm, 23SE. (1Provides detailed design and construction information).
* MorganRyan, PRB. A. and Mara, D. D. (19791983). A [http://documents1.worldbank.org/curated/en/412331468199470290/pdf/TAG6000Ventila0pe0design0guidelines.pdf Ventilated Improved Pit PrivyLatrines: Vent Pipe Design Guidelines]. UNDP Interregional Project INT/81/047, The World Bank and UNDP, Washington, D.C. Appropriate Technology, 6 (3)US.
