Composting toilets

A composting toilet is a type of dry toilet or micro-flush toilet system that uses a predominantly aerobic process to treat human excreta by composting or managed aerobic decomposition. These toilets generally use little to no water and may be used as an alternative to flush toilets that are coupled with septic systems or city sewer systems. They have found use in situations where no suitable water supply or sewer system and sewage treatment plant is available. They are in use in many roadside facilities and national parks in Sweden, Canada, US, UK and Australia. They are used in rural holiday homes in Sweden and Finland.

The human excreta is usually mixed with sawdust, coconut coir or peat moss to facilitate aerobic processing, liquid absorption, and odor mitigation. Most composting toilets use slow, cold composting conditions, sometimes connected to a secondary external composting step.

Composting toilets produce a compost that may be used for horticultural or agricultural soil enrichment if the local regulations allow this. A secondary stage is often needed to allow mesophilic composting to further reduce potential pathogens.

The term "composting toilet" is used quite loosely, and its meaning varies by country. For example, in English-speaking countries, the term "anaerobic composting" (equivalent to anaerobic decomposition) is used. 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.

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Wikipedia