During the start-up stage, stable power generation was
obtained after two cycles. Fig. 2 showed the output voltage
(R = 1000 V) steadily increased from 100 mV at 232.4 h to about
240 mV at 233.5 h when the anode chamber was refilled with the
fresh anode medium (point A). And then the synthetic wastewater
containing 50 ppm potassium dichromate (pH 2) was refilled the
cathode chamber and N2 was continuously sparged at a flow rate of
80 ml/min (point B). This led to a substantial increase of voltage
to 605 mV. Such a sharp increase of voltage was most likely due
to the high redox potential (1.33 V) of Cr2O7
2 in acidic conditions
as illustrated in Eq. (1). The SEM images (Fig. 3) shows that
anodic electrode surface is covered by bacilliform bacteria which
are responsible for electron transfer and current generation in
the MFC.