不干胶废弃物热解与燃烧动力学特性

采用热重分析方法对不干胶废弃物(PSAs)进行了热解和燃烧失重分析,并采用Doyle法拟合计算了PSAs热解和燃烧动力学参数。结果表明:当温度低于200℃或高于600℃,PSAs的热解和燃烧失重过程具有性;300~600℃时,PSAs热解过程具有3个失重峰,而其燃烧过程具有2个失重峰。动力学分析结果表明:PSAs的热解是由多阶段复杂的热裂解反应组成,其热解过程可用4个一级反应来描述,随着升温速率的提高热解阶段第1峰区表观活化能降低;而第2、3峰区以及半焦深度裂解阶段的第4峰区活化能逐渐升高;PSAs燃烧过程可用3个一级反应来描述,随着升温速率的提高,PSAs燃烧过程的表观活化能均逐渐降低,并且燃烧表观活化能均低于热解表观活化能。     

废弃植物中药渣的热解特性及动力学研究

采用热重分析法(TGA)对丹参中药渣的热解特性及其动力学规律进行了研究。分析了不同升温速率(10、30和50℃/min)和不同粒径(0.85~0.6、0.3~0.18和0.125~0.1 mm)药渣的热解特性。结果表明,药渣热解可分为3个阶段:预热干燥阶段、主热解阶段和碳化阶段,随升温速率的升高,热重(TG)和微分热重(DTG)曲线向高温侧移动,药渣的最大失重速率也显著增加;与大颗粒相比较小颗粒的挥发分产量较大。采用Coats-Redfern法和Flynn-Wall-Ozawa(FWO)法对药渣热解的动力学进行分析,选出了较为合理的机理函数,并计算得出药渣热解活化能为62~72 kJ/mol。     

灰色预测模型及分布活化能模型在废电路板热解中的应用

分别在管式炉反应器和热天平上对废电路板的热解行为进行实验研究。在管式炉反应器上考察了在同一升温速率（20 K/min）下不同热解终温 (400、500、600、700和800℃) 对废电路板热解产物产率的影响。在相关实验数据的基础上尝试用灰色理论及方法建立基于热解终温的废电路板热解灰色产率预测模型GM(1,1)，预测结果与实验数据对比表明，该预测模型精度较高，能够较好地对不同热解终温下废电路板热解产物产率进行预测。此外，在热天平上获得的不同升温速率（10、15和20 K/min）下的热失重曲线表明，废电路板的失重速率峰随升温速率的提高逐渐向高温侧移动。采用分布活化能模型对废电路板热失重曲线进行动力学分析，获得废电路板热解活化能的变化曲线。计算结果表明，废电路板热解过程中活化能并不是单一数值，而是随失重率变化的一个函数。所得废电路板热解活化能值在140～250 kJ/mol范围内变化，当失重率在10%～60%之间，活化能值总体呈缓慢上升的趋势，但当失重率＞60%时，活化能值由155.4 kJ/mol迅速增加到244.4 kJ/mol。     

不干胶废弃物热解焦燃烧特性

采用非等温热重分析和固定床热解实验研究了不干胶废弃物热解焦生成特性及热解焦燃烧特性,并计算了不同升温速率下热解焦的燃烧动力学参数。结果表明,不干胶废弃物热解焦产率随温度升高而逐渐降低,当热解终温在400~700℃时,热解焦产率在34.64%~22.03%之间;空气气氛下热解焦燃烧过程包括3个阶段:挥发分燃烧阶段(390~600℃)、混合燃烧阶段(390~600℃)和残炭燃烧与矿物分解阶段(650℃);升温速率对热解焦燃烧效果作用明显,升温速率越大,燃烧特性指数越高,燃烧稳定性越好;热解焦燃烧过程可以通过3个一级反应描述,当升温速率为40℃/min时热解焦燃烧各阶段表观活化能明显降低,表明升温速率提高有助于热解焦的燃烧反应活性,更有利于燃烧反应的进行。     

报废风机叶片热处理特性及动力学分析

为研究退役风机叶片热处理特性,开展风机叶片的玻璃纤维/环氧树脂风机叶片材料4个不同升温速率(5、10、20、40℃·min^-1)及2种载气氛围(氮气、空气)的热重实验,结合动力学方法对各个反应过程进行研究。热重分析表明玻璃纤维/环氧树脂风机叶片在氮气氛围下存在2个失重阶段,500℃以后质量基本稳定;在空气氛围下存在3个失重阶段,600℃以后质量基本稳定,说明氧气的参与影响了玻璃纤维/环氧树脂的热分解特性。对比不同升温速率下的TG/DTG曲线,随升温速率的提高,TG曲线逐渐向高温方向移动,DTG曲线最大失重率逐渐降低,整个反应过程的质量损失也发生小幅下降。使用Kissinger-Akahira-Sunose(KAS)和Flynn-Wall-Ozawa(FWO)方法研究其动力学过程,结果表明在热解和氧化反应条件下用2种动力学模型求解的活化能取值范围分别为135.14～207.24、137.64～207.58 kJ·mol^-1和117.95～172.19、119.31～173.22 kJ·mol^-1,平均值分别为179.30、...     

不同升温速率下城市污水污泥热解特性及动力学研究

利用差热-热重分析法和Coats-Redfern积分法,对杭州某污水处理厂污泥在不同升温速率下的热解特性及反应动力学特征进行研究。实验结果表明,热解温度从室温升至900℃时,污泥热解过程可分为4个失重阶段;升温速率对污泥热解转化率、挥发分析出温度以及最大失重率等热解特性参数都有显著影响。升温速率越高污泥最大失重率越大;而较低的升温速率延迟了污泥热解反应时间,导致污泥失重量相对较大。根据Coats-Redfern积分法计算结果,污泥在氮气氛围下的热解反应为二级反应模式。提高升温速率可显著增加污泥热解的表观活化能和频率因子。     

工业废水污泥的热解及升温速率对热解的影响

利用热重分析法对印染、中药和废水处理厂3种典型工业废水污泥进行了热解动力学实验研究。结果表明,工业污泥是一种高挥发分、低固定碳和低热值的劣质燃料。经过消化处理的污泥灰分含量较高,挥发分含量变小。热解过程中有3个失重速率较高的阶段,以挥发分的析出为主。升温速率对热解的最终失重率有重要影响。升温速率增加,热解更剧烈,但最终失重率的变化趋势与污泥种类有关;为使热解效果更好,不同种类的污泥应选择不同的升温速率。不同种类的污泥具有不同的热解特性,印染污泥挥发分析出阶段有2次热解。中药污泥活化能最小,印染污泥挥发分第2次热解的活化能比第1次大幅增加。     

船舶垃圾燃烧失重特性研究

在不同升温速率和不同O2气氛下对船舶垃圾(CSW)的燃烧特性进行热重分析,并使用不同方法对其进行动力学参数求解。根据船用焚烧炉的特点,选择温度范围为100~1 100℃,结果表明:CSW燃烬物较少,只有6.02%(质量分数);根据微分热重(DTG)曲线,燃烧的温度区间分为3段,其中在200~600℃反应基本完成,在600~800℃反应的物质较少。CSW在气氛O2/N2(体积比)=30∶70下的燃烧性能是3种气氛中最好的。在气氛O2/N2=30∶70下,通过FWO法计算得CSW的平均活化能为162.588kJ/mol,通过KAS法计算得CSW的平均活化能为160.677kJ/mol。     

初始温度对废轮胎热解的影响

以管式炉热解实验和热重分析为基础,研究了初始温度对废轮胎热解产率及气相产物特性影响。结果表明,初始温度对废轮胎的热解存在重要影响。热重分析结果表明,废轮胎的热解过程存在2个主要失重过程,第一失重温度区间为200～500℃,第二失重温度区间为650～800℃;升温速率仅改变了热解的最大失重速率,并未改变废轮胎最终热解失重率;可通过提高升温速率能够缩短热解反应时间。在初始温度低于100℃时,废轮胎在800℃时热解已基本结束;当终温为800℃、初始温度在100～550℃范围内时,随着初始温度的提高,固、气两相产物产率均提高,而液相产物产率降低;其中气相中H2、CO和CH4的含量高于初始温度小于100℃时的含量;分析认为,可以通过调节热解的初始温度调节废轮胎热解在不同热解阶段的时间分配,适当提高热解初始温度有利于提高整个热解过程中的时间利用效率、改变废轮胎热解产物的分布;废轮胎热解气化的最佳温度区间为500～800℃。     

TG-FTIR研究生物质成型燃料热解与燃烧特性

利用热重-红外联用分析仪(TG-FTIR)研究了生物质成型燃料(玉米秸杆)的热解和燃烧特性。结果表明,热解和燃烧反应过程均可分为3个阶段:干燥脱气(100~200℃)、挥发分反应(200~400℃)与碳化反应(400~1 000℃)。热解和燃烧主要失重阶段(200~400℃),燃烧反应速率总体上大于热解反应速率。利用Coats-Redfern方法对玉米秸杆的主要失重阶段进行动力学分析发现,热解和燃烧的反应过程符合一级反应模型;在主要失重阶段(200~400℃),热解和燃烧所需的活化能相差不大。FTIR分析表明,热解的气相产物主要分为轻质类气体(H2O、CO2、CO、CH4、HCl、NH3和HCN)和焦油类(酸类和酚类)物质,而燃烧的气相产物主要以CO2和H2O析出为主。     

Gold Mining: Is It Worth Its Weight?

Gold (Au) accounts for only 0.004 g/ton of the earth's crust and is the most desired element. With an average annual world production of approximately 2,500 tons, the current methods of Au mining in developing countries cause major environmental issues. These issues vary from deforestation to cyanide and mercury (Hg) contamination. This article presents several cases of environmental catastrophes caused by Au mining in different regions of the world (Africa, the Middle East, Eastern Europe, and South America). It discusses the currently available processes for the large-scale extraction of metallic Au grains and supports the need for an alternative sustainable process.     

Use of diffuse reflectance spectrometry in spot test reactions for quantitative determination of cations in water

Diffuse reflectance spectroscopy can be successfully used for the quantitative determination of small amounts of pollutants like metals. The remission function was found to be linearly proportional to the concentration, when we applied the Kubelka–Munk equation. The color reactions of Cu(II), Co(II), and Ni(II) with dithiooxamide, were realised on filter paper. Reaction between Fe(III) and ammonium thiocyanate was realized on filter paper and gelatine matrix. All measurements were accomplished with a laboratory-constructed reflectometer. We have obtained a calibration curve by plotting the optical density of reflectance A_R vs log of the mol l⁻¹ concentration. Limits of detection at the 10⁻⁴ M level were estimated for all the compounds. Linear dynamic range extend over one order of magnitude and shows the potential of device for the quantitative analysis of environmental pollutants.     

Distribution and sources of polyfluoroalkyl substances (PFAS) in the River Rhine watershed

The concentration profile of 40 polyfluoroalkyl substances (PFAS) in surface water along the River Rhine watershed from the Lake Constance to the North Sea was investigated. The aim of the study was to investigate the influence of point as well as diffuse sources, to estimate fluxes of PFAS into the North Sea and to identify replacement compounds of perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA). In addition, an interlaboratory comparison of the method performance was conducted. The PFAS pattern was dominated by perfluorobutane sulfonate (PFBS) and perfluorobutanoic acid (PFBA) with concentrations up to 181 ng/L and 335 ng/L, respectively, which originated from industrial point sources. Fluxes of ΣPFAS were estimated to be ∼6 tonnes/year which is much higher than previous estimations. Both, the River Rhine and the River Scheldt, seem to act as important sources of PFAS into the North Sea.     

Integrative approach to delineate natural attenuation of chlorinated benzenes in anoxic aquifers

Biodegradation of chlorobenzenes was assessed at an anoxic aquifer by combining hydrogeochemistry and stable isotope analyses. In situ microcosm analysis evidenced microbial assimilation of chlorobenzene (MCB) derived carbon and laboratory investigations asserted mineralization of MCB at low rates. Sequential dehalogenation of chlorinated benzenes may affect the isotope signature of single chlorobenzene species due to simultaneous depletion and enrichment of ¹³C, which complicates the evaluation of degradation. Therefore, the compound-specific isotope analysis was interpreted based on an isotope balance. The enrichment of the cumulative isotope composition of all chlorobenzenes indicated in situ biodegradation. Additionally, the relationship between hydrogeochemistry and degradation activity was investigated by principal component analysis underlining variable hydrogeochemical conditions associated with degradation activity at the plume scale. Although the complexity of the field site did not allow straightforward assessment of natural attenuation processes, the application of an integrative approach appeared relevant to characterize the in situ biodegradation potential.     

Emissions from soil fumigation in two raised bed production systems tarped with low permeability films

Raised beds are used to produce some high-value annual fruit and vegetable crops such as strawberry in California (CA) and tomato in Florida (FL), USA. Pre-plant soil fumigation is an important tool to control soil-borne pests in the raised beds. However, fumigant emissions have detrimental environmental consequences. Field trials were conducted to evaluate emissions of 1,3-dichloropropene (1,3-D) and chloropicrin (CP) in two different production systems with raised beds covered by different tarps. In the CA trial, InLine (60.8% 1,3-D and 33.3% CP) was drip-applied at 340 kg ha⁻¹ to 5 cm deep in the beds (30 cm high and 107 cm wide) tarped with polyethylene (PE) or virtually impermeable film (VIF). In the FL trial, carbonated Telone C35 (63.4% 1,3-D and 34.7% CP) was shank-applied at 151 kg ha⁻¹ to 20 cm deep in the beds (22 cm high and 76 cm wide) tarped with totally impermeable film (TIF). Emissions from tarped beds relative to furrows were contrary between the two trials. For the CA trial, the emission was 47% of applied 1,3-D and 27% of applied CP from PE tarped beds and 31% of applied 1,3-D and 15% of applied CP from VIF tarped beds, while that from uncovered furrows was <0.4% for both chemicals in both fields. In the FL trial, only 0.1% 1,3-D was emitted from the TIF tarped beds, but 27% was measured from the uncovered furrows. Factors contributing to the differences in emissions were chiefly raised-bed configuration, tarp permeability, fumigant application method, soil properties, soil water content, and fumigant carbonation. The results indicate that strategies for emission reduction must consider the differences in agronomic production systems. Modifying raised bed configuration and fumigant application technique in coarse textured soils with TIF tarping can maximize fumigation efficiency and emission reduction.     

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.     

Using a Set of Strategic Indicator Systems as a Decision-making Support Implement for Establishing a Recycling-oriented Society - A Taiwanese Case Study (16 pp)

Background Scope and Aims. To realize the vision of sustainable development (SD) originating from the ‘only one earth’ philosophy, and to integrate the conceptions of ecology and sustainability into the planning and decision-making criteria of urban growth management, the establishment of a recycling-oriented society (ROS) is essential. However, before the above intention can be achieved, it is indispensable to develop a system of strategic indicators for supporting a radical reformation of the urban development plan. Therefore, this study, based on the conception of the new urban development pattern ROS, attempted to carefully choose a sample city in Taiwan for launching a preliminary case study, and furthermore designed and proposed a concise and strategy-oriented assessment indicator system termed ROSAIS. ROSAIS, on the one hand, can act as a compass for understanding resource using efficiency and recycling status during city development and, on the other hand, can serve as an implement supporting decision-making for ROS construction.Methods According to the definition and spirit of ROS, the structure of ROSAIS should clearly represent the relationship between resources and environment in human activities. The eco-efficiency indicator system (EEIS) and environmental symbiosis indicator system (ESIS) can be considered two key sub-indicator systems, and are the necessary components of ROSAIS. EEIS chooses the dominant production sectors in urban economic activities to calculate their eco-efficiency (EE). Separately, for obtaining a consensus regarding the framework of ESIS, the questionnaire approaches and expert consultation, together with the research experience and foundation of current relevant studies and indicator systems, are applied when crucial resource and environmental issues and respective indicators are selected.Results and Discussion The calculation results of EEIS in this case study indicated that among the three dominant production activities (agricultural, fishery, and animal husbandry sector) the fishery sector has the highest EE, which indicates that the fishery activities and resources significantly influence the sustainability of the economic-environmental system of the sample city. Furthermore, according to a consensus achieved in ESIS, local green spaces, resource recovery, energy consumption pattern change, freshwater conservation and greenhouse effect abatement were considered as the five crucial issues influencing how the case study city can develop into an ES-city. The rate of local green spaces, resource recycling, freshwater conservation and the rate of reduction of nonrenewable energy use as well as carbon dioxide (CO2) emissions were used to evaluate the above five issues.Conclusion This case study is unparalleled in Taiwan. Even in Japan, where ROS legislation has been implemented, this kind of study remains in the preliminary stages. Furthermore, when communicating the indicator results, it is essential to provide the context and countermeasures of the crucial issues that are faced. The two sub-indicator systems proposed in this case study could comply completely with the above-mentioned requirements. For example, the EEIS provides information for achieving a balance between environmental burden and economic benefits among dominant production sectors; the ESIS provides information for setting strategies for overcoming the crucial issues faced. Recommendation and Outlook This study recommends that urban planers should consider the construction of the corresponding strategic indicator system to be indispensable, and makes further use of the indicator results related to the environmental education of residents for identifying and promoting participation with ROS, and turning them into implements for supporting urban SD decision-making. Furthermore, a successful indicator system depends on data availability and quality. This study recommends that urban planers should pay considerable attention to constructing relevant data collection channels, databases and the data quality.     

土壤改良剂对油菜富集238U、226 Ra及232 Th的影响

通过网室盆栽试验,研究了施加磷矿粉(PR)、羟基磷矿粉(HA)、豆渣(SM)、骨碳(BC)及硫酸亚铁等土壤改良剂对油菜(Brassica oleracea L.)自铀矿区污染农田土壤吸收铀(238U)、镭(226Ra)及钍(232Th)的影响.结果表明,不同处理下油菜茎叶对238U、226Ra及232Th的富集系数分别在3.6×10-3～6.2×10-3、6.2×10-3～10.0×10-3及0.9×10-4～2.0×10-4之间.上述不同改良剂处理均能在一定程度上降低植物对238U、226Ra及232Th的吸收,以SM、HA处理效果较显著,其中SM处理下238U、226Ra及232Th的富集系数分别比对照降低42.9%、39%和71%.SM及HA对降低铀矿区污染土壤中植物对上述核素的吸收和富集具有潜在的应用价值.     

Polychlorinated dibenzo-p-dioxins and related compounds: the blood levels of young Japanese women.

We investigated PCDDs and related compounds in the blood of young Japanese women, approximately 20 years of age, who had not yet had children, and discussed how the TEQ level of PCDDs and related compounds in their blood may affect the next generation. Means of total TEQ levels were 0.063 pg/g for whole blood basis and 21 pg/g for lipid basis. TEQ of PCDDs, PCDFs and coplanar PCBs accounted for about 43, 34 and 23% of the total TEQ in the whole blood basis, respectively. In the lipid basis, their values were about 44, 34 and 22%, respectively. Previously, we investigated PCDDs and related compounds levels in mother's breast milk, lymphocyte subpopulation and thyroid function of their children, and found negative correlations between the TEQ level of PCDDs and related compounds and CD4+/CD8+, and/or the TEQ level of PCDDs and related compounds and the T₄ level in 36 mothers and children. Of these cases, the average age was approximately 28 years. PCDDs and related compounds may be related to immunopathy, such as atopic dermatitis. The effects of PCDDs and related compounds on babies of young Japanese women are important and must be further evaluated.     

BAT and BEP as instruments for reducing emissions of unintentionally produced POPs and development of guidelines under the stockholm convention

The 6th Intergovernmental Negotiating Committee (INC 6), under the Stockholm Convention on POPs, gave an expert group the mandate to develop guidelines for the application and implementation of best available techniques (BAT) and best environmental practices (BEP) for the prevention and reduction of unintentionally produced and emitted POPs, including polychlorinated dibenzodioxins/-furans (PCDD/Fs), polychlorinated biphenyls (PCBs) and hexachlorobenzene (HCB). Measures to reduce or eliminate the release of these POPs to the environment can be found in Article 5 of the Convention. BAT and BEP are already being applied as emission reduction instruments in a number of industrialised countries and are elements of other major international treaties, e.g. the UN ECE Protocol on POPs and the Marine Convention's OSPAR and HELCOM, and of the EU Directive for Integrated Pollution Prevention and Control (IPPC Directive). Existing concepts are presented and compared with the requirements of the Stockholm Convention. Consequences, perspectives and questions for the future intersessional work of the above-mentioned Expert Group are discussed.