Biochemical energy conversion using immobilized whole cells of Clostridium butyricum

Hydrogen producing bacteria, Clostridium butyricum, were immobilized in agar gel (2 per cent). The immobilized whole cells were employed for continuous production of hydrogen from alcohol factory waste waters. The hydrogen production rate became constant above BOD 1500 ppm when hydrogen production was performed with a batch system. The immobilized whole cells continuously produced hydrogen over a 20-day period. The amount of hydrogen produced was about 6 ml/min/kg wet gels. Hydrogen produced was supplied to the hydrogen-oxygen (air) fuel cells. The maximum cell voltage of cell I and II was about 0.55 and 0.66 V respectively when the flow rate of hydrogen was 6 ml/min. The limiting current density changed from 0.4 to 40 mA/cm² as the resistance between the electrodes changed from 1 to 100 ω. The fuel cell was left on for 7 days and the current from 550 to 500 mA was obtained continuously over a 7 day period.