浅谈人工湿地

结合南水北调污水处理工程,通过现场试验的方法,探讨了芦苇湿地对COD、氮、磷等污染物的降解作用,得出了温度在人工湿地系统中对去除污染物有重要影响的结论,指出采用人工湿地既能带来社会效益、经济效益,还能带来环境效益。     

人工湿地污水处理的机理及研究方向

结合国内外研究实例,综合阐述了人工湿地对污水中氮、磷和有机物等污染物质的去除机理以及在此方面国内的研究现状,分析了提高人工湿地处理能力的方法和途径,说明了利用自然过程进行污染物降解的人工湿地可以成为许多地区的污水处理方式,并且对这一技术的研究方向进行了探讨。     

人工湿地污水处理技术

介绍了湿地的概念及其人工湿地的发展现状，阐述了人工湿地处理污水系统中人工基质、水生植物、微生物对废水污染物的去除机理，指出这种方法具有良好的实用价值和应用前景。     

人工湿地在生态住宅小区建设中的应用

人工湿地处理技术具有投资低、出水水质好、耗能低、抗冲击力强、操作简单和运行费用低等优点,本文介绍了用于景观水体水质净化的人工湿地系统的工艺流程及设计方法,该方法适用于以雨水或再生水为补充水源的人工景观水体水质净化工程。     

人工湿地污水处理技术及其在我国的应用前景

人工湿地是一种新型的污水处理工艺,主要介绍了人工湿地的基本构成:基质、植物、微生物三种主要构建类型,阐述了人工湿地对污染物的去除机理及其优缺点,最后对人工湿地在我国的应用前景进行了展望。     

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。     

人工湿地流程设计及要素浅析

指出人工湿地是一项水质净化效果好,建造、运行费用低的生态污水处理技术,通过一个人工湿地模型,简要阐述了人工湿地建设的框架、工艺流程以及与景观设计当中的配合运用,从而推广该技术的应用。     

人工湿地在高校污水中水回用处理中的应用

对人工湿地和几种常用的中水处理工艺进行比较,并将人工湿地成功运用于广州某高校的中水处理中,取得了良好的经济效益和社会效益,有效提高了高校水资源利用率,值得在其他高校推广应用。     

Pollutant removal from municipal sewage lagoon effluents with a free-surface wetland

This research project was initiated to refine the knowledge available on the treatment of rural municipal wastewater by constructed wetlands. To determine the treatment capacity of a constructed wetland system receiving municipal lagoon effluents, the wetland was monitored over one treatment season, from May 19 to November 3, 2000. The wetland system consisted of a three-cell free-surface wetland, phosphorus adsorption slag filters and a vegetated filter strip. Bimonthly water samples at the inlet and outlet of each component of the wetland system were analysed for biochemical oxygen demand, nitrate and nitrite, ammonia and ammonium, total Kjeldahl nitrogen (TKN), total suspended solids (TSS), total phosphorus (TP), ortho-phosphate (ortho-PO(4)), fecal coliforms (FCs) and Escherichia coli. The free-surface wetland cells treating the lagoon effluents achieved removals as follows: biochemical oxygen demand (34%), ammonia and ammonium (52%), TKN (37%), TSS (93%), TP (90%), ortho-PO(4) (82%), FCs (52%) and E. coli (58%). The wetland cells reduced total nitrogen, TP and biochemical oxygen demand to levels below the maximum permissible levels required for direct discharge to nearby receiving waters (TN<3.0 mg x L(-1), TP<0.3 mg x L(-1), BOD(5)<3.0 mg x L(-1)). The vegetated filter strip treating the effluents from the wetland cells achieved removals as follows: biochemical oxygen demand (18%), ammonia and ammonium (28%), TKN (11%), TSS (22%), TP (5%), FCs (28%) and E. coli (22%). It may therefore serve as an additional treatment stage further reducing the concentrations of these mentioned parameters. The slag filters reduced TP in the lagoon effluents by up to 99%, and, in this study, were concluded to be effective phosphorus adsorbers.     

人工湿地废水处理技术的应用与前景

介绍了人工湿地的概念和分类,比较了人工湿地废水处理技术与其他废水处理技术,得出了人工湿地污水处理厂的投资少且运行费用低的结论,阐述了人工湿地废水处理技术在国内外的应用情况,对该技术的应用前景进行了展望。     

复合垂直流人工湿地填料层高度对污染物去除率的影响

研究了复合垂直流人工湿地填料层高度对NH4+-N、TP、COD去除率的影响。结果表明,填料层高度越高,污染物去除率越高,但单位高度填料的去除效率下降,因此,通过增加填料层高度来提高污染物的去除率并不经济。随着流程的增加,NH4+-N、TP、COD去除率的变化趋势各不相同,湿地的表层对NH4+-N、COD、TP有较高的去除效率,但下行池表层比上行池表层的污染负荷高。     

Experimental study of pollutant accumulation on an urban road surface

An understanding of pollutant characteristics on impervious surfaces is essential to estimate pollutant washoff characteristics and to design methods to minimise the impacts of pollutants on the environment. This paper presents data on surface pollutant characteristics on an urban road surface in Melbourne, Australia, from samples collected over a 36 day period. The data indicate that buildup over the dry days occurs relatively quickly after a rain event, but slows down after several days as redistribution occurs. The surface pollutant also becomes finer over the dry days as it is disintegrated. The washoff of surface pollutant is dependent on the rainfall and runoff characteristics, but the results here show that common storms only remove a small proportion of the total surface pollutant load. The data also show that street sweeping may have an adverse impact on pollutant washoff because the street sweeper releases the finer material but only removes some of them, making the fine sediment available for washoff by the next storm. The data also show that most of the nutrients are attached to the finer sediments, and to effectively reduce nutrient loads in particulates, treatment facilities must be able to remove the finer particles (down to 50 μm for TP and down to 10 μm for TN), and not just the total sediment or suspended solid load.     

Water quality improvement in a full-scale tertiary constructed wetland: Effects on conventional and specific organic contaminants

The surface flow constructed wetland (SF CW) in Can Cabanyes (Granollers, Catalonia, northeastern Spain) was created as a part of a series of activities aimed at restoring a highly impacted fluvial peri-urban zone. The system is fed with a small part of the secondary effluent, which is not completely nitrified, from an urban wastewater treatment plant. Effluents in the SF CW were sampled between 2003 and 2006 for physical and chemical parameters and faecal bacteria indicators. In addition, 8 pharmaceuticals and personal care products (PPCPs) were measured in June 2005 and February 2006. The system showed a good reliability for ammonium and faecal bacteria removal, with average ammonium efficiencies between 64 and 87% and a removal of approximately 2 logarithmic units of Faecal Coliforms. A clear seasonal trend was observed for ammonium. The results for PPCPs demonstrated that the wetland has a good capacity for removing a large variety of these compounds; the removal efficiencies were higher than 70% for most of them, with the exception of clofibric acid (34%) and carbamazepine (39%). Although the chemical oxygen demand and total suspended solid removal rates were either low or zero because of the permanent eutrophic conditions of the system and the low incoming concentrations, the effluent quality is generally considered to be quite good.     

Sulphate reduction and the removal of carbon and ammonia in a laboratory-scale constructed wetland

Sulphate is a normal constituent of domestic wastewater and reduced sulphur compounds are known to be potent inhibitors of plant growth and certain microbial activities. However, the knowledge about sulphate reduction and the effect on the removal of C and N in constructed wetlands is still limited. Investigations in laboratory-scale constructed wetland reactors were performed to evaluate the interrelation of carbon and nitrogen removal with the sulphate reduction by use of artificial domestic wastewater. Carbon removal was found to be only slightly affected and remained at high levels of efficiency (75-90%). Only at sulphate reduction intensities above 75 mgl(-1) (50% removal), a decrease of carbon removal of up to 20% was observed. A highly contrary behaviour of ammonia removal was found in general, which decreased exponentially from 75% to 35% related to a linear increase of sulphate reduction up to 75 mgl(-1) (50% removal). Since sulphate removal is considered to be dependant on the load of electron donors, the carbon load of the system was varied. Variation of the load changed the intensities of sulphate reduction immediately, but did not influence the carbon removal effectiveness. Doubling of the carbon concentration of 200 mgl(-1) BOD(5) for domestic wastewater usually led to sulphate reduction of up to 150 mgl(-1) (100% removal). The findings show that, particularly in constructed wetland systems, the sulphur cycle in the rhizosphere is of high importance for performance of the waste water treatment and may initiate a reconsideration of the amount of sulphate present in the tap water systems.     

Annual cycle of nitrogen removal by a pilot-scale subsurface horizontal flow in a constructed wetland under moderate climate

The annual course of nitrogen removal in a stable operating subsurface horizontal flow constructed wetland (SSF) in a moderate climate was evaluated using a large pool of data from 4 years of operation. In spring and autumn removal efficiencies were found to depend on the nitrogen load in a linear mode. The efficiencies in winter and summer differed extremely (mean removal rates of 0.15/0.7 g m(-2) d(-1) (11%/53%) in January/August) and were independent of the nitrogen load (0.7-1.7 g m(-2) d(-1)) in principle. Oscillations of the removal rates in spring, forming several maxima, suggest seasonal specific effects caused by the dynamics of the plant-physiology finally determining the nitrification efficiency, i.e. via O(2)-supply. Nitrification is limited by temperature during all seasons and surprisingly in midsummer additionally restricted by other seasonal aspects forming a clear-cut relative nitrification minimum (mean rate of 0.43 g m(-2) d(-1) (32%)) in July. The importance and the effect of the plants' gas exchange and oxygen input into the rhizosphere are discussed. Denitrification was nearly complete in midsummer and was clearly restricted at seasonal temperatures below 15 degrees C.     

Impact of wedge-shaped roofs on airflow and pollutant dispersion inside urban street canyons

The objective of this study is to investigate numerically the effect of wedge-shaped roofs on wind flow and pollutant dispersion in a street canyon within an urban environment. A two-dimensional computational fluid dynamics (CFD) model for evaluating airflow and pollutant dispersion within an urban street canyon is firstly developed using the FLUENT code, and then validated against the wind tunnel experiment. It was found that the model performance is satisfactory. Having established this, the wind flow and pollutant dispersion in urban street canyons of sixteen different wedge-shaped roof combinations are simulated. The computed velocity fields and concentration contours indicate that the in-canyon vortex dynamics and pollutant distriburtion are strongly dependent on the wedge-shaped roof configurations: (1) the height of a wedge-shaped roof peak is a crucial parameter determining the in-canyon vortex structure when an upward wedge-shaped roof is placed on the upwind building of a canyon; (2) both the heights of upstream and downstream corners of the upwind building have a significant impact on the in-canyon vortical flow when a downward wedge-shaped roof is placed on the upwind building of a canyon, due to flow separation as wind passes through the roof peak; (3) the height of upstream corner of the downwind building is an important factor deciding the in-canyon flow pattern when a wedge-shaped roof is placed on the downwind building of a canyon; (4) the characteristics of pollutant dispersion vary for different wedge-shaped roof configurations, and pollution levels are much higher in the “step-down” canyons relative to the “even” and “step-up” ones.     

The role of free water surface constructed wetlands as polishing step in municipal wastewater reclamation and reuse

In Europe, the last two decades witnessed growing water stress, both in terms of water scarcity and quality deterioration, which prompted many municipalities for a more efficient use of the water resources, including a more widespread acceptance of water reuse practices. Treatment technology encompasses a vast variety of options. Constructed wetlands are regarded as key elements in polishing conventionally treated wastewater for recreational and environmental applications. A survey was conducted to assess the performance of tertiary free water surface constructed wetlands in treating both key and emerging contaminant categories in the perspective of water reuse. A database was created with information concerning systems with emerging and free-floating macrophytes. The database includes results from both full- and pilot-scale systems, and considers a broad variety of operating conditions. This paper provides an overview of the treatment performances of the constructed wetlands in the database and discusses their significance in the optic of water reclamation and reuse practices.     

几种经济型人工湿地基质的除污效能分析

采用填料柱模拟垂直潜流人工湿地处理城市生活污水,考察了几种我国常见的、从经济角度考虑可广泛采用的湿地基质--粗砂、瓜子片、砾石、高炉渣、钢渣、煤灰渣对污染物的去除能力和效果.在几种供试的基质中,钢渣和煤灰渣对出水pH值的影响较大,基质粒径越小则对SS的去除效果越好;对有机物去除效果的高低顺序为：砂子＞煤灰渣＞瓜子片＞砾石＞钢渣＞高炉渣,对氨氮去除效果的高低顺序为：砂子＞煤灰渣＞瓜子片＞高炉渣＞砾石＞钢渣,6种基质对TP都有较好的去除效果,其高低顺序为：钢渣＞煤灰渣＞砂子＞高炉渣＞瓜子片＞砾石.     

垂流式人工湿地处理官厅水库入库水研究

在官厅水库永定河入库口处进行了垂流式人工湿地对入库河水的净化试验 ,结果表明 ,在渗滤时间 <1h时垂流式人工湿地对河水就有较好的净化效果 (对有机污染物和NH+ 4 -N的去除率都能达到 80 %左右 ,对TN和TP的去除率为 40 %左右 )。     

Effect of plant species on water quality at the outlet of a sludge treatment wetland

Sludge treatment wetlands are mainly used to reduce the volume of activated sludge, and the pollutants at the outlet are generally returned to the wastewater treatment plant. However, in cases where sludges are produced far from treatment plants not only must the sludge be treated, but the discharge of pollutants into the surrounding environment must also be limited. The aim of this study was to evaluate the efficiency of different plant species in optimising pollutant removal in a decentralised sludge treatment wetland. In addition, a new system design was assessed, in which the wetland was not completely drained, and a saturated layer was created using an overflow. The experimental setup consisted of 16 mesocosms in total, planted with monocultures of Phragmites australis, Typha angustifolia and Scirpus fluviatilis, and unplanted controls, each in four replicates.The experiment was conducted during the third summer of operation after setup. The system was fed with highly concentrated fish farm sludge at a load of 30 kg of total solids m⁻² yr⁻¹. Results showed that such wetlands were highly efficient, with removal rates between 94% and 99% for most pollutants. Planted systems generally outperformed the unplanted control, with a significantly lower mass of pollutants at the outlet of the sludge treatment wetland planted with Phragmites, followed by those with Typha and then Scirpus. The distinct influence of plant species on pollution removal was explained by the sequestration of nitrogen and phosphorus in plant tissues and by the rhizosphere effect, which enhance the biodegradation of organic matter, allowed the nitrification process and created redox conditions favourable to the sorption of phosphorus. Filtration and evapotranspiration rates played a major role in limiting the discharge of pollutants, and the impact was enhanced by the fact that the sludge treatment wetland was not completely drained.