人工潜流湿地净化富营养化水体试验研究

【作者】 汤显强；

【导师】 黄岁樑；

【作者基本信息】 南开大学 ， 环境科学， 2009， 博士

【摘要】 人工湿地是自然湿地的人工强化,能通过对湿地各构成要素（填料、植物和微生物等）的优化管理提高污染物去除性能。人工垂直潜流湿地占地面积小、卫生状况好,近年来被广泛用于去除污染水体中的有机污染物和氮磷等营养盐污染物,在景观水体修复中表现出较大潜力。人工垂直潜流湿地有机物去除率较高,但无机氮、磷去除率相对较低。本论文系统研究人工湿地构成要素（填料和植物）对污染物去除的影响,选择去污性能优异的填料和植物构建人工垂直潜流湿地处理津河富营养化水体,探索和讨论间歇曝气和生物填料提高潜流湿地污染物去除效率的可行性。主要研究内容和研究结果如下:1.通过对孔隙率、干容重、粒径级配、水力渗透系数等物理性质的测定比较初步筛选湿地填料。结果表明质轻多孔、颗粒分布均匀、水力渗透系数较小的页岩较宜作为人工湿地去污主填料,质地密实,持水性较差的粗砾石适合作为支撑滤料分布和收集污水。2.结合填料物理性质测定在室内开展柱状填料去污比较实验,选择去污性能优异的湿地填料及其组合。研究结果表明页岩、麦饭石、铁矿石和粗砾石的津河水体净化性能差异显著,单一填料页岩COD、TN、TP去除效果最好。组合填料中页岩与粗砾石组合COD、TN和TP去除效果突出,粗砾石与铁矿石组合最差。3.填料类型、粒径、进水浓度和水力停留时间（HRT）等影响潜流湿地磷去除效率。四种填料最大磷吸附量顺序为页岩＞铁矿石＞麦饭石＞粗砾石,填料最大磷吸附量随着粒径的增大逐渐减小。HRT从2.2d增加到3.1d后,填料磷去除效果受进水浓度的影响减小,却更加依赖填料的磷吸附性能。4.根据湿地植物的生长状况、水体净化效果和组织氮磷累积性能筛选潜流湿地去污目标植物。研究结果表明7种水生植物芦苇、石菖蒲、千屈菜、美人蕉、黄花鸢尾、香蒲和水葱在津河富营养化水体中生长良好,氮磷净化效果优异。湿地植物地上和地下组织（根、茎和叶）生物量及氮、磷含量分析结果表明香蒲根系发达,地上组织氮、磷累积量高,适宜用作人工湿地去污植物。5.结合曝气生物滤池的优点在潜流湿地填料内部引入间歇曝气,研究溶解氧可利用性对湿地去污性能的影响。结果表明间歇曝气能够有效提高津河水体COD、NH₄⁺-N、TN、SRP和TP去除效率,但曝气产生的有氧环境不利于硝酸盐氮（NO₃^--N）去除。植物分析结果表明间歇曝气抑制香蒲地上组织生物量的增加,但能够有效提高茎、叶中氮磷含量。6.基于生物接触氧化池的优点,采用生物填料（聚丙烯多面空心小球）替代部分页岩研究生物填料对湿地去污性能的影响。结果表明生物填料能够有效提高津河水体COD、NH₄⁺-N、TN、SRP和TP去除效率,但对硝酸盐氮（NO₃^--N）去除影响不显著。植物分析发现生物填料抑制香蒲地上组织生物量的增加,但能够有效提高茎、叶中氮磷含量。7.采用聚丙烯多面空心小球替换部分页岩构建生物填料人工湿地,研究间歇曝气对生物填料人工湿地去污性能的影响。结果表明间歇曝气能够有效提高生物填料人工湿地COD、NH₄⁺-N、TN、SRP和TP去除效率,但不利于硝酸盐氮（NO₃^--N）去除。植物分析结果表明间歇曝气能够使生物填料人工湿地内香蒲地上组织生物量及氮磷含量有不同程度增加。8.双因素方差分析（Two way ANOVA）检验结果表明间歇曝气对COD、NH₄⁺-N、NO₃^--N、TN、SRP和TP去除有显著影响。生物填料对COD、NH₄⁺-N和TN去除影响显著。除NH₄⁺-N外,间歇曝气和生物填料组合对其余污染物的去除均无显著影响。假如湿地植物组织仅从水体提取营养,氮磷累积性能分析结果表明香蒲地上组织氮磷吸收贮存性能的改善是间歇曝气和生物填料提高潜流湿地整体氮磷去除效率的重要原因。更多还原

【Abstract】 Constructed wetlands are engineered systems designed and constructed to utilize the natural processes involving wetlands vegetation, soils and their associated microbial assemblages to assist in treating wastewater. Due to their relatively small space requirements and good sanitary conditions, vertical subsurface flow（VSSF） constructed wetlands have recently become a common choice for the removal of organic matter, nitrogen and phosphorus and showed great potential in restoration of polluted landscape waters. The current efficiency with which VSSF removes most organic substances is satisfactory, but the removal of nitrogen and phosphorus is known to be somewhat problematic. In this dissertation, effect of wetlands components including substrate and plant on nutrient removal was evaluated and optimum candidate substrates and plants were selected to construct VSSF constructed wetlands treating eutrophic Jinhe River water. The role of intermittent artificial aeration and biofilm carrier （polyhedron hollow polypropylene ball （PHPB）） in nutrient removal was also explored. The main contributions to the current research of this topic are described below:1. Measurement of dry weight, hydraulic conductivity, particle size distribution, porosity and other selected physical properties was conducted to make the primary selection of candidate substrates. High porosity, uniformity of particle size distribution and low hydraulic conductivity, these good qualities showed shale had the potential to be packed as wetlands main filter media while close grained gravel had low water retention capacity, and should be used to distribute and collect water.2. Indoor column purification experiments were initiated to make further selection of wetlands substrates. Shale, coarse gravel, hornblende and iron stone showed significant difference in Jinhe River water treatment capacity, and shale performed best in COD, TN and TP removal. Moreover, combination between shale and coarse gravel treated COD, TN and TP well, while coarse gravel and ironstone contributed little to above nutrient variables removal.3. Phosphorus removal by VSSF constructed wetlands depended on substrates type and grain size, influent concentration and hydraulic residence time （HRT）. The ranking order of the maximum phosphorus adsorption capacity for the substrates was as follows: shale > ironstone > hornblende > coarse gravel. After HRT values were increased from 2.2days to 3.1 days, phosphorus removal performance was more dependent on substrate phosphorus adsorption than on influent concentrations.4. Growth conditions, purification performance and biomass nutrient （nitrogen and phosphorus） accumulation capacity of selected candidate wetlands plants were investigated. All of the seven species including Phragmites communis, Typha angustifolia Linn, Acorus tatarinowii Schott, Lythrum salicaria Linn, Iris wilsonii C. H. Wright, Canna generalis and Scirpus validus Vahl grew well in the constructed wetlands, and showed excellent nitrogen and phosphorus removal performance. Aboveground and belowground biomass （root, stem and leaf） production and corresponding nitrogen and phosphorus content analysis suggested that Typha angustifolia Linn had high root biomass production, excellent nutrient uptake capacity and can be used potentially as constructed wetlands plant to remove nitrogen and phosphorus.5. Take the advantageous of aerated biofilter, intermittent artificial aeration was introduced to VSSF constructed wetlands to investigate the effect of oxygen availability on nutrient removal. In contrast with the non-aerated wetlands, intermittent artificial aeration greatly enhanced COD, NH₄⁺-N, TN, SRP and TP reduction but reduced NO₃^--N removal. The analysis of wetlands plant biomass indicated that intermittent aeration restrains the increase in biomass production, but stimulates assimilation of nitrogen and phosphorus into stems and leaves.6. Like bio-contact oxidation process, biofilm carrier （PHPB） was used to replace part of shale and packed as wetlands substrate to examine its impact on nutrient removal. In contrast to wetlands without biofilm carrier, polypropylene pellets improved the COD, NH₄⁺-N, TN, SRP and TP removal. Biofilm carrier, however, played no significant role on NO₃^--N removal. The analysis of wetlands plant biomass indicated that bioflim carrier restrains the increase in biomass production, but stimulates uptake of nitrogen and phosphorus into stems and leaves.7. Effect of intermittent artificial aeration on nutrient removal by VSSF constructed wetlands using biofilm carrier as part of substrate was evaluated. In contrast with the non-aerated wetlands, intermittent artificial aeration greatly enhanced COD, NH₄⁺-N, TN, SRP and TP reduction but reduced NO₃^--N removal. The analysis of wetlands plant biomass indicated that intermittent aeration stimulates the increase in biomass production and enhanced the accumulation of nitrogen and phosphorus into stems and leaves.8. Finally, further two-way ANOVA analysis results indicated that intermittent artificial aeration led to significant statistic difference in COD, NH₄⁺-N, NO₃^--N, TN, SRP and TP removal. The using of PHPB as part of wetlands substrate was significant for COD, NH₄⁺-N and TN removal. Except for NH₄⁺-N, no significant interaction effect between intermittent artificial aeration and PHPB on other nutrient variables removal was detected. If plant uptake and store nitrogen and phosphorus only occurred from water column, mass balance calculation showed that the enhancement in nitrogen and phosphorus accumulation by intermittent artificial aeration and PHPB was the major factor responsible for the total observed improvement in nitrogen and phosphorus removal.更多还原