微污染水源水人工湿地预处理效能与机理研究

采用水平潜流人工湿地与往复流潜流人工湿地对微污染水源水进行预处理试验,以提高饮用水源水质,减轻给水厂负荷.试验是在济南引黄水库玉清湖水库进行的,经过近1a的试验,结果表明:在水力负荷0.2m~3/(m~2·d)运行条件下,水平潜流人工湿地与往复式人工湿地都有较好的处理效果.水平潜流人工湿地COD、TN、NH_4~+-N、TP的平均去除率分别达到50.14%、53.81%、48.68%、50.83%;往复流潜流人工湿地对COD、TN、NH_4~+-N、TP的平均去除率分别达到51.35%、54.95%、49.83%、51.87%.同时,通过对湿地中的植物与基质研究表明:人工湿地对污染物的处理过程是物理、化学和生物及其协同作用.     

水力负荷对湖滨带人工湿地除磷效果的影响

分析了湖滨带复合人工湿地的各单元在旱季和雨季的除磷效果。结果表明，在进水TP浓度较高时，沉淀池对TP的去除效果较明显，旱、雨季的不同水力负荷对处理效果几乎没有影响。雨季时潜流人工湿地内发生了不溶性磷的吸附和沉积，实现了对磷的去除；旱季时由于水力负荷极小，水体流动性差，系统内处于厌氧状态，出现了磷的释放。雨季时，表面流人工湿地对磷的去除效果没有沉淀池和潜流人工湿地的理想，旱季的低水力负荷对除磷效果没有显著的影响。     

潜流人工湿地的局限性与运行问题

针对目前在潜流人工湿地技术认识上的一些分歧，从湿地植物的输氧能力、人工湿地脱氮除磷能力和设计参考依据等方面，探讨了人工湿地的应用局限性，总结了湿地运行中存在的问题及解决措施，指出了深入研究潜流人工湿地处理机制的必要性。     

基于多参数评价体系的三种人工湿地净化能力研究

以玉溪海绵城市试点区人工湿地项目为依托,对表面流、水平潜流和垂直潜流三种类型人工湿地净化能力进行了多参数评价。通过对多个污染物参数进行为期两年的污染物监测,对比分析了三种人工湿地的水质净化能力。通过试验研究发现,三种类型人工湿地对污染物的去除效果和机理不同,对BOD_5去除率最高;对水质中BOD_5、COD、TN、TP和高锰酸盐指数指标去除效果最好的为垂直潜流人工湿地,水平潜流人工湿地次之,去除效果最差的为表面流人工湿地;对水质中NH_4~+-N去除效果最好的为垂直潜流人工湿地,表面流人工湿地次之,去除效果最差的为水平潜流人工湿地;在不同类型人工湿地对植被的N含量、P含量、N积累量和P积累量方面,垂直潜流人工湿地均显著高于水平潜流和表面流人工湿地。     

小城镇污水处理工程技术评价

污水处理工程为例,以SBR工艺、氧化沟、潜流式人工湿地为评价对象,通过三工艺设计数据的比较,利用ANP模型下的BOCR模式,计算了三种工艺的最终排序。通过计算发现,在不同准则条件下,三种工艺的排序并不完全相同。在收益准则下的排序为SBR工艺、氧化沟、潜流式人工湿地;在机会、成本的准则下的排序为氧化沟、SBR工艺、潜流式人工湿地;在风险条件下的排序为潜流式人工湿地、SBR工艺、氧化沟。通过规一化计算,在BOCR的综合考虑条件下的排序为SBR工艺、氧化沟、潜流式人工湿地。     

基质强化型潜流人工湿地净化景观水的研究

以天然沸石和水化硅酸钙为材料,构建新型潜流人工湿地装置,并与传统的砾石型潜流人工湿地装置进行对照,研究其净化低污染景观水的效果。在水力负荷为0.3 m3/(m2.d)的条件下连续运行8个月,基质强化型潜流湿地对浊度、COD、TN、氨氮、TP的去除效果均明显高于传统的砾石床潜流湿地,且去除效果较为稳定。其对浊度的去除率为70.4%～95.9%,对COD的去除率为33.3%～92.1%,对TN的去除率为27.6%～54.0%,对TP的去除率为59.0%～75.8%。将水力负荷提高到0.6和1.2 m3/(m2.d)时,对各指标的去除率均降低,但浊度的降幅较小,COD、TN和TP的降幅较大。因此,如果以改善景观水体透明度为目的,可以考虑采用高水力负荷;而如果以营养盐的去除为目的,则采用低水力负荷运行为佳。     

莲花湖人工湿地对污水的净化效果研究

以莲花湖复合式人工湿地为研究对象,分析了对COD、TN、TP的去除效果,以期为中国东北地区构建人工湿地提供技术支持.研究结果表明,垂直潜流湿地对COD的去除效果比水平潜流湿地强;同表流湿地相比,潜流湿地对COD的去除效果相对较好.莲花湖人工湿地对TN的去除效果比较显著;在各湿地单元中,下行流湿地对TN的去除率最低.垂直潜流湿地对TP的去除效果明显比水平潜流湿地强,表流湿地对TP的去除效果最好;水平潜流湿地容易发生基质堵塞,影响了其净化功能.人工湿地系统对COD和TP的去除效果在8月和9月最为显著,7月、8月及9月下旬对TN的去除效果最好.对TP的去除率从10月下旬开始出现负值,丧失了除磷功能.     

寒冷地区应用人工湿地处理污水研究进展＊

低温影响人工湿地污水的处理效果,限制了人工湿地在寒冷地区的推广应用。文章综合分析了影响寒冷地区人工湿地污水处理效果的因素,提出：潜流式的人工湿地具有一定的保温特点,在潜流湿地土壤上面铺盖一定厚度的覆盖物可以提高保温效果,再选择科学合理的工艺流程——复合垂直流等可提高人工湿地的污水处理效率。有关实例也证明：通过合理的设计,人工湿地可以在寒冷地区成功越冬。     

水平潜流人工湿地在工业废水处理中的应用

水平潜流人工湿地作为一种非常有效的污水处理工艺,应用于工业废水的处理已经30多年。综述了近年来国内外水平潜流人工湿地在石油化工、食品、酿酒、造纸、制革、纺织,钢铁和制药等工业废水处理系统中的应用,指出了水平潜流人工湿地的应用前景和研究方向。     

北运河人工湿地设计及运行分析

为探索人工湿地技术应用于北运河污染河水处理的设计参数和经验,同时将河水处理后部分回用,构建了表流-潜流复合人工湿地处理系统,项目设计处理规模为5 000 m~3/d。湿地投运后3个月进出水水质监测分析结果表明:可以通过在湿地进水前端设置旋流沉砂器等预处理设施,或将表流湿地单元前置于潜流湿地单元,来实现对湿地进水SS质量浓度的降低;同时表流湿地前置于潜流湿地还可以提高进水中DO质量浓度,提高潜流湿地的NH_3-N去除率;合理搭配的沉水植物群落可以实现对NH_3-N和TP良好的去除作用。     

Microbial biomass, activity and community composition in constructed wetlands

The aim of the current article is to give an overview about microbial communities and their functioning but also about factors affecting microbial activity in the three most common types (surface flow and two types of sub-surface flow) of constructed wetlands. The paper reviews the community composition and structural diversity of the microbial biomass, analyzing different aspects of microbial activity with respect to wastewater properties, specific wetland type, and environmental parameters. A brief introduction about the application of different novel molecular techniques for the assessment of microbial communities in constructed wetlands is also given. Microbially mediated processes in constructed wetlands are mainly dependent on hydraulic conditions, wastewater properties, including substrate and nutrient quality and availability, filter material or soil type, plants, and different environmental factors. Microbial biomass is within similar ranges in both horizontal and vertical subsurface flow and surface flow constructed wetlands. Stratification of the biomass but also a stratified structural pattern of the bacterial community can be seen in subsurface flow systems. Microbial biomass C/N ratio is higher in horizontal flow systems compared to vertical flow systems, indicating the structural differences in microbial communities between those two constructed wetland types. The total activity of the microbial community is in the same range, but heterotrophic growth is higher in the subsurface (vertical flow) system compared to the surface flow systems. Available species-specific data about microbial communities in different types of wetlands is scarce and therefore it is impossible make any general conclusions about the dynamics of microbial community structure in wetlands, its relationship to removal processes and operational parameters.     

Flow patterns of dairy wastewater constructed wetlands in a cold climate

Conservative tracer experiments, and spatial temperature and dissolved oxygen mapping within four subsurface treatment wetlands employed in this study demonstrated the importance of supplemental aeration and vegetation in reducing preferential flows in cold climate treatment wetlands. Four constructed wetlands, employing horizontal subsurface flow were used to treat dairy wastewater in a 2 x 2 factorial design consisting of two wetland cells with vegetation and two with supplemental aeration. Four tracer studies were conducted between November 2004 and May 2005. Two key observations were made, demonstrating that vegetation and aeration can be utilized in cold regions to prevent clogging and freezing, thereby reducing preferential flow paths which can reduce treatment efficiencies: (1) vegetation contributed to thermal protection and (2) aeration increased temperature and mixing. A comparison of multiple wetland cells with varying flow rates showed that the use of pore volume in tracer response curves was a better indicator of preferential flows than other indicators including volumetric efficiency, hydraulic efficiency and number of continuosly stirred tank reactors (CSTRs). This research helps further establish how constructed wetlands are a viable tool for treating wastewater in cold climates.     

Simulation of the treatment performance of outdoor subsurface flow constructed wetlands in temperate climates

Numerical models are a means to increase the understanding of the processes occurring in the "black box" constructed wetland. Once reliable models for constructed wetlands are available they can be also used for evaluating and improving existing design criteria. The paper shows simulation results for outdoor experimental subsurface vertical flow constructed wetlands using CW2D, a multi-component reactive transport module developed to simulate transport and reactions of the organic matter, nitrogen and phosphorus in subsurface flow constructed wetlands. The surface area of the experimental vertical flow bed was 20 m(2). The organic load applied was 27 g COD m(-2) d(-1) (corresponding to a specific surface area of 3 m(2) per person). The aim of the work is to calibrate the model for temperature dependency that has been implemented in CW2D. Water temperature during the investigation period varied between 4 degrees C and 18 degrees C. The measured effluent concentrations during summer could be simulated using the standard CW2D parameter set when the flow model was calibrated well. However, the increasing effluent concentrations at low temperatures could not be simulated with the standard CW2D parameter set where temperature dependencies are considered only for maximum growth, decay, and hydrolysis rates. By introducing temperature dependencies for half-saturation constants for the hydrolysis and nitrification processes it was possible to simulate the observed behaviour. The work presented is a step on the way to validate the CW2D module. Model validation is a necessary step before numerical simulation can be finally used in practice, e.g. for checking existing design guidelines.     

Model-based design of horizontal subsurface flow constructed treatment wetlands: a review

The increasing application of constructed wetlands for wastewater treatment coupled with increasingly strict water quality standards is an ever growing incentive for the development of better process design tools. This paper reviews design models for horizontal subsurface flow constructed treatment wetlands, ranging from simple rules of thumb and regression equations, to the well-known first-order k-C* models, Monod-type equations and more complex dynamic, compartmental models. Especially highlighted in this review are the model constraints and parameter uncertainty. A case study has been used to demonstrate the model output variability and to unravel whether or not more complex but also less manageable models offer a significant advantage to the designer.     

Alternative analysis of BOD removal in subsurface flow constructed wetlands employing Monod kinetics

A new, mechanistic approach for design and analysis of subsurface flow (SSF) constructed wetlands is presented. The model is based on the assumption that the biological processes in wetlands, like other biological systems, exhibit Monod kinetics. A Monod approach fits well with observed wetland performance. It predicts first-order behaviour at low concentrations, that is, pollutant removal rates which increase with increasing pollutant concentration; and zero-order or saturated behaviour at high pollutant concentrations, that is, a maximum pollutant removal rate. A kinetic analysis of subsurface flow constructed wetlands exhibiting Monod kinetics reveals that loading rate, as well as the zero-order degradation rate constant, are essential parameters for efficient wetlands design for the removal of organic carbon. In particular, Monod kinetics enables the identification of an absolute maximum removal rate which is necessary to prevent undersizing in design. This is significant because it represents a theoretical upper bound on loading rate for wetlands design. The analysis is applied to wetlands data collected in North America by the US EPA in order to extract design criteria for BOD removal. It reveals that maximum loadings for SSF wetlands are at least 80 kg ha-1 d-1 for BOD. In addition, a new dimensionless performance efficiency parameter, omega, is presented as a more effective means of comparing wetland performance.     

人工湿地预处理微污染原水的脱氮除磷性能研究

分别采用推流式潜流湿地、往复流式潜流湿地、芦苇床表流湿地、蒲草床表流湿地四种人工湿地对微污染原水进行预处理,对比研究了四种人工湿地对总氮、氨氮、硝态氮及总磷的去除效果。结果表明,蒲草床表流湿地对总氮具有较高的去除率,在夏季和秋季去除率基本保持在60％～90％之间,四种湿地对总磷的去除率既不明显也不稳定。     

The effect of primary treatment and flow regime on clogging development in horizontal subsurface flow constructed wetlands: An experimental evaluation

The effect of both the type of primary treatment (hydrolitic up-flow sludge blanket (HUSB) reactor and conventional settling) and the flow regime (batch and continuous) on clogging development in subsurface flow constructed wetlands (SSF CWs) was studied. Clogging indicators (such as accumulated solids, hydraulic conductivity and drainable porosity) were determined in an experimental plant with three treatment lines. Correlations were encountered between the solids accumulated and both saturated hydraulic conductivity and drainable porosity reduction over time (74.5% and 89.2% of correlation, respectively). SSF CW implemented with a HUSB reactor accumulated ca. 30% lower sludge (1.9 kg DM/m²) than a system with a settler (2.5-2.8 kg DM/m²). However, no significant differences were recorded among treatment lines concerning hydraulic parameters (such as hydraulic conductivity or porosity). Root system development contributed to clogging. Accordingly, planted wetlands showed between 30% and 40% and 10% lower hydraulic conductivity and porosity reduction, respectively, than non-planted wetlands.     

不同人工湿地对微污染原水处理效果的研究

采用人工湿地预处理微污染黄河原水,分别研究了推流式潜流人工湿地、往复式潜流人工湿地、芦苇床表流人工湿地、蒲草床表流人工湿地对总氮和COD的去除效果。结果表明,推流式人工湿地和往复式人工湿地对总氮和硝态氮的去除效果无明显差别,但去除率要低于表流人工湿地。蒲草床表流人工湿地对总氮和硝态氮的平均去除率分别为84．33％和76．32％,去除效果好于芦苇床表流人工湿地。各人工湿地对COD的去除率在30％-65％之间,不同人工湿地对COD的去除效果差别不明显。人工湿地处理微污染黄河原水的效果明显,出水水质可满足城市供水水源水质标准的要求。     

往复流人工湿地处理城市污水的效能研究

使污水周期性地往复流过水平潜流湿地而构成往复流人工湿地,以提高人工湿地处理污水的效能.对两块大小、填料、植物都完全相同的往复流湿地和单向流湿地进行了历时为8个月的对比试验,结果表明：在同等运行条件下,两种人工湿地对COD、SS的去除率大致相当,分别为76.3%和97.1%;往复流人工湿地对TP、TN、NH3-N等指标的去除效果明显优于单向流湿地,其对TP、TN、NH3-N的去除率分别为76.3%、41.7%、35.6%,而单向流湿地的只有65.2%、27.6%、16.9%.