Composting Toilets: How it works: Temperature

Installation | Moisture | Oxygen | Temperature | Pathogens

The heat coming from piles of organic material is generated by the feeding and multiplication of millions of microorganisms. Technically, the stage of the temperature cycle below 40 °C is termed mesophilic, above 40 °C is thermophilic.

Composting is most rapid in the thermophilic stage. As the temperature rises over 40 °C, mesophilic organisms die out and are replaced by an upsurge in the population of thermophilic organisms; the agents of fastest decomposition.

Nature Loo functions well in both thermophilic and mesophilic stages, but in most cases it operates in the faster, thermophilic stage. This happens for a couple of reasons:

1. Air is drawn into the Nature Loo through the toilet pedestal. As the air inside a house is usually warmer than the air outside, the Nature Loo chamber is also kept warmer. In colder climates, the chamber can also be insulated with a thermal insulation material.
2. The containers are black. This means they are an excellent absorber of heat, especially if located in natural sunlight as is recommended once they are full. Unlike most other composting toilets where the chambers are located under a house, the full Nature Loo chambers are exposed to natural sunlight for at least 50% of the composting cycle. In the case of the Excel the optimum temperature is maintained by the thermostatically controlled heater.

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Influence of time and temperature
on selected pathogens in night soil and sludge

(a) Enteric viruses (b) Shigella (c) Taenia
(d) Entamoeba histolytica (e) Vibrio cholera

Source: Featchem and others, Sanitation and Disease.