Significance of water level in affecting cathode potential in electro-wetland

Abstract Bioelectricity production is always restricted by the limited cathode performance in integrated constructed wetland-microbial fuel cells (termed as electro-wetlands). Generally, the cathodes are located at the air-water interface for an oxygen-rich environment. However, its performance may still be unsatisfactory, resulting in a low bioelectricity production. After a long term trial in previous study, we recognised that the position of the electron collector in the cathode significantly affected the bioelectricity production in electro-wetlands. In this study, two cathode configurations of electron collector at the air-water interface and above water level for 1.5 cm, respectively, were evaluated for cell voltage and power density in a vertical up-flow electro-wetland. Results showed that maximum total power density was increased from 31 mW/m 2 to 165 mW/m 2 when the cathode electron collector was changed from the air-water interface to 1.5 cm above water level, proving that cathode configuration is the key factor in bioelectricity production.