人工湿地废水处理机理

对人工湿地的构造、作用机理进行了较详尽的说明,湿地中物理、化学及生物协同作用以及湿地植物输氧造成的湿地基质中好氧、缺氧和厌氧状态的交替出现是保证其对氮磷及有机物具有较强处理效率的原因。研究表明：对进水浓度较低的城市污水,湿地的ＢＯＤ５和ＣＯＤ去除率大于８０％,出水ＢＯＤ２为１０ｍｇ／Ｌ左右。总氮及总磷去除率可大６０％和９０％,较常规二级处理方式具有一定的优越性。     

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.     

Nitrate Removal in a Restored Spring‐Fed Wetland,Pennsylvania, USA1

ABSTRACT:  In 2001, the 1.04‐ha Hornbaker wetland in south‐central Pennsylvania was restored by blocking an artificial drainage ditch to increase water storage and hydraulic retention time (HRT). A primary goal was to diminish downstream delivery of nitrate that enters the wetland from a limestone spring, its main source of inflow. Wetland inflow and outflow were monitored weekly for two years to assess nitrate flux, water temperature, pH, and specific conductivity. In Year 2, spring discharge was measured weekly to allow calculation of nitrate loads and hydraulic retention time. Surface runoff was confirmed to be a small fraction of wetland inflows via rainfall‐runoff modeling with TR‐55. The full dataset (n = 102) was screened to remove 13 weeks in which spring discharge constituted < 85% of total inflows because of high precipitation and surface runoff. Over two years (n = 89), mean nitrate‐nitrogen concentrations were 7.89 mg/l in inflow and 3.68 mg/l in outflow, with a mean nitrate removal of 4.19 mg/l. During Year 2 (n = 47), for which nitrate load data were available, the wetland removed an average of 2.32 kg N/day, 65% of the load. Nitrate removal was significantly correlated with HRT, water temperature, and the concentration of nitrate in inflow and was significantly greater during the growing season (5.36 mg/l, 64%) than during the non‐growing season (3.23 mg/l, 43%). This study indicates that hydrologic restoration of formerly drained wetlands can provide substantial water quality benefits and that the hydrologic characteristics of spring‐fed wetlands, in particular, support effective nitrogen removal.     

Variations in Base‐Flow Nitrate Flux in a First‐Order Stream and Riparian Zone1

Abstract: Nonpoint source pollution, which contributes to contamination of surface waters, is difficult to control. Some pollutants, particularly nitrate (), are predominantly transmitted through ground water. Riparian buffer zones have the potential to remove contaminants from ground water and reduce the amount of that enters surface water. This is a justification for setting aside vegetated buffer strips along waterways. Many riparian zone hydrologic models assume uniform ground‐water flow through organic‐rich soil under reducing conditions, leading to effective removal of ground‐water prior to discharge into a stream. However, in a small first‐order stream in the mid‐Atlantic coastal plain, base‐flow generation was highly variable (spatially and temporally). Average base‐flow loads were greater in winter than summer, and higher during a wetter year than in dryer years. Specific sections of the stream consistently received greater amounts of high ground water than others. Areas within the riparian zone responsible for most of the exported from the watershed are termed “critical areas.” Over this 5‐year study, most of the exported during base flow originated from a critical area comprising less than 10% of the total riparian zone land area. Allocation of resources to address and improve mitigation function in critical areas should be a priority for continued riparian zone research.     

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.     

Assessing the Effectiveness of a Constructed Arctic Stream Using Multiple Biological Attributes

Objective assessment of habitat compensation is a central yet challenging issue for restoration ecologists. In 1997, a 3.4-km stream channel, designed to divert water around an open pit diamond mine, was excavated in the Barrenlands region of the Canadian Arctic to create productive stream habitat. We evaluated the initial success of this compensation program by comparing multiple biological attributes of the constructed stream during its first three years to those of natural reference streams in the area. The riparian zone of the constructed stream was largely devoid of vegetation throughout the period, in contrast to the densely vegetated zones of reference streams. The constructed stream also contained lower amounts of woody debris, coarse particulate organic matter (CPOM), and epilithon; had lower coverage by macrophytes and bryophytes; and processed leaf litter at a lower rate than reference streams. Species richness and densities of macroinvertebrates were consistently lower in the constructed stream compared to natural streams. This contributed to differences in macroinvertebrate assemblage structure throughout the period, although assemblages showed some convergence by year 3. The effectiveness of the constructed stream to emulate natural streams varied somewhat depending on the biological attribute being evaluated. Assessments based on individual attributes showed that minimal to moderate levels of similarity between the constructed stream and natural streams were achieved. A collective assessment of all biological and ecosystem attributes suggested that the constructed stream was not a good surrogate for natural streams during these first years. Additional time would be required before many characteristics of the constructed stream would resemble those of reference streams. Because initial efforts to improve fish habitat in the constructed stream focused on physical structures (e.g., weirs, vanes, rock, groins), ecological factors limiting fish growth were not considered and likely constrained success. We suggest that a greater focus on organic characteristics and vegetation within the stream and its riparian zone could have accelerated compensation. The addition of woody debris and CPOM, combined with planting of shrubs and herbs along the stream, should provide a source of allochthonous matter for the biotic community while large cobble and boulders should improve the physical stability of stream system, protecting its organic components.     

人工湿地生态修复旅游景区污染水体的研究

提出了采用人工湿地并配合植物操控技术治理旅游景区污染水体,并建立了示范工程.经调试运行,在日处理水量为145 m3条件下,人工湿地对TN、TP、COD和BOD5的去除率分别为63.12%,40.47%,83.07%和73.45%.工程通过2个月的运行,污染水体的水质得到明显改善.该技术为旅游景区和景点的污水治理提供了新途径.     

亚铁对水平潜流人工湿地反硝化作用的影响

亚铁离子可以作为电子供体参与反硝化作用,某些微生物可以通过氧化亚铁离子还原硝酸盐,从而去除污水中的硝态氮.本研究通过在潜流人工湿地中添加Fe2+,分析不同初始Fe2+浓度对反硝化过程的强化效果及不同C/N对Fe2+参与反硝化作用的影响.结果表明,Fe2+的添加可以显著提高人工湿地反硝化能力,进水NO-3-N为30 mg·L-1、C/N为2、水力停留时间为1 d,添加45 mg·L-1Fe2+的人工湿地中硝氮去除率可以提高24%;硝氮去除率随初始Fe2+浓度的增加而增加.C/N与初始Fe2+浓度对反硝化作用都具有显著影响且两者具有交互作用,碳源的存在可以促进Fe2+参与的反硝化作用.     

山地小微湿地生态修复探讨 ——以梁平区猎神村梯塘小微湿地为例

小微湿地是乡村景观的组成部分,是乡村重要的水土基础设施.湿地的功能已经得到广泛认同,但过去多关注大面积成片分布的沼泽、湖泊、滨海湿地及大型河流湿地等,而对于那些数量众多、分散分布的小型和微型湿地却缺少关注.2018年10月,《湿地公约》第十三届缔约方大会通过了中国政府提交的《小微湿地保护与管理决议草案》,小微湿地的保护...     

碎石床湿地去除城镇污水厂出水中磷的研究

为解决城镇污水二级生物处理厂脱磷不达标的问题,设计了潜流碎石床湿地,通过其填料的吸附、沉淀和植物摄取作用,对二级生化处理后的城镇污水进行脱磷试验。结果表明碎石床湿地有较高的脱磷效果,当进水TP为1.74mg/L时,出水为0.25mg/L,去除率为85.63%,同时对BOD5、COD、SS、NH3-N等也有一定去除作用。出水不仅能满足《污水综合排放标准》(GB8978-96)一级,而且满足《城市污水再生利用景观环境用水水质标准》(GB/T18921-2002),污水可以回用。潜流碎石床湿地深度脱磷技术运行费用低、管理方便、环境景观好、有推广应用价值。