经济作物型人工湿地对农村生活污水氮磷去除特性的研究

发布时间：2018-09-13 07:55

【摘要】：相较于生物技术,人工湿地在实现脱氮除磷功能上投资和运行成本更低,管理更为简单,在农村生活污水处理工程中备受青睐。但是传统人工湿地技术多栽培景观植物,经济价值不高,这对于以农业生产为主要经济来源的农村地区而言,改变了土地原有的利用价值,减少了经济收入。同时多数景观植物到冬季地上部分枯萎,一些常绿植物在低温条件下进入休眠期,导致冬季人工湿地污染物净化效率和景观效益降低。基于此,研究将水生植物滤床技术、人工湿地技术与蔬菜无土栽培技术、温室蔬菜技术相融合,构建水生蔬菜滤床-蔬菜型潜流人工湿地组合系统,按蔬菜生长季节划分研究组合生态系统全年对生活污水经二级处理后尾水中氮、磷营养盐的去除特性,得出以下结论：(1)夏秋季,不同植物配置下组合生态系统对TN、TP单位面积去除速率分别为3.2～4.2g/(m2·d)和0.33～0.45g/(m2·d)。空心菜、茭白与大型景观植物再力花、美人蕉TN去除负荷低14%左右,TP无明显差别。水生蔬菜滤床系统对于组合系统TN、TP去除率的贡献平均值分别为42.2%和44.6%。水力负荷对营养盐的去除效粜影响较大,水力负荷减小到0.18 m3/(m2 d),9个所试系统TN、NH4+、TP的去除率平均值分别提高到72.9%、77.7%和84.3%；另外,氮素组成也是一个重要的影响因素,c(NO3-)/c(TN)从0.38增加到0.71,NH4+-N、TN的去除率都有不同程度提高,说明提高生物生态组合工艺前段生物单元硝化率对于生态单元氮素的去除是有一定的积极意义的。从沿程变化规律看,无论是滤床系统还是潜流人工湿地系统,营养盐的去除都集中在前端,因此,在组合生态系统的构型上不必追求过高的长宽比。(2)冬春季,在塑料温室的保温作用下,种植不同蔬菜的组合生态系统对TN、TP单位面积去除速率分别为3.2～3.5 g/(m2·d)和0.20～0.26g/(m2·d)。与夏秋季净化效能相比,冬春季TN去除速率下降不明显,但是TP去除速率出现了一定程度下降。水力负荷从0.30 m3/(m2·d)减小到0.18m3/(m2·d),TN、NH4+、TP去除率有不同程度的提高。氮素组成和碳源是影响氮素净化效果的两个主要因素。随着c(NO3-)/c(NH4+)从1.20变化到1.84,NH4+-N去除率出现了先上升后下降的变化规律,TN去除率先上升后趋于平缓。进水碳氮比从2.0增加到4.1,TN去除率均值从42.1%增加到70.2%。不同系统不同负荷下,TN、NH4+、TP浓度均沿程规律性递减,并且营养盐的去除集中在滤床和潜流湿地前段,水力负荷减小时,递减规律和前段降幅更明显。(3)从全年运行效果看,在水力负荷为0.24 m3/(m2·d),TN、NH4+、TP平均浓度分别为27.4mg/L,10.8mg/L,2.0mg/L的进水条件下,夏秋季空心菜-空心菜、空心菜-茭白、番茄-再力花以及冬春季塑料温室条件下豆瓣菜-豆瓣菜、生菜-水芹、水芹-莴苣几种组合系统的出水NH4+-N、TN基本都达到了《城镇污水处理厂污染物排放标准》(GB18918-2002)-级A标准,前两种组合TP可达-级A标准,其他组合TP满足-级B标准。塑料温室的保温作用保证了组合生态系统全年在同-水力负荷下达到相同出水标准。TP去除率的提高需进-步增加基质层厚度或投加石膏等废料将磷素带出系统。(4)水生蔬菜滤床-潜流人工湿地生产的蔬菜维生素C含量和可溶性糖含量分别在36.%75.9mg/100g、0.477-0.894g/100g的范围内,品质好；硝酸盐含量在89.1～195.4mg/kg范围内,远低于432mg/kg的参考标准。除空心菜Hg含量和生菜Pb含量超标,其他蔬莱均无出现重金属污染现象,食用安全。蔬菜中,空心菜全氮、全磷积累量(氯、磷回收量)最高,分别为73.0g/m2和19.8g/m2；茭白,水芹,豆瓣菜在氛、磷咨源回收上也比较可观。以夏秋季种植空心菜,冬春季种植豆瓣菜为例粗略估算组合牛杰系统生产效益,扣除组合系统建设、塑料温室大棚建设以及种子投入等费用,亩产效益25340元。.研究结果表明：水生蔬菜滤床-潜流人工湿地技术在深度净化农村生活污水的同时有效回收氮磷资源,将无土栽培与污水处理有机结合,并可产生可观的经济效益。
[Abstract]:Compared with biotechnology, constructed wetlands have the advantages of lower investment and operation cost, simpler management, and are favored in rural domestic sewage treatment projects. At the same time, most landscape plants withered in winter and some evergreen plants entered dormancy under low temperature, which resulted in the decrease of pollutant purification efficiency and landscape benefit of winter constructed wetlands. Soilless vegetable cultivation technology and greenhouse vegetable technology were combined to construct a combined aquatic vegetable filter bed-vegetable subsurface flow constructed wetland system. The removal characteristics of nitrogen and phosphorus nutrients in the tail water of domestic sewage after secondary treatment were studied year-round according to vegetable growth season. The following conclusions were drawn: (1) Different plant configurations in summer and autumn. The removal rates of TN and TP per unit area were 3.2-4.2 g / (m2.d) and 0.33-0.45 g / (m2.d), respectively. The removal loads of TN and TP in Holly, Zizania latifolia and Canna were about 14% lower than those in large-scale landscape plants. The contribution of aquatic vegetable filter bed system to TN and TP removal rates were 42.2% and 44.2% respectively. The average removal rates of TN, NH4 +, TP in nine test systems were increased to 72.9%, 77.7% and 84.3%, respectively. In addition, nitrogen composition was also an important influencing factor, C (NO3-) / C (TN) increased from 0.38 to 0.71, NH4 + - N, TN removal rates varied from 0.38 to 0.71. Increasing the nitrification rate of the biological unit in the front stage of the bio-ecological combination process is of positive significance to the removal of nitrogen in the ecological unit. (2) In winter and spring, the removal rates of TN were 3.2-3.5 g / (m2.d) and 0.20-0.26 g / (m2.d) per unit area, respectively. Compared with the purification efficiency in summer and autumn, the removal rate of TN in winter and spring was not obvious, but the removal rate of TP appeared. Hydraulic load decreased from 0.30 m3 /(m2 d) to 0.18 m3 /(m2 d), TN, NH4 +, TP removal rate increased in varying degrees. Nitrogen composition and carbon source were the two main factors affecting nitrogen purification efficiency. With the change of C (NO3 -) / C (NH4 +) from 1.20 to 1.84, NH4 + - N removal rate increased first and then decreased, and TN removal rate was the first. The influent C/N ratio increased from 2.0 to 4.1, and the average TN removal rate increased from 42.1% to 70.2%. The concentrations of TN, NH4+, TP decreased regularly along the process under different loads in different systems, and the removal of nutrients was concentrated in the front of filter bed and subsurface wetland, and the decreases were more obvious when hydraulic loads decreased. The results showed that the effluent NH of several combined systems, i.e. watering with hydraulic load of 0.24 m3 /(m2.d), TN, NH4 +, TP of 27.4 mg/L, 10.8 mg/L and 2.0 mg/L respectively, was obtained under the conditions of summer and autumn hollow cabbage, water spinach, water lily, tomato-reed and winter and spring plastic greenhouse. 4 + - N, TN basically reached < urban sewage treatment plant pollutant discharge standard > (GB18918-2002) - A standard, the first two combinations of TP can reach - A standard, the other combinations of TP meet - B standard. Plastic greenhouse warming ensures that the combined ecosystem in the same - hydraulic load to achieve the same water discharge standard throughout the year. (4) The content of vitamin C and soluble sugar in vegetable produced by aquatic vegetable filter bed-subsurface flow constructed wetland were in the range of 36.% 75.9 mg/100g and 0.477-0.894 g/100g, respectively, with good quality; the content of nitrate was in the range of 89.1-195.4 mg/kg, far below 432 mg/kg. Standard. Except for Hg content of water spinach and Pb content of lettuce, no heavy metal pollution was found in other vegetable grains, which was safe to eat. Taking the cultivation of watercress in winter and spring as an example, the production benefit of the combined Niujie system was roughly estimated, deducting the cost of the construction of the combined system, the construction of plastic greenhouse and seed input, and the yield benefit was 25 340 yuan per mu. The organic combination of soilless culture and sewage treatment can bring considerable economic benefits.
【学位授予单位】：东南大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X703

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