进水C/N对表面流—水平流人工湿地氮和

通过模拟试验，研究在进水氮浓度不同条件下C/N对种植美人蕉的表面流—水平流人工湿地氮元素和COD去除能力的影响，并初步探讨其作用机理。结果表明：在营养生长期和开花期，低C/N有利于人工湿地系统中总氮和铵态氮的去除，C/N越高，硝态氮去除越彻底，而低C/N条件下，表面流—水平流人工湿地内的硝化作用限制了硝态氮的去除效果；对比2个生长期，各处理组总氮和硝态氮的去除能力相当，而开花期各处理组人工湿地铵态氮的去除能力高于营养生长期。C/N对人工湿地系统COD的去除效果的影响较少，2个生长期COD的去除效果相当，各处理组人工湿地系统COD的去除率约高于90%。随着停留时间的增加，人工湿地氮元素和COD的去除率均增加。对pH而言，湿地系统出水pH总体上先升高后趋于平稳，而氧化还原电位则先降低后升高最后趋于平稳，随C/N增加，出水pH降低，而氧化还原电位升高；营养生长期出水pH高于开花期，而氧化还原电位则呈相反表现。进水C/N和人工湿地系统共同影响着出水pH和氧化还原电位。

Effect of C/N Ratio on Nitrogen and COD Removal in Combining Surface Flow and Horizontal Flow Constructed Wetlands

The effect of C/N ratio on nitrogen and COD removal in combining surface flow and horizontal flow constructed wetlands under different influent nitrogen concentrations, as well as the preliminary influence mechanism was investigated in this simulation experiment. The results showed that, during the vegetative period and the flowering period, low C/N ratios were in favor of total nitrogen and ammonium-nitrogen removal in the wetlands, and nitrate-nitrogen removal was more complete with C/N ratio increasing, while nitrification in the wetlands limited nitrate-nitrogen removal under low C/N ratio. Comparing the two growth periods, the removal capacity of total nitrogen as well as nitrate-nitrogen was similar under different C/N ratios, whereas ammonium-nitrogen removal was higher during the vegetative period than during the flowering period. However, no obvious influence on COD removal by C/N ratio was found in all the treatments at the same growth period, and COD removal was also similar during the two growth periods, and their efficiencies in all the treatments were greater than 90%. With the increase of retention time, the removal efficiencies of both nitrogen and COD increased. The effluent pH value generally rose firstly and then kept a stable trend in all the treatments, while oxidation-reduction potential dropped firstly, rose secondly and then maintained a stable trend. The pH value decreased with C/N ratio increasing in the effluent, while oxidation-reduction potential increased. Besides, pH value was higher during the vegetative period than during the flowering period in the effluent, while oxidation-reduction potential was lower during the vegetative period than during the flowering period. Influent C/N ratio and the wetland system jointly affected the effluent pH and oxidation-reduction potential.