Co-digestion of oil palm trunk hydrolysate with slaughterhouse wastewater for thermophilic bio-hydrogen production by Thermoanaerobacterium thermosaccharolyticm KKU19

Abstract

The key factors influencing a co-digestion of the oil palm trunk (OPT) hydrolysate with a slaughterhouse wastewater (SHW) to produce hydrogen by Thermoanaerobacterium thermosaccharolyticum KKU19 were investigated. The OPT hydrolysate was obtained by the hydrolysis of OPT by microwave-H2SO4 method using 1.56% (w/v) H2SO4 and 7.50 min reaction time at 450 W. The Plackett–Burman method was used to screen the key factors that influenced the hydrogen production potential (Ps). Results indicated that initial cell concentration, tCOD/TN (total COD/total nitrogen) ratio and CuSO4 concentration influenced the Ps. These factors were further optimized using response surface methodology (RSM) with central composite design (CCD). A maximum Ps of 2604 ± 86 mL H2/L substrate was achieved at an initial cell concentration of 224 mg dry cell/L, tCOD/TN ratio of 49.87 and CuSO4 concentration of 13.33 mg/L. The main soluble metabolite products were butyric and acetic acids. The Ps obtained when the hydrolysate was supplemented with SHW (2604mL ± 86 mL H2/L substrate) was comparable to the Ps obtained when it was supplemented with yeast extract at the same tCOD/TN (2802 ± 87 mL H2/L substrate). This result suggests that SHW can be used to replace the costly nitrogen source.