微曝气生态浮床水芹吸收N P的特性及其对系统去除N P贡献的研究

Characteristics and Contribution of Oenanthe javanica Uptake to Nitrogen and Phosphorus Removal Based on a Micro-aerated Ecological Floating Bed

针对污染河水黑臭缺氧、NH4+-N含量高等问题,研发了一种"漂浮载体悬挂弹性生物膜填料+水生植物并辅以人工微曝气系统"的微曝气生态浮床系统,以漂浮植物水芹为例研究了系统中水芹对N、P的吸收特性和去除作用。结果表明,随着水芹的生长其生物量干重显著增加,生长80d左右时总生物干重在2497.2～3144.4g·m-2之间,上、下部生物量比平均为13.4。不同部位水芹N、P的含量不同,总的趋势为含N量叶>根>茎,含P量茎>根>叶。不同生长时间水芹N、P含量及其吸收速率不同:随着水芹的生长,组织内N、P含量逐渐降低,N的吸收速率总趋势为60～80d>35～60d>1～35d,P的吸收速率总趋势为35～60d>1～35d>60～80d。而随着水芹的生长吸收N、P的总量却在逐渐增加,吸收N的总量从17.69g·m-2增加到61.66g·m-2,吸收P的总量从4.99g·m-2增加到13.55g·m-2,这主要取决于自身的生物量和N、P的含量。水芹对N、P的积累主要集中在上部,分别占N、P吸收总量的92.2%～93.4%、92.5%～93.1%。水芹生长35、60、80d时,吸收N量占系统TN去除量的比率分别为4.50%、6.06%和6.87%,水芹对P的吸收量分别占系统去除P总量的18.53%、26.82%、22.00%。水芹对N、P的吸收仅是微曝气生态浮床净化系统去除N、P的一个途径,但水芹根际微生物的作用不可忽视。

A micro-aerated ecological floating bed system was developed to mitigate the negative influences of black-odor, oxygen deficiency and high concentration of ammonia-nitrogen in polluted fiver systems. The system was comprised mainly by biofilm packing, floating aquatic macrophyte and auxiliary aeration device. Taking Oenanthe javanica as an example of water plant, the characteristics and contribution of its uptake to nitrogen （N） and phosphorus （P） removal in the system were studied in a period of 80 days in situ. Significant growth of the plant Oenanthe jav anica was observed with total biomass （dry weight） ranging from 2 497.2 g·m^-2 to 3 144.4 g·m^-2, and a biomass ratio of 13.4 between above water and underwater part at the end of the study. Different concentrations of N and P were found in different parts of Oenanthe javanica with the following orders： leaf〉root〉stem for N and stem〉root〉leaf for P respectively. The uptake rates for N or P were demonstrated highly dynamic in different growth periods with general trends：60-80 d〉35-60 d〉1-35 d for N and 35-60 d〉1-35 d〉60-80 d for P respectively. However, the total uptake of N and P by Oenanthe javanica was increased gradually. Total N uptake increased from 17.69 g·m^-2 to 61.66 g·m^-2 and total P from 4.99 g·m^-2 to 13.55 g·m^-2 from the start to the end of the experiment, which was mainly depended on biomass of the plant and concentrations of N and P in the respective tissues. Most N and P were enriched in the above water part, which accounted for 92.2%-93.4% and 92.5%-93.1% of total N and P uptake, respectively. The uptake of N by Oenanthe javanica accounted for 4.50%, 6.06% and 6.87% of total N removal of the system at the days of 35, 60, and 80 d of the experiment, while the uptake of P accounted for 18.53%, 26.82% and 22.00% of total P removal in the system at respective sampling days. This study suggested that Oenanthe javanica uptake was not the main mechanism for TN and TP removal in the system and rhizosphere bacteria Oenanthe javanica might play an important role in N removal of the system.