The effects of C. vulgaris inoculum density on the MFC performance
were compared on the polarization and power output
behavior (Fig. 4). The control-MFC (without inoculating algae) gave
a highest voltage of 65 mV (Fig. 4a). This result was lower than the
previous experiments which reported that the highest voltages
were more than 100 mV at different conditions with enough oxygen
supply (Mohan et al., 2010; Goud and Mohan, 2011). Among
six treatments, control-MFC has the lowest bioelectricity production
performance compared with other groups. The highest voltage
increased to around 170 mV in the presence of 150 mg L1
C. vulgaris. However, when the initial inoculum density increased
to 200 and 250 mg L1, the highest voltage dropped to 117 and
98 mV, respectively. The changes of power density also exhibited