초록
Cheese whey wastewater diluted to 10 g lactose/L was initially subjected to dark-fermentation by Enterobacter aerogenes MTCC 2822, and the VFAs-rich spent medium (acetic acid 1900 mg/L, butyric acid 537 mg/L, and traces of propionic acid) was subjected to photo-fermentation through enrichment by Ni<SUP>2+</SUP> (0-8 μmol/L), Fe<SUP>2+</SUP> (0-100 μmol/L) or Mg<SUP>2+</SUP> (0-15 mmol/L) in batch mode by Rhodopseudomonas BHU 01 strain. The maximum cumulative H<SUB>2</SUB> production (144 ml) and yield (58 mmol) was obtained at 4 μmol Ni<SUP>2+</SUP>/L. Likewise, Fe<SUP>2+</SUP> (60 μmol/L) resulted in maximum cumulative H<SUB>2</SUB> production (139 ml) and yield (56 mmol). Nevertheless, 6 mmol of Mg<SUP>2+</SUP> did not significantly affect H<SUB>2</SUB> production (110 ml) or yield (44 mmol); the latter value in close proximity with the control (37 mmol). The concomitant reduction in COD was maximum (15.61%) for 4 μmol Ni<SUP>2+</SUP>/L, followed by 15.33% for 60 μmol Fe<SUP>2+</SUP>/L, and the least for 6 mmol Mg<SUP>2+</SUP>/L (14.5%). The observations suggest the role of Fe<SUP>2+</SUP> and Ni<SUP>2+</SUP> in regulation of nitrogenase and hydrogenase, while that of Mg<SUP>2+</SUP> mainly in the biosynthesis of photopigment bacteriochlorophyll (Bchl).