出水口位置对垂直潜流人工湿地净化的影响

研究出水口位置对垂直潜流人工湿地净化的影响。垂直潜流人工湿地以间歇进水方式运行,进水水力负荷为0.125m3/(m2.d),进水来自南宁市琅东污水处理厂初沉池出水。研究结果表明,出水口位置对垂直潜流人工湿地净化有显著影响。与底部出水相比,中部出水的TN、SS和COD去除率分别提高了8.01%、8.48%、7.99%,出水NO-3-N质量浓度降低了9.38 mg/L;但NH+4-N去除率则降低了26.25%,TP去除率降低了21.21%。     

自由表面流人工湿地微生物气溶胶研究

微生物气溶胶的种类、浓度和粒径分布与人类健康关系密切。采用MD8空气浮游菌采样仪和FA-1型6级筛孔撞击式空气微生物采样器,对人工湿地细菌和真菌气溶胶的数量和粒径分布进行研究。结果表明,人工湿地进水前,细菌和真菌气溶胶平均值较低,分别为64.0、126.0CFU/m3;进水后,细菌气溶胶平均值在6月26日达到最高,为2292.5CFU/m3,真菌气溶胶平均值在8月27日达到最高,为6200.0CFU/m3;易进入肺部的细菌和真菌(粒径为0.65～4.70μm)粒子数分别占粒子总数的22.2%～62.3%、54.2%～87.6%;空气细菌中值直径为1.88～4.13μm,空气真菌中值直径在3.00μm左右波动。空气细菌中革兰氏阳性菌明显多于革兰氏阴性菌,空气真菌主要为酵母菌、镰刀菌属、枝孢属、毛霉属、交链孢属、肉座菌属、枝霉属、青霉属和曲霉属。     

非均质多孔介质对水平潜流人工湿地水力效率的影响

对比以不同粒径(4～9、8～12、11～17mm)非均质多孔介质(玻璃珠)作为基质的水平潜流人工湿地(以有机玻璃板材模拟)的水力效率、水力停留时间等参数,并参照其流态变化进行分析。结果表明:(1)均以上端为进水口、下端为出水口,水流流经不同粒径玻璃珠的水平潜流人工湿地会产生不同的流态。(2)玻璃珠粒径小(4～9mm)的水平潜流人工湿地中,染料在其中运动并最终能够迁移到出水口的有效空间最大,空间利用率最大,则有效体积比最大,染料流经区域面积最大;转角处染料呈圆角流过,死区范围小。(3)当玻璃珠粒径为4～9mm时,水平潜流人工湿地具有最长的平均水力停留时间(0.437 8h)和最小的水流散度(标准方差为0.052 5),使得水平潜流人工湿地的有效体积比最高(0.495 7),水力效率也最高(0.469 6)。随着粒径的增大,平均水力停留时间缩短,水流散度增大,而有效体积比和水力效率均呈减小趋势。(4)合理的水力停留时间分布能够提高有效体积比,而有效体积比越高,即污水在水平潜流人工湿地中运动并最终能够迁移到出水口的有效空间越大,污染物与基质以及附着在基质上的微生物的接触越充分,从而提高污染物的去除率。     

Effect of vegetation in pilot-scale horizontal subsurface flow constructed wetlands treating sulphate rich groundwater contaminated with a low and high chlorinated hydrocarbon

In order to characterize the effect of vegetation on performance of constructed wetlands (CWs) treating low and high chlorinated hydrocarbon, two pilot-scale horizontal subsurface flow (HSSF) CWs (planted with Phragmites australis and unplanted) treating sulphate rich groundwater contaminated with MCB (monochlorobenzene, as a low chlorinated hydrocarbon), (about 10 mg L⁻¹), and PCE (perchloroethylene, as a high chlorinated hydrocarbon), (about 2 mg L⁻¹), were examined. With mean MCB inflow load of 299 mg m⁻² d⁻¹, the removal rate was 58 and 208 mg m⁻² d⁻¹ in the unplanted and planted wetland, respectively, after 4 m from the inlet. PCE was almost completely removed in both wetlands with mean inflow load of 49 mg m⁻² d⁻¹. However, toxic metabolites cis-1,2-DCE (dichloroethene) and VC (vinyl chloride) accumulated in the unplanted wetland; up to 70% and 25% of PCE was dechlorinated to cis-1,2-DCE and VC after 4 m from the inlet, respectively. Because of high sulphate concentration (around 850 mg L⁻¹) in the groundwater, the plant derived organic carbon caused sulphide formation (up to 15 mg L⁻¹) in the planted wetland, which impaired the MCB removal but not statistically significant. The results showed significant enhancement of vegetation on the removal of the low chlorinated hydrocarbon MCB, which is probably due to the fact that aerobic MCB degraders are benefited from the oxygen released by plant roots. Vegetation also stimulated completely dechlorination of PCE due to plant derived organic carbon, which is potentially to provide electron donor for dechlorination process. The plant derived organic carbon also stimulated dissimilatory sulphate reduction, which subsequently have negative effect on MCB removal.     

Evaluation of PPCPs removal in a combined anaerobic digester-constructed wetland pilot plant treating urban wastewater

The removal efficiency of 16 pharmaceuticals and personal care products (PPCPs) from urban wastewater (dissolved and particulate phases) was evaluated for the first time in a hybrid pilot plant consisting of an upflow anaerobic sludge blanket reactor followed by two sequentially connected horizontal flow constructed wetlands: a surface flow wetland (SF CW) and a subsurface flow wetland (SSF CW). Whereas the PPCP removal associated with the dissolved phase exhibited a seasonal pattern, the fraction associated with the suspended solids showed less seasonality. In the dissolved phase, the overall removal efficiency in summer ranged from 70% to 85% for salicylic acid (SAL), methyl dihydrojasmonate, caffeine (CAF), ketoprofen and triclosan, whereas in winter it declined for most of the PPCPs to between 30% and 50%, except for CAF and SAL (>80%) and carbamazepine and butylated hydroxyl toluene (11-18%). In the suspended solids, the removal exceeded 80% for most of the target PPCPs. The efficiency of the different treatment steps was also compound-dependent, but the SF CW generally exhibited the highest removal efficiency for most of the contaminants analyzed. The characterization of the organic matter retained in the wetland gravel beds revealed the occurrence of hydrophobic contaminants such as phthalate esters and fragrances at moderate concentrations (i.e., up to 3.5 μg kg⁻¹), which declined strongly over the course of the different treatment steps. In the SF CW, the net mass accumulation rates of tonalide and galaxolide were 4 and 23 g y⁻¹ respectively, whereas in the SSF CW they were 0.3 and 1.8 g y⁻¹ respectively.     

Performance of hybrid constructed wetland systems for treating septic tank effluent

The integrated wetland systems were constructed by combining horizontal-flow and vertical-flow bed, and their purification efficiencies for septic tank effluent were detected when the hydraulic retention time （HRT） was 1 d, 3 d, 5 d under different seasons. The results showed that the removal efficiencies of the organics, phosphorus were steady in the hybrid systems, but the removal efficiency of total nitrogen was not steady due to high total nitrogen concentration in the septic tank effluent. The average removal rates of COD （chemical oxygen demand） were 89%, 87%, 83%, and 86% in summer, autumn, winter and spring, respectively, and it was up to 88%, 85%, 73%, and 74% for BOD5 （5 d biochemical oxygen demand） removal rate in four seasons. The average removal rates of TP （total phosphorous） could reach up to 97%, 98%, 95%, 98% in four seasons, but the removal rate of TN （total nitrogen） was very low. The results of this study also indicated that the capability of purification was the worst in winter. Cultivating with plants could improve the treated effluent quality fTom the hybrid systems. The results of the operation of the horizontal-flow and vertical-flow cells （hybrid systems） showed that the removal efficiencies of the organics, TP and TN in horizontal-flow and vertical-flow cells were improved significantly with the extension of HRT under the same season. The removal rate of 3 d HRT was obviously higher than that of 1 d HRT, and the removal rate of 5 d HRT was better than that of 3 d HRT, but the removal efficiency was not very obvious with the increment of HRT. Therefore, 3 d HRT might be recommended in the actual operation of the hybrid systems for economic and technical reasons.     

Cost effective management of stochastic coastal water pollution

This study develops a theoretical tool for investigating the impact on cost effective coastal water management from explicit treatment of: coastal pollutant transports, stochastic pollutant transports in the catchment areas, and wetlands as a pollutant abatement option. It is applied to a relatively well investigated estuary, Himmerfjärden, south of the Swedish capital, Stockholm. The theoretical results indicate that all three factors influence cost effective allocation of measures and associated design of economic instruments. The consideration of stochastic pollutant transports will increase costs, but the direction of influence of the other two factors cannot be determined without empirical support. The application to nitrogen transport in Himmerfjärden shows that, for target nitrogen reductions given in terms of a percentage of pre-abatement loads, the inclusion of coastal transports in the cost calculations lowers the estimated total costs for targets interpreted in terms of nitrogen loads to the marine water. The alternative investigated target interpretation was in terms of nitrogen loads to coastal waters. Depending on the ability of wetlands to abate nitrogen and to change the variance in pollutant load to the coastal recipients, costs are either increased or decreased as compared to when wetlands are excluded as nitrogen abatement options.     

生物生态耦合技术处理农村生活污水的应用研究

在对“厌氧池+跌水充氧接触氧化池+水耕蔬菜型人工湿地”生物生态耦合技术应用于农村生活污水处理进行实证研究的基础上,进一步探讨了生物与生态处理单元各自的主要去除对象和效率,为生物生态技术的合理耦合提供了依据。结果表明：在进水COD、TN、TP质量浓度波动范围为51.20~211.12,28.29~122.12,1.26~5.97mg/L时,出水平均质量浓度为15.80,5.51,0.34mg/L,出水水质达到《城镇污水处理厂污染物排放标准（GB 18918—2002）》一级A标准。污水中COD、TN、TP的78%,85%,50%的去除是在生物处理单元完成的,而TP的达标排放还必需生态处理单元的参与。整个处理技术处理效果良好,运行费用低,适合在条件允许的农村地区推广使用。     

植物配置对构造湿地根际区硝化菌群及脱氮影响

研究了3种植物配置对构造湿地根际区硝化菌群数量及脱氮效果影响的情况。结果表明:3个湿地池植物根际区数量均较多,富营养化河水加上充足的溶解氧含量和合适的pH值及水温为硝化菌群的生长繁殖提供了良好的物质及环境条件;根须硝化菌群数量平均比基质高1个数量级,溶解氧含量的不同可能是造成这种差异的主要原因;表明微生物的硝化和植物对氮素的同化利用在湿地池脱氮中发挥了重要作用。     

Inventorying and Monitoring Wetland Condition and Restoration Potential on a Watershed Basis with Examples from Spring Creek Watershed, Pennsylvania, USA

We developed an approach for inventorying wetland resources, assessing their condition, and determining restoration potential in a watershed context. This article outlines how this approach can be developed into a Wetland Monitoring Matrix (WMM) that can help resource management agencies make regulatory and nonregulatory decisions. The WMM can be embedded in a standard planning process (Wetlands, Wildlife, and Watershed Assessment Techniques for Evaluation and Restoration, or W³ATER) involving the setting of objectives, assessing the condition of the resource, prioritizing watersheds or sites, implementing projects, and evaluating progress. To that process we have added the concepts of reference, hydrogeomorphic (HGM) classification, and prioritization for protection and restoration by triage or adaptive management. Three levels of effort are possible, increasing in detail and diagnostic reliability as data collection shifts from remote sensing to intensive sampling on the ground. Of key importance is the use of a consistent set of monitoring protocols for conducting condition assessments, designing restoration and creation projects, and evaluating the performance of mitigation projects; the same variables are measured regardless of the intended use of the data. This approach can be tailored to any region by establishing a reference set of wetlands organized by HGM subclasses, prioritizing watersheds and individual wetlands, and implementing consistent monitoring protocols. Application of the approach is illustrated with examples from wetlands and streams of the Spring Creek Watershed in central Pennsylvania, USA.