污染物负荷与组成对潜流人工湿地脱氮效果影响研究

Research on Influence of Pollutant Loading and Composition on Total Nitrogen Removal in Subsurface Flow Constructed Wetland System

为研究污染物负荷与组成对人工湿地系统脱氮效果的影响,在构建小试湿地试验装置的基础上,使用模拟污水进行了TN去除试验。试验的影响因素包括:水力学停留时间,单一污染物负荷量,ρ(C):ρ(N),TN组成,有机质(以COD计)-氨氮-硝氮比例等。其中,3种污染物最佳比例试验采用正交试验法进行。停留时间试验、单一负荷试验、ρ(C):ρ(N)试验、TN组成试验得到各自的变化趋势,并能够用人工湿地基本理论解释。正交试验确定的3种污染物的最佳比例质量浓度为:有机质:氨氮:硝氮=20:3:3。结论认为,湿地脱除污染物的不同机理是影响TN去除效果根本原因。氨氮的去除主要是依靠好氧微生物的作用,硝氮的去除则主要依靠反硝化菌的作用,并需要充足的碳源。TN组成问题应综合考虑氨氮和硝氮的负荷总量和水力学停留时间。3种污染物对TN去除影响的主次顺序为:氨氮>硝氮>有机质,最优方案的理论TN去除率达到92.26%。此外,可能还存在着其它重要的影响人工湿地TN去除率的因素。

Based on a small scale constructed wetland system, a series of total nitrogen removal test was done using simulated wastewater to determine the influences of the loading and composition factors including HRT, single pollutant loading, carbon and nitrogen ratio, total nitrogen composition and organic matter - ammonia nitrogen - nitrate nitrogen ratio, which used orthogonal test method. The results showed each trend in the test could be explained by the basic theory of constructed wetlands respectively. The orthogonal test showed the best ratio of three pollutants was 20：3：3. The conclusion is that different mechanisms of pollutant removal affect the total nitrogen removal efficiency. Ammonia removal relies mainly on the aerobic microorganisms, while nitrate nitrogen removal is largely dependent on the denitrifying bacteria and the amount of carbon source. Comprehensive consideration between total loading and HRT should be taken while the best composition of nitrogen is determined. The sequence of pollutants influence is ammonia〉nitrate〉organic, and the theoretical optimal TN removal rate is 92.26%. In addition, there may also be other important influence factors in wetland nitrogen removal issue.