ABSTRACT
High organic content in palm oil mill effluent (POME) makes it a good commodity for biogas production, specifically methane, through anaerobic digestion. In the early days, anaerobic digestion of POME was much concentrated on a single-stage treatment system but the treatment paradigm was shifted to a two-stage treatment for the enhancement and more consistent methane production. The shifting towards two-stage treatment systems yielded another valuable renewable energy, i.e., hydrogen. Nevertheless, hydrogen generation fluctuated owing to the lignocellulosic compounds that resisted the conversion. This leads to the utilization of advanced oxidation processes as a pretreatment to elevate the biodegradability degree of POME. Therefore, the aim of this chapter is to provide the current advances and fundamental aspects of the pre-treatment methods employed in enhancing the biogas production during anaerobic digestion of POME. Briefly, two commonly studied processes are ozonation and Fenton treatment. Fundamental theory suggests that both oxidation processes generate hydroxyl radicals that react non-selectively with lignocellulosic compounds thereby intensifying the biodegradation of organics. However, only ozonation pretreatment was investigated for the biogas production efficiency. Fenton treatment studies emphasized on the organics and color removal. Whether it is ozonation or Fenton, the dosage employed would be the determining factor in the pretreatment of POME.
