Valorization of food waste to multiple bio-energies based on enzymatic pretreatment: A critical review and blueprint for the future

Abstract

Food wastes were mainly composed of lipids, carbohydrates and proteins, and they could be converted to different bio-energies. The state-of-art of multiple bio-energies production from food waste and enzymatic pretreatment were reviewed with problems being summarized. In situ-produced enzyme from food waste was looked as an economical alternative to expensive commercial enzymes. Based on summarization, an integrated process for simultaneous biodiesel, bioethanol, and biomethane production from food waste pretreated by in-situ produced enzyme was proposed as a blueprint for valorization of food waste to multiple bio-energies. The results of mass and energy balances of this process showed that enzymatic pretreatment could save about 48% energy consumption of hydrothermal treatment for lipid separation, the net energy output could be as high as 3009 MJ/t food waste, and the organic solid contents of food waste could be reduced by more than 94%. Recommendations for future studies were proposed at last.