Two-stage thermophilic bio-hydrogen and methane production from oil palm trunk hydrolysate using Thermoanaerobacterium thermosaccharolyticum KKU19

Abstract

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)2/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 Thermoanaerobacterium thermosaccharolyticum KKU19 in the first stage. The maximum hydrogen production potential of 2179 mL H2/Lsubstrate 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-CODadded with 83% COD removal.