Anaerobic digestion is a biological process of the organic substrate degradation in the absence of free oxygen. Degradation takes place by bacteria that obtain the oxygen necessary for their vital functions from biomass. There is no better technological solution in the absolute sense, each system has peculiarities that must be considered in the feasibility and design study phases.
In wet processes, anaerobic digestion takes place in cylindrical tanks (CSTR – Continuous flow Stirred Tank Reactor) heated and mixed in an environment characterized by a dry matter content of 10% or less. The process can be carried out in thermophilic or mesophilic conditions and the retention times usually vary between 15 and 30 days. Each digester is equipped with a mixing system that guarantees perfect digestate homogenization and heat distribution.