Study On The Influences Of Nitrosification In Tannery Wastewater

Tannery wastewater has a high level of contamination of ammonia nitrogen. But it would cause serious environmental harm that the wastewater containing nitrogen was discharged into rivers directly before it was treated. It would reduce the water quality, impact the fishery production and endanger human health.The conventional method to remove ammonia nitrogen is the entire nitrification. While this experiment used a new nitrogen removal process by nitrosification, which kept the nitrification in the nitrate stage and then made the denitrification. The critical factor was to realize the accumulation of nitrite and to prevent the transformation of nitrate. Nitrosification had some merits, such as reducing the amount of alkali, decreasing the supply of oxygen and saving carbons.In this paper, the ammonia nitrogen removal of tannery wastewater by the method of nitrosification was investigated. Some influences of temperature, pH and dissolved oxygen(DO)on the nitrosification of the tannery wastewater was studied in a sequencing batch reactor ( SBR). At first, aeration way of the nitrosifition was discussed. Then the nitrosification in different temperature was examined by holding the pH and DO steadily. The effect of pH on the nitrosification was also examined with the temperature and DO steadily.The processes showed that the nitrosification of tannery wastewater could be achieved by intermittent aeration. The results indicated that the nitrosification had the best effects comparatively when the temperature was 31±1℃and the pH was 7.8-8.2. And the nitrosification was enhanced a lot after the sodium bicarbonate - sodium hydroxide buffer solution was put into the system, which demonstrated that keeping pH steadily in the system was an important factor to affect the nitrosification. In addition, it was needed to choose a proper C/N to get a better effect.