人工湿地不同水流方式对生活污水净化的比较

通过小型复合流式人工湿地实验,监测了CODcr、TN、TP、NO3--N、NH4 -N等指标,旨在通过实验,找到处理污水的最佳水流方式.结果表明,垂直流和垂直流搭配对CODCr、TN、NH4 -N去除最好;而潜流和潜流搭配对NO3--N去除最好.人工湿地基质是影响磷的处理效果的主要因素,通过合理的操作方式可以最终从污水中除磷.在复合型人工湿地中延长水力停留时间能增加污染物的去除率.     

潜流人工湿地系统水力设计原则及类型

水力学条件是潜流型人工湿地建立及维持最重要的决定因子,直接关系人工湿地污水处理系统中的流速、流态、停留时间以及与植物生长关系密切的水面线控制等水力因子的设计和确定。概括分析了潜流型人工湿地水力设计的原则和类型,提出了复合潜流人工湿地系统水力模型构建的方法,以及形成系统的水流条件控制方法的研究路线,以期为潜流人工湿地优化设计、优化运行及机理模型的建立提供理论基础。     

人工湿地对化粪池出水净化效果的研究

通过在同种基质上种植相同数目的芦苇,研究了垂直流人工湿地对化粪池出水的净化效果以及不同水力停留时间对污水净化效果的影响。结果表明,同种填料、不同水力停留时间对污水中TP、NH3-N、COD的净化效果不同。由于芦苇根系和微生物的吸收与分解作用以及基质的吸附作用,种植芦苇的人工湿地的出水水质要比没种芦苇的好。     

W-SFCW和SFCW的水流特性试验研究

运用化学工程中反应器理论,试验分析波式潜流人工湿地(W-SFCW)中的停留时间分布。比较分析传统潜流湿地和理想反应器的流态特征,得出结论:在同样的水力负荷条件下,相对传统潜流人工湿地(SFCW),W-SFCW具有将污染物浓度降到同一浓度值所需时间更短、去除效率更高的内在机制。     

电厂冲灰水人工湿地的系统设计

人工湿地是指人工筑成水池或沟槽,填充一定深度的基质,种植芦苇等根系发达的水生植物,污水由湿地的一端进入,以推流方式与布满生物膜的介质和溶解氧进行充分的植物根区接触,进行吸附、过滤、及湿硝化、反硝化作用而获得净化。人工湿地分为表面流人工湿地和潜流流人工湿地,潜流流人工湿地可分为水平潜流流人工湿地和垂直     

垂直流人工湿地对河涌污水的处理效果研究

研究垂直流人工湿地系统在珠江三角洲城市河涌污水净化中的作用。以广州市猎德涌为例,采用芦苇、风车草、宽叶香蒲、美人蕉4种不同植物构成的垂直流人工湿地对污水中NH4^＋—N、CODcr及TP的去除进行实验研究。结果表明,在水力停留时间3d、连续进水的情况下,4种植物对CODcr的去除效果差异性不是很显著。     

城市湖泊污水处理的实验分析

以西安市兴庆湖为研究对象,对湖泊的水质进行了水平潜流和自由表面流净化的实验研究,比较了两种湿地的净化效果。在相同的水力负荷、水力停留时间、水深等条件下,分析了两种人工湿地对城市湖泊中的有机物、氮、磷等主要污染物的净化效果,及不同影响因素对系统处理效果的影响,比较了两种人工湿地的优缺点。     

水力负荷及季节变化对人工湿地处理效率的影响

研究了水力负荷及季节变化对人工湿地强化净化五里湖湖水处理效率的影响因素,试验时间从2004年8月3日~2006年1月15日。研究表明,随水力负荷的增加,垂直流、潜流和自由表面流人工湿地的处理效率均呈下降趋势,尤以自由表面流人工湿地变化最为明显。对于五里湖水体,适宜的进水负荷为0.8m3/(m2·d)左右,此时垂直流、潜流人工湿地的TN和TP的去除效率均在50%以上。各人工湿地随季节的变化去除效率排序为夏季>秋季>春季>冬季。TP的去除率随季节变化相对比较平稳,TN次之,NH3-N、CODMn变化较大,冬季去除率下降尤为明显。     

复合垂直流人工湿地系统对小清河污水的净化效果研究

研究了复合垂直流人工湿地处理系统在停留时间为3d时对小清河污水的净化效果.结果表明,复合垂直流人工湿地系统处理效果相当稳定,其对小清河出水中COD、BOD5、TP、TN、SS的平均去除率分别为85%、89%、94%、34%和74%以上.而种植植物的系统去除效果明显高于无种植植物系统的去除效果.     

人工潜流湿地系统在查干湖养殖污水净化处理中的应用研究

为验证人工潜流湿地系统在养殖污水净化方面发挥的作用，基于查干湖野鸭湾野鸭救护繁育站为研究对象的水循环体系，以养殖尾水水质净化为目标，采用复合垂直流潜流湿地污水处理技术进行养殖污水净化处理，开展人工潜流湿地水质净化系统研究。工程建设运行后于鸭舍、沉淀池、湿地出口设置3处水质检测采样点，通过对水质检测数据进行对比分析，评价潜流湿地系统的水质净化效果，为吉林西部河湖连通区典型湖泊湿地生态修复及黑臭水体治理提供技术样板。     

Diversity of ammonia oxidising bacteria in a vertical flow constructed wetland.

Vertical flow constructed wetlands (VFCWs) with intermittent loading are very suitable for nitrification. Ammonia oxidising bacteria (AOB) are the limiting step of nitration. Therefore the AOB community of a full-scale VFCW, receiving municipal wastewater, was investigated within this study. The diversity of the functional gene encoding the alpha-subunit of the ammonia monooxygenase (amoA), present only in AOB, was assessed by denaturing gradient gel electrophoresis (DGGE). Only very few amoA sequence types dominated the wetland filter substrate; nevertheless a stable nitrification performance could be observed. During the cold season the nitrification was slightly reduced, but it has been shown that the same AOB could be identified. No spatial AOB pattern could be observed within the filter body of the VFCW. The most prominent bands were excised from DGGE gels and sequenced. Sequence analyses revealed two dominant AOB lineages: Nitrosomonas europaea/"Nitrosococcus mobilis" and Nitrosospira. Species of the Nitrosomonas lineage are commonly found in conventional wastewater treatment plants (WWTPs). In contrast, members of the Nitrosospira lineage are rarely present in WWTPs. Our observations indicate that the AOB community in this VFCW is similar to that found in horizontal flow constructed wetlands, but differs from common WWTPs regarding the presence of Nitrosospira.     

Assessment of Suspended Solid Removal in a Surface Flow Constructed Wetland Using a Three-Dimensional Numerical Model

Surface flow constructed wetlands (SFCWs) have been widely used to treat various types of wastewater and stormwater due to the advantages such as low costs for operating and maintenance compared with conventional treatment systems. In SFCW, the flow pattern, which is determined by the geometric features including bed morphology and vegetation distribution, significantly influences the removal processes of suspended solids and other pollutants. In this study, a three-dimensional computational fluid dynamics model, that integrates hydrodynamic model and the Lagrangian particle tracking model, is applied to determine the effectiveness of a SFCW in removing suspended solids based on the predicted flow characteristics and distribution of suspended solids in the wetland. After the validation, the three-dimensional numerical model is applied to illustrate the three-dimensional internal flow pattern in the wetland. The predicted concentrations of suspended solids at several cross-sections in downstream direction are compared with the field sampling data and also the results from a traditional first-order decay model. The results show that the 3D model performs reasonably well predicting complex flow fields associated with complex wetland geometry. This study indicates that the 3D model is an effective tool to support the management and operation of field SFCWs. Also, it can help to improve the design of SFCWs providing better understanding of interactions among the geometric features, the flow characteristics and the contaminants behaviors.     

Effect of recirculation on organic matter removal in a hybrid constructed wetland system

This research project aimed to determine the technologically feasible and applicable wastewater treatment systems which will be constructed to solve environmental problems caused by small communities in Turkey. Pilot-scale treatment of a small community's wastewater was performed over a period of more than 2 years in order to show applicability of these systems. The present study involves removal of organic matter and suspended solids in serially operated horizontal (HFCW) and vertical (VFCW) sub-surface flow constructed wetlands. The pilot-scale wetland was constructed downstream of anaerobic reactors at the campus of TUBITAK-MRC. Anaerobically pretreated wastewater was introduced into this hybrid two-stage sub-surface flow wetland system (TSCW). Wastewater was first introduced into the horizontal sub-surface flow system and then the vertical flow system before being discharged. Recirculation of the effluent was tested in the system. When the recirculation ratio was 100%, average removal efficiencies for TSCW were 91 +/- 4% for COD, 83 +/- 10% for BOD and 96 +/- 3% for suspended solids with average effluent concentrations of 9 +/- 5 mg/L COD, 6 +/- 3 mg/L BOD and 1 mg/L for suspended solids. Comparing non-recirculation and recirculation periods, the lowest effluent concentrations were obtained with a 100% recirculation ratio. The effluent concentrations met the Turkish regulations for discharge limits of COD, BOD and TSS in each case. The study showed that a hybrid constructed wetland system with recirculation is a very effective method of obtaining very low effluent organic matter and suspended solids concentrations downstream of anaerobic pretreatment of domestic wastewaters in small communities.     

人工湿地污水处理系统优化设计模型

针对污水处理厂进水水质和水量的不确定性,考虑进水水量、TSS、BOD5、TN、TP的区间变化,以出水时TSS、BOD5、TN、TP的质量浓度标准为约束条件,单元面积为决策目标,以费用最小为目标函数,建立基于一级动力学污染物去除模型的人工湿地污水处理系统区间数优化设计模型。该模型包含初沉池、人工湿地床(表面流和潜流式)两个单元,考虑了设计中的不确定性因素。实例计算表明,模型适用性较好。     

Vertical flow constructed wetland for textile effluent treatment.

A pulse feed vertical flow constructed wetland (VFCW) proved to be efficient in the treatment of a textile effluent being able to buffer, dilute and treat an Acid Orange (AO7) accidental discharge. The influence of the flooding level (FL) and pulse feed (PF) duration on the removal efficiencies of a VFCW was examined. Average AO7 removal efficiencies of 70% were achieved for an AO7 Inlet concentration of 700 mgl(-1) applied during 15 min cycle(-1) (every three hours) at a hydraulic load of 13 lm(-2) cycle(-1) and an FL of 21%. The VFCW was modelled by analogy with a combination of ideal reactors. The simplest combination that best reproduced the experimental results was an association of 2 reactors in series plus 1 reactor accounting the dead volumes. The model parameters helped to understand the hydrological and kinetic processes occurring in VFCW. Through the model simulation it was shown that 3 VFCW in series were enough to efficiently treat an organic mass load of 76 gAO7 m(-2) day(-1) in 9 hours and fulfil the discharge legislation. In this work it was possible to establish that the overall degradation kinetics was of first order.     

人工湿地中水生植物的作用和选择

综述国内外有关人工湿地水生植物在污水净化过程中的作用及其选择的研究成果,提出了人工湿地系统水生植物有待进一步研究的问题。人工湿地水生植物的主要作用为:吸收利用和吸附富集污染物质、传输氧到湿地系统、为微生物提供栖息地、维持系统的稳定、积累有机物质。人工湿地系统要选择栽种耐污能力强、去污效果好、适合当地环境、根系发达、有一定经济价值的水生植物。     

Damk?hler number design method to avoid clogging of subsurface flow constructed wetlands by heterotrophic biofilms.

Clogging of subsurface flow (SSF) treatment wetlands from excess biofilm growth is a design problem for which only empirical guidelines exist. A method is proposed to systematically analyse this type of clogging as a design tool. In recognition of the physical reality that most SSF treatment wetland processes are a function of biofilm surface area, a Damk?hler number (Da) definition based on aggregate specific surface area is used to investigate a method of predicting clogging induced by heterotrophic biofilms growing on treatment media.     

Mechanical resistance properties of gravel used in subsurface flow constructed wetlands: implications for clogging

Gravel constitutes the filter medium in subsurface flow constructed wetlands (SSF CWs) and its porosity and hydraulic conductivity decrease over time (clogging), limiting the lifespan of the systems. Using gravel of poor quality accelerates clogging in wetlands. In this study, gravel samples from six different wetland systems were compared with regards to their mineral composition and mechanical resistance properties. Results showed that both mineralogy and texture are related to mechanical resistance. Accordingly, gravel with high content of quartz (> 80%) showed a lower percentage of broken particles (0.18-1.03%) than those with lower content of quartz (2.42-4.56% media broken). Although granite is formed by high durability minerals, its non-uniform texture results in a lower resistance to abrasion (ca. 10% less resistance than calcareous gravel). Therefore, it is recommended to use gravels composed mainly of quartz or, when it is not available, limestone gravels (rounded and uniform) are recommended instead. The resistance to abrasion (LAA test) seems to be a good indicator to determine the mechanical properties of gravels used in CWs. It is recommended to use gravels with LAA below 30% in order to avoid a rapid clogging due to gravel crumbling and subsequent mineral solids accumulation.     

温度和基质对人工湿地脱氮除磷效果的影响

构建由潜流人工湿地和表流人工湿地串联而成的复合人工湿地系统,研究了复合人工湿地脱氮除磷效果以及温度和基质对人工湿地脱氮除磷效果的影响。结果表明,复合人工湿地TP、氨氮平均去除率为33.64%、57.24%;水温降低会导致人工湿地氮磷去除率下降;基质为粗砂的潜流人工湿地脱氮除磷能力大于基质为砾石的潜流人工湿地。     

The ecological value of constructed wetlands for treating urban runoff.

The Sweetwater Authority's urban runoff diversion system (URDS) comprises constructed wetlands on a hillside between the town of Spring Valley and the Sweetwater Reservoir, California, USA. The URDS were designed to divert dry-weather and first-flush urban runoff flows from the Sweetwater reservoir. However, these constructed wetlands have developed into ecologically valuable habitat. This paper evaluates the following ecological questions related to the URDS: (1) the natural development of the species present and their growth pattern; (2) the biodiversity and pollutant stress on the plants and invertebrates; and (3) the question of habitat provided for endangered species. The URDS wetlands are comprised primarily of rush (Scirpus spp.) and cattails (Typha spp.). This vegetative cover ranged from 39-78% of the area of the individual wetland ponds. Current analyses of plant tissues and wetland sediment indicates the importance of sediment sorption for metals and plant uptake of nutrients. Analyses of URDS water following runoff events show the URDS wetlands do reduce the amount of nutrients and metals in the water column. Invertebrate surveys of the wetland ponds revealed lower habitat quality and environmental stress compared to unpolluted natural habitat. The value of the wetlands as wildlife habitat is constrained by low plant biodiversity and pollution stress from the runoff. Since the primary Sweetwater Authority goal is to maintain good water quality for drinking, any secondary utilization of URDS habitat by species (endangered or otherwise) is deemed an added benefit.