ASBR reactor: Anaerobic sequencing high rate anaerobic batch reactor (ASBR) is a Iowa State process developed by Dague and co-workers at University. The promising feature of the ASBR process is that granular be and in this way higher biomass can be maintained in the reactor with efficient biomass setting and a long solids retention time (sRT). There are five stages to treatment: (1) Fill, (2) React, (3) Settle, (4) Decant, and (5) Idle.