低C/N比污水反硝化过程中亚硝态氮累积特性研究

Study on nitrite-N accumulation characteristics during denitrification process in low C/N ratio sewage

以乙酸钠为碳源,采用序批实验研究低C/N比污水在不同温度反硝化过程中的亚硝态氮累积规律。研究结果表明,不同温度下低C/N比污水均能在反硝化过程中累积亚硝态氮。在同一温度下,随着初始C/N比增加,亚硝态氮最大累积率随之增加,温度为15℃时亚硝态氮最大累积率增幅最大,C/N比为1.03时,亚硝态氮最大累积率仅为18.8%,而C/N比为4.16时,亚硝态氮最大累积率高达83.9%;在同一水平的C/N比下,随着温度升高,亚硝态氮最大累积率也随之呈增加的趋势;当C/N比为1左右,温度从15℃上升到25℃时,亚硝态氮最大累积率从18.8%上升到51.7%;在较高温度、较高C/N比下,反应初期由于乙酸钠具有一定弱碱性导致系统pH迅速上升,随着硝态氮逐渐还原成亚硝态氮,乙酸钠被分解成CO_2,pH逐渐下降,待硝酸盐完全去除,进一步发生亚硝态氮还原,系统pH再次上升。

Batch denitrification experiments were carried out,using sodium acetate as carbon source,to investigate the effects of temperature on nitrite accumulation of low C/N ratio sewage during denitrification process.The results showed that nitrite accumulation was observed at different temperatures in sewage with different C/N ratio.At the same temperature,higher maximum nitrite accumulation ratio（NAR）could be obtained as a result of the increase of C/N ratio.The highest increment of maximum NAR appeared at 15 ℃,with maximum NAR was only 18.8% at C/N ratio of 1.03,and the maximum NAR reached 83.9% at C/N ratio of 4.16.At the same C/N ratio,higher maximum NAR could be observed at higher temperature.When the temperature was increased from 15 ℃ to 25 ℃,the maximum NAR was also increased from 18.8%to 51.7% at C/N ratio of about 1.As the alkalescence of sodium acetate,pH went up to the maximum value at the initial reaction stage.When nitrate was reduced to nitrite,sodium acetate was converted into carbon dioxide,which resulted in the decreasing pH values.When nitrate was completely removed,nitrite began to be further reduced and pH went up again.