地下水厂泥饼的活化及其负载滤料去除水中氨

Removal of ammonium from water by mud cake for groundwater treatment plant:activity formation and application as filter media coating

为了将富含锰(Mn)的地下水厂泥饼回收应用于催化氧化去除水中氨(NH_(4)^(+)-N),对泥饼催化氧化活性形成(简称活化)过程进行优化,探究活化泥饼除NH_(4)^(+)-N效能与机理,并考察其负载滤料实际运行效果.结果表明:活化的最优条件为每克泥饼投加1.5mg NH_(4)^(+)与0.5mgMn^(2+),NH_(4)^(+)-N去除速率最大可达0.243mg/(g·h).活化泥饼与挂膜形成的活性滤膜相比已形成了较高的催化氧化活性.活化泥饼对NH_(4)^(+)-N的去除过程符合一阶幂律动力学模型.在298.15K~318.15K,NH_(4)^(+)-N的催化氧化活化能为10.70kJ/mol.在滤柱实验中通入1.5mg/LNH_(4)^(+)-N,地下水及自来水的启动时间分别为9和13d,最大去除效率可达到93.5%和82.42%.通过SEM、EDS和XPS分析发现,活化过程使得泥饼表面形成丰富的孔隙并发生了锰氧化物(MnO_(x))沉积.推测活化泥饼除NH_(4)^(+)-N主要通过活化过程中锰自催化氧化形成MnO_(x),进而催化氧化氨形成硝氮,最终脱附去除.活化泥饼不含大肠杆菌等致病微生物且没有重金属析出风险,是一种经济高效且清洁环保的水处理材料.

In order to apply the manganese(Mn)rich mud cake collected from underground water works to remove ammonium(NH_(4)^(+)-N)from water,the process of catalytic oxidation activity formation of mud cake(referred as activation)was optimized.The effectiveness and mechanism of NH_(4)^(+)-N removal by activated mud cake were investigated,and the actual operation effect of its coated filter media was examined.The results showed that the optimal conditions of activation were 1.5mg NH_(4)^(+)and 0.5mg Mn^(2+)per gram of mud cake,and the maximum NH_(4)^(+)-N removal rate could reach 0.243mg/(g·h).The activated mud cake has developed a higher catalytic oxidation activity than the active film.The NH_(4)^(+)-N removal process by the activated mud cake followed the first-order power-law kinetic model.The activation energy of NH_(4)^(+)-N was 10.70kJ/mol between 298.15K and 318.15K.In the column experiment,when the influent NH_(4)^(+)-N concentration was 1.5mg/L,the start-up time of groundwater and tap water was 9 and 13d,and the maximum removal efficiency could reach 93.5% and 82.42%,respectively.The SEM,EDS,and XPS analyses revealed that the activation process resulted in the formation of abundant pores on the surface of the mud cake and the deposition of manganese oxide(MnO_(x)).It was speculated that the removal of NH_(4)^(+)-N by activated mud cake was mainly through the autocatalytic oxidation of manganese to form MnO_(x),and then catalytic oxidation of NH_(4)^(+)-N to form nitrate,and finally removal by desorption.The activated mud cake does not contain pathogenic microorganisms such as E.coli and has no risk of heavy metal precipitation.It is an cost-effective,clean,and environmentally friendly water treatment material.