Enhancement on the simultaneous removal of nitrate and organic pollutants from groundwater by a three-dimensional bio-electrochemical reactor

To improve denitrification performance and effective degradation of organic pollutants from micro-polluted groundwater simultaneously, a novel three-dimensional (3D) bio-electrochemical reactor was developed, which introduced activated carbon into a traditional two-dimensional (2D) reactor as the third electrode. The static and dynamic characteristics of the reactor were investigated with special attentions paid to the performance comparison of these two reactors. In the 3D reactor both TOC and nitrate removal efficiency were greatly improved, and the formation of nitrite byproduct is considerably reduced, comparing with that of the 2D reactor. The role of activated carbon biofilm was explored and possible remediation mechanisms for the 2D and 3D reactors were suggested. In such a 3D reactor, the denitrification rate improved greatly to 0.288 mg NO3–N/cm2/d and the current efficiency could reach as high as 285%. Further, it demonstrated good performance stably against variable conditions, indicating very promising in application for groundwater remediation.