초록
<P><B>Abstract</B></P> <P>The two-stage process for thermophilic bio-hydrogen production followed by methane production was examined on a hydrolysate obtained from oil palm trunk (OPT). The optimum conditions for lime pretreatment and enzymatic hydrolysis of OPT was a lime loading of 0.2 g Ca(OH)<SUB>2</SUB>/g-OPT, pretreatment time of 60 min, temperature of 121 °C and enzyme loading of 35 filter paper units/g-OPT. A maximum total reducing sugar yield of 473 mg/g-OPT was obtained, which was 2.7-fold higher than that of untreated OPT. The OPT hydrolysate was used as a substrate for bio-hydrogen production by <I>Thermoanaerobacterium thermosaccharolyticum</I> KKU19 in the first stage. The maximum hydrogen production potential of 2179 mL H<SUB>2</SUB>/L<SUB>substrate</SUB> was obtained under the optimum conditions of 16.5 g/L initial substrate concentration, initial pH of 6.7 and 54.5 °C, respectively. Acidic effluent was used to produce methane in the second stage in which the methane yield of 272.4 mL/g-chemical oxygen demand (COD) was achieved. The two-stage hydrogen and methane production resulted in energy yield of 10.6 kJ/g-COD<SUB>added</SUB> with 83% COD removal.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Lime pretreatment followed by enzymatic hydrolysis gave sugar yield of 473 mg/g. </LI> <LI> H<SUB>2</SUB> production from oil palm trunk hydrolysate was optimized by RSM. </LI> <LI> Hydrogen production potential of 2179 mL/L was achieved under optimum conditions. </LI> <LI> Two-stage process gave energy yield 13 fold higher than sole H<SUB>2</SUB> production process. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>