Operation of an Experimental Test Unit for the Bioconversion of Waste and Biomass to Methane

摘要

The data collected at the experimental test unit (ETU) for three different feed materials indicate that an unmixed, solids concentrating (SOLCON) digester consistently outperforms a conventional Continuous Stirred Tank Reactor (CSTR), operating on feed slurries containing 5 to 10 weight percent solids. Methane yields have exceeded a CSTR digester in all cases by 10% to 50%. This type of digestion system is also extremely stable and flexible. Over 3-1/2 years of uninterrupted operation have been logged in the digester. During that time feedstocks, loading rates, and temperatures were changed without the need to reinoculate a ''stuck'' digester. Transition periods for different feedstocks and loading rates have been very smooth. Even the transition from mesophilic to thermophilic was uneventful. However, transitions from thermophilic operation back to mesophilic operation will require longer periods and special operating techniques to avoid a ''stuck'' digester. Following the operating campaign on sorghum, the digester culture was transferred for 1 day to a holding tank to allow inspection of the digester. Despite the unmixed operation, no unusual solids accumulations or ''dead zones'' were observed. All internals were in excellent condition. 3 refs., 4 figs., 7 tabs. (ERA citation 14:019475)