Microbial fuel cell (MFC) is a novel energy conversion device which is able to convert chemical energy into electrical energy. In MFCs

organic matter was degraded in ways of microbial metabolism and bioelectricity conversion. According to the different allocation requirements of energy in the process of operation

the energy flow could be controlled by changing the operation parameters. In this study

MFCs factors

such as pH

organic load

dissolved oxygen

electrical conductance and external resistance

were applied by orthogonal design experiments to optimize parameters for regulation of energy flow. The results showed that the highest efficiency of electric energy conversion was 8.74% and the loads and resistances were significant factors. On the other hand

the highest efficiency of biological metabolism was 66.03% and the load and pH were significant factors. Therefore

when the system was under the same load condition

if the MFC were used as an electrical conversion units

the external resistances should be controlled

while if organic matter conversion capacity was required to be improved

the pH should be controlled.