Development and utilization of aerobic granules for the palm oil mill (POM) wastewater treatment

The high COD and turbidity level of palm oil mill (POM) wastewater has been the driving force to find an efficient treatment system. In this work, biological and adsorption methods are integrated and used to treat the POM wastewater. In biological treatment, aerobic granules are developed and used in the sequencing batch reactor (SBR), whereas in adsorption treatment, the waste aerobic granules (WAG) are utilized as adsorbent. Response Surface Methodology (RSM) has been used to model and optimize the adsorption of biologically treated POM wastewater. Aerobic granules took 110 days to appear and the average diameter was 0.9 mm (with a maximum value of 3.1 mm). The aerobic granules are able to remove 88% of the influent COD at organic loading rate (OLR) of 3.0 kg COD/m3 day. The increase of OLR to 6.0 kg COD/m3 day did not affect the COD removal efficiency and the aerobic granules immediately responded to the OLR increase. The adsorption system revealed that the 21% of the remaining COD (of the biologically treated POM wastewater) and almost 99% of the turbidity were removed. At optimum point (3.28 cm of bed height and 2.13 ml/min flow rate), the amount of COD and turbidity removed are 21% and 96%, respectively.

► Aerobic granules were developed in palm oil mill (POM) wastewater for the first time.
► No pH adjustment was done on the POM wastewater (the sole feed to reactor).
► Aerobic granules appear within 110 days.
► Up to 93% COD removal achieved in SBR.
► Waste aerobic granules used to adsorb remaining COD and turbidity.