Reactivation of Preserved Aerobic Granular Sludge Using Palm Oil Mill Effluent

Generation of wastes in the form of palm oil mill effluent (POME) is unavoidable due to increase in oil palm development worldwide. Direct discharge of POME into receiving water bodies is strongly discouraged due to high chemical and biochemical oxygen demand concentrations, respectively. Aerobic granulation technology features microbial aggregates generated following immobilization and cell-to-cell adhesion of multiple bacteria. Primary observation has shown that bacterial aggregates may survive for a long period of time at 4°C and possess the capability to recover their metabolic activities upon reactivation. In this study, preserved aerobic granular sludge previously developed using POME was reactivated in modified laboratory scale sequencing batch reactors (SBRs) termed as R1 and R2 which were operated at fixed OLR of 2.5 kgCOD m -3 d -1 . R1 was operated with the preserved granules while R2 was the control reactor. Microscopic examinations have shown good microstructure of aggregates in R1 as compared to R2. Good chemical oxygen demand (COD) removal of 75% was achieved in R1 as compared to 68% in R2 indicating successful reactivation of aerobic granules despite 3 months preservation period.