复合人工湿地系统对二级出水中汞的去除效果

Performance of Hybrid Constructed Wetland for Mercury Removal in Effluent from the Secondary Biological Treatment System

为了分析薛城污水处理厂复合人工湿地系统(水平潜流+表面流)对二级出水中汞的去除效果,对水体中总汞、溶解态汞、颗粒态汞和水体理化性质等指标进行了测定。结果表明,薛城复合人工湿地系统对汞的去除效果受温度、溶解氧、pH的影响;5月份系统对总汞的去除率为96.47%,表面流人工湿地去除率大于水平潜流人工湿地;9月份系统对总汞的去除率为97.58%,水平潜流人工湿地去除率大于表面流人工湿地。复合人工湿地系统出水中总汞浓度为1.90~3.59 ng/L,符合《地表水环境质量标准》(GB 3838—2002)Ⅰ类水中汞浓度不超过50 ng/L的要求。可见,薛城复合人工湿地系统能够有效去除外源汞,该系统对于保障南水北调东线水质安全具有重要生态价值。

The total mercury,dissolved mercury,particulate mercury and physicochemical indexes of effluent from the secondary biological treatment system of Xuecheng Wastewater Treatment Plant was tested to investigate the performance of hybrid constructed wetland system(horizontal subsurface flow constructed wetland and surface flow constructed wetland)for mercury removal.The mercury removal performance of the hybrid constructed wetland system was affected by temperature,dissolved oxygen and pH.The removal rate of total mercury was 96.47%in May,and the removal rate of surface flow constructed wetland was higher than that of horizontal subsurface flow constructed wetland.In September,the removal rate of total mercury was 97.58%,and the removal rate of horizontal subsurface flow constructed wetland was higher than that of surface flow constructed wetland.The total mercury concentration in effluent from the hybrid constructed wetland system was 1.90-3.59 ng/L,which met the requirement of Environmental Quality Standards for Surface Water(GB 3838-2002)classⅠlimit(no more than 50 ng/L).In conclusion,the hybrid constructed wetland system in Xuecheng can effectively remove exogenous mercury,which has important ecological value for ensuring the water quality safety of the eastern route of the South-to-North Water Diversion Project.