Nitrate and COD Reduction Contrast of Biofilm-Electrode Reactor in Different Position of Denitrogenation Process

To achieve effective combination of hydrogen autotrophic denitrification and traditional biological denitrogenation, two groups of experiments were designed with a self-made experimental biofilm-electrode reactor (BER) put ahead or behind in biological denitrogenation process for the treatment of domestic wastewater from septic tank. On different conditions, the nitrate and the COD reducing efficiency of the biofilm- electrode reactor were contrasted. The experimental results implied that the position of BER in denitrogenation process would strongly affect the reduction rate of the nitrate of BER. With the optimum current intensity of 20 mA, the highest nitrate reduction rate of 68.5% would be achieved as the BER was put behind in denitrogenation process, with 29% increased compared with the condition of putting ahead. The highest COD reduction rate of the BER was respectively 27%(with BER put behind) and 17.9%(with BER put ahead), which implied the presence of heterotrophic denitrification process in BER device. Further analyses were given from the view of microbe nutrition. It can be inferred that the denitrogenation process with the BER put behind may provide better nutrition conditions for denitrifying micro-organisms on which autotrophic and heterotrophic denitrification process might be carried out in combination.