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

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.