Coking wastewater total nitrogen removal method

The invention discloses a coking wastewater total nitrogen removal method which comprises a nitrifying process and a denitrifying process, wherein the nitrifying process adopts three sections of nitrifying: in the first section of nitrifying, the DO (Dissolved Oxygen) is controlled to be more than or equal to 0.5 mg/L but less than or equal to 1.5 mg/L, and the wastewater retention time is controlled within 25-32 hours; in the second section of nitrifying, the DO is controlled to be more than or equal to 2 mg/L but less than or equal to 4 mg/L, and the wastewater retention time is controlled within 18-24 hours; and in the third section of nitrifying, the DO is controlled to be more than 4 mg/L but less than or equal to 5.5 mg/L, and the wastewater retention time is controlled within 10-15 hours. The coking wastewater total nitrogen removal method has the beneficial effects that through NO2, the denitrification is directly carried out, so that the defect of low carbon-nitrogen ratio of coking wastewater is overcome, the denitrifying rate is improved, and further, the COD (Chemical Oxygen Demands) removal effect is improved, the alkaline input of the nitrifying sections is reduced, and the dosing cost is reduced; the water outlet index of the coking wastewater processed by the coking wastewater total nitrogen removal method is close to the national primary discharge standard; and the coking wastewater total nitrogen removal method is also suitable for the treatment of pharmaceutical wastewater, fermentation wastewater, foodstuff enterprise wastewater and other refractory production wastewater as well as municipal sewage and domestic sewage.