Techno-economic assessment of an integrated algae-based biorefinery with palm oil mill

Abstract

Palm oil production has become a major contributor to the economy of several tropical countries where palm oil trees can be grown commercially, particularly due to its high productivity and capability to yield more oil from less land area. Palm oil milling activities generate wastewater that is highly polluted and requires to be treated before it can be discharged into the environment. The wastewater generated from the milling activities is defined as palm oil mill effluent (POME). Studies have shown that algae can be grown using wastewater. The utilisation of algae for POME treatment coupled with biogas facilities in the palm oil mill can simultaneously remediate the wastewater and reduce the cost for nutrient and freshwater supplies required for algae growth. This paper investigates the techno-economic potentials of an integrated algae-based biorefinery with palm oil mill. The proposed superstructure for the integrated bio-refinery includes carbon sequestration, algae growth with wastewater integration from biogas effluent, algae harvesting and dewatering, algal oil extraction, algal oil upgrading, and residual algae processing. Based on the techno-economic analysis conducted, the results show that the processing pathway which consists of open pond, flocculation with alum and centrifugation, drying, solvent extraction with hexane/isopropanol, base catalysed transesterification of algal oil, and combustion of residual algae produces the highest profit of 7.73 x 105 USD/y.