冬、夏两季组合湿地系统的净化力对比分析

CONTRASTIVE ANALYSIS OF SEASONAL CHANGES ON POLLUTANT REMOVAL RATE OF A CONSTRUCTED WETLAND SYSTEM ESTABLISHED FOR TREATMENT OF POLLUTED RIVER

建立了用以处理污染河流水体的"表面流湿地-垂直流湿地-稳定塘"组合人工湿地系统,日处理水量为7万t,水力停留时间为24 h,对比分析了组合人工湿地系统冬、夏两季的水体净化力。结果表明:冬、夏两季组合湿地系统出水中COD、氨氮、TP、TN月均值可达GB 3838—2002《地表水环境质量标准》IV类标准,不同单元之间净化力差异显著,垂直流湿地贡献率最大;组合湿地系统对COD和氨氮去除率存在显著的季节性差异,冬季对COD和氨氮的平均去除率分别为25.97%和30.26%,显著低于夏季的43.07%和54.20%;组合湿地系统对氮、磷去除效果季节性差异不显著,冬季对TN和TP的平均去除率分别为48.35%和59.26%,而夏季组合湿地系统对TN和TP的平均去除率分别为48.87%和55.26%。要克服冬季对组合湿地系统净化力的影响,需考虑增强垂直流湿地单元的吸附过滤功能和提高湿地系统冬季的生物活性。

A constructed wetland system was established by combining of ＂surface-flow-vertical subsurface flow-stabilization basin＂units for polluted river treatment. The processing capacity of the wetland system could reach up to 70 000 ton per day,while the HRT was determined as 24 h. The effect of seasonal temperature（ mainly winter and summer） variation on removal ratio of the pollutant was measured. The results were indicating that the monthly average effluent quality of the system could meet the level IV of ＂Surface Water Environment Quality Standard＂（ GB 3838—2002）. Significant differences in treatment efficiency among surface-flow,vertical subsurface flow and stabilization basin were determined,while the pollutant removal ratio for vertical subsurface flow was relatively higher; COD and NH4^＋-N removal ratio for the wetland system could reach up to 25. 97% and 30. 26%,respectively in winter,which was apparently lower than that of 43. 07% and 54. 20% in summer.The seasonal differences for removal of phosphorus and nitrogen were relatively insignificant. The removal rates of TN and TP could reach up to 48. 35% and 59. 26% in winter,compared with 48. 87% and 55. 26%,respectively in summer. Further enhancing the bio-activity of the system in winter and increasing in the adsorption and filtration capacity of vertical subsurface flow were both considered as essential measures to strengthen the treatment efficiency and stability of the wetland system.