设置饱和带对生物滞留去除地表径流中N、P的影响  

Removal of Dissolved Nitrogen and Phosphorus in Urban Stormwater by Bioretention Cell Incorporated a Submerged Zone

作　　者：颜子钦 李立青[1] 刘雨情 涂声亮[1] 

机构地区：[1]中国地质大学环境学院,湖北武汉430074

出　　处：《中国给水排水》2017年第11期33-38,共6页China Water & Wastewater

基　　金：国家水体污染控制与治理科技重大专项(2012ZX07307001)

摘　　要：生物滞留设施被广泛应用于城市地表径流污染的控制,其中基质组成、植物和饱和带是影响其去除N、P的关键。通过构建以河砂与紫色土为混合基质的生物滞留系统,种植根系发达的草本植物紫穗狼尾草,研究设置饱和带与否对去除城市地表径流中溶解性N、P的影响。结果表明,生物滞留以80%河砂与20%紫色土为混合过滤基质,在进水PO_4^(3-)-P平均浓度为(0.33±0.04)mg/L时,出水PO_4^(3-)-P平均浓度可达到(0.03±0.01)mg/L,平均去除率为91.5%;进水NH+4-N平均浓度为(3.00±0.37)mg/L,出水NH+4-N平均浓度为(1.15±0.19)mg/L,平均去除率为61.3%。基质吸附与离子交换是去除城市地表径流中PO_4^(3-)-P和NH_4^+-N的主要途径,生物滞留设置饱和带与否,不影响对PO_4^(3-)-P和NH_4^+-N的去除。但设置饱和带可显著提高对NO_3^--N的去除率。不设置饱和带时进水NO_3^--N平均浓度为(3.89±0.19)mg/L,出水平均浓度为(3.76±0.52)mg/L,平均去除率为3.4%;设置饱和带时进水NO_3^--N浓度为(3.69±0.16)mg/L,出水平均浓度为(0.75±0.04)mg/L,平均去除率为79.8%。停留时间是影响NO_3^--N去除的重要因素。对于种植紫穗狼尾草、设置饱和带且不加碳源的生物滞留系统,通过延长停留时间可以有效去除城市地表径流中的NO_3^--N。Urban runoff is an increasingly important source of excess nitrogen （ N ） and phosphorus （P） to local receiving waters. Bioretention has become one of the most frequently used facility to control urban stormwater pollution. Its design variables including filter medias, plant species and saturated zone have large impacts on nitrogen and phosphorus removal. This study investigates the role of filter media, vegetation and saturated zone （SZ） in achieving dissolved nitrogen and phosphorus removal in bioretention systems. A large bioretention cell （4.5 m long by 1.8 m wide, with a depth to hold 75 cm filter media, plus a 25 cm freeboard） was constructed and created a submerged zone in the lower half of the bioretention cell. The bioretention cell was filled with the mixture of 80% river sand and 20% purple soil （400 mm）, coarse washed sand （200 ram）, pea gravel （50 mm） and gravel （100 mm）. The native species P. alopecuroides was selected and planted because of its high biomass and strong roots. The results demonstrated that the bioretention system could effectively remove PO4^--P and NH4^＋ -N from urban runoff. When the influent concentrations of PO4^3- -P and NH4^＋ -N were （0.33 ±0.04） mg/L and （3.00 ± 0.37 ） mg/L, the effluent concentrations of PO4^3- - P and NH4^＋ - N were （ 0.03 ± 0.01 ） mg/L and （1.15 ±0.19） mg/L, with removal rates of 91.5% and 61.3% , respectively. Adsorption and ion exchange are the major removal mechanisms for PO4^3- -P and NH4^＋ -N in the bioretention filter media. The use of a saturated zone could not influence PO4^3- - P and NH4^＋ - N removal efficiencies. The saturat- ed zone could significantly enhance the NO3^- - N removal. The NO3^- - N concentration only decreased from （3.89 ±0.19） mg/L to （3.76 ±0.52） mg/L with the removal efficiency of 3.4% when the satu- rated zone was not used. However, the NO3^- -N concentration decreased from （3.69 ±0.16） mg/L to （0.75±0.04） mgc/L with the removal rate of 79.8% whe

关 键 词：城市地表径流 生物滞留 氮 磷 饱和带 

分 类 号：X52[环境科学与工程—环境工程]