Biogas production by an anaerobic digestion process from orange peel waste and its improvement by limonene leaching: Investigation of H2O2 pre-treatment effect

Abstract

ABSTRACTOrange peel waste is considered as an important feedstock for anaerobic digestion to generate bio-energy such as bio-hydrogen and bio-methane; however, its use as an energy source is still not important worldwide. Therefore, in the current study, the biochemical methane potential test was carried out to estimate the biogas production from orange peel waste by using an anaerobic digestion process in the thermophilic phase (T = 55°C). In order to investigate the antimicrobial and the inhibiting effect of limonene contained in orange peels on biogas production two experimental setups were operated simultaneously using de-oiled and crude orange peel wastes, respectively. For further enhancement of the biogas production, a pre-treatment was applied using hydrogen peroxide (H2O2) at different concentrations up to the optimum value to increase soluble chemical oxygen demand (COD). The obtained results showed an important increase in biogas production: From 170 mL.gTVS−1 for the untreated sample to 750 mL.gTVS−1 after pre-treatment, and the composition analysis of the biogas indicated that average methane yields represent up to 50% of the total production. This increase was observed after steam distillation and was attributed to the removal of the antimicrobial compound.