Study On The New Biological Denitrogenation Technology In The Treatment Of Coking Wastewater

Denitrification was one of the important disposal processes for coking wastewater including massive ammonia-N. The discharged ammonia-N seriously polluted the waterbodies. Traditional denitrogenation technology had such problems as long processing time, high operating cost etc. In this paper, a new type biology denitrogenation technology, which could control the water pollution and protect the aquatic environment more well, was concerned to dispose the problems.On the basis of many literatures, the new biological denitrification process called "Partial-nitritacation—Anaerobic Ammonium Oxidation" has been studied originally on the coking wastewater treatment and certain results have been acquired.First of all, in the laboratory aerobic and anaerobic microorganism was cultivated and domesticated successfully from the returned sludge of secondary sedimentation tank of the coked plant of Anshan Iron and Steel Group. At the same time, the start-up of the nitrious nitrification bioreactor and anaerobic ammonium oxidation bioreactor were completed according to the microorganism characteristics.The influential factors of Partial-nitritacation—Anaerobic Ammonium Oxidation Process in the treatment of coking wastewater were investigated. The optimal conditions for the nitrous nitrification were obtained as following: temperature about 35℃, pH value about from 8.1 to 8.3, hydraulic residence time about 16h, sludge residence time about from 15d to 60d. While the optimal conditions of anaerobic ammonium oxidation bioreactor were achieved as following: NH₄⁺/NO₂^- ratio about from 1.7 to 2.2, pH value about 8.0, temperature about 35℃. These reaction conditions could be applied in the pratical engineerings.The operating condition and treatment effect of every unit were concerned; further more, the feasibilities of new process were verified in the test of disposing the coking wastewater in the whole system. The results showed that drainage water conformed to the standard GB8978-96(A Level) when coking wastewater was treated by the new process. The treatment parameters of the system were gained as following: ammonium-N removal efficiency 96% and above, total nitrogen removal efficiency varied from 64% to 72% and chemical oxygen demand removal efficiency in the range of 93% to 95%.