Strategies for improving biogas production of palm oil mill effluent (POME) anaerobic digestion: A critical review

The sustainable practice in the palm oil industry, which provides the global most demanded edible oil has a long way to be well developed. One of the most challenging problems is the management of palm oil mill effluent (POME). The current most applied treatment method of POME is anaerobic ponding system, which is not environmental friendly. This is because a large amount of the generated greenhouse gases is not captured, but escaped into the atmosphere. It is so critical to encourage the sustainable practice of closed anaerobic digestion system in the palm oil industry for utilizing POME to generate renewable biogas. For this, theoretical and technological studies of improving biogas production by POME anaerobic digestion are essential as the supporting research. Therefore, this paper will firstly discuss the influential factors of anaerobic digestion on the biogas production, then review the strategies which had been applied to improve the biogas production of POME anaerobic digestion. A lot of efforts have been made to emphasize on the co-digestion and biomass retention improvement within the digester. Other studied strategies include the POME pretreatment, additives supplementation, and bioreactor modification. By operating the anaerobic digester successfully, these applied strategies had positive response to the biogas production. However, the effectiveness of these strategies cannot be compared directly with each other, due to the different operating conditions. Overall, the studied strategies seem to be insufficient and lack of breakthrough.