复合塘-湿地系统水生植物时空分布对氮磷去除的影响

利用复合生态塘-湿地处理系统水生植物时空格局异质性,研究了水生植物分布对氮、磷去除影响.结果表明,水生植物种类和数量的分布差异导致各单元氮、磷去除呈现不同的周期变化;水生植物主要通过改变硝化/反硝化进程、自身代谢和化学沉降速率影响NH3、NOx-、有机氮和总磷的去除.系统不同单元中氮、磷去除机制差异决定了NH3和总磷主要在曝气养鱼塘(去除率分别为29.5%、30.1%)、鱼塘(16.9%、17.8%)和水生植物塘(24.5%、19.4%)去除;NOx-主要在芦苇湿地(出水<0.4 mg/L)去除;而有机氮则主要在复合兼性塘(32.3%)和鱼塘(28.1%)去除.此外,生态塘出水中水生植物绝大部分被芦苇湿地所截滤,它们的腐败/释放导致湿地中NH3和总磷的表观去除率偏低(分别小于8.5%和11.5%).

Effect of spatiotemporal patterns of hydrophytes on N and P removal in a multistage ponds-wetlands treatment system

The effects of variations in hydrophytes on nitrogen and phosphorus removal were evaluated in different units of a com- bined pond-wetland wastewater treatment facility, based on the heterogeneity of spatiotemporal patterns of hydrophytes in these sys- tems. Variations in species and biomass of hydrophytes led to periodic variations in nitrogen and phosphorus removal in each unit. Hydrophytes affected the removal of NH3, NOx , total phosphorus and organic nitrogen through influencing rates of various mecha- - nisms, especially nitrification-denitrification, chemical precipitation and metabolism of algae. Different mechanisms involved in nitrogen and phosphate removal determined that different species of nitrogen and phosphate are mainly removed in different unit. Briefly, the removal of NH3 and total phosphorus mainly occurred in aeration-fish ponds (29.5%, 30.1%), fish ponds (16.9%, 17.8%) and hydrophyte ponds (24.5%, 19.4%); the removal of NOx mainly occurred in the constructed wetland (<0.4 mg/L in final effluent); - and the removal of organic nitrogen mainly occurred in hybrid facultative ponds (32.3%) and fish ponds (28.1%). Additionally, con- structed wetland exhibits relatively low potential of removing NH3 and total phosphate, less than 8.5% and 11.5% respectively, ow- ing to its high capacity of filtrating algae and subsequent mineralization of algae biomass.