Effects of initial seed concentration on the startup of the anaerobic sequencing batch reactor

This study focused on the startup of the anaerobic sequencing batch reactor (ASBR) developed by Dague and co-workers at Iowa State University. The ASBR relies on four cycles of fill, react, settle and decant. The internal clarification and settling of biomass eliminates the need for a separate clarifier. The batch operation is also important in producing a cyclic behavior in the F/M (food to microorganism) ratio. In the ASBR, the F/M ratio is high immediately after feeding, but low at the end of the react phase. These alternating ``feast`` and ``famine`` conditions in the ASBR are the keys to high substrate conversion to methane (during the feast) and efficient biomass settling (during the famine). This research was undertaken to obtain ASBR startup data which may be used for actual treatment plant startup. The objectives were to develop an effective startup protocol for the ASBR and to determine an optimum granular biomass concentration and organic loading that would result in stable and fast startup. Two reactors were operated as ASBRs, seeded with varying amounts of granular biomass, and used to treat a synthetic milk waste. The startup procedure involved step-wise increases in the organic loading rate until a load of 10more » g COD/L/d was reached.« less