4种人工湿地填料对磷的吸附特性分析

Phosphorus adsorption characteristics of four substrates in constructed wetland

采用等温吸附、吸附动力学、填料饱和吸附后磷素释放实验,研究了紫色土、河沙、页岩、石灰岩对磷的吸附特征,结果表明Langmuir和Freundlich等温吸附方程均能很好地拟合各填料对磷的吸附特征,各填料对磷的最大吸附量大小顺序依次为石灰岩(666.67 mg/kg)>河沙(500.00 mg/kg)>页岩(434.78 mg/kg)>紫色土(416.67 mg/kg);从反应速率来看,吸附过程都可分为快、中、慢3个阶段;相对一级动力学方程、双常数方程而言,Elovich方程对4种填料的吸附动力学特征拟合最好,决定系数R^2在0.831～0.966之间;从磷的解吸率来看,各填料释磷大小顺序依次为河沙(4.257%)>页岩(3.803%)>石灰岩(3.638%)>紫色土(2.134%)。综合考察得出,石灰岩更适合作为人工湿地污水除磷的填料。

The phosphorus adsorption characteristics of four substrates （purples soil, river sands, shale, limestone） in constructed wetland were studied by isothermal adsorption experiment, adsorption kinetics experiment, saturated substrates phosphorus desorption experiment. The results showed that the behaviors of phosphorus adsorption to substrates can well be fitted to both Langmuir and Freundlich isothermal adsorption equations. The phosphorus adsorption capacity of four substrates followed that limestone （666.67 mg/kg） 〉 river sands （500.00 mg/kg） 〉 shale （434.78 mg/kg） 〉 purples soil （416.67 mg/kg）. For the rate of absorption, the process of adsorption could be divided into fast, middle and slow stages. Elovich equations could be accurately fitted for describing absorption characteristic of four substrates （R^2 = 0. 831 - 0. 966）. The rate of saturated substrates phosphorus desorption followed that river sands （4. 257% ） 〉 shale （3. 803% ） 〉 limestone （3. 638% ） 〉 purples soil （2. 134% ）. The combined investigation of four substrates showed that limestone was a better constructed wetland substrate.