Effect of iron concentration on continuous H 2 production using membrane bioreactor

Abstract

The effect of FeSO 4 on continuous H 2 production in a membrane bioreactor (MBR) was investigated using anaerobic mixed microflora under mesophilic condition. The H 2 production of 41.6 l/day was obtained at 10.9 mg FeSO 4/l, which was 1.59 times higher than that at 2.7 mg FeSO 4/l. Between 2.7 and 13.7 mg FeSO 4/l, the H 2 production rate increased in parallel with the H 2 yield under high-cell-density condition. For the same amounts of FeSO 4, increases in butyric acid together with decreases in lactic acid promoted a reduction of the number of protons and the resultant release of H 2. The hydrogenase activity of 1.08 mg methylene blue (M.B) reduced/min at 10.9 mg FeSO 4/l was about sixfold higher than at 2.7 mg FeSO 4/l. These results suggest that the addition of iron and sulfur to an MBR is an important key factor in the enhancement of H 2 production.