Effects of electrode gap and wastewater condition on the performance of microbial fuel cell coupled constructed wetland

The effects of electrode gap, PB solution concentration and azo dye on the wastewater treatment and electricity generation of microbial fuel cell coupled constructed wetland (CW-MFC) were studied. The electrode gap had obvious influence on the decolorization, while the influence of PB concentration on the decolorization was not obvious. The best decolorization efficiency was 91.05% and was gained when the electrode gap was 13.2 cm. The smaller the electrode gap, the smaller the ohmic resistance. However, a too small electrode gap would reduce the electricity generation. The best PB concentration in this study was 50 mM. In the glucose group, when the PB concentration was 50 mM, the power density was enhanced to 0.38 W/m3, while the PB concentration was 5 mM, the power density was only 0.14 W/m3. In the ABRX3 group, when the PB concentration was 50 mM, the power density was 0.18 W/m3, while when the PB concentration was 5 mM, the power density was 0.12 W/m3. The electricity generation performance of the CW-MFC was enhanced with an increase in running time. Long-time running CW-MFC got a higher cathode potential and a smaller internal resistance.