Construction and preliminary studies on the direct microbial fuel cell

The mediators added in indirect microbial fuel cells are often toxic, unstable and costly. Direct microbial fuel cells do not need mediators during oxidation of carbohydrate or organic acids, overcoming the above problems, so it can be used in bioremediation and treatment of waste water. In the present work, Geobacter metallireducens, a dissimilatory ferric reducing microorganism that can use Fe(OH)3 as the electron acceptor, was used to construct the direct microbial fuel cell. Geobacter metallireducens was inoculated into chambers in which a graphite electrode served as the sole electron acceptor and acetate was the electron donor. Electricity production and mechanism were preliminarily studied. The direct microbial fuel cell was successfully constructed. It was proved that microbial electricity production was mainly due to the cells attached to the electrode. Electrode-attached cells completely oxidized acetate to the levels below detection limit ( less than or equal 10 μmol/L). The electron recovery was 80%, and current density was up to 704.4 mA/m2.