Biological hydrogen production by enriched anaerobic cultures in the presence of copper and zinc.

Batch experiments were carried out to examine the productions of hydrogen and volatile fatty acids from glucose by enriched anaerobic culture in the presence of Cu and Zn. Results showed the specific hydrogen production rate was enhanced by the dosage of Cu at 50-100 mg/dm3 or the dosage of Zn at 10-250 mg/dm3, but was inhibited by Cu over 200 mg/dm3 or Zn at 500 mg/dm3. The hydrogen production yield was enhanced by Cu of 5-400 mg/dm3 or Zn of 5-500 mg/dm3. Productions of acetate and propionate were inhibited by Cu of 5-400 mg/dm3 or Zn of 5-500 mg/dm3. On the other hand, production of butyrate was stimulated, whereas production of ethanol was not affected. In terms of the CI,50 values. Cu was more toxic than Zn. The modified Gompertz equation was able to properly describe the cumulative hydrogen production in the presence of Cu or Zn.