Types of Anaerobic processes:
The anaerobic digestion can be grouped into two categories depending upon the suspended and attached bacterial growth within the reactor.
a] Mobilized cell Process :
In this process, bacterial cells are in suspension and are completely mixed with the reactor. The mixing is providing by artificial means.
b] Immobilized Cell Process
In immobilized cell process, the bacteria are concentrated within the reactor by attaching themselves to an inherent supporting media or by way of attaching themselves together to form conglobe rates which settle rapidly. Three types of processes are characterized for immobilized cells.
i) Fixed – Medium System : The bacterial attachment medium is stationary and liquid flow regime is by plug flow.
ii) Completely mixed fixed film system : The bacterial attachment medium and the liquid regime are uniform throughout the system.
iii) Fluidized-Bed System : Fluidization offers mixing of the medium uniformly within the reactor. When little or no recycle is required for fluidization the liquid follows a plug flow pattern while bio-film approaches completely mixed state.