A successful design

previously adapted for treatment of complex wastewaters in a microbial fuel cell (MFC)

was used to fabricate two MFCs

with a few changes for cost reduction and ease of construction. Performance and electrochemical characteristics of MFCs were evaluated in different environmental conditions (in complete darkness and presence of light)

and different flow patterns of batch and continuous in four hydraulic retention times from 8 to 30 h. Changes in chemical oxygen demand

and nitrate and phosphate concentrations were evaluated. In contrast to the microbial fuel cell operated in darkness (D-MFC) with a stable open circuit voltage of 700 mV

presence of light led to growth of other species

and consecutively low and unsteady open circuit voltage. Although the performance of theMFC subjected to light (L-MFC)was quite lowand unsteady in dynamic state (internal resistance = 100 Ω

power density = 5.15 W·m

-3

)

it reached power density of 9.2 W·m

-3

which was close to performance of D-MFC (internal resistance = 50 Ω

power density = 10.3 W·m

-3

). Evaluated only for D-MFC

the coulombic efficiency observed in batch mode (30%) was quite highe

r than the maximum acquired in continuous mode (9.6%) even at the highest hydraulic retention time. In this study

changes in phosphate and different types of nitrogen existing in dairy wastewater were investigated for the first time. At hydraulic retention time of 8 h

the orthophosphate concentration in effluent was 84% higher compared to influent. Total nitrogen and total Kjeldahl nitrogen were reduced 70% and 99% respectively at hydraulic retention time of 30 h

while nitrate and nitrite concentrations increased. The microbial electrolysis cell (MEC)

revamped from D-MFC

showed the maximum gas production of 0.2 m

3

H

2

·m

-3

·d

-1

at 700 mV applied voltage.