Co-pyrolysis of Palm Empty Fruit Bunch and Palm Kernel Shell with Palm Oil Mill Effluent (POME) Sludge

Abstract

In Malaysia, the largest contributor to biomass is from the palm oil sector. Therefore, palm-based biomass has been extensively studied for bioenergy applications. Fast pyrolysis of biomass provides a liquid fuel called bio-oil, which has many potential uses. However, a low pH of bio-oil made a challenge to utilize as it is. Therefore, in this study, empty fruit bunch (EFB) and palm kernel shell (PKS) were subjected to co-pyrolysis with POME sludge individually. The reason behind this was that the bio-oil derived from EFB and PKS are acidic, whereas bio-oil from POME sludge is basic. Hence, it was hypothesised that through the co-pyrolysis, bio-oil with lower acidity might be obtained. Chemical characterization revealed that POME sludge contains alkali and alkaline earth metals (AAEMs), which may play a significant role in influencing the weight loss of EFB and PKS, also the bio-oil yield. The co-pyrolysis of EFB and PKS with POME sludge at different ratios were initially carried out via thermogravimetric analysis (TGA). Results showed that for the co-pyrolysis of PKS, a positive synergistic effect was observed when 50 wt.% of POME sludge was employed. Then, pyrolysis and co-pyrolysis experiments were carried out in a fixed bed reactor at 600°C. The bio-oil yield obtained from PKS was 44.5 ± 0.7 wt.%. In contradiction to TGA studies, the bio-oil yield for co-pyrolysis of PKS and POME sludge showed a negative synergistic effect.