Electricity generation from indole and microbial community analysis in the microbial fuel cell

Abstract

Indole is a typical refractory and inhibitory compound present in coking wastewater. The aim of this study was to investigate possible electricity generation with indole degradation in the microbial fuel cell (MFC). Experiments were conducted in two types of the MFC: a continuous-fed MFC (C-MFC) and a batch-fed MFC (B-MFC). In the C-MFC, the maximum power densities reached 45.4, 51.2, and 2.1 W/m(3), respectively, from using 1000 mg/L glucose, a mixture of 1000 mg/L glucose and 250 mg/L indole, and 250 mg/L indole as the fuel. When using 250 mg/L indole as the fuel, the removal efficiency of indole was up to 88% within 3 h. Increasing indole concentrations from 250 to 1500 mg/L resulted in decrease of the maximum power densities from 2.1 to 0.8 W/m(3), and average degradation rates from 41.7 to 8.9 mg/(Lh). Compared with the C-MFC, the B-MFC increased the maximum power densities from 2.1 to 3.3 W/m(3) and the coulombic efficiencies from 0.7% to 81.5%. Microbial community analyses showed that the addition of indole obviously changes the microbial community of the anode electrode, including the changes of relative abundance and emergence of new species. The results should be useful for treatment of wastewater containing indole.