Resumen
Experimental studies of two-phase anaerobic digestion of corn steep liquor in semi-continuous automatic and semi-automatic modes of operation of a cascade of two anaerobic bioreactors with monitoring and control systems were performed. Corn steep liquor?a waste product from the process of treating corn grain for starch extraction?was used as a substrate in the process of anaerobic digestion with simultaneous hydrogen and methane production. The daily yields of biohydrogen in bioreactor 1 of the cascade (with a working volume of 8 dm3) are variable. In good operation, they are in the range of 0.7 to 1.0 L of biogas from a 1 dm3 working volume of the bioreactor, and the optimal pH is in the range of 5.0?5.5. The concentration of hydrogen in the biogas from the hydrogen bioreactor 1 is in the range of 14?34.7%. The daily yields of biomethane in bioreactor 2 of the cascade (with a working volume of 80 dm3) vary in the range 0.4 to 0.85 L of biogas from a 1 dm3 working volume of the bioreactor, and the concentration of methane in the biogas from bioreactor 2 is high and remains practically constant (in the range 65?69%). At a dilution rate of 0.4 day-1 and an organic loading rate of 20 gL for bioreactor 1, respectively, and a dilution rate of 0.05 day-1 for bioreactor 2, the best results were obtained. The computer control system is presented. Some energetical considerations were discussed.