Civil and Construction Engineering
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Timothy Ellis

Associate Professor
Environmental Engineering

375 Town Engineering
Iowa State University
Ames, IA 50011
(515) 294-8922

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Updated by Tim Ellis
November 03, 2006

Static Granular Bed Reactor

The static granular bed reactor (SGBR) system was developed by researchers at Iowa State University.  The SGBR utilizes a bed of active anaerobic granules in a downward flow regime (see Figure 3).  The innovation in this reactor configuration is that it uses the highly active anaerobic granules (just as in a UASB system), but it operates in a downflow mode.  The advantage of a downflow configuration is that the biogas that is generated rises and is easily separated from the granules and the liquid at the top of the reactor.  Granule buoyancy is not a detriment to process performance in the SGBR as it is in the UASB.  In contrast to the UASB, there is no need for a sophisticated three phase solids, gas, and liquid separator.  Neither is there a need for recirculation pumps, timers, mixers, or other ancillary equipment that are required for the UASB systems.  Consequently, the effluent quality of the SGBR is improved in comparison to the UASB.   The biomass granules are retained within the reactor by the use of a gravel underdrain and temperature and hydraulic loading changes are not expected to significantly affect effluent quality.

The technological innovation of the SGBR is that it uses the highly active anaerobic granular biomass in a downflow configuration.  Other reactor configurations use downward flow regime (e.g., the anaerobic filter can be operated in a downflow mode), but the SGBR is the first system to use anaerobic granules in a downflow mode.  This configuration allows for an exceptional effluent quality, simple operating characteristics, and smaller volume requirements.