초록
<P><B>Abstract</B></P> <P>Boosted by the high temperatures in which vinasse is generated (90 °C–100 °C), this study evaluated the effect of an extreme thermophilic condition (70 °C) on sugarcane vinasse Dark Fermentation (DF) in an Anaerobic Structured Bed Reactor (ASTBR). Four hydraulic retention times (HRT) (19, 15, 12 and 8 h) were evaluated. Higher HRT resulted in a greater H<SUB>2</SUB> production rate (690 mLH<SUB>2</SUB>.d<SUP>−1</SUP>.L<SUP>−1</SUP>), higher yields (1.8 molH<SUB>2</SUB>.mol<SUB>Glucose</SUB> <SUP>−1</SUP>) and greater stability. The extreme temperature inhibits microorganisms' extracellular polymer production, thus leading to a disperse growth, preventing excess biomass accumulation, which was previously reported as the main drawback in H<SUB>2</SUB> production at lower temperatures. The ASTBR higher void index is also responsible for lower biomass/solids retention. The H<SUB>2</SUB> production main route was through the lactic/acetic acid pathway, which is highly reliant on the pH of fermentation broth. The main genus involved in H<SUB>2</SUB> production at 70 °C were <I>Clostridium</I>, <I>Pectinatus, Megasphaera</I> and <I>Lactobacillus.</I> </P> <P><B>Highlights</B></P> <P> <UL> <LI> Extreme temperature enabled long term H<SUB>2</SUB> production in sugarcane vinasse fermentation. </LI> <LI> Comparatively to lower temperature, H<SUB>2</SUB> yields four times higher were observed at 70 °C. </LI> <LI> Lactic/acetic pathway was the main route for H<SUB>2</SUB> production with sugarcane vinasse. </LI> <LI> At appropriate pH, lactic acid bacteria are beneficial to biological H<SUB>2</SUB> production. </LI> </UL> </P>