人工复合土层去除再生水中微量有机污染物的研究进展

再生水经深度处理后资源化回用是缓解水资源紧缺问题的有效途径之一。由于微量有机污染物的持久性与累积性,所以其在再生水及地下水中也有检出,且在极低浓度下能对人体健康及生态环境产生不利影响。人工复合土层利用物理、化学吸附、生物降解等作用实现污染物的去除,具有投资少、运行成本低、操作简单等优点,去除能力与污染物的迁移转化规律密切相关。目前对复合土层系统的研究主要包括渗滤介质、系统复氧方式、微生物特性、堵塞问题、运行方式,但主要集中在对常规污染物的去除,对水体中微量有毒有害污染物的研究缺乏。提高复合土层系统对再生水中微量有机污染物去除的稳定性及持久性,在实际工程应用中具有重要意义。     

光化学氧化技术去除水中有机污染物的试验研究

以自来水为试验对象，对紫外－臭氧和紫外－二氧化钛两种光化学氧化技术对水中微量有机污染物的去除进行了试验研究，结果表明两种工艺的UVA（紫外吸光度）去除率均达到80％以上，对氯仿的去除也均能达到国家饮用水标准。在此基础上，自制了一种催化剂膜，并取得了预期的处理效果，有望在新型净水技术及设备的研制和开发上得到应用。     

4种湿地植物对人工湿地净化生活污水的影响比较

不同类型人工湿地对生活污水的处理效果,受到许多因素的影响,其中不同植物类型的选择,可能会造成人工湿地对主要污染物COD、TN和TP的净化效果发生很大差异。研究了4种湿地植物(菖蒲、香蒲、千屈菜和水葱)在水平潜流、垂直上行流和下行流人工湿地中对人工合成的生活污水的处理效果和主要污染物(COD、TN和TP)去除率的季节变化,通过比较不同植物类型在不同湿地类型中对主要污染物的去除效果分析了可以达到最佳污水净化效果的启动条件。结果表明:香蒲在垂直下行流湿地去除有机污染物效果最好,去除率可达85.55%;水葱在垂直上行流湿地去除TN效果最好,去除率可达57.52%,香蒲在垂直上行流湿地去除TP效果最好,去除率可达84.28%。     

沸石强化A/O生物脱氮工艺中有机污染物的降解作用研究

拉曼光谱、TOC和UV254测试结果显示,在沸石强化A/O生物脱氮-同步化学除磷工艺中,城市污水中的溶解性和非溶解性有机污染物易被含沸石活性污泥吸附,由于含沸石活性污泥的异养菌较常规A/O生物脱氮工艺污泥的异养菌高数倍至55倍,其有机污染物的生物降解能力得到改善,COD去除率维持在90%左右,0.22 μm膜过滤液TOC去除率接近97%,0.45 μm滤纸过滤液TOC去除率达到92%,并使包括一些难降解有机物在内的有机污染物得到进一步降解.     

生态净化工艺在上海崇明农村污水的应用研究

介绍生态净化的工艺方法。通过在上海崇明前卫村建立示范工程,研究以高效生态纤维塘＋潜流式人工湿地组合工艺对有机污染物、氮、磷、浊度等去除效果与机理。结果表明,COD、TN、TP和浊度的平均去除率分别为53.4%、45.3%、49.8%和94.89%。去除有机污染物主要靠微生物代谢,氮的去除主要靠微生物硝化与反硝化,总磷主...     

垃圾渗滤液同时硝化反硝化处理中有机污染物去除效果

采用同时硝化反硝化对某垃圾填埋场渗滤液进行处理，并对有机物去除效果进行分析。实验结果表明，反应器对渗滤液中COD、氨氮、总氮和部分有机物具有较好的处理效果，COD、氨氮和总氮的平均去除率为82.34%、99.82%和65.31%。GC-MS分析总共检测出53种主要有机污染物，其中邻苯二甲酸二丁酯等29种有机物的去除率达100%，乙基苯等5种有机物的去除率高于90%，邻苯二甲酸二异辛酯等8种有机物的去除率介于60%和90%之间，此外还有4-苯基戊醇等5种有机物去除率低于60%。反应器内存在亚硝氮途径的脱氮反应形式。     

射频加热强化土壤气相抽提技术的应用

热强化土壤气相抽提技术是一种高效的土壤治理技术,广泛应用于包气带土壤中挥发性有机污染物的去除。在天津某有机污染场地开展射频加热强化土壤气提技术应用研究,研究了射频阳极连接方式对场地加热效果的影响,并考察了该技术对实验场地的实际修复效果。结果表明,射频阳极采用并联方式连接对场地的加热效果较好,加热10 d后,场地温度升高约40℃;随着SVE系统工作时间的延长,场地温度逐渐下降,土壤气中TVOCs的浓度逐渐下降;经过约2个月的修复,中浅层土壤中污染物的总去除率约90%,氯仿去除率达95%,深层土壤中的污染物去除率约64%。     

应用自动识别和定量系统评价两种污水再生工艺对微量有机污染物的去除效果

采用气质联用分析,并结合自动识别与定量系统(AIQS-DB)考察2种再生水厂采用的深度处理工艺对微量有机污染物的去除效果。结果表明,以污水为原水的膜生物反应器(MBR)+臭氧氧化+生物活性炭滤池(BAC)工艺用于再生水生产,MBR工艺对有机污染物的去除起主要作用;城市污水厂二级出水为原水的混凝沉降+浸没式超滤(SMF)/连续微滤(CMF)+部分反渗透(RO)+臭氧氧化工艺用于再生水生产,其SMF和CMF工艺段的膜截留作用均可有效消减有机污染物含量,SMF的效果优于CMF;2种工艺中采用的臭氧技术都能进一步加强部分物质的去除效果。气质联用结合AIQS-DB可用于再生水中污染物的筛查和不同污水再生工艺对微污染物消减效果的评价。     

复合人工湿地中低浓度有机物的去除及Monod模型模拟

以复合人工湿地工程实例为研究对象,研究了其在连续5个月内对低浓度有机污染物的深度处理效果,采用简化的Monod动力学模型对研究湿地进行模拟并验证,讨论了污染负荷与去除率的相关性以及BOD/COD比值对有机污染物降解系数的影响。研究湿地总面积为5 000 m2,进水水量为860～1 560 m3/d,水力停留时间为1.48～2.69 d,水力负荷为0.17～0.31 m/d,进水中有机污染物浓度较低(BOD53.0～25.6 mg/L;COD 22.9～89.8 mg/L)。结果表明,复合湿地组合形式对BOD5和COD的去除率分别介于37.9%～79.0%和41.0%～68.7%之间,简化的Monod模型对湿地中BOD5和COD去除的预测值与实验观测值吻合程度较好;BOD5、COD的去除率分别随着进水BOD5和COD浓度的增加而增大,而增长趋势逐渐变缓,当有机污染负荷低时,模型的K值较小;低浓度有机污染物在VSF、FWS和HSF湿地中的去除效率与有机物是否容易或者缓慢被微生物降解的性质相关性较差,这可能与人工湿地中存在的其他因素促进了有机污染物的去除有关。     

环境水体微污染有机物及其去除技术研究进展

水体有机污染物因其生物毒性对人体健康和生态环境造成了严重的危害。随着环保技术的发展,高浓度有机污染物已得到很好的去除。检测水平的不断提高使微量有机污染物日益受到广泛关注。为了深入地研究微污染有机物及其去除技术,对微污染有机物的种类、性质和危害进行了详细阐述,并综述了国内外生物法、膜处理技术、高级氧化技术、吸附技术对微污染有机物的去除效果,总结了各种技术的优缺点。     

多相催化-臭氧氧化法处理模拟有机磷农药废水

实验通过臭氧氧化法来降解模拟废水中的有机磷农药,将其转化为无害物质,并试验研究了在废水中加入2种自制的催化剂对降解结果的影响。采用气相色谱法测定水中有机磷农药的量。结果表明,只用臭氧处理的情况下1周后有机磷的去除率为78.03%;在催化剂A存在下,去除率可达93.85%;在催化剂B存在下,去除率可达为88.35%。结果表明,臭氧氧化法对此类污水具有较好的降解作用,尤其在有催化剂存在的情况下处理效果更好,在室温和中性介质中均属于一级反应。     

多相催化-臭氧氧化法处理模拟有机磷农药废水

实验通过臭氧氧化法来降解模拟废水中的有机磷农药，将其转化为无害物质，并试验研究了在废水中加入2种自制的催化剂对降解结果的影响。采用气相色谱法测定水中有机磷农药的量。结果表明，只用臭氧处理的情况下1周后有机磷的去除率为78．03％；在催化剂A存在下，去除率可达93．85％；在催化剂B存在下，去除率可达为88．35％。结果表明，臭氧氧化法对此类污水：具有较好的降解作用，尤其在有催化剂存在的情况下处理效果更好，在室温和中性介质中均属于一级反应。     

Tracer diffusion from a horizontal fracture into the surrounding matrix: measurement by computed tomography

The vertical diffusion of NaI solution from a horizontal fracture into and within the surrounding matrix was tracked and quantified over time using an artificially fractured chalk core (30x5 cm) and a second-generation X-ray computed tomography (CT) scanner. The different tracer-penetration distances imaged in the matrix above and below the horizontal fracture are indicative of a greater tracer mass penetrating into the lower matrix. The enhanced transport in the matrix below the fracture was related to the Rayleigh-Darcy instability induced by the density differences between the heavier tracer solution in the fracture (1.038) and the distilled water that had initially resided in the matrix. Our observations suggest that below the fracture, the tracer is propagated by an advection-diffusion process that is characterized by both higher rates and higher concentrations relative to its propagation by diffusion above the fracture. The experimental results suggest that the prediction of contaminant migration in a rock intersected by both vertical and horizontal (e.g. along bedding planes) fractures is difficult because of density effects that result in different solute-penetration rates.     

Accidental Versus Operational Oil Spills from Shipping in the Baltic Sea: Risk Governance and Management Strategies

Marine governance of oil transportation is complex. Due to difficulties in effectively monitoring procedures on vessels en voyage, incentives to save costs by not following established regulations on issues such as cleaning of tanks, crew size, and safe navigation may be substantial. The issue of problem structure is placed in focus, that is, to what degree the specific characteristics and complexity of intentional versus accidental oil spill risks affect institutional responses. It is shown that whereas the risk of accidental oil spills primarily has been met by technical requirements on the vessels in combination with Port State control, attempts have been made to curb intentional pollution by for example increased surveillance and smart governance mechanisms such as the No-Special-Fee system. It is suggested that environmental safety could be improved by increased use of smart governance mechanisms tightly adapted to key actors’ incentives to alter behavior in preferable directions.     

Environmental Persistence of Chemicals

- DOI: http://dx.doi.org/10.1065/espr2006.01.008 Background The hazard criterion of persistence as it applies to chemicals in the environment is reviewed and discussed. This quantity can not be measured directly in the environment, thus it must be estimated using models that synthesise information on chemical half-lives and partitioning properties, the nature of the environment and how the chemical is released into the environment. Main Features It is suggested that the preferred criterion is the average residence time of the chemical in the environment, i.e. conceptually the sum of the life-times of all molecules (attributable only to losses by degrading reactions) divided by the number of molecules. If all chemical fate processes are first order, this persistence is independent of the quantity of chemical introduced and whether introduction is steady- or unsteady-state in nature. It is shown that in a multimedia environment persistence is affected not only by degradation kinetics, but also by mode-of-entry and partitioning. For screening level purposes a Level II equilibrium model may be adequate but a Level III model is generally preferable for estimating the average persistence. If a distribution of persistences is required a dynamic Level IV model must be used. Discussion The implications for regulating chemicals on the basis of persistence are discussed. Conclusion It is concluded that the preferred strategy is to use Level II, III, and IV models and that the use of only degradation kinetics or media-specific half-lives can be misleading and uneconomical.     

Macrodispersion by diverging radial flows in randomly heterogeneous porous media

Radial flow takes place in a heterogeneous porous formation where the transmissivity T is modelled as a stationary random space function (RSF). The steady flow is driven by a given rate, and the mean velocity is radial. A pulse-like of a tracer is injected in the porous formation, and the thin plume spreads due to the fluctuations of the velocity which results a RSF as well. Transport is characterized by the mean front, and by the second spatial moment of the plume. We are primarily interested in tracer macrodispersion modelling. With the neglect of pore-scale dispersion, macrodispersion coefficients are computed at the second order of approximation, without neglecting the head-gradient fluctuations. Although transport is non-ergodic at the source, it is shown that ergodicity is achieved at small distances from the source. This is due to the fact that close to the source local velocities are quite large, and therefore solute particles become uncorrelated very soon. Under ergodic conditions, we compare macrodispersion mechanism in radial flows with that occurring in mean uniform flows. At short distances the spreading effect is highly enhanced by the large variability of the flow field, whereas at large distances transport exhibits a lesser dispersion due to the reduction of velocities. This supports the explanation provided by Indelman and Dagan (1999) to justify why the macrodispersivity is found smaller than that pertaining to mean uniform flows. The model is tested against a tracer transport experiment (Fernàndez-Garcia et al., 2004) by comparing the theoretical and experimental breakthrough curves. The accordance with real data, that is achieved without any fitting to concentration values, strengthens the capability of the proposed model to grasp the main features of such an experiment, the approximations as well as experimental uncertainties notwithstanding.     

Calcium-lead interactions involving earthworms. Part 1: The effect of exogenous calcium on lead accumulation by earthworms under field and laboratory conditions

Earthworms (Lumbricus rubellus and Dendrodrilus rubidus) were collected from several acidic and calcareous abandoned ferrous metalliferous mine sites. Tissue lead concentrations were substantially lower than the total soil lead concentrations, except at one site (Cwmystwyth) where the tissue lead concentrations of both species were approximately 5 to 10 times higher than that of the soil. Soil lead was the major factor in determining the tissue lead concentration, although it was demonstrated that both soil pH and soil calcium concentration could markedly increase the % variance in tissue lead concentration. These findings help explain the apparent anomaly in tissue lead concentrations of earthworms from Cwmystwyth, where the soil is acidic and has exceptionally low calcium concentrations. Soil-liming experiments provided supportive evidence that soil pH, coupled with soil calcium, influences lead accumulation by earthworms, but a filter paper feeding experiment provided unequivocal evidence that soil calcium concentration alone can influence lead accumulation by earthworms. It is concluded that, although lead accumulation by earthworms is influenced by both physico-chemical and biochemical mechanisms, the latter over-rides the former, i.e. soil calcium is more important factor in determining the accumulation of lead earthworms than is soil pH.     

Particulate organic matter in the sea: the composition conundrum

As organic matter produced in the euphotic zone of the ocean sinks through the mesopelagic zone, its composition changes from one that is easily characterized by standard chromatographic techniques to one that is not. The material not identified at the molecular level is called "uncharacterized". Several processes account for this transformation of organic matter: aggregation/disaggregation of particles resulting in incorporation of older and more degraded material; recombination of organic compounds into geomacromolecules; and selective preservation of specific biomacromolecules. Furthermore, microbial activities may introduce new cell wall or other biomass material that is not easily characterized, or they may produce such material as a metabolic product. In addition, black carbon produced by combustion processes may compose a fraction of the uncharacterized organic matter, as it is not analyzed in standard biochemical techniques. Despite these poorly-defined compositional changes that hinder chemical identification, the vast majority of organic matter in sinking particles remains accessible to and is ultimately remineralized by marine microbes.     

The foundations of environmental decision-making

An account of judgement is developed, which is used to show that deliberative procedures can provide a substantially different input to environmental decision-making from that afforded by cost-benefit analysis and, specifically, by the method of contingent valuation. It is argued that environmental concern typically invokes values, which are in turn formed and expressed through the exercise of judgement – itself the outcome of a deliberative rather than a calculative process. It is concluded that environmental concern is more effectively articulated through deliberative procedures than through the method of cost-benefit analysis.     

不同共代谢基质对四氯乙烯的厌氧生物降解研究

用驯化好的厌氧污泥对葡萄糖、乳酸盐和醋酸盐作为电子供体时四氯乙烯(PCE)的降解进行研究。实验结果表明,PCE是通过还原脱氯发生生物降解的。实验的回归结果表明,反应均符合一级动力学反应速率,常数的大小依次为k乳酸>k葡萄糖>k醋酸。表明乳酸盐作为电子供体时PCE的降解速率较快,说明在实验条件下乳酸盐是最合适的电子供体。并且在整个实验过程中由共代谢基质提供的电子供体不是PCE降解的限制因素。