冷、暖季型水生植物配置提高人工湿地脱氮效果

发布时间：2018-05-01 18:04

本文选题：浮床人工湿地 + 水芹　；参考：《南京大学》2017年硕士论文

【摘要】：当前,人工湿地被广泛地应用于各类污、废水的处理。然而,尾水深度净化人工湿地存在严重C/N失衡问题,碳源不足限制了湿地脱氮能力的发挥,导致湿地脱氮效果不理想。加之水生植物的生长及微生物的活性与温度有显著关系,在冬季低温条件下人工湿地去除尾水中过量的氮元素更是一个挑战。大量研究表明,添加植物碳源可以有效改善人工湿地脱氮效果,但植物碳源的改善效果受添加方式、添加量和添加时机的影响极大,而且鲜有研究将植物碳源添加对人工湿地净化效果的影响和自然条件下植物材料的分解过程两个方面结合起来。因此,本文设计了暖季型植物轮叶黑藻(Hydrillaverticillata)和冷季型植物水芹菜(Oenanthe javanica)组合配置的浮床人工湿地系统,监测了受试植物动态变化,检测了湿地系统水体溶氧量(DO)、水体叶绿素含量的变化,研究了轮叶黑藻在秋冬季凋亡分解对湿地系统除氮效果的影响,旨在验证冷、暖季型水生植物配置提升C/N失衡水体氮去除率的可行性。并利用稳定性同位素15N标记技术探讨轮叶黑藻残体分解前期对湿地系统氮素迁移转化的影响,为人工湿地生态净化工程提供理论指导。实验结果表明:(1)水芹菜在秋冬季浮床人工湿地系统中表现出较好的低温适应性。实验前期,各处理组水芹菜的地上、地下干重以及总干重均呈上升趋势;温度降至5℃后,部分叶片发黄枯萎,各处理组水芹菜的地上干重均有不同程度的下降,但主干与地下部分仍保持正常。实验期间各处理组水芹菜根系活力总体呈减弱趋势,实验结束时,LN组(贫营养水体+水芹菜处理组)、LA组(贫营养水体+水芹菜+轮叶黑藻处理组)、HN组(富营养水体+水芹菜处理组)、HA组(富营养水体+水芹菜+轮叶黑藻处理组)分别为31.73 μg(1g·2h)-1、26.67 μg·(1g·2h)-1、63.73μg·(1g·2h)-1、35 2 μgμg·(1g·2h)-1。(2)轮叶黑藻分解释碳过程可以分为两个阶段。实验开始时轮叶黑藻刚进入衰亡期,分解迅速,实验后期由于温度降低,分解减慢,最终轮叶黑藻干重减少57%。四个周期内,LA组、HA组的水体COD值分别显著高于LN组、HN组,说明轮叶黑藻在秋冬季衰亡分解能够释放大量的有机物,可以作为外加碳源提高湿地系统的有机碳含量。(3)轮叶黑藻过量分解会增加湿地系统水体叶绿素含量、降低水体溶氧量。在整个实验过程中,LA组、HA组水体叶绿素含量分别显著高于LN组、HN组;在第一、二周期,LA组、HA组的水体溶氧量分别显著低于LN组、HN组;而且实验期间,LA组、HA组水芹菜的地下部分干重、根系活力普遍更低,这与轮叶黑藻分解消耗水体溶氧,影响水芹菜根部呼吸有关。(4)利用冷、暖季型水生植物配置提高C/N失衡湿地氮去除率是可行的。在四个周期中,HA组水体平均C/N比均显著大于HN组,HA组最大时是HN组的2.36倍。与HN组相比,HA组的TN去除率分别提升23.03%、10.9%、18.55%和 22.93%,NO3--N 去除率分别提升 38.28%、20.74%、17.87%和 17.06%。表明暖季型植物在秋冬季的分解可以提高浮床人工湿地系统C/N比,促进反硝化作用,提高湿地系统TN和NO3--N的去除率。(5)轮叶黑藻残体分解前期对湿地系统氮素迁移转化产生一定影响。一方面,轮叶黑藻残体分解前期会通过影响植物生长减弱植物吸收去除NH4+-N这一途径;另一方面,又会促进系统反硝化作用,有利于去除系统NO3--N。同时轮叶黑藻残体能通过吸附作用降低水体NH4+-N浓度,不会造成水体氮素污染。
[Abstract]:At present, artificial wetland is widely used in various kinds of pollution and wastewater treatment. However, there is a serious C/N imbalance in the constructed wetland with deep tail water purification. The lack of carbon source limits the ability of nitrogen removal in wetland, which leads to the poor effect of nitrogen removal in wetlands. A large number of studies have shown that adding plant carbon sources can effectively improve the effect of nitrogen removal in artificial wetland, but the effect of plant carbon source is greatly influenced by addition methods, and the effect of adding and adding time is greatly influenced by the addition of plant carbon source to artificial wetland. The influence of chemical effect and the decomposition process of plant material under natural conditions are combined. Therefore, a floating bed artificial wetland system with warm season plant Hydrillaverticillata and cold season plant water celery (Oenanthe javanica) is designed in this paper. The dynamic changes of the plants are monitored and the wetland system is detected. The effects of DO and chlorophyll content on the removal of nitrogen in the wetland system in autumn and winter were studied. The purpose of this study was to verify the feasibility of cold and warm season aquatic plants to improve the nitrogen removal rate of C/N unbalance water in the water body, and to explore the decomposition of the residues of rotaleaf montane by the 15N labeling technique of stable isotopes. The effect of earlier period on Nitrogen Migration and transformation of wetland system provides theoretical guidance for the ecological purification project of artificial wetland. The experimental results show that: (1) the water celery showed good low temperature adaptability in the floating bed artificial wetland system in autumn and winter. When the degree was reduced to 5 degrees, some leaves were yellow and wilted, and the dry weight of water celery in each treatment group decreased in varying degrees, but the main and underground parts remained normal. During the experiment, the root vigor of the water celery was generally weakened. At the end of the experiment, the LN group (the poor nutrient water body + water celery treatment group), the LA group (poor nutrient body + water celery) HN group (eutrophic water + parsley treatment group), group HA (eutrophic water + water celery + leaf black algae treatment group) were 31.73 mu g (1g. 2H) -1,26.67 mu g. (1g. 2H) -1,63.73 mu g. (2) decomposition of black algae (2) can be divided into two stages. The decomposition of the algae was rapid, and the decomposition and decomposition slowed down in the later period of the experiment. The dry weight of black algae was reduced in four cycles. The COD value of the water body in group LA and HA group was significantly higher than that of LN group and HN group, which indicated that the decomposition and decomposition of the algae in autumn and winter could release a large amount of organic matter, which could be used as an added carbon source to improve the wetland. The content of organic carbon in the system. (3) excessive decomposition of the leaf black algae will increase the content of chlorophyll in the water body of the wetland system and reduce the oxygen content of the water body. In the whole experiment, the content of chlorophyll in the water body of the LA group and the HA group is significantly higher than that of the LN group, the HN group; in the first, second cycle, the LA group and the HA group, the oxygen content is significantly lower than that of the LN group, the HN group and the experimental period. Between group LA and group HA, the underground part of water celery was dry and the root activity was generally lower, which was related to the decomposition of dissolved oxygen in water body and the respiration of root of water celery. (4) it was feasible to use cold and warm season aquatic plants to improve the nitrogen removal rate of C/N unbalanced wetland. In the four cycles, the average C/N ratio of the water body of the HA group was significantly greater than that of the HN group, HA The maximum of the group was 2.36 times that of the HN group. Compared with the HN group, the TN removal rate of the HA group increased by 23.03%, 10.9%, 18.55% and 22.93% respectively. The NO3--N removal rate was increased by 38.28%, 20.74%, 17.87% and 17.06%. respectively. The decomposition of warm season plants in autumn and winter could improve the C/ N ratio in the floating bed artificial wetland system, promote the denitrification and improve the TN and NO of the wetland system. The removal rate of 3--N. (5) a certain effect on Nitrogen Migration and transformation of the wetland system in the early stage of the decomposition of the residues of the residue of phylodenticus in the wetland system. On the one hand, the early decomposition of the residues of the residues of the leaves of the leaves of the leaves will weaken the absorption and removal of the NH4+-N by plant growth and weaken the plant's absorption and removal. On the other hand, it will also promote the denitrification of the system, which is beneficial to the removal of the system NO3--N. at the same time. The black algae can reduce the NH4+-N concentration of water by adsorption, and will not cause nitrogen pollution.

【学位授予单位】：南京大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X173;X703

【参考文献】