潜流人工湿地处理农田退水的温室气体排放特征研究

Study on Greenhouse Gas Emission Characteristics of Subsurface Flow Constructed Wetland Treating Farmland Recessed Water

人工湿地作为一种生态、低耗的污水处理技术,在去除污染物的同时,也产生和排放温室气体。本研究基于处理农田退水的中型人工湿地系统,探讨了不同运行方式、湿地构型和水力停留时间等因素对温室气体排放的影响。结果表明:运行方式对温室气体排放的影响受到水力停留时间的制约。水力停留时间1d时,连续运行的潜流湿地的CH4排放通量[-0.062mg/(m^(2)·h)]显著高于间歇运行的潜流湿地[-0.225mg/(m^(2)·h)](P<0.01),间歇运行的潜流湿地N_(2)O排放通量略高于连续运行的潜流湿地。水力停留时间1—3d时,水平潜流湿地的CH4排放通量和N_(2)O排放通量均显著高于垂直潜流湿地的CH4排放通量和N_(2)O排放通量(P<0.01);水力停留时间与温室气体排放通量呈正相关。研究结果可为降低人工湿地的温室气体排放提供参考。

Constructed wetlands,as an ecological and low-cost wastewater treatment technology,are associated with the generation and emission of greenhouse gases while removing pollutants.This study investigates the impact of different operational modes,wetland configurations,and hydraulic retention time on greenhouse gas emissions based on a medium-sized constructed wetland system used for treating agricultural run off.The findings demonstrate that the operational mode is constrained by the hydraulic retention time in terms of greenhouse gas emissions.When the hydraulic retention time is set at 1 day,the CH4 emission flux from continuously operated horizontal subsurface flow wetlands[-0.062 mg/(m^(2)·h)]is significantly higher than that from intermittently operated horizontal subsurface flow wetlands[-0.225 mg/(m^(2)·h)](P<0.01).The N_(2)O emission flux from intermittently operated horizontal subsurface flow wetlands is slightly higher than that from continuously operated ones.For a hydraulic retention time of 1-3 days,both CH4 and N_(2)O emission fluxes from horizontal subsurface flow wetlands are significantly higher than those from vertical subsurface flow wetlands(P<0.01).Furthermore,there is a positive correlation between hydraulic retention time and greenhouse gas emission flux.These research findings provide insights into reducing the greenhouse gas emissions from constructed wetlands.