北方多级复合人工湿地对微污染河水的净化效率:以廊坊龙河湿地为例

The Efficiency of Purifying Slightly Polluted River Water by Multi-stage Composite Constructed Wetland in North China:A Case Study of Longhe Wetland in Langfang

人工湿地广泛应用于污水处理厂尾水深度处理、微污染河水净化、微污染水源水质提升等领域,多级复合人工湿地通过组合不同类型人工湿地,有效提升湿地系统对污染物的去除率。本研究在河北廊坊龙河进行试验,以高效沉淀池为预处理,组合两级潜流湿地与表流湿地建成多级复合人工湿地,研究了湿地及不同功能单元对微污染河水的净化效率,探究了不同基质及植物配置条件的湿地单元在不同季节对化学耗氧量(COD_(Cr))、氨氮(NH_(3)-N)、总磷(TP)等污染物的去除率及其驱动因子。结果表明:微污染河水经多级复合人工湿地系统净化后,水质提升至稳定达标地表水环境质量Ⅲ类,湿地全年对COD_(Cr)、NH_(3)-N、TP的平均去除率分别达到48.4%、75.5%、57.9%。在潜流-表流复合湿地中,潜流湿地是去除氮、磷等污染物的主要功能单元,且其对污染物的去除率主要受污染物浓度的驱动。龙河湿地对污染物的去除率受季节变化的显著影响,湿地净化效率在冬季最低,在春秋季达到最高。

Constructed wetland is widely used for deep processing in waste water treatment plant,purification of slightly polluted river water,quality improvement of slightly polluted water sources,etc.Combining different types of constructed wetlands,the multi-stage composite constructed wetlands can effectively improve the removal rate of pollutants in wetland system.In this study,experiments were carried out in Longhe River of Langfang,Hebei Province.Two stages of subsurface flow wetlands and surface flow wetland were combined to build a multi-stage composite constructed wetland with a high efficiency sedimentation basin as pre-treatment.We studied the purification efficiency of the wetland system and the functional units,investigated the removal of COD_(Cr),NH_(3)-N,TP and other pollutants as well as the driving factors in wetland units with different substrates and plant configuration conditions in different seasons.The results showed that the water quality of the slightly polluted river was improved to the levelⅢin the surface water environmental quality standards stably after the multi-stage composite constructed wetland system.The annual average removal efficiency of COD_(Cr),NH_(3)-N and TP reached 48.4%,75.5%and 57.9%,respectively.In the subsurface-surface flow wetlands,the subsurface flow wetland is the main functional unit for removing nitrogen,phosphorus and other pollutants,which is mainly driven by pollutant concentration.The removal efficiency of pollutants in Longhe wetland was significantly affected by seasonal variation,and the efficiency was the lowest in winter and the highest in spring and autumn.