基质在人工湿地处理生活污水中的研究现状

基质是人工湿地的重要组成部分,本文总结了基质对氮、磷的去除作用,并对解决基质的堵塞问题提出几点建议,最后总结基质的选择方法。     

人工湿地基质除磷研究进展

基质除磷被认为是人工湿地磷去除的主要方式，除磷效果不仅受基质自身物理化学性质的影响，还受水力条件、磷负荷、pH值、季节、温度、有机负荷、溶解氧、干湿交替等因素的影响。本文较系统分析了湿地基质除磷的作用机理和基质除磷效率的影响因素，最后对今后研究的方向进行了展望。     

人工湿地系统在垃圾渗滤液处理中的应用

介绍了人工湿地的组成和类型,人工湿地去除渗滤液中有机物、氮、磷和重金属的机制。分析了影响人工湿地处理渗滤液效率的因子,并且结合人工湿地设计和运行维护提出了相关建议。根据国内外成功的工程实例,分析了人工湿地处理垃圾渗滤液的经济优势、生态优势,展示了该处理技术广泛的应用前景,对以后的研究进行了展望。     

从潜流式人工湿地设计谈提高氮去除率方法的途径

从相关文献与实际工程来看,潜流式人工湿地对含氮污染物的去除效果与含碳污染物的去除比相对较弱。参考国内外大量文献资料,根据潜流式人工湿地的常规工艺和脱氮机理,本文总结并提出了一些提高污水氮去除率的方法。指出应根据具体的情况选择合适的植物和基质、通过工程措施和工艺组合、优化工艺设计及其他一些方法来创造脱氮所需环境,从而达到提高潜流式人工湿地氮去除率的目的。     

太湖流域污水处理设施尾水深度脱氮除磷工艺

文章以太湖流域污水处理设施尾水为例,研究出"水质水量调节—垂直潜流人工湿地—水平潜流人工湿地"的尾水深度脱氮除磷工艺,在人工湿地中使用铝污泥复合填料,研究成果可为太湖流域污水处理设施的深度处理及提标改造提供关键技术支持。     

钢渣沸石强化冬季人工湿地处理生活污水的应用研究

为构建一个冬季脱氮除磷效果好的人工湿地系统,选用钢渣、沸石及耐低温常绿鸢尾,构建两组潜流人工湿地(CW1,CW2)。冬季(8～12.3℃)条件下,考察两者对于城镇生活污水的净化效果。结果表明,钢渣—沸石—鸢尾人工湿地(CW2)对生活污水中的NH~+_4-N、TN平均去除率为95.46%、95.68%,达到GB18918-2002一级A标。人工湿地对TP及COD平均去除率为75.71%、55.22%,达到GB18918-2002一级B标。低温条件下,CW2仍保持良好的脱氮除磷效果且能耗低,可进行推广应用。     

表面流人工湿地磷循环生态动力学模型及实现方法

人工湿地做为一种高效低耗的新型污水处理工艺日益为人们所关注,特别是表面流人工湿地所特有的区域生态效益和脱氮除磷效果,但其污染物去除的内在机制并不为人们所完全掌握。本文详细地介绍了表面流人工湿地磷循环生态动力学模型的设计思想、具体结构、数学模式和实现方法,并对生物生长、死亡和土壤作用模块的各种不同实现方法傲了深入细致地分析探讨。结果表明人工湿地生态动力学模型由于假设歧义、实现方法不统一、模型参数测定手段的缺乏等因素的影响,导致其模拟结果的误差偏大,在表面流人工湿地多介质环境条件下多形态磷循环机理和多学科交叉研究方面还需要进行更深入、细致的工作,来对模型不断完善以推动对人工湿地污水处理工艺的完全掌握和科学应用。     

水生植物石菖蒲在人工湿地水质净化中的应用

综述了石菖蒲在人工湿地水质净化中发挥的重要作用,植物通过吸附吸收、促进微生物的硝化反硝化作用等来实现氮、磷和有机污染物等的去除.分析了植物特性、植物搭配、环境因子以及水力负荷等对石菖蒲净化水质效率的影响.归纳了石菖蒲的生态习性和人工湿地设计时需要综合考虑的因素,对今后石菖蒲在人工湿地水污染控制等领域的应用进行了展望.     

3种人工湿地填料对磷的动态吸附特征

以河沙、页岩、石灰石等3种重庆常见基质为人工湿地填料,探讨了磷负荷和有机负荷对基质动态除磷效果的影响。结果表明,在同等磷负荷和有机负荷情况下,3种填料的去除效果依次为石灰岩（河沙（页岩;有机负荷对各填料除磷有重要的影响,随着有机负荷的增加,填料除磷率均有不同程度的降低。有机负荷对石灰岩除磷的影响较大,对河沙除磷的影响相对较小。     

人工湿地污水处理系统脱氮机理研究进展

本文介绍了近年来人工湿地污水处理系统脱氮机理的研究情况,阐述了人工湿地脱氮的三种途径：植物和其它生物的吸收作用、微生物的生物转化作用及氨气的挥发作用,其中微生物的生物转化作用是人工湿地主要的脱氮方式.同时对影响人工湿地脱氮效率的主要因素：温度、pH值、氧化还原电位、溶解氧、微生物可利用有机碳与硝态氮、停留时间等都作了比较详细的介绍,为进一步开展人工湿地脱氮机理的研究和优化人工湿地污水处理系统设计提供参考.     

Nutrient processing capacity of a constructed wetland in western Ireland

In Ireland, constructed wetland systems are increasingly being used to perform tertiary treatment on municipal waste effluent from small towns and villages located in areas whose receiving waters are deemed sensitive. The bedrock formation in the west of Ireland is primarily karst limestone and where the overburden-soil cover is very shallow, such waters are highly sensitive to pollution sources, as little or no natural attenuation and/or treatment will occur. Constructed wetland technology has been seen to offer a relatively low-cost alternative to the more conventional tertiary treatment technologies, particularly when dealing with low population numbers in small rural communities. This paper examines the waste treatment performance, in terms of nutrient (P and N) reduction, of a recently constructed surface-flow wetland system at Williamstown, County Galway, Ireland. Performance evaluation is based on more than two years of water quality and hydrological monitoring data. The N and P mass balances for the wetland indicate that the average percentage reduction over the two-year study period is 51% for total N and 13% for total P. The primary treatment process in the wetland system for suspended solids (between 84 and 90% reduction), biological oxygen demand (BOD) (on average, 49% reduction), N, and P is the physical settlement of the particulates. However, the formation of algal bloom during the growing season reduces the efficiency of the total P removal.     

Nutrient transport in a restored riparian wetland

We determined the water quality effect of a restored forested riparian wetland adjacent to a manure application area and a heavily fertilized pasture in the Georgia Coastal Plain. The buffer system was managed based on USDA recommendations and averaged 38 m in width. Water quality and hydrology data were collected from 1991-1999. A nitrate plume in shallow ground water with concentrations exceeding 10 mg NO3-N L(-1) moved into the restored forested riparian wetland. Along most of the plume front, concentrations were less than 4 mg NO3-N L(-1) within 25 m. Two preferential flow paths associated with past hydrologic modifications to the site allowed the nitrate plume to progress further into the restored forested riparian wetland. Surface runoff total N, dissolved reactive phosphorus (DRP), and total P concentrations averaged 8.63 mg N L(-1), 1.37 mg P L(-1), and 1.48 mg P L(-1), respectively, at the field edge and were reduced to 4.18 mg N L(-1), 0.31 mg P L(-1), and 0.36 mg P L(-1), respectively, at the restored forested riparian wetland outlet. Water and nutrient mass balance showed that retention and removal rates for nitrogen species ranged from a high of 78% for nitrate to a low of 52% for ammonium. Retention rates for both DRP and total P were 66%. Most of the N retention and removal was accounted for by denitrification. Mean annual concentrations of total N and total P leaving the restored forested riparian wetland were 1.98 mg N L(-1) and 0.24 mg P L(-1), respectively.     

Nutrient and sediment removal by a restored wetland receiving agricultural runoff

Few studies have measured removal of pollutants by restored wetlands that receive highly variable inflows. We used automated flow-proportional sampling to monitor the removal of nutrients and suspended solids by a 1.3-ha restored wetland receiving unregulated inflows from a 14-ha agricultural watershed in Maryland, USA. Water entered the wetland mainly in brief pulses of runoff, which sometimes exceeded the 2500-m3 water holding capacity of the wetland. Half of the total water inflow occurred in only 24 days scattered throughout the two-year study. Measured annual water gains were within 5% of balancing water losses. Annual removal of nutrients differed greatly between the two years of the study. The most removal occurred in the first year, which included a three-month period of decreasing water level in the wetland. In that year, the wetland removed 59% of the total P, 38% of the total N, and 41% of the total organic C it received. However, in the second year, which lacked a drying period, there was no significant (p > 0.05) net removal of total N or P, although 30% of the total organic C input was removed. For the entire two-year period, the wetland removed 25% of the ammonium, 52% of the nitrate, and 34% of the organic C it received, but there was no significant net removal of total suspended solids (TSS) or other forms of N and P. Although the variability of inflow may have decreased the capacity of the wetland to remove materials, the wetland still reduced nonpoint-source pollution.     

Recent Land Cover History and Nutrient Retention in Riparian Wetlands

Wetland ecosystems are profoundly affected by altered nutrient and sediment loads received from anthropogenic activity in their surrounding watersheds. Our objective was to compare a gradient of agricultural and urban land cover history during the period from 1949 to 1997, with plant and soil nutrient concentrations in, and sediment deposition to, riparian wetlands in a rapidly urbanizing landscape. We observed that recent agricultural land cover was associated with increases in Nitrogen (N) and Phosphorus (P) concentrations in a native wetland plant species. Conversely, recent urban land cover appeared to alter receiving wetland environmental conditions by increasing the relative availability of P versus N, as reflected in an invasive, but not a native, plant species. In addition, increases in surface soil Fe content suggests recent inputs of terrestrial sediments associated specifically with increasing urban land cover. The observed correlation between urban land cover and riparian wetland plant tissue and surface soil nutrient concentrations and sediment deposition, suggest that urbanization specifically enhances the suitability of riparian wetland habitats for the invasive species Japanese stiltgrass [Microstegium vimenium (Trinius) A. Camus].     

Enzyme-based resource allocated decomposition and landscape heterogeneity in the Florida Everglades

Enzyme catalyzed reactions are generally considered the rate-limiting step in organic matter degradation and may be significantly influenced by the structure and composition of plant communities. Changes in these rates have the potential to effect long-term peat accumulation and influence the topography of a wetland ecosystem. To determine habitat influences on enzyme activities, we examined slough and sawgrass plots within enriched and reference phosphorus (P) sites in the Everglades. Assays were performed for the enzymes involved in carbon (C), nitrogen (N), and P cycling and lignin depolymerization. Enzyme activities were normalized and analyzed in terms of a resource allocation strategy. Plant composition was found to significantly alter the allocation of enzymatic resources due to varying substrate complexities. Potential decomposition in the slough was less influenced by lignin than in the sawgrass habitats. Additionally, an index relating hydrolytic and oxidative enzymes was significantly greater in the slough habitats, whereas C/N ratios were significantly lower. These indices suggest more favorable decomposition conditions and thus slower peat accretion within the slough communities, which may contribute to the development of elevation differences within the sawgrass ridge and slough topography of the Everglades.     

Mechanisms of nutrient attenuation in a subsurface flow riparian wetland

Riparian wetlands are transition zones between terrestrial and aquatic environments that have the potential to serve as nutrient filters for surface and ground water due to their topographic location. We investigated a riparian wetland that had been receiving intermittent inputs of NO3- and PO4(3-) during storm runoff events to determine the mechanisms of nutrient attenuation in the wetland soils. Few studies have shown whether infrequent pulses of NO3- are sufficient to maintain substantial denitrifying communities. Denitrification rates were highest at the upstream side of the wetland where nutrient-rich runoff first enters the wetland (17-58 microg N2O-N kg soil(-1) h(-1)) and decreased further into the wetland. Carbon limitation for denitrification was minor in the wetland soils. Samples not amended with dextrose had 75% of the denitrification rate of samples with excess dextrose C. Phosphate sorption isotherms suggested that the wetland soils had a high capacity for P retention. The calculated soil PO4(3-) concentration that would yield an equilibrium aqueous P04(3-) concentration of 0.05 mg P L(-1) was found to be 100 times greater than the soil PO4(3-) concentration at the time of sampling. This indicated that the wetland could retain a large additional mass of PO4(3-) without increasing the dissolved P04(3-) concentrations above USEPA recommended levels for lentic waters. These results demonstrated that denitrification can be substantial in systems receiving pulsed NO3- inputs and that sorption could account for extensive PO4(3-) attenuation observed at this site.     

人工湿地污水处理系统工艺设计研究

本文阐述了人工湿地污水处理系统工艺设计的主要内容及存在的若干问题，提出了开展人工湿地工艺设计研究的一些设想。人工湿地工艺设计研究包括人工湿地基质构建、植物群落构建和人工湿地构造与工程参数三个方面。目前，由于在污染物净化机理、系统水力学和污染物降解动力学等方面认识不足，制约了人工湿地工艺设计水平的提高，因此，深入研究污染物净化机理、开展人工湿地基质与植物筛选与组合研究、创建适合植物生长的人工生境、优化水力学模型和污染物降解动力学模型．将有利于提高人工湿地工艺设计水平。     

Nitrification and denitrification rates of Everglades wetland soils along a phosphorus-impacted gradient

Little information is available on the effect of phosphorus (P) enrichment on nitrogen (N) biogeochemical cycling in wetland soil. Of particular importance are the coupled nitrification-denitrification reactions that regulate the microbially mediated loss of N from wetland systems. Soils from the northern Florida Everglades have been affected by P loading from surface waters over the past 40 years. Elevated P levels have been show to have an effect on the size and activity of the microbial pool and a decrease in the N to P ratio of the microbial biomass. The objective of the study was to determine if P enrichment in soils affected microbial activities related to nitrification and denitrification in these flooded, peat soils. Potential nitrification rates of soil and detritus were determined using constantly stirred reactors under aerobic conditions while denitrification rates were determined from anaerobic incubations of slurry. Nitrification rates showed two distinct linear phases, a slower initial rate, signifying activity of nitrifiers present, followed by a sharp increase in the NH4+ conversion rate indicative of maximum potential rates. Initial rates of nitrification were highest in the surficial detrital layer decreasing with soil depth and did not correlate to soil total P. The potential rates of nitrification were 13 times greater than the initial rates. Potential denitrification rates were highest in the detritus and 0- to 10-cm soil interval with significantly lower values in the 10- to 30-cm soil interval, significantly correlated to total P of the soil. A significant (P < 0.01) relationship was seen between potential denitrification rates and soil total P suggesting an increased rate of N removal from P-enriched regions of the northern Everglades.     

Efficacy of natural wetlands to retain nutrient, sediment and microbial pollutants

Wetlands can improve water quality through natural processes including sedimentation, nutrient transformations, and microbial and plant uptake. Tailwater from irrigated pastures may contribute to nonpoint source water pollution in the form of sediments, nutrients, and pathogens that degrade downstream water quality. We examined benefits to water quality provided by a natural, flow-through wetland and a degraded, channelized wetland situated within the flood-irrigation agricultural landscape of the Sierra Nevada foothills of Northern California. The non-degraded, reference wetland significantly improved water quality by reducing loads of total suspended sediments, nitrate, and Escherichia coli on average by 77, 60, and 68%, respectively. Retention of total N, total P, and soluble reactive P (SRP) was between 35 and 42% of loads entering the reference wetland. Retention of pollutant loads by the channelized wetland was significantly lower than by the reference wetland for all pollutants except SRP. A net export of sediment and nitrate was observed from the channelized wetland. Decreased irrigation inflow rates significantly improved retention efficiencies for nitrate, E. coli, and sediments in the reference wetland. We suggest that maintenance of these natural wetlands and regulation of inflow rates can be important aspects of a best management plan to improve water quality as water runs off of irrigated pastures.     

Nutrient removal in a pilot and full scale constructed wetland, Putrajaya city, Malaysia

Putrajaya Wetlands in Malaysia, a 200ha constructed wetland system consisting of 24 cells, was created in 1997-1998 to treat surface runoff caused by development and agricultural activities from an upstream catchment before entering Putrajaya Lake (400ha). It was designed for stormwater treatment, flood control and amenity use. The water quality improvement performance of a section of the wetland cells is described. The nutrient removal performance was 82.11% for total nitrogen, 70.73% for nitrate-nitrogen and 84.32% for phosphate, respectively, along six wetland cells from Upper North UN6 to UN1 from April to December 2004. Nutrient removal in pilot scale tank systems, simulating a constructed wetland and planted with examples of common species at Putrajaya, the Common Reed Phragmites karka and Tube Sedge Lepironia articulata, and the capacity of these species to retain nutrients in above and below-ground plant biomass and substrate is reported. The uptake of nutrients by the Common Reed and Tube Sedge from the pilot tank system was 42.1% TKN; 28.9% P and 17.4% TKN; 26.1% P, respectively. The nutrient uptake efficiency of the Common Reed was higher in above-ground than in below-ground tissue. The results have implications for plant species selection in the design of constructed wetlands in Malaysia and for optimizing the performance of these systems.