Temporal evolution in PPCP removal from urban wastewater by constructed wetlands of different configuration: a medium-term study

Pharmaceuticals and personal care products (PPCPs) are widely distributed in urban wastewaters and can be removed to some extent by constructed wetlands (CWs). The medium-term (3-5 years) behaviour of these systems regarding PPCP removal is still unknown. Seven mesocosm-scale (1 m²) CWs of different configurations were operated outdoors for 39 months under the same conditions to assess their PPCP removal ability and temporal evolution. CWs differed in some design parameters, namely plant presence, species chosen (Typha angustifolia vs Phragmites australis), flow configuration and presence/absence of gravel bed (floating macrophytes surface flow, FM-SF; free-water surface flow, FW-SF; free-water subsurface flow, FW-SSF; or conventional horizontal subsurface flow, SSF). PPCP efficiencies decreased throughout time and performance differences among CWs disappeared with the systems aging. This could be due to a homogenization process in the systems caused by detrimental factors like saturation, clogging and shading. Winter efficiencies were lower than summer ones for salicylic acid, caffeine, methyl dihydrojasmonate, galaxolide and tonalide, and seasonal biological activities seem key factors to explain this fact. Maximal removal efficiencies were achieved in an unplanted-FW-SSF for ketoprofen (47-81%), naproxen (58-81%) and salicylic acid (76-98%); in an unplanted-SSF for caffeine (65-99%); in a Phragmites-FM-SF for ibuprofen (49-96%) and diclofenac (16-68%); in a Typha-FM-SF for carbamazepine (35-71%); and in a Typha-FW-SSF for methyl dihydrojasmonate (71-96%), galaxolide (67-82%) and tonalide (55-74%). Photodegradation could be involved in ketoprofen, naproxen, ibuprofen and diclofenac removal. Carbamazepine and diclofenac were moderately removed by the most efficient CWs studied. Carbamazepine might be eliminated by vegetal uptake.     

昆明市湿地公园地表灰尘重金属污染特征及健康风险评价

城市湿地公园是人们休闲娱乐的重要场所,但其地表灰尘的人群暴露健康风险却鲜有报道。该研究收集昆明市3个最受欢迎的湿地公园景区地表灰尘样品,利用等离子发射光谱仪(ICP-OES)测定灰尘中Pb、Cd、Hg、As、Zn、Cr、Cu、Ni、Co、Mn含量,使用地累积指数法(I_geo)、污染负荷指数法(PLI)和潜在生态风险指数法(RI)探讨湿地公园灰尘重金属污染特征,借助美国环保署健康风险评价模型,开展成人和儿童的重金属健康风险评价。结果表明：灰尘中10种重金属平均含量均超昆明市土壤背景值,其中Cd、Hg和Zn平均含量超背景值6倍,Cr、Ni、Co的I_geo<1。污染负荷指数法结果显示Hg、Cd、Zn中度污染,Pb、Cu和As则具有中等以上生态风险。人体健康风险评价结果显示,经口摄入为重金属主要暴露途径,其次是皮肤直接接触和呼吸吸入。Ni、As、Cd、Co和Cr的致癌风险值均小于10^-6,但若长期处于此种环境,可能会存在潜在的致癌风险。对于非致癌元素而言,Pb、Zn、Cu、Mn非致癌健康风险值都远小于1,即风险可以忽略。     

复合构建湿地运行初期理化性质及氮的变化

研究了在间歇式进水条件下，复合构建湿地系统对氮的去除效果，阐述了湿度要、溶氧、pH等理化因子变化的原因。实验初期，系统尚处于不稳定时期，对N的去除不够理想。随着筚驼逐步步和稳定状态，对KN、NH4^ 、N、NO2^-有明显的去除效果，平均去除率分别为50％、66％和71％。硝化－反硝化作用是氨氮去除的主要途径。从总体上看，有植物系统中硝态氮的出水含量较对照系统同，说明间歇式进水以及植物的存在都有利于硝化作用的发生。实验发现，复合构建湿地在冬季仍能较好地改善水质，是一种有效的水链管理对策，对受污水体水质改善和水生态系统恢复具有重要意义。     

水处理污泥处理处置研究进展

污水污泥是城市废水处理后的终端产物,既是一种生物质原料,可以被有效地资源化和能源化,同时又含有大量有毒有害物质,如何妥善地处理处置污水污泥,已成为全社会关注的课题。浅析了污水污泥的处理处置方法以及当前的研究热点和新技术。污泥处理处置的发展方向为减量化、稳定化,以及在无害化前提下的资源化、能源化。     

芦苇湿地对造纸废水中有机污染物的去除效果及机理

为了对芦苇湿地对造纸废水中有机污染物的去除效果及降解机理进行研究,本文采用GC-MS联用仪对经芦苇湿地处理前后造纸废水中有机污染物的组成和含量进行测定,并通过叠放色谱图的方法对造纸废水中有机污染物的降解效果进行分析。结果表明:(1)经芦苇湿地处理前造纸废水中共测出30种有机污染物,其中8种被列入美国EPA环境优先控制污染物黑名单。(2)纸浆造纸废水生物塘-芦苇湿地复合处理系统对有毒有机污染物基本上达到了较好的去除效果:有机污染物总量减少80%以上,且降解后的产物多为毒性较小的烷烃类。(3)利用质谱手段对有机污染物的降解规律进行了初步研究。该研究为造纸废水处理和资源化利用提供了科学依据,为"造纸废水-芦苇-造纸"生态纸业循环经济模式的进一步推广应用奠定了基础。     

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.     

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。     

The Ecotoxicological Recovery of Ely Creek and Tributaries (Lee County, Va) After Remediation of Acid Mine Drainage

The Ely Creek watershed (Lee County, VA) was determined in 1995 to be the most negatively affected by acid mine drainage (AMD) within the Virginia coalfield. This determination led the US Army Corps of Engineers to design and build passive wetland remediation systems at two major AMD seeps affecting Ely Creek. This study was undertaken to determine if ecological recovery had occurred in Ely Creek. The results indicate that remediation had a positive effect on all monitoring sites downstream of the remediated AMD seeps. At the site most impacted by AMD, mean pH was 2.93 prior to remediation and improved to 7.14 in 2004. Benthic macroinvertebrate surveys revealed that one AMD influenced site had increased taxa richness from zero taxa in 1997 to 24 in 2004. While in situ testing of Asian clams resulted in zero survival at five of seven AMD influenced sites prior to remediation, some clams survived at all sites after. Clam survival was found to be significantly less than upstream references at only two sites, both downstream of un-mitigated AMD seeps in 2004. An ecotoxicological rating (ETR) system that combined ten biotic and abiotic parameters was developed as an indicator of the ecological status for each study site. A comparison of ETRs from before and after remediation demonstrated that all sites downstream of the remediation had experienced some level of recovery. Although the remediation has improved the ecological health of Ely Creek, un-mitigated AMD discharges are still negatively impacting the watershed.     

Modelling Wetland Bird Response to Water Level Changes in the Lake Ontario – St. Lawrence River Hydrosystem

Lake Ontario and St. Lawrence River (LOSL) wetland bird abundance and diversity are greatly influenced by lake and river hydrology. Our study used an interdisciplinary ecosystem approach, blending avian and plant ecology, ecohydraulic, statistical ecology and modelling to evaluate potential impacts of water level fluctuations on indicator species representative of the wetland breeding bird assemblages in the entire LOSL freshwater system. Multi-year (2000–2003) bird surveys captured bird distribution and density in wetland habitats under varying degrees of water inandation, depth and fluctuation. Analyses revealed strong associations between estimated breeding pair densities and plant communities, water depth, and degree of water level fluctuation during the breeding season for a suite of wetland bird species using marsh, wet meadow, shrub swamp and treed swamp habitats. These quantitative associations were used to develop wetland bird performance indicators for use in a LOSL water regulation review study. Several bird species also nest at or near the water surface and are thus vulnerable to nest flooding or stranding. Changes to the seasonal hydrology of Lake Ontario and St. Lawrence River that result in an increased frequency or magnitude of these nest failure events may have a significant impact on regional population sustainability. Long term nest record databases were analyzed to create nesting flooding and stranding probability equations based on water level increases and decreases during the breeding season. These species-specific nesting relationships were incorporated into a reproduction index.Many breeding bird species were strongly associated with specific wetland plant communities. Predicted habitat suitability, as measured by estimated breeding pair density, can also change significantly within a specific wetland plant community based solely on changes in water depth during the breeding season. Three indicator species, Black Tern, Least Bittern and Virginia Rail were selected as key environmental performance indicators for alternate regulation plan comparisons.Water regulation criteria should be such that the long term diversity and abundance of wetland plant communities and frequency of spring flooding in marsh habitats during breeding are not reduced. Magnitude and frequency of water level change during the nesting season (May–July) can also adversely impact reproductive success of many wetland bird species. As such, regulation criteria that increase the seasonal magnitude and frequency of water level change may be detrimental to the long term viability of certain regional breeding bird populations.     

Modeling Wetland Plant Community Response to Assess Water-Level Regulation Scenarios in the Lake Ontario – St. Lawrence River Basin

The International Joint Commission has recently completed a five-year study (2000–2005) to review the operation of structures controlling the flows and levels of the Lake Ontario – St. Lawrence River system. In addition to addressing the multitude of stakeholder interests, the regulation plan review also considers environmental sustainability and integrity of wetlands and various ecosystem components. The present paper outlines the general approach, scientific methodology and applied management considerations of studies quantifying the relationships between hydrology and wetland plant assemblages (% occurrence, surface area) in Lake Ontario and the Upper and Lower St. Lawrence River. Although similar study designs were used across the study region, different methodologies were required that were specifically adapted to suit the important regional differences between the lake and river systems, range in water-level variations, and confounding factors (geomorphic types, exposure, sediment characteristics, downstream gradient of water quality, origin of water masses in the Lower River). Performance indicators (metrics), such as total area of wetland in meadow marsh vegetation type, that link wetland response to water levels will be used to assess the effects of different regulation plans under current and future (climate change) water-supply scenarios.The Canadian Crown reserves the right to retain a non-exclusive, royalty free licence in and to any copyright.