硝酸盐氮对海菜花湿地处理低污染水的影响

为研究不同进水ρ（NO₃--N）下海菜花湿地对氮磷的去除效果及海菜花的生长情况和经济效益，在进水ρ（NH₄+-N）和ρ（TP）分别为（1.07±0.11）和（0.41±0.03）mg/L，水力负荷为0.05 m3/（m2·d）的条件下，构建了进水ρ（NO₃--N）依次为（1.52±0.48）（5.62±0.41）和（9.78±0.24）mg/L的三组湿地.结果表明:① 进水ρ（NO₃--N）为（1.52±0.48）（5.62±0.41）和（9.78±0.24）mg/L时，湿地运行稳定所需时间分别为15、55和69 d，ρ（NO₃--N）越高，湿地运行稳定所需的时间越长；运行稳定后三组湿地出水ρ（NO₃--N）分别为（0.24±0.03）（0.30±0.01）和（0.65±0.14）mg/L，NO₃--N去除率均达85%以上.② 湿地运行50 d后出水ρ（TP）均高于进水，后续试验应对基质进行改良.③ 进水ρ（NO₃--N）为（9.78±0.24）mg/L的湿地中海菜花叶片叶绿素及茎的收获量均明显低于其余两组湿地，较高的ρ（NO₃--N）对海菜花生长有明显的抑制作用.④ 进水ρ（NO₃--N）为（5.62±0.41）mg/L的湿地经济效益最大，为6.2×104元/（hm2·a）.研究显示，ρ（NO₃--N）低于10 mg/L时，海菜花湿地能有效去除低污染水中的NO₃--N；当ρ（NO₃--N）为5 mg/L左右时，湿地有较好的经济价值. 

Effects of Nitrate Concentration on the Running Characteristics of Ottelia acuminate Wetlands Treating Low-Level Contaminated Water

To study the influence of nitrate on the nitrogen and phosphorus removal and Ottelia acuminate growth and its benefits, three O. acuminate wetlands were built for different influent nitrate concentrations (ρ(NO₃--N)) of (1.52±0.48) (5.62±0.41) and (9.78±0.24) mg/L. All wetland influent ammonia concentration (ρ (NH₄+-N)), total phosphorus concentration (ρ(TP)) and hydraulic load were (1.07±0.11) mg/L, (0.41±0.03) mg/L and 0.05 m3/(m2·d). The results showed:(1) when the influent ρ(NO₃--N) was (1.52±0.48) (5.62±0.41) and (9.78±0.24) mg/L, the times needed for the wetlands to reach stable state were 15, 55 and 69 days respectively, and the higher the influent ρ(NO₃--N), the longer the time needed. The corresponding effluent ρ(NO₃--N) was (0.24±0.03) (0.30±0.01) and (0.65±0.14) mg/L, and the nitrate removal rates were all above 85% at stable state. (2) After 50 days' operation, the effluent ρ(TP) was higher than influent ρ(TP) for all experimental wetlands, and the wetland substrate should be improved in future study. (3) The Ottelia leaf chlorophyll and Ottelia stem harvested at (9.78±0.24) mg/L influent ρ(NO₃--N) were significantly lower than those at (1.52±0.48) and (5.62±0.41) mg/L influent ρ(NO₃--N), which indicated that high nitrate concentration had obvious inhibitory effect on Ottelia growth. 4) The highest economic benefit (6.2×104 RMB/(hm2·a)) was obtained at (5.62±0.41) mg/L influent ρ(NO₃--N) condition. NO₃--N could be removed effectively from the low-level contaminated water when the influent ρ(NO₃--N) was lower than 10.00 mg/L, and better economic benefit could be obtained when the influent ρ(NO₃--N) was about 5.00 mg/L.