NOVELTY - A three-stage continuous wastewater denitrification method of a microbial fuel cell comprises performing a wastewater treatment by controlling three-stage continuous wastewater denitrification microbial fuel cell device, and placing prepared anode and carbon fiber felt cathode in the corresponding anode chamber and cathode chamber while controlling volume ratio of the ammonia-nitrogen wastewater to the immobilized bacteria in each anode chamber at 1:0.6-1, and filling 3 L of cathode and anode liquors in cathode and anode water inlet devices.    USE - A three-stage continuous wastewater denitrification method of a microbial fuel cell.    DETAILED DESCRIPTION - A three-stage continuous wastewater denitrification method of a microbial fuel cell comprises taking a 0.5-1 cm thick square carbon fiber felt with a length of 16 cm and a width of 16 cm, and taking 16 strip-shaped carbon fiber felts having a length of 16 cm, width of 1 cm and thickness of 0.5-1 cm; fixing symmetrically fixing every 8 strip-shaped carbon fiber felts on surfaces of both sides of the square carbon fiber felt by carbon fiber filaments at a distance of 1 cm to form a carbon fiber felt electrode plate, placing the carbon fiber felt electrode plate into deionized water, heating to boiling for 30 minutes, cooling naturally the carbon fiber felt electrode plate to obtain a carbon fiber felt anode plate (10), and freeze-drying the anode plate at 4 degrees C to obtain anode plate; inoculating Pseudomonas putida (CGMCC NO:1.1003) stored on an inclined plane into a seed culture medium (50 ml), culturing at 30 degrees C, pH of 7 and vibration speed of 150 revolutions/minute for 2 days, and freeze-drying at 4 degrees C to obtain culture solution; adding polyvinyl alcohol (9-11) and sodium alginate (0.5-0.7) to distilled water (80-120 ml), heating to boiling while stirring, cooling to room temperature, adding activated carbon (1-1.3 g) and prepared culture solution (8-12 ml), and mixing to obtain coating solution; coating the prepared coating solution on freeze-dried carbon fiber felt anode plate, soaking coated anode plate in a saturated boric acid solution having 2 wt.% calcium chloride, adding sodium carbonate solution to control pH value at 6.5-7, freeze-drying at 4 degrees C for 3 hours, gelatinizing the anode plate to obtain an electrode, washing with distilled water for 8-10 times, and freeze-drying at 4 degrees C to obtain an electrode; taking a 1 cm thick square carbon fiber felt with a length of 16 cm and a width of 16 cm, soaking the square carbon felt into deionized water for 30 minutes, cooling naturally to room temperature, and freeze-drying at 4 degrees C to obtain a carbon fiber felt cathode plate (11); using ammonia-nitrogen wastewater having a pH of 6.8-7.2 as anode liquor and freeze-drying anode liquor at 4 degrees C, and using nitrogen containing wastewater having a pH of 6-7 as a cathode liquor and freeze-drying at 4 degrees C; performing a wastewater treatment by controlling three-stage continuous wastewater denitrification microbial fuel cell device at 15-35 degrees C, and placing prepared anode and carbon fiber felt cathode in the corresponding anode chamber and cathode chamber while controlling volume ratio of the ammonia-nitrogen wastewater to the immobilized bacteria in each anode chamber at 1:0.6-1; and filling 3 L of cathode and anode liquors in cathode and anode water inlet devices, starting water inlet (1) valves of two electrode chambers, allowing nitrogen containing wastewater and ammonia-nitrogen wastewater to flow into the cathode and anode chambers of the continuous treatment device, regulating the water inlet valves, controlling the wastewater inlet flow velocity at 0.4-0.8 ml/minute, and monitoring the output voltage of the microbial fuel cell online by an electrochemical workstation, and monitoring the changes of the respective wastewater every 24 hours. The seed culture medium comprises (g/l) potassium nitrate (0.6), potassium dihydrogen phosphate (1), magnesium sulfate heptahydrate (1) and sodium succinate (2.4). The ammonia-nitrogen wastewater comprises (g) ammonium sulfate (0.3-0.4), potassium dihydrogen phosphate (0.75), potassium dihydrogen phosphate trihydrate (2.216), magnesium sulfate heptahydrate (0.025), and trisodium citrate (1.81). The nitrogen containing wastewater comprises potassium dihydrogen phosphate (1), magnesium sulfate heptahydrate (1), potassium nitrate (0.3-4.51) and L-ascorbic acid (0.1-0.2). An INDEPENDENT CLAIM is included for the three-stage continuous wastewater denitrification microbial fuel cell device.    DESCRIPTION OF DRAWING(S) - The drawing is a schematic view of a three-stage continuous wastewater denitrification microbial fuel cell device.    Water inlet (1)    Liquid paraffin (5)    Heat exchange disk pipe (7)    Carbon fiber felt anode plate (10)    Carbon fiber felt cathode plate (11)