潜流湿地填料比选及对氨氮的去除效应研究

为了提高西北地区潜流湿地净化污水中氮的效率,采用吸附动力学和热力学实验,对比研究了6种填料对水中氨氮的吸附特性。结果表明:砾石、生物炭、红砖、瓷砖、无烟煤和混凝土渣对氨氮的吸附平衡时间分别为12、24、17、12、8、12h,吸附量体现为生物炭>砾石>无烟煤>瓷砖>混凝土渣>红砖。6种填料对氨氮的动力学吸附过程符合准二级动力学模型,吸附过程受到固体颗粒表面液膜影响,并非速率控制单独起作用。溶液浓度和温度升高有利于填料对氨氮的吸附,6种填料对氨氮的吸附过程符合Freundlich模型,表明吸附过程为多分子层吸附且吸附表面不均匀。6种填料对氨氮的吸附以物理吸附为主,吸附为吸热过程、焓推动作用,均不属于自发过程。6种填料都适合作潜流湿地填料,但生物炭对氨氮吸附效果最佳。

Study on comparison and selection of subsurface flow wetland filler and its removal effect on ammonia nitrogen

In order to improve the efficiency of purification of nitrogen from sewage by subsurface flow wetland in Northwest China,the adsorption characteristics of six kinds of fillers on ammonia nitrogen in water were studied by adsorption kinetic and thermodynamic experiments.The results showed that the adsorption equilibrium time of ammonia nitrogen for gravel,biochar,red brick,tile,anthracite and concrete slag was 12,24,17,12,8 and 12 h,respectively.The order of adsorption capacity was biochar>gravel>anthracite>tile>concrete slag>red brick.The kinetic adsorption process of ammonia nitrogen on six kinds of fillers conformed to the quasi-second-order kinetic model,and the adsorption process was affected by the liquid film on the surface of solid particles,it was not rate control alone.The increase of solution concentration and temperature was beneficial to the adsorption of ammonia nitrogen on fillers.The adsorption process of ammonia nitrogen on six kinds of fillers conformed to Freundlich model,indicating that the adsorption process was multi-molecular layer adsorption and the adsorption surface was uneven.The adsorption process of ammonia nitrogen on six kinds of fillers was mainly physical adsorption,endothermic and enthalpy promotion,which was not spontaneous process.Therefore,six kinds of fillers were suitable for subsurface flow wetland,but biochar had the best adsorption capacity on ammonia nitrogen.