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Electricity generation from rice bran in microbial fuel cells

View Article: PubMed Central - PubMed

ABSTRACT

Background: Rice bran is a by-product of the rice milling process and mostly discarded in Japan. Although many studies have shown that microbial fuel cells (MFCs) are able to generate electricity from organic wastes, limited studies have examined MFCs for generating electricity from rice bran.

Findings: Laboratory-scale single-chamber MFCs were inoculated with paddy field soil and supplied with rice bran for examining electricity generation. Power outputs and microbiome compositions were compared between MFCs containing pure water as the liquid phase (MFC-W) and those containing mineral solution (MFC-M). Polarization analyses showed that both MFCs successfully generated electricity with the maximum power densities of 360 and 520 mW m−2 (based on the projected area of anode) for MFC-W and MFC-M, respectively. Amplicon-sequencing analyses revealed that Trichococcus and Geobacter specifically occurred in anode biofilms in MFC-W and MFC-M, respectively.

Conclusions: The results suggest that rice bran is a feasible fuel by itself for generating electricity in MFCs.

No MeSH data available.


Changes in E values during the operation of MFC-W and MFC-M. Rice bran was added at time points indicated with arrows
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Fig1: Changes in E values during the operation of MFC-W and MFC-M. Rice bran was added at time points indicated with arrows

Mentions: MFC-W and MFC-M were operated for approximately 130 days (Fig. 1), and, during the operation, rice bran was added when E dropped down to below 0.1 V (once every 10–20 days). After an initial acclimatization period (approximately 30 days), the addition of rice bran resulted in immediate increases of E up to over 0.5 V. We conducted the polarization analysis when E was over 0.5 V, and typical polarization and power curves are shown in Fig. 2a. The average values of Pmax were compared between MFC-W and MFC-M (Fig. 2b), showing that MFC-M generated significantly higher outputs than MFC-W. However, it is also noteworthy that MFC-W (containing only rice bran) generated the substantial level of output, suggesting that rice bran is a feasible substrate by itself for generating electricity in MFCs. In MFCs, microbes oxidize organic matter and release electrons that are transferred to anodes, resulting in electricity generation (Watanabe 2008). The present study shows that rice bran is a potent organic substrate. In addition, it is likely that minerals and vitamins contained in rice bran stimulated the growth of microbes involved in electricity generation in MFCs.Fig. 1


Electricity generation from rice bran in microbial fuel cells
Changes in E values during the operation of MFC-W and MFC-M. Rice bran was added at time points indicated with arrows
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5120057&req=5

Fig1: Changes in E values during the operation of MFC-W and MFC-M. Rice bran was added at time points indicated with arrows
Mentions: MFC-W and MFC-M were operated for approximately 130 days (Fig. 1), and, during the operation, rice bran was added when E dropped down to below 0.1 V (once every 10–20 days). After an initial acclimatization period (approximately 30 days), the addition of rice bran resulted in immediate increases of E up to over 0.5 V. We conducted the polarization analysis when E was over 0.5 V, and typical polarization and power curves are shown in Fig. 2a. The average values of Pmax were compared between MFC-W and MFC-M (Fig. 2b), showing that MFC-M generated significantly higher outputs than MFC-W. However, it is also noteworthy that MFC-W (containing only rice bran) generated the substantial level of output, suggesting that rice bran is a feasible substrate by itself for generating electricity in MFCs. In MFCs, microbes oxidize organic matter and release electrons that are transferred to anodes, resulting in electricity generation (Watanabe 2008). The present study shows that rice bran is a potent organic substrate. In addition, it is likely that minerals and vitamins contained in rice bran stimulated the growth of microbes involved in electricity generation in MFCs.Fig. 1

View Article: PubMed Central - PubMed

ABSTRACT

Background: Rice bran is a by-product of the rice milling process and mostly discarded in Japan. Although many studies have shown that microbial fuel cells (MFCs) are able to generate electricity from organic wastes, limited studies have examined MFCs for generating electricity from rice bran.

Findings: Laboratory-scale single-chamber MFCs were inoculated with paddy field soil and supplied with rice bran for examining electricity generation. Power outputs and microbiome compositions were compared between MFCs containing pure water as the liquid phase (MFC-W) and those containing mineral solution (MFC-M). Polarization analyses showed that both MFCs successfully generated electricity with the maximum power densities of 360 and 520 mW m−2 (based on the projected area of anode) for MFC-W and MFC-M, respectively. Amplicon-sequencing analyses revealed that Trichococcus and Geobacter specifically occurred in anode biofilms in MFC-W and MFC-M, respectively.

Conclusions: The results suggest that rice bran is a feasible fuel by itself for generating electricity in MFCs.

No MeSH data available.