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Composting toilet

A composting toilet is a type of dry toilet that treats human excreta by a biological process called composting. This process leads to the decomposition of organic matter and turns human excreta into compost-like material but does not destroy all pathogens. Composting is carried out by microorganisms (mainly bacteria and fungi) under controlled aerobic conditions. Most composting toilets use no water for flushing and are therefore called 'dry toilets'. A composting toilet is a type of dry toilet that treats human excreta by a biological process called composting. This process leads to the decomposition of organic matter and turns human excreta into compost-like material but does not destroy all pathogens. Composting is carried out by microorganisms (mainly bacteria and fungi) under controlled aerobic conditions. Most composting toilets use no water for flushing and are therefore called 'dry toilets'. In many composting toilet designs, carbon additives such as sawdust, coconut coir, or peat moss is added after each use. This practice creates air pockets in the human excreta to promote aerobic decomposition. This also improves the carbon-to-nitrogen ratio and reduces potential odor. Most composting toilet systems rely on mesophilic composting. Longer retention time in the composting chamber also facilitates pathogen die-off. The end product can also be moved to a secondary system – usually another composting step – to allow more time for mesophilic composting to further reduce pathogens. Composting toilets, together with the secondary composting step, produce a humus-like endproduct that can be used to enrich soil if local regulations allow this. Some composting toilets have urine diversion systems in the toilet bowl to collect the urine separately and control excess moisture. A 'vermifilter toilet' is a composting toilet with flushing water where earthworms are used to promote decomposition to compost. Composting toilets do not require a connection to septic tanks or sewer systems unlike flush toilets. Common applications include national parks, remote holiday cottages, ecotourism resorts, off-grid homes and rural areas in developing countries. The term 'composting toilet' is used quite loosely, and its meaning varies by country. For example, in Germany and Scandinavian countries, composting always refers to a predominantly aerobic process. This aerobic composting may take place with an increase in temperature due to microbial action, or without a temperature increase in the case of slow composting or cold composting. If earth worms are used (vermicomposting) then there is also no increase in temperature. Composting toilets differ from pit latrines and arborloos, which use less controlled decomposition and may not protect groundwater from nutrient or pathogen contamination or provide optimal nutrient recycling. They also differ from urine-diverting dry toilets (UDDTs) where pathogen reduction is achieved through dehydration (also known by the more precise term 'desiccation') and where the feces collection vault is kept as dry as possible. Composting toilets aim to have a certain degree of moisture in the composting chamber. Composting toilets can be used to implement an ecological sanitation approach for resource recovery, and some people call their composting toilet designs 'ecosan toilets' for that reason. However, this is not recommended as the two terms (i.e. composting and ecosan) are not identical. Composting toilets have also been called 'sawdust toilets', which can be appropriate if the amount of aerobic composting taking place in the toilet's container is very limited. The 'Clivus multrum' is a type of composting toilet which has a large composting chamber below the toilet seat and also receives undigested organic material to increase the carbon to nitrogen ratio. Alternatives with smaller composting chambers are called 'self-contained composting toilets' since the composting chamber is part of the toilet unit itself. Composting toilets can be suitable in areas such as a rural area or a park that lacks a suitable water supply, sewers and sewage treatment. They can also help increase the resilience of existing sanitation systems in the face of possible natural disasters such as climate change, earthquakes or tsunami. Composting toilets can reduce or perhaps eliminate the need for a septic tank system to reduce environmental footprint (particularly when used in conjunction with an on-site greywater treatment system).

[ "Toilet", "Sanitation", "Compost" ]
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