Oil palm empty fruit bunch (EFB) is a high-volume lignocellulosic residue of the palm oil industry whose basic physical and chemical properties were established in the first article of this series. Building on that baseline, this article reports field-scale ("bucket") testing of a multi-stage process to convert EFB fibre into a soluble hydrolysate: hot-water oil stripping, alkaline (sodium hydroxide) hydrolysis, water washing, and enzymatic saccharification, followed by filtration and concentration. Testing was performed on ~1 kg samples of fresh EFB collected at a working mill in West Kalimantan, Indonesia, and progress was tracked as chemical oxygen demand (COD). Hot-water stripping at 100 C released soluble COD up to ~23,000 mg/L; combining hot-water stripping with 1.0 % NaOH in a single stage gave ~43,500 mg/L (CODt). Alkaline-stage soluble COD rose with hydroxide concentration, from 10,780 mg/L at 0.5 % to 30,800 mg/L at 2.0 % NaOH. After enzymatic hydrolysis (cellulase, 50 C, 72 h, COD-corrected for the acetic acid used in pH adjustment), the cellulose-to-glucose conversion yield reached a maximum of 16.3 % at 2.0 % NaOH; the yields were re-derived independently from the raw COD data and confirmed. Severity-factor analysis (log R0 = 1.3-1.8) shows the process operated at low pre-treatment severity, which accounts for the modest sugar yield relative to literature routes using high-severity (~200 C) hydrothermal pre-treatment. The cost-benefit of the process - the balance between the recoverable COD or sugar and the energy, chemical and capital cost required to obtain it - is the subject of a subsequent article in this series.
Spagnuolo et al. (Wed,) studied this question.