초록
<P><B>Abstract</B></P> <P>The conversion of agro-industrial byproducts, residues and microalgae, which are representative or adapted to the Mediterranean climate, to hydrogen (H<SUB>2</SUB>) by <I>C. butyricum</I> was compared. Five biomass types were selected: brewery’s spent grain (BSG), corn cobs (CC), carob pulp (CP), <I>Spirogyra</I> sp. (SP) and wheat straw (WS). The biomasses were delignified and/or saccharified, except for CP which was simply submitted to aqueous extraction, to obtain fermentable solutions with 56.2–168.4 g total sugars L<SUP>−1</SUP>. In small-scale comparative assays, the H<SUB>2</SUB> production from SP, WS, CC, BSG and CP reached 37.3, 82.6, 126.5, 175.7 and 215.8 mL (g biomass)<SUP>−1</SUP>, respectively. The best fermentable substrate (CP) was tested in a pH-controlled batch fermentation. The H<SUB>2</SUB> production rate was 204 mL (L h)<SUP>−1</SUP> and a cumulative value of 3.9 L H<SUB>2</SUB> L<SUP>−1</SUP> was achieved, corresponding to a H<SUB>2</SUB> production yield of 70.0 mL (g biomass)<SUP>−1</SUP> or 1.6 mol (mol of glucose equivalents)<SUP>−1</SUP> <SUB>.</SUB> The experimental data were used to foresight a potential energy generation of 2.4 GWh per year in Portugal, from the use of CP as substrate for H<SUB>2</SUB> production.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Mediterranean waste biomasses are suitable for fermentative H<SUB>2</SUB> production. </LI> <LI> Sugar-rich carob pulp (CP) extract is obtained by simple water extraction. </LI> <LI> The fermentation of CP extract by <I>C. butyricum</I> produces 215.8 L H<SUB>2</SUB> kg <SUB>d.w.</SUB> <SUP>−1</SUP>. </LI> <LI> The H<SUB>2</SUB> production rate from CP extract in bioreactor is 440 mL (L h)<SUP>−1</SUP>. </LI> <LI> Through H<SUB>2</SUB> production, CP can potentially generate 2.4 GWh y<SUP>−1</SUP> in Portugal. </LI> </UL> </P>