Abstract：In order to realize effective nitrogen removal in the polluted rivers and rapidly measuring ammonia nitrogen changes, the nitrogen conversion and removal effect in the overlying water were researched with intermittent aeration. The study also investigated the correlation between DOM fluorescence intensity and ammonia nitrogen concentration by excitation-emission matrix spectroscopy. The process showed that intermittent aeration realized the repeated nitrification and denitrification in the overlying water. Ammonia nitrogen obviously decreased in the stage of nitrification and increased in the stage of denitrification, while nitrate nitrogen and nitrite nitrogen significantly increased in the stage of nitrification and decreased in the stage of denitrification, and total nitrogen always declined. The removal effect of ammonia nitrogen and total nitrogen increased along with increasing DO concentration, total nitrogen declined to 5.11, 1.42, 1.13, 0.91mg/L and ammonia nitrogen declined to 4.13, 1.30, 0.85, 0.72mg/L respectively when DO concentration was 3.5, 4.5, 5.5 and 6.5mg/L, respectively. The changes of fluorescence intensity indicated that the changes of low excitation wavelength tyrosine and tryptophan had the same trend with those of ammonia nitrogen. The sum of fluorescence intensity of the low excitation wavelength tyrosine and tryptophan showed a good linear correlation with ammonia nitrogen concentration with correlation coefficient 0.974, 0.972, 0.966, and 0.984 when DO concentration was 3.5, 4.5, 5.5 and 6.5mg/L, respectively. The study demonstrates that ammonia nitrogen concentration can be rapidly predicted by detecting the total fluorescence intensity of the low excitation wavelength tyrosine and tryptophan and the process of the intermittent aeration can be controlled flexibly and timely based on the changes of the ammonia nitrogen concentration, and then provides a quick and effective control technique and theoretical support for polluted river.
