초록
<P><B>Abstract</B></P> <P>By-products from sugarcane mills have a considerable energy potential, and therefore have been studied aiming to generate biogas emphasising biohydrogen (bioH<SUB>2</SUB>). Sugarcane molasses, a byproduct from sugar production, are rich in carbohydrates, thus easily biodegraded by anaerobic microorganisms. This study evaluated the production of bioH<SUB>2</SUB> in unfavorable pH (3.80) using molasses as a feedstock in an anaerobic structured bed reactor (AnSTBR-A) under thermophilic conditions (55 °C). The AnSTBR-A operated with an organic loading rate (OLR) of 60 g L<SUP>−1</SUP> d<SUP>−1</SUP> was able to produce bioH<SUB>2</SUB> under long-term operation (392 days). The hydrogen yield (HY) was 1.18 mol H<SUB>2</SUB> mol total carbohydrates<SUP>−1</SUP>. The results highlighted HY variation concomitant with metabolite concentrations. The main role to bioH<SUB>2</SUB> production in AnSTBR-A was acetate + lactate → butyric + bioH<SUB>2</SUB>, with a predominance of the organism belonging to the <I>Thermoanaerobacterium</I> genus.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Thermophilc dark fermentation at sugarcane molasses was assessed. </LI> <LI> Long-term continuous biohydrogen production was achieved at low pH (3.8). </LI> <LI> Acetate and lactate co-fermentation was the primary metabolic pathway. </LI> <LI> Thermoanaerobacterium as the predominant genus in the reactor. </LI> </UL> </P>