Comparative Study of Freely Suspended and Immobilized Microalgae for Palm Oil Mill Effluent (POME) Treatment

Palm Oil Mill Effluent (POME) generated as by-product during clarification and purification process to produce Crude Palm Oil (CPO), contains harmful heavy metals, high Chemical Oxygen Demand (COD), Biochemical Oxygen Demand (BOD) and mineral contents such as Nitrogen, Phosphorous which can cause severe pollution to the environment. To encounter this problem, the utilization of microalgae can solve the problem of POME remediation. However, the major challenge to utilizing algae is the challenges faced in harvesting and drying the algae after the remediation process. In this research, freely suspended and immobilized microalgae species Nannochloropsis Oculata and Chlorella sp. has been used. The main objective of this study was to evaluate the potential of immobilized microalgae for POME treatment. The changes of parameters in COD, BOD, TN and heavy metals have been tested after 8 and 16 days of treatment. The influence of different concentrations of filtered and centrifuged POME in sea water (1, 5, 10, 15 and 20%) on microalgae cell growth, lipid contents and POME remediation has been investigated. Immobilized Chlorella sp. and Nannochloropsis Oculata had enhanced cell growth and lipid accumulation at 10% POME with maximum specific growth rate (0.21 d-1, 0.108 d-1), doubling time (3.96 d-1, 6.41 d-1) and lipid content (31.67%, 31.45%), respectively, after 16 days of shake flask cultivation. Immobilized microalgae cultivation with POME media also enhanced the removal of heavy metals such as Fe(III) and Mn(II), COD (91-99%), BOD (82-99), and TN (78-98%).