处理微污染河水的人工湿地中磷的去除特征及吸附形态分布

通过在野外条件下构建两座潜流人工湿地,考察了湿地对微污染水体中磷的净化效果,以及湿地填料对4种主要形态磷的吸附特征.结果表明,湿地对总磷(TP)的平均去除率在30％左右,颗粒性总磷(STP)去除比例略高于溶解性总磷(DTP).两个湿地中TP的出水负荷随其进水负荷的升高线性增大,而磷的单位面积去除负荷与进水负荷呈对数关系,迸水负荷超过1000 g·m-2·d-1后,去除负荷没有发生明显变化.4种主要形态磷的吸附量关系表现为钙镁磷(Ca/Mg-P,12582和11052 mg)＞铁铝磷(Fe/Al-P,5312和5750 mg)＞弱吸附磷(Plabile-P,2054和1207 mg)＞腐殖质磷(Humic-P,-362和-136 mg).湿地3层填料对Humic-P和Plabile-P的吸附能力有限,且伴有解吸现象,而Ca/Mg-P和Fe/Al-P的吸附主要发生在卵石和碎砖层,碎石层对湿地中磷的去除贡献较低.栽种植物对湿地中填料对磷的吸附影响较小.

Removal characteristics and adsorption distribution of phosphorus in subsurface flow constructed wetland for purifying slightly polluted river water

To investigate the purification efficiencies and adsorption characteristics of four main forms of phosphorus in substrates, two subsurface flow constructed wetlands (CWs) were built under field conditions to purify the slightly polluted river water. The results showed that the average total phosphorus (TP) removal rate was about 30%, and the suspended total phosphorus (STP) removal rate was slightly higher than that of dissolved total phosphorus (DTP). The TP effluent loading increased linearly with that of influent loading, and a logarithmic relationship existed between influent loading and removal loading of per unit area. When influent loading was over 1000 g·m^-2·d^-1, almost no changes in removal loading was observed. There were significant differences in four main forms of phosphorus adsorption of substrates in these two experimental CWs, with Ca/Mg-P (12582 and 11052 mg) > Fe/Al-P (5312 and 5750 mg) > Plabile-P (2054 and 1207 mg) > Humic-P (-362 and -136 mg). The adsorbing capacities for Humic-P and Plabile-P were lower than those of Ca/Mg-P and Fe/Al-P. Ca/Mg-P and Fe/Al-P were mainly adsorbed by pebble and brick, while gravel contributed insignificantlyin removing phosphorus. The phosphorus adsorbed by substrates was not affected greatly by planting macrophytes in CWs.