高炉矿渣基质人工湿地除磷特性研究

Phosphorus removal efficiency of blast-furnace slag substrate in constructed wetland

以冶金废物高炉矿渣作为人工湿地基质,研究了其对生活污水中磷的去除效果。等温吸附/解吸实验结果表明:高炉矿渣的磷素理论饱和吸附量为3 333 mg.kg-1,是沙子(270 mg.kg-1)的12倍;高炉矿渣基质的磷吸附解吸率为0.68%,也远小于沙子的7.59%。复合垂直流湿地各基质层对磷的吸附量实验结果表明,表层基质层磷含量远高于其他层,各基质层磷含量沿水流方向和基质深度呈逐渐降低的趋势;表层添加高炉矿渣的湿地单元,表层基质对磷的吸附效果远高于对照。结果表明,高炉矿渣基质具有较强的磷吸附能力,作为人工湿地基质是可行的,建议根据表层基质磷吸附饱和情况,随着植物的收割适当更换表层基质,延缓湿地的除磷年限。

The slag of blast-furnace （SBF） was used as the substrate of constructed wetland to investigate its effect on phosphorus removing in domestic wastewater. The isotherms adsorption experiment shows that the phosphorus adsorption capacity of SBF is 3 333 mg·kg^-1 ,which is about 12 times that of the sand （270 mg·kg^-1 ）. Phosphorus desorption characteristics of those two substrates （SBF and sand） are compared. The ratio of phosphorus desorption of SBF is 0.68% ,and it is far less than that of the sand （7.59%）. Phosphorus adsorption experiments of the integrated vertical flow constructed wetland （IVCW） in different substrates were analyzed. The results show that the phosphorus contents of surface substrates are much higher than those of the others. The phosphorus contents in different substrates show decreasing tendency along the water flow direction and the depth of the substrates. The phosphorus contents in the SBF surface substrate are much higher than control check （CK）. The resuits indicate that the SBF can be used as the constructed wetland substrate because of its high adsorption capability of phosphorus. It suggests that the surface substrates in constructed wetland should be changed following the harvest time of plants based on the saturation conditions of the phosphorus adsorption, which can increase the effect of phosphorus removing in constructed wetlands.