生活污水不同进水C/N比负荷对垂直潜流式人工湿地排放温室气体的影响

人工湿地处理的生活污水含氮量或者有机物含量很高时,可能会造成人工湿地在处理污水的过程中排放大量温室气体。研究了垂直潜流式人工湿地在人工合成的生活污水不同污染物进水C/N负荷条件下污水处理效果和温室气体(CO2和CH4)的排放量,利用现场测量和碳平衡模型估算分析了可以达到最佳污水净化效果和最少温室气体排放量的污染物进水C/N负荷条件。结果显示,在进水C/N负荷为C/N=6∶1~9∶1时可以得到最佳的污染物去除率。温室气体CH4排放量较CO2排放量可以忽略不计,而在进水C/N负荷为C/N=3∶1~6∶1时可以实现最少的温室气体排放。综上所述,最优的进水C/N负荷确定为C/N=6∶1,此时人工湿地可以得到较高的污染物去除率而排放较少的温室气体。

Effect of various inflow domestic sewage C/N ratios on greenhouse gases emission from vertical subsurface flow constructed wetlands

When using constructed wetlands for wastewater treatment, higher inputs of nitrogen and organic matter may produce greenhouse gases originating from the carbon cycle of the constructed wetlands. This study focused on the greenhouse gases (CO₂ and CH₄) emission from vertical subsurface flow constructed wetlands under various inflow domestic sewage with various C/N ratios. The optimal C/N ratios for the most efficient nutrient removal with the lowest greenhouse gases emission rate were evaluated. The highest nutrient removal efficiency was achieved under C/N ratios between 6:1 and 9:1. The CH₄ emission can be negligible comparing to the CO₂ emission. The lowest greenhouse gases emission was achieved by C/N ratios between 3:1 and 6:1. Therefore, the optimal C/N ratios is determined as 6:1 where the highest nutrient removal and lowest greenhouse gases emission rate can be achieved simultaneously.