Using electric field to enhance the activity of anammox bacteria

Electric field was applied to enhance the activity of anaerobic ammonium oxidation (anammox) bacteria for nitrogen removal in this study. The effect of different distributive modes with the total electric field time of 6 h/24 h (R2) and 18 h/24 h (R3) at 2 V/cm was determined through long-term tests. With the continuous application time increasing from 3 to 9 h in R3 (1 to 3 h in R2), the total nitrogen removal rate (NRR) showed an acceleration trend. When the electric field was applied continuously for 9 h (R3, mode 3, application-rest time: 9 h-3 h), the NRR dramatically increased 38.7 % over that of control on day 160. Besides, it was demonstrated that the increase of crude enzyme activities and the cell quantities were the main reasons for the enhancement of nitrogen removal performance of the anammox process. Additionally, transmission electron microscope observation proved the morphological change of anammox biomass under electric field application.