Effect of different yeast extract concentration in membrane-less microbial fuel cell (ML-MFC) for electricity generation using food waste as carbon sources

Abstract

Electricity constitutes one of the basic energies of our everyday life and approximately 14 % of the global population does not have the access to electricity. An abundance of waste is generated daily wherein food waste constitutes 45 % of the composition. A mediator-less and membrane-less single-chambered microbial fuel cell (ML-MFC) has the potential to serve as a cost-effective solution for food waste treatment and electricity power generation at no additional cost for the substrate. Food waste from E-Idaman Sdn. Bhd. Kedah was utilised in this study to generate electrical energy while focusing on the effect of different yeast extract concentrations on the performance of the ML-MFC. Electrogenic bacterial (EB) culture employed in this study acted as a catalyst for the power generation and was isolated from a previous ML-MFC study. The proximate analysis of food waste observed carbon constituting the greatest composition at 30.02 %. From the conducted preliminary study which compared three different strains of EB to be introduced in the ML-MFC, Bacillus subtillis sp. exhibited the highest specific growth rate, μ, (0.117 g. L−1/h) and shortest doubling time, Td, (5.93 h). One-factor-at-a-time (OFAT) method was utilised to evaluate the performance of the ML-MFC. 15 g/L yeast extract concentration obtained the greatest power density (628.05 × 106 mW/m2), substrate degradation efficiency (12.3 %), COD removal (99 mg/L) and biomass (44.32 mg/L). This showcased that the addition of extra yeast extract concentration into the food waste had boosted the efficiency of EB’s growth resulting in greater consumption of carbon source (removed COD value; bioremediation) in the food waste.