Mesophilic digester or Mesophilic biodigester is a kind of biodigester that operates in temperatures between 20 °C and about 40°, typically 37 °C.
This is the most used kind of biodigester in the world.
More than 90% of worldwide biodigesters are of this type.
In contrast, thermophilic digesters are less than 10% of digesters in the world, as it's more difficult to maintain the higher temperatures in a treatment plant, and they typically perform worse at separating liquids out of the sludge.
[1] Mesophilic digesters are used to produce biogas, biofertilizers, and sanitarization mainly in tropical countries such as India and Brazil.