The production of acetone-buta nol-ethanol from oil palm wastes by Clostridium acetobutyricum and utilisation of the wastewater for polyhydroxybutyrate production

Abstract

Oil palm wastes including palm oil mill effluent (POME), empty fruit bunch (EFB), palm pressed fibre (PPF) and palm kernel shell (PKS) were collected and utilised as substrate for acetone-butanolethanol (ABE) production. Each waste was pre-treated before use. POME was centrifuged to obtain the supernatant. EFB, PPF and PKS were pre-treated by steam explosion and hydrolysed by cellulase from Aspergillus Niger. The cultivation of Clostridium acetobutyricum under 180 ml of diluted POME supplemented with 10 g litre-1 of pre-treated EFB gave the maximum ABE and total acids at 3.8 g litre-1 and 2.0 g litre-1, respectively. The ABE production was then recovered by distillation. The wastewater after distillation was collect and characterised. Wastewater contained organic acid profiles such as acetic acid, particularly propionic and butyric acid in the amount of 0.1-1.0 g litre-1. Acetic and butyric present in wastewater can possibly be used for polyhydroxybutyrate (PHB) production. Therefore, the wastewater was utilised as substrate for PHB production by Cupriavidus necator. The maximum PHB (48.4% of dry cell weight, DCW) was obtained after 60 hr of cultivation. The polymer was identified by gas chromatography to be PHB when compared to commercially available product.