三种人工湿地填料对氨氮与磷的吸附特性

采用等温吸附、吸附动力学、填料饱和吸附后氨氮与磷解吸实验,研究了浮石、陶结和陶粒对氨氮和磷的吸附特征。结果表明,Langmuir和Freundlich等温吸附方程均能较好拟合各填料对氨氮和磷的吸附特征,各填料对氨氮的最大吸附量顺序依次为浮石(64.91 mg/kg)>陶结(36.11 mg/kg)>陶粒(22.23 mg/kg),对磷的最大吸附量顺序依次为浮石(127.77 mg/kg)>陶粒(15.38 mg/kg)>陶结(无吸附);各填料对氨氮与磷的全程平均吸附速率大小顺序与最大吸附量大小顺序一致;Bangham吸附速率方程能较好描述浮石与陶粒对氨氮与磷、陶结对氨氮的等温吸附动力学特征;氨氮解吸风险为陶粒>陶结>浮石,磷解吸风险为陶结>陶粒>浮石。综合考虑,浮石更适合作为去除污水中氨氮与磷的人工湿地填料。

Ammonium nitrogen and phosphorus adsorption characteristics of three substrates in constructed wetland

The ammonium nitrogen(NH+4-N) and phosphorus(P) adsorption characteristics of pumice,lightweight ceramic pellet,haydite were studied by isothermal adsorption experiment,adsorption kinetics experiment,saturated substrates NH+4-N and P desorption experiment.The results showed that the behaviors of NH+4-N and P adsorption to substrates could well be fitted to both Langmuir and Freundlich isothermal adsorption equations.The NH+4-N adsorption capacity of three substrates followed that pumice(64.91 mg/kg)>lightweight ceramic pellet(36.11 mg/kg)>haydite(22.23 mg/kg),and the P adsorption capacity followed that pumice(127.77 mg/kg)>haydite(15.38 mg/kg)>lightweight ceramic pellet(no adsorption).The rate of absorption of three substrates followed the same sequences with the pollutants adsorption capacity.Bangham equations could be accurately fitted for describing absorption characteristic of three substrates.The rate of saturated substrates NH+4-N and P desorption followed that haydite>lightweight ceramic pellet>pumice and lightweight ceramic pellet>haydite>pumice respectively.The combined investigation of three substrates shows that pumice is a better constructed wetland substrate to remove NH+4-N and P from wastewater.