Effect of the ammonia concentration on the performance of wetland microbial fuel cells

Abstract

This work explores the effect of the ammonia concentration on the wetland synthesis of microbial fuel cell (MFC) and on the production and the efficiency of sewage purification. Four ammonia concentrations from 1 to 30 mg/L have been selected. Under the fixed condition of a chemical oxygen demand (COD) concentration of 200 mg/L, a constructed wetland microbial fuel cell (CW-MFC) could be built. The results show that by selecting the optimum ammonia concentration the production of the CW-MFC could be promoted; a higher ammonia concentration (>20 mg/L) is found to inhibit the production activity of CW-MFC. In the optimum conditions, Cathode and anode thickness is 10 cm, the ammonia concentration is 10 mg/L, the COD concentration of 200 mg/L, the maximum power density of the battery is 13.6 W/m3, the corresponding current density is 148.6 A/m3 and the battery internal resistance is 270 Ω. At the ammonia nitrogen concentration of 10 mg/L, the removal rates of ammonia nitrogen and COD were up to 89.7% and 98.47% respectively. As the ammonia nitrogen concentration increased to 30 mg/L, the ammonia nitrogen and COD removal rates decreased to 74.6% and 90.69% respectively. That is, when the ammonia nitrogen concentration is 10 mg/L, CW-MFC can exhibit the best performance.