Li Li-Qing, Hu Nan, Liu Yu-Qing, Tu Sheng-Liang, Chen Hua-Chao
School of Environmental Studies, China University of Geosciences, Wuhan 430074, China.
Hubei Academy of Forestry, Wuhan 430075, China.
Huan Jing Ke Xue. 2017 May 8;38(5):1881-1888. doi: 10.13227/j.hjkx.201612215.
Multiple chemical forms of nitrogen in urban storm water make its management challenging. Three types of bioretention systems were constructed in 2015 with loamy sand as filter media, including a conventional freely drained bioretention (CB), a modified bioretetion incorporated a submerged zone (MB1), and a modified bioretention incorporating a submerged zone with woodchips addition (MB2). This study investigated the role of vegetation, the use of submerged zone and carbon addition in achieving co-optimized dissolved nitrogen removal in bioretention systems. Twelve bioretention columns were monitored over a 12-month period of dosing with synthetic storm water under varying hydrology and nitrogen loading rates. All the studied bioretention systems could achieve very good ammonia removal (more than 95%) at an average inflow ammonia concentration of (5.45±2.21) mg·L. The filter media sorption, nitrification and plants uptake were the main removal pathways for incoming ammonia. The effluent nitrate concentrations of the CB, MB1 and MB2 were (4.04±2.64)mg·L (31.3%), (0.84±1.18) mg·L (85.7%), and (0.26±0.48) mg·L (95.6%), respectively, at the average inflow nitrate concentration of (5.88±2.32) mg·L. The use of the native species , a submerged zone and woodchips addition could effectively decrease the effluent nitrate concentration, reduce the washout and achieve high nitrate removal. Both plants uptake and denitrification were the two major pathways for removal of inflow nitrate. Inflow magnitude, antecedent dry days and inflow nitrate concentration were the main factors influencing the effluent nitrate concentrations for the three bioretention systems. The results highlighted that the bioretention design of the native species incorporated a submerged zone with 10% woodchips addition could consistently and effectively remove storm water nitrate under hydrological regime and nitrogen loading rates.
城市雨水中多种化学形态的氮使其管理颇具挑战性。2015年构建了三种以壤质砂土为过滤介质的生物滞留系统，包括常规自由排水生物滞留系统（CB）、设有淹没区的改良生物滞留系统（MB1）和设有添加木屑淹没区的改良生物滞留系统（MB2）。本研究调查了植被、淹没区的使用和碳添加在生物滞留系统中实现协同优化溶解态氮去除方面的作用。在12个月的时间里，对12个生物滞留柱进行监测，使其在不同水文条件和氮负荷率下接受合成雨水注入。所有研究的生物滞留系统在平均进水氨浓度为(5.45±2.21)mg·L时，都能实现非常好的氨去除效果（超过95%）。过滤介质吸附、硝化作用和植物吸收是去除进水氨的主要途径。在平均进水硝酸盐浓度为(5.88±2.32)mg·L时，CB、MB1和MB2的出水硝酸盐浓度分别为(4.04±2.64)mg·L（31.3%）、(0.84±1.18)mg·L（85.7%）和(0.26±0.48)mg·L（95.6%）。使用本地物种、设置淹没区和添加木屑可有效降低出水硝酸盐浓度，减少冲刷并实现高硝酸盐去除率。植物吸收和反硝化作用是去除进水硝酸盐的两个主要途径。进水流量、前期干旱天数和进水硝酸盐浓度是影响这三种生物滞留系统出水硝酸盐浓度的主要因素。结果表明，包含10%木屑添加的设有淹没区的本地物种生物滞留设计，在水文条件和氮负荷率下能够持续有效地去除雨水中的硝酸盐。
