芦苇碳源水平潜流人工湿地强化农田退水脱氮效能研究

Nitrogen removal of Phragmites Australis packed horizontal surface flow constructed wetland for agricultural runoff treatment

以洱海地区硝酸盐占比高、C/N比低的农田退水为处理对象,将经济易得的芦苇(Phragmites Australis)碎段投加于水平潜流湿地(Horizontal Subsurface Flow Construction Wetland,HSFW)构建PHSFW湿地,并研究其对模拟农田退水中氮的强化去除效能.结果表明:①投加芦苇碎段的PHSFW湿地的启动速度及脱氮效能优于未投加芦苇的PHSFW_(0)湿地,在工况1(进水TN为(18.2±1.6)mg·L^(-1)、HRT=3 d、第29~41 d)和工况2(进水TN为(17.6±0.7)mg·L^(-1)、HRT=2d、第42~81 d)条件下PHSFW的TN平均去除率分别为77.0%±9.0%和68.9%±7.0%,与PHSFW_(0)相比分别提高了56.0%和50.3%;②在工况4(进水TN为(16.7±0.7)mg·L^(-1)、HRT=3 d、第130~149 d)条件下,PHSFW脱氮效能最高,其出水TN可满足《地表水环境质量标准》(GB 3838-2002)Ⅳ类水标准;③PHSFW在工况1出现了较为明显的TP、COD_(Mn)、NH_(4)^(+)-N和NO_(2)^(-)-N积累情况,运行稳定后在工况4条件下,出水COD_(Mn)、NH_(4)^(+)-N、NO_(2)^(-)-N浓度可满足地表水Ⅲ类水标准.PHSFW具有优异的脱氮效能,但仍应采取相关措施以避免湿地运行初期阶段出水COD_(Mn)、NH_(4)^(+)-N、NO_(2)^(-)-N和TP的积累.

To treat the low carbon/nitrogen(C/N)ratio and high nitrate proportion agricultural runoff of Erhai Lake region,the economical and easily obtained Phragmites Australis pieces were supplied as external carbon source,which were packed into the horizontal subsurface flow constructed wetland(HSFW),and the enhanced nitrogen removal efficiency was extensively investigated.The results were as follows:①Both of the startup speed and nitrogen removal efficiency of the HSFW packed with Phragmites Australis(PHSFW)were remarkably higher than those of the control HSFW(PHSFW_(0)),i.e.without Phragmites Australis addition.Under operation condition I((18.2±1.6)mg·L^(-1)influent TN,3 d HRT,29~41 d period)and II((17.6±0.7)mg·L^(-1)influent TN,2 d HRT,42~81 d period),the average TN removal of PHSFW were 77.0%±9.0%and 68.9%±7.0%,which were 56.0%and 50.3%higher than those of HSFW0.②Under operation condition IV((16.7±0.7)mg·L^(-1)influent TN,3 d HRT,130~149 d period),the nitrogen removal of PHSFW was the highest,and the effluent TN could meet the Class IV standard of Environmental Quality Standards for Surface Water(GB 3838-2002)in China.③Significant TP,COD_(Mn),NH_(4)^(+)-N,and NO_(2)^(-)-N accumulation was occurred during operation condition I period.Under the operation condition IV,i.e.the stable period of PHSFW,the effluent COD_(Mn),NH_(4)^(+)-N,and NO_(2)^(-)-N could meet the Class III standard of Environmental Quality Standards for Surface Water(GB 3838-2002)in China.PHSFW has excellent nitrogen removal performance.However,certain measures should be taken to avoid the accumulation of COD_(Mn),NH_(4)^(+)-N,and NO_(2)^(-)-N in the effluent during operation condition I period.