Journal of Energy Bioscience 2024, Vol.15, No.5, 289-300 http://bioscipublisher.com/index.php/jeb 289 Research Insight Open Access Process Study on Microbial Conversion of Kitchen Waste into Biodiesel Jiaju Wang, Qi Lin, Wei Zhou Biotechnology Research Center, Cuixi Academy of Biotechnology, Zhuji, 311800, China Corresponding email: wei.zhou@cuixi.org Journal of Energy Bioscience, 2024, Vol.15, No.5 doi: 10.5376/jeb.2024.15.0027 Received: 19 Jul., 2024 Accepted: 29 Aug., 2024 Published: 17 Sep., 2024 Copyright © 2024 Wang et al., This is an open access article published under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Preferred citation for this article: Wang J.J., Lin Q., and Zhou W., 2024, Process study on microbial conversion of kitchen waste into biodiesel, Journal of Energy Bioscience, 15(5): 289-300 (doi: 10.5376/jeb.2024.15.0027) Abstract This study explores the microbial process of converting kitchen waste into biodiesel, with a focus on identifying efficient microbial strains and optimizing the conversion process. The study identified several key findings. First, the filamentous fungi Mortierella isabellina NRRL 1757 demonstrated high lipid productivity and versatility when grown on various waste substrates, including glycerol, orange peel extract, and ricotta cheese whey, with lipid productivities of 0.46, 1.24, and 0.91 g/(L d), respectively. Additionally, the fatty acid profile of the produced lipids was highly compatible with biodiesel production, similar to commonly used palm and Jatropha oils. Another significant discovery was the use of the algae strain Golenkinia sp. SDEC-16, which showed the highest power density, biomass concentration, and total lipid content when used in microbial fuel cells with kitchen waste anaerobically digested effluent, achieving a lipid content of 38%. Furthermore, the bacteriumKlebsiella variicola TB-83 was found to produce ethanol efficiently from biodiesel-derived glycerol under alkaline conditions, with a maximum ethanol production of 9.8 g/L. The findings of this study suggest that microbial conversion of kitchen waste into biodiesel is a viable and sustainable approach. The identified microbial strains, particularly Mortierella isabellina NRRL 1757 and Golenkinia sp. SDEC-16, show great potential for high lipid production, making them suitable candidates for biodiesel manufacturing. Additionally, the ability of Klebsiella variicolaTB-83 to produce ethanol from biodiesel waste further supports the feasibility of integrating waste-to-energy processes. Keywords Microbial conversion; Kitchen waste; Biodiesel; Mortierella isabellina; Golenkinia sp.; Klebsiella variicola; Lipid production; Ethanol production 1 Introduction Kitchen waste, a significant component of municipal solid waste, is rich in organic materials that can be repurposed for various applications. The valorization of kitchen waste not only addresses waste management issues but also provides a renewable resource for biofuel production. The organic content in kitchen waste, such as carbohydrates, proteins, and lipids, makes it an ideal substrate for microbial processes aimed at producing biodiesel (Cheirsilp and Louhasakul, 2013; Carmona-Cabello et al., 2020; Zhang et al., 2020). The global increase in waste generation poses substantial challenges for waste management systems. Traditional disposal methods, such as landfilling and incineration, contribute to environmental pollution and greenhouse gas emissions. Concurrently, the reliance on fossil fuels for energy production exacerbates climate change and depletes finite resources. Integrating waste management with renewable energy production, such as converting kitchen waste into biodiesel, offers a sustainable solution to these intertwined challenges (Almeida et al., 2012; Zheng et al., 2012; Li et al., 2013). Biodiesel is a biodegradable, renewable fuel that can be used in conventional diesel engines with minimal modifications. It offers several environmental benefits, including reduced emissions of carbon monoxide, particulate matter, and unburned hydrocarbons. Biodiesel production from waste materials, such as kitchen waste, further enhances its sustainability by utilizing low-cost feedstocks and reducing waste disposal issues. The fatty acid profiles of microbial lipids derived from waste are comparable to those of traditional plant oils, making them suitable for biodiesel production (Cheirsilp and Louhasakul, 2013; Srivastava, 2019; Carmona-Cabello et al., 2020).
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