Sustainable electric power generation from live anaerobic digestion of sugar industry effluents using microbial fuel cells

Abstract

Environmental problems related to water sanitation are not restricted to developing countries alone, but it is the most basic human and environmental need all around the world. Waste water from the sugar industry is rich in organic matter, which, when indiscriminately disposed of or inadequately treated, leads to soil and water pollution. Eliminating these pollutants is the need of the hour and hence promising technologies like microbial fuel cells (MFCs) are of great relevance to mitigate environmental pollution. Water sanitation coupled with electricity generation in MFCs is always appreciated. MFCs are fuel cells which convert chemical energy to electrical energy by microbial actions. The present study couples crude sugarcane effluent along with anaerobic sludge to enhance energy recovery as well as waste water treatment. The performance of MFCs in power generation with varying input factors is predicted and validated using artificial neural networking to tune the optimum conditions for the proper functioning of MFCs. The tuned conditions provide more negativity to the bacterial cells in the system and results in efficient bacteria–electrode interaction. This reduces the internal resistance of the system to 1.63 × 10³ Ω cm² and thus causes faster transfer of electrons to the electrodes. This results in the achievement of a high power density of 8314 mW m⁻², which is approximately twice as high as that obtained from crude sugarcane effluent. In the present study, we also explore the microbial diversity of the biofilm at the anode of a tuned MFC. A detailed phylogenetic analysis reveals the presence of 82% exoelectrogens and 18% methanogens with the dominance of members of Firmicutes, which favor sustained electricity production in the present system. The more realistic information about the developed sugar effluent-based MFC technology in commercialization is evident from the calculated low cost–benefit ratio. Thus the authors proved the sustainability and feasibility of the developed MFC. This work is a tangible step towards the implementation of such MFC technology in the sugarcane or other food industry for a waste-free sustainable society.