HYDRODYNAMIC CHARACTERISTICS OF THE ANAEROBIC BAFFLED REACTOR

The anaerobic baffled reactor (ABR) contains a mixed anaerobic culture segregated into compartments. This paper presents residence time distribution studies done on both clean and working reactors, to investigate the mixing patterns and dead spaces in this novel type of reactor. The results show that the mixing is characterized by a number of theoretical perfectly-mixed compartments which correlates closely with the actual number of compartments in the reactor, especially at low hydraulic residence times (HRT). The fraction of dead space in the ABR is low compared to other designs of anaerobic digesters. The dead space can be shown to be made up partly of biological dead space (due to presence of biomass) which decreases with HRT, and partly of hydraulic dead space (due to the flow patterns) which increases with HRT. Hence there is no direct correlation between dead space and HRT.