5种人工湿地基质对磷的吸附特性研究

吸附和沉淀作用是基质除磷的主要方式。文章选取陶粒、火山岩、砾石、麦饭石和钢渣为对象,通过静态吸附实验研究它们对磷的吸附能力和影响去除效率的因素。结果表明,Langmuir方程和Freundlich方程均能合理地描述各基质的等温吸附特性。30℃时Langmuir方程中表征理论饱和吸附量的G0由大到小依次为钢渣>陶粒>火山岩>麦饭石>砾石,Freundlich方程中反应吸附能力的k由大到小的规律同G0一致,表明富含Ca2+、Mg2+、Fe3+、Al 3+的基质吸附能力强。随着温度的升高,各基质对磷的吸附能力和去除效率均增加。pH值对各基质除磷效率的影响各异,因为pH值对人工湿地系统的影响体现在多方面,具体表现取决于哪方面是控制因素。陶粒对pH值的缓冲性能最好,钢渣系统的出水pH值偏碱,需要进行调节。除砾石外各基质在风干后对磷的去除效率均得到一定程度的恢复,说明干湿交替是有效的基质强化和再生的方式。用钢渣作为载体,水泥和陶粒做成浆体的基质复配方法行之有效,既保证了去除效率,又降低了出水pH值。

Study of adsorption properties of phosphorus by five constructed wetland matrixes

Adsorption and precipitation are the main ways of phosphorus removal by matrix.The ceramsite,volcanics,gravel,maifanitum and slag are chosen as objects,and the adsorption capacity of phosphorus on them and the factors that influence the removal efficiency are investigated.The results show that the adsorption properties of phosphorus by five matrixes are in accordance with Langmuir equation and Freundlich equation.When the temperature is 30 ℃,the parameter G0 which represents theoretical saturation adsorption quantity can be ranged from high to low as slag>ceramsite>volcanics>maifanitum>gravel;the change rule of parameter k which represents adsorption capacity is in line with that of the parameter G0.These indicate that the matrix which is rich in Ca2+,Mg2+,Fe3+,Al3+ has large capacity in adsorption.As the temperature rises,the adsorption capacity and removal efficiency both increase.The pH value has different effects on different matrixes,because the pH value influences constructed wetland system in many ways,and the specific performance depends on what is the control factor.The ceramsite has the best buffering capacity,and the effluent of slag system is alkaline,which should be regulated.The removal efficiency of phosphorus by each matrix is recovered in a certain degree after drying except gravel,which explains that the alternation of being dry and wet is an effective way to strengthen and regenerate matrixes.The method of choosing slag as carrier and making cement and ceramsite into slurry to compose a new matrix is effective,because it not only ensures the removal efficiency but also lowers the pH value of effluent.