In the renewable energy field, a digester, or fermenter, is a large silo in which organic waste is used to form what is known as an organic suspension. This suspension con-sists of waste from agribusiness processes and munici-pal solid waste mixed with livestock slurry or herbaceous crops. Digesters produce biogas, which mainly consists of methane, used to generate electricity.

Digesters are vessels in which the anaerobic digestion of biomass occurs. In other words, micro-organisms break the biomass down.

The mechanical seal on the agitator has to ensure a seal between the rotating shaft and the tank wall in order to prevent undesirable process leakage to the atmosphere.