New insight of combined hydrothermal and ultrasonic pretreatment for methane production from anaerobic digestion of food waste

ABSTRACT

Food waste (FW) biotransformation into bioenergy has garnered a lot of scientific interest as a way to address the energy crisis and trash disposal issues. FW is converted into biogas, a gaseous combination of biomethane and carbon dioxide. In order to valorize FW, anaerobic digestion (AD) with combined pretreatment (hydrothermal (HT) and ultrasonic (US)) is used as a potential method. Three digesters were investigated: the control (unpretreated), HT(121°C) + US, and HT(134°C) + US, respectively. Based on changes in the combined pretreatment conditions, the paper assessed the methane productivity. Furthermore, kinetic modeling was evaluated with six kinetic models. The results show that the HT pretreatment at 121°C combined with US improves the volatile solid (VS) removal to 73 ± 5% and the methane yield to 529.7 ± 11 NmL/gVS. Both the Transference model and the first order have the greatest fits in terms of R², and they also have the best fits in terms of relative errors, and methane production rate, respectively. The combined pretreatment has a positive impact on increasing methane yield as well as stabilizing the anaerobic digestion process.

GRAPHICAL ABSTRACT

KEYWORDS:

• Anaerobic digestion
• combined pretreatment
• food waste
• hydrothermal pretreatment
• ultrasonic pretreatment

Acknowledgements

The authors of this research study are much appreciated by the Moroccan Ministry of Higher Education for Scientific Research for providing financing for it under the PPR2 priority project.

Disclosure statement

No potential conflict of interest was reported by the author(s).