초록
<P><B>Abstract</B></P> <P>Two-step hybrid system of microbiological hydrogen production with the diluted solid wastes from chewing gum production as a substrate was studied. As the first step, dark fermentation with the digested sludge at different concentrations of waste was performed. The effluent originating from the dark process was subsequently applied in photofermentation with <I>Rhodobacter sphaeroides</I> bacteria. In the first step, the degradation of sweetening substances as well as Talha gum remaining in waste was observed. Hydrogen, carbon dioxide and liquid metabolites (Volatile Fatty Acids - VFAs) were the main products. The maximum hydrogen production in dark fermentation (0.36 L/L<SUB>medium</SUB>) was observed at concentration of 67 g waste/L. Effluents from the first step, containing mainly xylitol, butyric, acetic, lactic and propionic acids, served as the source of organic carbon for photofermentation. The maximum amount of hydrogen at this step reached 0.80 L H<SUB>2</SUB>/L of diluted (1:8) effluent. The presence of significant concentration of ammonium ions (∼480 mg/L) in non-diluted effluent completely ceased the hydrogen formation by nitrogenase, therefore reduction in the amount of NH<SUB>4</SUB> <SUP>+</SUP> ions in the medium was necessary. This was realized by the dilution of effluent from dark fermentation. The total amount of hydrogen produced in sequential dark and photo-fermentation process under the optimized reaction conditions reached the volume of ∼6.7 L H<SUB>2</SUB>/L of non-diluted waste.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Microbiological hydrogen generation - hybrid system. </LI> <LI> H<SUB>2</SUB> production in dark- and photofermentation from chewing gum production wastes. </LI> <LI> Decomposition of Talha gum during dark fermentation with anaerobic digested sludge. </LI> <LI> <I>Rhodobacter sphaeroides</I> utilized xylitol and VFAs from dark fermentation effluents. </LI> <LI> 80% COD reduction in a two-step process. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>