生物净化低温高铁锰氨氮地下水氨氮去除机制

Removal mechanism of ammonia nitrogen in bio-purification process for high iron and manganese removal from low temperature groundwater

在某水厂,对"两级曝气+两级过滤"生物净化工艺净化低温高铁锰氨氮(5~7.8℃,Fe_(2+)>8.0mg/L,Mn^(2+)>3.0mg/L,NH_4^+-N>3.0mg/L)地下水过程中,氨氮去除机制进行了试验研究.试验表明:一级和二级滤柱分别存在45.22%和35.97%的氮素损失(TN_(loss)),DO实际耗值分别比理论值少24.67%和22.27%.利用DO计量关系证明TN_(loss)过程是耗氧过程,TN_(loss)与TN_(loss)的DO耗值线性相关性较好,R2>0.970.分析表明:TN_(loss)产生于自养脱氮过程,与吸附、生物同化、异养反硝化和锰氧化耦合反硝化机制无关.利用氮素守恒和DO计量关系定量计算,一级和二级滤柱分别有51.40%、40.93%的氨氮由自养脱氮过程去除.生物硝化耦合自养脱氮是氨氮去除的主要途径,且进水氨氮浓度越高,自养脱氮比例越高.

The removal mechanism of ammonia nitrogen(NH4+-N)was analyzed about“two-stage aeration and two-stage filtration”process that was used to remove high iron(Fe2+>8.0mg/L),manganese(Mn2+>3.0mg/L)and NH4+-N(>3.0mg/L)from low temperature(5~7.8℃)groundwater in a drinkingwater plant.The experiments showed that there was45.22%and35.97%nitrogen losses(TNloss)in the primary and secondary filter columns,respectively,and the actual DO consumption was24.67%and22.27%lower than the theoretical DO consumption.Moreover,the TNloss process was proved to be accompanied with DO consumption by DO measurement relationship.There was a good linear relationship between TNloss and its DO consumption,R2>0.970.The analysis demonstrated that autotrophic nitrogen removal(N-removal)was the cause of TNloss,which was independent on the adsorption,biological assimilation,heterotrophic denitrification and manganese oxidative coupling denitrification.The calculation based on quantitative relationship between nitrogen conservation and DO measurement indicated that the contribution of autotrophic N-removal to NH4+-N removal was51.40%and40.93%in the primary and secondary filter columns,respectively.Both the nitrification reaction and the autotrophic N-removal process were the significant removal mechanism of NH4+-N.Moreover,with the higher concentration of NH4+-N,the contribution of autotrophic N-removal was also higher.