人工湿地填料强化除磷研究

填料吸附法是人工湿地去除农村生活污水中磷素的主要方式.对不同类型填料及其组合在吸附除磷方面进行计论,认为合成填料在单一填料中除磷效果最优,其次是工业废料、天然填料;而组合填料明显好于单一填料.建议在人工湿地填料的选用中,应根据水质特点和填料特性选择不同填料组合强化除磷.     

复合垂直流人工湿地脲酶和磷酸酶活性与黑臭河水净化效果

[目的]研究复合垂直流人工湿地脲酶和磷酸酶活性与黑臭河水的净化效果.[方法]以蜂巢石和软性填料为基质,通过构建生物栅复合垂直流人工湿地系统强化处理黑臭河水,并测定人工湿地不同功能区中2种填料的脲酶和磷酸酶活性,研究2种填料在不同功能区的挂膜性能.[结果]软性填料生物膜上的脲酶和磷酸酶活性显著高于蜂巢石填料生物膜上的活性,说明选择软性填料更利于生物膜的生长;脲酶活性与总氮的去除率显著相关,而磷酸酶活性与总磷的去除率相关性不显著.[结论]该研究结果为利用脲酶和磷酸酶活性作为评价黑臭河水净化效果和挑选合适的填料提供了依据.     

白钨选矿尾水悬浮物人工湿地基质沉降模拟研究

人工湿地在运用过程中表现出对悬浮物良好的去除作用,但其去除机理和规律的研究却不够透彻。为了探究白钨选矿尾水悬浮物的去除效果及固体颗粒在人工湿地基质中的沉降规律,选择花岗岩或石英,构建水平潜流人工湿地系统,考察水力坡度对悬浮物去除效果的影响,分析沉积颗粒粒径。结果表明:人工湿地对悬浮物有良好的去除效果;6～12 mm的花岗岩作填料,水力坡度为0.25%时,去除效率在60%以上,出水中悬浮物的含量在40 mg/L左右;预处理的絮凝过程将无法沉降的2μm以下的颗粒物从63%降至20%以下,颗粒中值粒径由1.64μm扩大至3.97μm;沉积物粒径分布在3.5～23.6μm间,沉降距离可依据Stokes定律推算。     

提高人工湿地脱氮除磷性能的强化技术及其在有色金属工业废水中的应用

人工湿地因具有良好的脱氮除磷性能而广泛应用于生活污水尾水和工业废水的深度处理。然而,随着环保政策要求的日益严格,传统的人工湿地对不同水质污水的处理能力有限,从而导致多数污水处理难以满足达标排放的要求。因此,越来越多的强化技术与手段被应用于人工湿地系统,以增强人工湿地的污染物净化性能。主要从合理设计人工湿地、联合预处理工艺构建复合人工湿地系统以及保温和溶解氧控制等方面综述当前提高人工湿地脱氮除磷性能的强化技术,并简要概述了人工湿地在处理有色金属工业废水中的应用。     

复合型人工湿地系统设计参数研究

针对目前在矿区污水处理应用的人工湿地系统存在的问题,利用人工土壤快渗作为人工湿地系统的预处理措施构建复合型处理系统,依托实例分别确定了两个子系统的设计指导原则及核心控制指标,分析各项设计参数及其影响因素,对后续工程设计及项目实施奠定基础,并为改进矿区人工湿地系统提供了借鉴作用。     

人工湿地在酸性矿山废水处理中的应用

随着经济建设的快速发展,我国矿山废水产生的环境问题日益严重,矿山废水的污染已成为制约矿业经济可持续发展的主要因素之一。文章介绍了酸性主要污染物及其危害,人工湿地处理系统的特点及利用人工湿地系统处理酸性矿山废水的机理与效能。     

复合型人工湿地处理农村散户生活污水的研究

为提高人工湿地系统全年对农村散户生活废水的处理效率、运行稳定性及经济价值,对四种基质进行了试验研究,并针对春夏秋和冬季分别构建了四种复合型水生植物人工湿地系统,结果表明:绿沸石和页岩陶粒对NH_3-N、TP分别表现出最好的吸附效果;旱伞草+空心菜/水芹菜复合湿地系统在秋季和冬季分别表现出较高的污染物整体去除率及较好的长期运行稳定性,旱伞草+空心菜对COD、NH_3-N和TP去除率分别为75%～80%、80%以上、59%～63%;旱伞草+水芹菜对COD、NH_3-N和TP去除率分别为68%～72%,74%～77%和53%～57%。复合型人工湿地全年污染物去除效率高,并可提供优质蔬菜、美化农村环境,具有较好的观赏和经济价值及应用前景。     

宝钢外排综合废水人工湿地生态净化回用处理中试研究

钢铁企业外排综合废水的处理回用是降低吨钢耗新水量的有效途径。通过宝钢围厂河调研可知,围厂河接纳的废水资源量丰富,但较高的Fe、Mn浓度限制了其资源化利用。研究了将锰砂作为填料应用于人工湿地中处理宝钢外排综合废水,结果表明,锰砂人工湿地可有效去除废水中的Fe、Mn等污染物,出水达到了《城市污水再生利用工业用水水质》(GB/T 19923-2005)和宝钢生产用水的水质要求。锰砂人工湿地运行稳定,受水力停留时间HRT、季节、温度等因素影响较小,运行成本较低,具有良好的经济效益。     

表面流人工湿地处理生活污水研究——以浙江省舟山城北水库人工湿地为例

对浙江省舟山市城北水库自由表面流人工湿地运行的污水净化效果和处理系统存在的问题进行了分析和研究.结果表明,湿地在2010年5-10月运行的6个月中,对污水中COD、BOD5、TN、NH4-N和NO3-N的去除率分别为64.40%、44.83%、72.83%、60.98%和35.06%.此外,对工程运行状况的观测发现,人工湿地存在入水量不足及植物管理不善等问题.     

轧钢废水深度处理及生态化再生利用技术

人工湿地技术以其较低的运行成本及简便的管理模式近年来被广泛地应用在工业废水深度处理和污水的再生回用中.采用锰砂和砾石填料的人工湿地试验装置应用在轧钢废水深度处理中,并对污染物的去除效果进行了分析,利用人工湿地中的填料、微生物、植物协同作用研究轧钢废水中COD和总磷等污染物的去除效果,研究发现,经过湿地处理后,COD等出水水质指标能够满足《城市污水再生利用工业用水水质》(GB/T19923-2005)标准.     

Design Model for COD Removal in Constructed Wetlands Based on Biofilm Activity

Current design criteria for free-water-surface constructed wetlands are based on either empirical relationships or first-order reaction rates and do not emphasize the microbial activity. This study was conducted to evaluate the role of biofilm bacteria present in free-water-surface constructed wetland beds in the removal of organic matter. A kinetic model incorporating the biofilm kinetics and dispersion number was proposed to predict chemical oxygen demand removal in free-water-surface constructed wetlands. The model parameters were determined from laboratory experiments and from the literature. The proposed kinetic model satisfactorily predicted chemical oxygen demand removal efficiencies in a pilot-scale constructed wetland unit located in the tropics. A design chart and a design example based on the kinetic model are given.     

Evaluating Four Storm-Water Performance Metrics with a North Carolina Coastal Plain Storm-Water Wetland

Storm-water best management practices (BMPs) are typically assessed using the performance metric of pollutant concentration removal efficiencies. However, debate exists whether this is the most appropriate metric to use. In this study, a storm-water wetland constructed and monitored in the coastal plain of North Carolina is evaluated for water quality and hydrologic performance using four different metrics: concentration reduction, load reduction, comparison to nearby ambient water quality monitoring stations, and comparison to other wetlands studied in North Carolina. The River Bend storm-water wetland was constructed in spring 2007 and was monitored from June 2007 through May 2008. Twenty-four hydrologic and 11 water quality events were captured and evaluated. The wetland reduced peak flows and runoff volumes by 80 and 54%, respectively. Reductions were significant. Concentrations for the following pollutants increased: total kjeldahl nitrogen (TKN), NH4–N, total nitrogen (TN), and total suspended solids (TSS); inflow and outflow concentrations did not change for total phosphorus (TP), while only NO2–3–N and orthophosphorus (OP) concentrations were lower at the outlet. Using a load reduction metric, results were strikingly different, showing positive load reductions of 35, 41, 42, 36, 47, 61, and 49% for these respective pollutants: TKN, NO2–3–N, NH4–N, TN, TP, OP, and TSS. When comparing the effluent concentrations from the wetland to ambient water quality in the Trent River, all effluent nitrogen species concentration were either similar or lower. TP and TSS concentrations leaving the wetland were higher than ambient water quality data. Finally, by comparing pollutant concentrations among different North Carolina wetlands, it is apparent the River Bend wetland received relatively “clean” water and released water with pollutant concentrations comparable to all other studies examined. Major conclusions from this study include: (1) storm-water wetlands sited in sandier soils (such as those of the North Carolina coastal plain) should be considered a low impact development tool and (2) the selection of performance metric has a pronounced bearing on how a BMP’s performance is perceived. Sole reliance on a concentration reduction metric is discouraged.     

High Rates of Ammonia Removal in Experimental Oxygen-Activated Nitrification Wetland Mesocosms

While constructed treatment wetlands are very efficient at polishing nitrate from secondary effluent, they are much less effective at removing ammonia. A key factor that limits ammonia oxidation via biological nitrification in vegetated wetlands is low levels of dissolved oxygen. This study evaluated the effectiveness of side-stream oxygenation to enhance ammonia removal in replicate surface-flow experimental mesocosms containing wetland sediment and plants (Typha spp.). Mesocosms had a water volume of 29.5 L, a hydraulic retention time of 5 days, and a hydraulic loading rate of 4.3 cm/d, and were loaded with synthetic secondary effluent contain 10 mg-N/L of ammonia. Relative to nonoxygenated controls, oxygenation increased ammonia removal rates by an order of magnitude. Areal removal rates increased from 40?mg-N/m2/d to 450?mg-N/m2/d, concentration removal efficiency increased from 10 to 95%, and area-based first-order removal rates increased from <2?m/year to 50–75 m/year. Ammonia removal rates in oxygenated mesocosms were 2- to 4-fold higher than rates reported for full-scale constructed wetlands treating secondary effluent. Results show that oxygen-activated nitrification wetlands, a hybrid of conventional oxygenation technology and wetland ecotechnology, hold promise in economically enhancing rates of ammonia removal and shrinking the wetland area needed to polish ammonia-dominated secondary effluent. Further study is needed to confirm that oxygenation can promote high rates of ammonia removal at the field scale.     

Contaminant assimilation within the water column of two newly created prairie wetlands

This research examined the influence of abiotic factors on contaminant assimilation within the water column of two wetlands (RMA3 and RMA4) located on Rocky Mountain Arsenal National Wildlife Area, north of Denver, Colorado, USA. We define contaminant assimilation as the ability of a wetland system to reduce negative impacts of contaminants on aquatic organisms. To examine the influence of abiotic factors (i.e., alkalinity, suspended solids), chronic toxicity tests were performed from February 1992 through November 1993. Ceriodaphnia dubia were exposed to water from the wetlands, which was spiked with Zn. These tests indicated higher assimilative capacity in wetland RMA4 relative to RMA3. Dissolved organic carbon (DOC) was significantly greater in RMA4 than in RMA3, suggesting that it may have influenced differences in bioavailability of Zn in wetland water. Suspended solids were also consistently higher in RMA4 than in RMA3. To test the influence of suspended solids on contaminant assimilation, C. dubia were exposed to filtered and unfiltered Zn-spiked water from RMA4. The greater toxicity of Zn to C. dubia in filtered water indicated that suspended solids were important in ameliorating impacts of Zn in RMA4. Results from this study suggest that from the suite of variables assessed, DOC and suspended solids were the most important physiochemical influences on Zn toxicity within the water column of these two wetlands. Differences in habitat characteristics of RMA3 and RMA4 demonstrated the importance of site-selection toward functional design of wetlands.     

Evaluation of Storm-Water Wetlands in Series in Piedmont North Carolina

Three storm-water wetlands in series were monitored in a heavily urbanized 12.5 ha watershed in Mooresville, North Carolina. Monitoring of this system allowed an examination of the diminishing returns provided by three successive best management practices (BMPs) of a similar type. At least 80% of the total concentration reduction for all pollutants occurred within the first wetland cell. Only the first wetland cell significantly (p<0.05) reduced all pollutants tested. No pollutant was significantly reduced from the outlet of Wetland Cell 2 to the outlet of Wetland Cell 3 (p<0.05). Median complete system (outlet of Wetland Cell 3) effluent concentrations for total suspended solids, total phosphorus, total nitrogen, and turbidity were 8, 0.09, 0.73 mg/L, and 10 NTU, respectively, which compared favorably to published results. Organic nitrogen generated from wetland vegetation seemed to result in a background source of nitrogen in the wetlands, supporting the idea of an irreducible concentration for nitrogen in these systems. The results indicate that the successive BMPs in a series do not perform as well as the first when each BMP uses similar removal mechanisms.     

钢渣改性制备高性能化工填料的研究与应用

摘要：钢渣是炼钢过程中产生的一种无机固体废弃物,其产量大、利用率低,目前主要用于水泥、混凝土等建筑材料领域,存在安定性不良、产品价值相对局限等问题。橡胶、涂料的制备过程中通常需要添加各种填料来降低生产成本和改善产品性能,常用的填料炭黑、硫酸钡等生产工艺复杂,资源消耗较大。钢渣中SiO2、CaO、MgO、FexOy等成分与多孔结构具有制备化工填料的潜在价值。研究表明,结合常温造孔与表面改性技术,采用磷酸溶液去除钢渣中f CaO协同硅烷偶联剂改性处理钢渣表面制备钢渣基橡胶填料,实现了在橡胶输送带覆盖胶中替代补强填料炭黑达到30%;在粒径、孔结构控制技术的基础上结合真空负压技术研制15~23μm钢渣基复合颜填料,其添加量为涂料总量的10%~25%,实现了颜填料阻燃 防锈 填充多功能一体化。钢渣改性制备高性能化工填料实现了钢铁企业“以废增效”和跨产业企业“以废降本”,具有广阔的发展前景。     

Risk assessment in the regulatory process for wetlands

This paper presents an ecosystem-based approach to risk assessment in freshwater wetlands. The key concept in this approach is that the primary biotic and abiotic components that determine the structural and functional characteristics of wetlands are inseparable. Each component should be identified and its contribution to ecosystem functions or human values determined when deciding whether a stressor poses an unreasonable risk to the sustainability of a particular wetland. Understanding the major external and internal factors that regulate the operational conditions of wetlands is critical to risk characterization. Determining the linkages between these factors, and how they influence the way stressors affect wetlands, is the basis for an ecosystem approach. Adequate consideration of wetland ecology, hydrology, geomorphology, and soils can greatly reduce the level of uncertainty associated with risk assessment and lead to more effective risk management. In order to formulate effective solutions, wetland problems must be considered at watershed, landscape, and ecosystem scales.     

Regulations and Liabilities of Constructed Wetlands for Aquacultural Wastewater Treatment

Treatment and reuse of wastewater is a key constraint to increased aquaculture development worldwide. Constructed treatment wetlands have significant advantages over conventional and other natural systems technologies. The two main types of systems are free water surface and subsurface flow constructed wetlands. There is regulatory oversight at the federal, state, and county levels, with requirements of the Clean Water Act providing the most guidance. Legal liabilities are dominated by the risks associated with bioaccumulation of toxic materials in the wetlands and the effects they may have on migratory birds and endangered species. Technical aspects of water quality discharge are explained and related to regulatory enforcement. The status of existing regulations that affect wetland use are reviewed—the Clean Water Act, National Environmental Policy Act, Migratory Bird Treaty Act, Endangered Species Act, Coastal Zone Act, and the Concentrated Aquatic Animal Production regulation. The Hawaii Revised Statutes and Hawaii Administrative Rules are also reviewed for their regulation of wetlands. Major findings of six court cases with application to wetlands are presented. Three case studies, the Kesterson Marsh, the Arcata Marsh and Wildlife Sanctuary, and a New Mexico State University study on recirculating wastewater aquaculture are provided, which demonstrate successes and failures that provide lessons to help conform to the regulations in place for water discharge.     

Nutrient removal from piggery effluent using vertical flow constructed wetlands in southern Brazil

Santa Catarina State, southern Brazil, has the greatest swine breeding activities of Latin America. Generally, the piggery wastewater is treated in pond systems that are able to remove organic material according to local environmental legislation. However, these systems do not remove nitrogen and phosphorus efficiently. This work deals with a post-treatment system, using vertical flow constructed wetlands. The experiment was conducted in a swine production farm which has 45,000 animals. Although the pond system was able to partially remove the content of nutrients, their concentration in the effluent was high for environmental disposal. A four-bed vertical flow constructed wetland pilot plant, using Typha spp., was built. The pilot plant operated for 280 days for beds 2-4 (sand 2). However, the experiments with beds 1-3 (sand 1) were stopped after 111 days of operation, when a reduction in the wastewater drainage was observed. The beds with sand 2 showed a 33% COD removal, and about 49% of nitrification was observed from 111 days until the end of the operation. PO(4)-P removal was 45% with a loading rate of around 1.36 g m(-2) d(-1).