Characteristics of phosphorous adsorption on three substrates used in constructed wetland
3种人工湿地基质对磷的吸附特性

The phosphorous adsorption characteristics of three substrates (shale,haydite,gravel) in constructed wetland were studied by isotherm adsorption and adsorption kinetics experiment.The results showed that both Freundlich and Langmuir equations were well fitted for describing the adsorption characteristics of these substrates.To simulate the equilibrium phosphorous adsorption data,the Freundlich equation was better than the Langmuir equation.The maximum phosphorus adsorption capacity of shale increased as the grain size of the material decreased.The phosphorous theoretical saturated adsorption capacity of three substrates followed the order shale (527.992 mg/kg)> haydite (328.165 mg/kg)>gravel (129.729 mg/kg).The process of adsorption could be divided into fast,middle and slow stages.The rate of adsorption followed that shale > haydite >gravel.Pseudo second order kinetics,dual constant and Elovich equations could be suitable to describe adsorption characteristics of three substrates.In terms of correlation coefficient,Elovich equation was the best model.