Microbial fuel cells equipped with an iron-plated carbon-felt anode and Shewanella oneidensis MR-1 with corn steep liquor as a fuel.

A single chamber type microbial fuel cell (MFC) with 100 mL of chamber volume and 50 cm2 of air-cathode was developed in this study wherein a developed iron-plated carbon-felt anode and Shewanella oneidensis MR-1 were used. The performance of the iron-plated carbon-felt anode and the possibility of corn steep liquor (CSL) as a fuel, which was the byproduct of corn wet milling and contained lactic acid, was investigated here. MFCs equipped with iron-plated or non-plated carbon-felt anodes exhibited maximum current densities of 443 or 302 mA/m2 using 10 g/L of reagent-grade lactic acid, respectively. In addition, using centrifuged CSL without insoluble ingredients or non-centrifuged CSL as a fuel, the maximum current densities of the MFCs with iron-plated carbon-felt anode were 321 or 158 mA/m2, respectively. This report demonstrated the effect of iron-plated carbon-felt anode for electricity generation of MFC using S. oneidensis MR-1 and the performance of CSL as a fuel.

Starch-fueled microbial fuel cells by two-step and parallel fermentation using Shewanella oneidensis MR-1 and Streptococcus bovis 148.

Shewanella oneidensis MR-1 generates electricity from lactic acid, but cannot utilize starch. On the other hand, Streptococcus bovis 148 metabolizes starch and produces lactic acid. Therefore, two methods were trialed for starch-fueled microbial fuel cell (MFC) in this study. In electric generation by two-step fermentation (EGT) method, starch was first converted to lactic acid by S. bovis 148. The S. bovis 148 were then removed by centrifugation, and the fermented broth was preserved for electricity generation by S. oneidensis MR-1. Another method was electric generation by parallel fermentation (EGP) method. In this method, the cultivation and subsequent fermentation processes of S. bovis 148 and S. oneidensis MR-1 were performed simultaneously. After 1, 2, and 3 terms (5-day intervals) of S. oneidensis MR-1 in the EGT fermented broth of S. bovis 148, the maximum currents at each term were 1.8, 2.4, and 2.8 mA, and the maximum current densities at each term were 41.0, 43.6, and 49.9 mW/m2, respectively. In the EGP method, starch was also converted into lactic acid with electricity generation. The maximum current density was 140-200 mA/m2, and the maximum power density of this method was 12.1 mW/m2.