Utilization of Microalgae Cultivated in Palm Oil Mill Wastewater to Produce Lipid and Carbohydrate by Employing Microwave- Assisted Irradiation

Background: Palm oil mill effluent (POME) is dominant agroindustrial wastewater in Indonesia and Malaysia. Some kind of microalgae can utilize the wastewater as media of cultivation, and produce value-added compounds. However, the production of lipid and carbohydrate from microalgae cultivated on untreated POME medium were not clearly reported. Objective: to cultivate Chlorella vulgaris, Dunaliella salina, and Spirulina platensis on a media containing the different concentration of POME to produce lipid and carbohydrate by employing a microwave assisted method. Methods: microalgae were cultivated on different POME concentration (10-30% v/v) to replace synthetic medium at 13 days of cultivation. The microwave-irradiation was employed on lipid extraction, carbohydrate hydrolysis, and fatty acid methyl ester (FAME) formation. GC/MS was employed to analyze the fatty acid and hydrocarbon compound on the lipid. Chemical oxygen demand (COD) on the medium was analyzed before and after the cultivation. Results: Growth rate of the microalgae were decreased along with the increasing of POME addition except for C.vulgaris. The lipid and carbohydrate content were influenced by POME except for D. salina. The microwave-assisted method successfully enhanced carbohydrate yield in the hydrolysis process. The highest productivity was found on C.vulgaris with 12.60 mg/L/d lipid, and 11.22 mg/L/d carbohydrate, and remove 74% COD content. The highest FAME content was recorded from S. platensis. Conclusion: In summary, the microalgae can utilize POME wastewater in low concentration under mixotrophic condition. The microwave-assisted method seems promising in the integrated biorefinery process of producing value-added compound from microalgae.