不同人工湿地基质对磷的吸附性能研究

Phosphorus Adsorption Properties of Different Substrates in Constructed Wetland

通过基质磷素吸附动力学、等温吸附以及基质饱和吸附后磷素解吸实验,研究陶瓷滤料、红泥、水洗砂、炉渣4种人工湿地基质净化磷素的效果,评价其基质磷素饱和吸附后磷素解吸可能造成的二次污染风险。结果表明,在溶液磷(P)浓度为5～150mg.L-1条件下,Langmuir和Freundlich等温吸附方程均能很好地描述陶瓷滤料和红泥两种基质的磷素吸附过程,陶瓷滤料用Langmuir方程比Freundlich方程的拟合程度更好,红泥则相反。4种基质对磷素的吸附量顺序依次为红泥>陶瓷滤料>炉渣>水洗砂。从磷素的解吸率来看,4种基质释磷顺序依次为炉渣>水洗砂>陶瓷滤料>红泥,水洗砂和炉渣吸附磷素后的解吸率较高,其他两种基质磷素解吸的比例很低。综合评价,陶瓷滤料更适合作为人工湿地污水除磷的基质。

Constructed wetlands are widely used to purify wastewater in some developing countries. As filter substrates in such wetland, these substrates play vital role on removal of pollutants from wastewater. Selecting suitable substrates is one of the effective ways to improve the performance of constructed wetland on treating wastewater. The purification effect of the four different substrates （ceramic filter, red mud, water washing sand and slag）for phosphorus in a constructed wetland was studied by substrate phosphorus adsorption dynamics, isothermal adsorption and phosphorus desorption after being saturated adsorption. The possible secondary pollution risk caused by phosphorus desorption after being saturated adsorption by substrates was also evaluated. The results showed that both Langmuir and Freundlich isothermal adsorption equation could well describe the phosphate adsorption process of ceramic filter and red mud suhstrates under the conditions of phosphorus（ P ） concentration for 5 - 150 mg＂ L^-1. For the ceramic filter, the regression level used with Langmuir equation was better than that of Freundlich equation, it was opposite for the red mud. The phosphorus adsorption capacity order of the four substrates was followed that red mud〉 ceramic filter〉slag〉water washing sand. Seen from the phosphorus desorption rate, the order was followed that slag〉water washing sand〉ceramic fiher〉red mud. The desorption rate of water washing sand and slag after adsorbing phosphorus was higher, but the phosphorus desorption proportion of the other two substrates was very low. Comprehensive evaluation, the ceramic filter was more suitable for phosphorus removal in constructed wetland.