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Effects of electrodes geometric area on wastewater treatment and power generation in microbial fuel cell (MFCs)

pubblicazioni - Poster

Effects of electrodes geometric area on wastewater treatment and power generation in microbial fuel cell (MFCs)

Power generation in microbial fuel cells (MFCs) depend on the biochemical reactions (electron generation) carried out by biofilms attached on anode surfaces and the electrochemical reactions (electron acceptance) carried out on cathode surfaces. This study focused on the effects of anode and cathode area on power generation and wastewater treatment in MFCs. Three MFCs with different anode geometric areas (10, 20 and 40 cm2) were examined. Plain carbon cloth was used as anode and platinum-coated carbon cloth (Pt loading 0.09 mgPt/cm2) as cathode. Two different cathode geometric areas (3 and 6 cm2) were tested. The single chamber MFCs (volume 0.13 L) was inoculated with raw wastewater. Sodium acetate was added periodically as substrate in two concentrations (1 and 3 g/L). The results showed that the increase in anode areas (2-10 cm2) gave notable increase (20%) in power generation and wastewater treatment (Chemical Oxygen Demand: COD removal) (Table 1), which was probably due to a higher amount of the biofilm growing on a larger anode surface. Further increase in anode area (10-20 cm2) caused only the 4-9 % increase in the COD removal and 5-9% increase in daily COD removal rate. Slight increase in power generation and COD removal occurred at the anode area of 40 cm2. This indicated that the power generation and wastewater treatment reach a plateau after anode areas increased to certain levels. The double cathode area (3 to 6 cm2) provided 5% increase in power generation and 10% increase in COD removal. This indicated that increasing cathode areas could slightly enhance the capability of electron acceptance in MFCs. In addition, this study showed that higher COD concentrations (1-3 g/L) led to higher power generation. This study emphasizes the importance of choosing an optimum cathode/anode area rate for high power generation and that of larger anode area to increase the COD removal. It was shown that anode area might be a limiting factor in MFCs, and an increase in the anode area resulted in higher power generation, COD removal efficiency. This study revealed a new approach to optimize anode and cathode areas for power generation and wastewater treatment in MFCs.

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