초록
<P><B>Abstract</B></P> <P>Biohydrogen production from buffalo slurry (BS) co-fermented with cheese whey (CW) and crude glycerol (CG) was investigated using a suitable microbial community (F210) as inoculum. Mixture Design was used to find the optimal composition (%) of the three substrate components and to investigate the effect of the mixing ratio on Bio-H<SUB>2</SUB> yields. Maximum H<SUB>2</SUB> yield estimated through the model was around 117 mL H<SUB>2</SUB>/g VS<SUB>added</SUB>, while the maximum experimentally detected was 111.6 ± 21.8 mL H<SUB>2</SUB>/g VS<SUB>added</SUB>, obtained for a mixing ratio of substrate composition of 66% BS and 33% CW (<I>R</I> <SUP>2</SUP> = 0.962; <I>p</I>-value = 0.0001). CW was clearly the most suitable substrate (with a relative contribution higher than 46%), but led to a rapid drop in pH from 6.5 to 4, while BS showed high buffering capacity by maintaining the pH above 6. Interestingly, the co-digestion of the different substrates decreased the H<SUB>2</SUB> production lag phase <I>λ</I>; in particular the presence of BS shortened the lag period (<I>λ</I> < 3 h) and increased the degradation efficiency of CG.</P> <P>The results demonstrate the usefulness of the mixture design for finding the optimal substrate composition, using BS as co-fermentation substrate to obtain high H<SUB>2</SUB> production yields. Moreover the response surface shows the possibility of mixing the substrates in different ways, while maintaining H<SUB>2</SUB> production within an optimum range: 105–117 mL H<SUB>2</SUB>/g VS<SUB>added</SUB>. This might offer a considerable advantage in the effective management of systems or processes, in which the substrates availability may change over the time.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Maximum H<SUB>2</SUB> yield estimated by the statistical model reached 117 mL H<SUB>2</SUB>/g VS<SUB>added</SUB>. </LI> <LI> Effective H<SUB>2</SUB> production was obtained without use of synthetic growth medium. </LI> <LI> Buffalo slurry showed high buffering capacity by maintaining the pH above 6. </LI> <LI> Co-digestion of the different substrates decreased the H<SUB>2</SUB> production lag phase <I>λ</I>. </LI> <LI> Mixture design proved to be a useful optimization and decision-making tool. </LI> </UL> </P>