Synergizing food waste management and microalgae biorefinery for bioenergy production: Recent advance on direct and indirect conversion pathways

Food waste is a persistent global environmental issue that contributes to global warming and climate change by releasing significant amounts of greenhouse gases as it decomposes in landfills. Converting food waste into bioenergy could serve as a sustainable solution. Direct conversion of food waste through methods like anaerobic digestion, fermentation, and pyrolysis, produces diverse energy products. Besides, the indirect approach of cultivating microalgae using food waste as alternative medium provides a sustainable solution, as microalgae can assimilate nutrient-rich components (e.g., nitrogen, phosphorus, and carbon), converting them into valuable biomass that can be processed into biofuels. This review work provides a holistic review of food waste-to-energy conversion methods, both direct and indirect, evaluating their feasibility and benefits. Specifically, a comprehensive analysis of using microalgae grown on food waste for biofuel production is provided, offering insights into how the method could effectively address both environmental and energy crises, and contribute to sustainable development goals. Future research should focus on enhancing conversion process efficiency, optimizing microalgae bioprocess, and scaling-up these technologies to industrial levels, while addressing challenges such as economic feasibility, supportive policies, and robust supply chains. Collaboration among industry, academia, and government is essential to boost the global implementation of these technologies.