【作者】 杨旭；

【导师】 于水利；

【作者基本信息】 哈尔滨工业大学 ， 市政工程， 2008， 博士

【摘要】 近年来,由于水环境污染日益严重,水源地水质恶化,现有常规饮用水处理工艺难以适应当前饮用水水质状况。因此,寻找一种高效、简单、经济的微污染饮用水源预处理技术就十分必要。为此,本研究以济南玉清湖水库为依托,分别采用水平流人工湿地系统、上下折流人工湿地系统和表流人工湿地系统对沉砂后的微污染黄河水进行了预处理试验,对微污染饮用水源人工湿地预处理效能与作用机理展开了研究。经预处理效能试验研究表明:水平流人工湿地系统对COD,TP,TN和NH4+-N平均去除率分别为49.55%,49.36%,52.81%和48.36%;上下折流人工湿地系统对COD,TP,TN和NH4+-N平均去除率分别为55.87%,50.42%,58.74%,和55.74%;表流人工湿地系统对COD,TP,TN和NH4+-N平均去除率分别为38.27%,41.69%,45.80%和39.86%。上下折流人工湿地处理效果最佳,其次是水平流人工湿地,表流人工湿地处理效果最差。通过对人工湿地处理系统影响因素分析表明:进水流量的控制非常关键,适宜的进水流量处理效果最佳;季节温度与处理效果密切相关,处理效果总的趋势为夏季优于秋季,秋季优于春季,冬季最差;从试验期间进水污染物浓度来看,系统对污染物去除量随进水污染物浓度的增加而增加,没有出现明显的偏离。这表明在玉清湖水库现有的进水污染物浓度条件下,对湿地系统不会存在污染负荷过重的威胁,也说明系统仍有承载更大污染负荷的潜力;同时,根据不同污染物的降解情况,构建了三套人工湿地系统的一级动力学降解模型。通过对人工湿地沿程及不同高度的污染物浓度变化试验分析表明,人工湿地系统对污染物的降解是沿人工湿地水流方向逐渐降低的,污染物主要在前部去除的,潜流人工湿地床体上部对污染物去除效果更好。通过对湿地植物与基质作用研究表明:一方面,植物通过吸收直接去除氮、磷,而且在生长季节作用更明显,另一方面植物根系可以过滤、截留去除水中污染物,并为微生物提供附着表面,从而发挥了微生物的降解作用,这在人工湿地系统起重要的作用;在植物作用分析中我们还看到在床体前部植物生长效果略好于后部,对氮、磷吸收也略高于后部,这正与湿地系统对污染物的降解是沿人工湿地水流方向逐渐降低相吻合。人工湿地基质能够吸附水中一定的污染物质,而且,成熟基质表面布满了各种类型微生物。试验表明基质具有很强的污染物降解能力,对水中污染物的去除发挥重要作用。采用聚合酶链式反应—变性梯度凝胶电泳(Polymerse Chain Reaction- Denaturing Gradient Gel Electrophoresis, PCR-DGGE)考察了三套人工湿地系统生物学特性,结果表明不同类型的人工湿地系统对微生物种群结构和分布具有显著影响。同时,也揭示了在人工湿地系统中微生物的群落结构沿水流方向的变化规律。在上下折流式人工湿地系统中,优势菌群由系统前端的Vogesella属和Microvirgula属演变成后端的Rhodoferax属和Fulvimonas属;在水平流人工湿地系统中,优势菌群由系统前端的Cetobacterium属和Thermofilum属演变成后端的Sulfuricurvum属和Xylophilus属;在表流人工湿地系统中,优势菌群由系统前端的Fulvimonas属演变成后端的Salinisphaera属。通过对三套人工湿地系统中细菌的分离、纯化和筛选得到5株具有聚磷性能的菌株、6株具有硝化性能的菌株和6株具有反硝化性能的菌株。通过16SrDNA测序,得到了筛选出来的17株细菌的DNA全序列,并在GenBank中进行了相似性检索,结果表明:筛选得到的17株细菌分别属于Bacillus属和Delftia属。说明这两个菌属的细菌在三套人工湿地系统中是普遍存在的,并对污染物去除起着重要作用。对试验的上下折流人工湿地系统、表流人工湿地系统以日均进水量2m3,运行周期20年为例进行经济核算。结果表明:上下折流人工湿地建设投资为2076.73元,运行成本为0.05元/t;而表流人工湿地建设投资为2365.01元,运行成本为0.05元/t。这表明人工湿地预处理技术是经济可行的。更多还原

【Abstract】 In recent years, as the increasing pollution of the water environment, the water quality of the water resource becomes worse, so that the conventional water treatment processes couldn’t adapt to the present situation of water quality. Thus an efficient, simple and economic micro-polluted drinking water resource pretreatment process is badly wanted. This research was carried out in Yuqing Lake Reservoir in Jinan, and there were three types of the constructed wetland systems, including horizontal flow constructed wetland system, up and down fold flow constructed wetland system and surface flow constructed wetland system. All the wetland systems were used to pretreat the raw water which came from Yellow river after sedimentation. The objective of this study was to investigate the pretreatment efficiency and mechanism of the constructed wetland systems.The results of pretreatment efficiency experiment showed that the average removal efficiencies of COD, TP, TN and NH4+-N were 49.55%, 49.36%, 52.81% and 48.36% in the horizontal flow constructed wetland system respectively. The average removal efficiencies of COD, TP, TN and NH4+-N were 55.87%, 50.42%, 58.74% and 55.74% in the up and down fold flow constructed wetland system respectively. The average removal efficiencies of COD, TP, TN and NH₄⁺-N were 38.27%, 41.69%, 45.80% and 39.86% in the surface flow constructed wetland system respectively. Among the three types of the constructed wetland systems, the up and down fold flow constructed wetland system had the best performance, followed by the horizontal flow constructed wetland system and the surface flow constructed wetland system performed the worst.From the analysis of the impact factors in the constructed wetland systems, it can be seen that a key factor was to control the influent flux, and proper influent flux can obtain the optimum treatment effect. The disposal performance was closely correlated with the temperature of different seasons. And the trend of treatment effects in summer had the best treatment performance. They performed better in autumn than in spring, and in winter they performed the worst. During the experiment, the removal efficiencies of the pollutants increased with an increase of the pollutants concentration in the raw water, and there was no obvious deviation. This indicated that the concentration of the pollutants in YuQing lake reservoir influent can’t threaten the steady operation of the constructed wetland system. It was also observed that the systems had the ability to bear higher load of pollution. Meanwhile, according to the degration situation of different contaminants, first order kinetics removal model for these three constructed wetland systems was established.According to the longitudinal variation of pollutants concentration in constructed wetland and different height, it can be clearly observed that the pollutants removal efficiencies in the constructed wetland systems declined along the water flow direction, and most of the pollutants were removed in the front of the water flow direction. Moreover, the upside of the subsurface constructed wetland system had a better treatment effect.From the analysis of the plants and substrates in the constructed wetland systems, it can be clearly observed that the plants removed the nitrogen and phosphorus directly by absorption, and this process performed better in the growing season of plants. On the other hand, the pollutants in the raw water were filtrated and absorbed by the plants’roots. The roots also provided a habitat for the microorganism and then, the microorganism played a degradation function on the pollutant, which had a significant effect in the constructed wetland systems. The plants on the foreside of the bed grew better than those grew on the rearward, and they can also absorb more nitrogen and phosphorus. This regulation was accorded with the one that the pollutants removal efficiencies declined along the water flow direction. The substrate in the constructed wetland systems can absorb a lot of pollutants, and there were many microorganisms on the mature substrate surface. Experiment showed that the substrate had a strong ability of biodegradation, and played an important role in the process of pollutants removal.The microbial community characteristic was investigated by PCR-DGGE, and the results showed that different types of constructed wetlands exerted great influence on the structure and distribution of microbial community. At the same time, it revealed the regularity that the structure of microbial community in the constructed wetland system varied with the orientations of the water flow. In the up and down fold flow constructed wetland system, the predominant microbial community was Vogesella sp. and Microvirgula sp. in the foreside of the system, and the predominant microbial community was Rhodoferax sp. and Fulvimonas sp. in the rearward. In the horizontal flow constructed wetland system, the predominant microbial community was Cetobacterium sp. and Thermofilum sp. in the foreside of the system, and the predominant microbial community was Sulfuricurvum sp. and Xylophilus sp. in the rearward. In the surface constructed wetland system, the predominant microbial community was Fulvimonas sp. in the foreside of the system, and the predominant microbial community was Salinisphaera sp. in the rearward. This also revealed the variational law of the microbial community along water flow direction in the constructed wetlands.Five strains of phosphorus-accumulating organisms, six strains of nitrobacteria and six strains of denitrifying bacteria were isolated from the three constructed wetland systems. From the 16SrDNA sequences measurement the full sequences of the seventeen strains that screened out the constructed wetland systems were obtained, and similarity retrieval was carried out in GenBank and the most similar strains were obtained. It was found that the isolated strains belonged to Bacillus sp. and Delftia sp., which indicated that there were a lot of bacteria belonging to those two genera in the constructed wetland systems. It played an important role in removing the pollutants.Economic analysis of the up and down fold flow constructed wetland system and the surface flow constructed wetland system were carried out when influent quantity was 2m3·d-1and the circulate cycle was 20 years. The results showed that the construction cost of the former system was 2076.73 yuan and the operation cost was 0.05 yuan/t. the construction cost of the latter system was 2365.01 yuan, and the operation cost was 0.05 yuan/t. It can be concluded that the constructed wetland pretreatment system was an economical pretreatment system.更多还原