초록
<P><B>Abstract</B></P> <P>Batch factorial experiments were performed on cheese whey+wastewater sludge mixtures to evaluate the influence of pH and the inoculum-to-substrate ratio (ISR) on fermentative H<SUB>2</SUB> production and build a related predictive model. ISR and pH affected H<SUB>2</SUB> potential and rate, and the fermentation pathways. The specific H<SUB>2</SUB> yield varied from 61 (ISR=0, pH=7.0) to 371L H<SUB>2</SUB>/kg TOC<SUB>whey</SUB> (ISR=1.44gVS/g TOC, pH=5.5). The process duration range was 5.3 (ISR=1.44gVS/g TOC, pH=7.5) − 183h (ISR=0, pH=5.5). The metabolic products included mainly acetate and butyrate followed by ethanol, while propionate was only observed once H<SUB>2</SUB> production had significantly decreased. The multiple metabolic products suggested that the process was governed by several fermentation pathways, presumably overlapping and mutually competing, reducing the conversion yield into H<SUB>2</SUB> compared to that expected with clostridial fermentation.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Biohydrogen production from cheese whey was studied through factorial experiments. </LI> <LI> The role of pH and ISR on H<SUB>2</SUB> production was specifically assessed. </LI> <LI> Regression and response surface analyses were used to interpret the results. </LI> <LI> Multiple fermentation pathways were likely to overlap during fermentation. </LI> <LI> The maximum yield was 371LH<SUB>2</SUB>/kgTOC<SUB>whey</SUB> for ISR=1.44gVS/gTOC and pH=5.5. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>