A national inventory to estimate release of polychlorinated dibenzo-p-dioxins and dibenzofurans in Portugal

Taking into account current environmental concerns, the main objective of this work focused a national inventory aiming to estimate the amount of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/PCDF) released in Portugal in 2006. The methodology used was based on the Standardized Toolkit for Identification and Quantification of Dioxins and Furan Releases, developed by UNEP Chemicals, in 2005. The method allows the assessment of the amount of PCDD/PCDF released into the environment along five vectors involving air, water, land, products and residues. Facing some difficulties mainly regarding to the availability of data for some activities known to produce PCDD/PCDF, three scenarios (Sc1 to Sc3) corresponding to lower, central and upper estimates were established. The Sc1 scenario (lower estimate) includes the situations where in case of doubt or scarce information, reduced or none emission values were assumed, Sc2 refers to a central estimate, which is believed to be the most realistic for the Portuguese situation, while Sc3 corresponds to the worst case (upper estimate). The results obtained pointed out that the total amount of PCDD/PCDF emitted in Portugal during the period under analysis was in the range of 51.2-217.9 g TEQ year⁻¹, with the most likely value of 95.2 g TEQ year⁻¹ achieved under the Sc2 scenario. This study also showed that the methodology developed by UNEP Chemicals is a very simple one, and the main difficulty is the availability of data. The main indicators calculated in this study were 8.98 μg TEQ/(year person) by taking into account the total amount of PCDD/PCDF released, and 3.63 μg TEQ/(year person) when only air emissions were considered.     

Plant communities in relation to flooding and soil contamination in a lowland Rhine River floodplain

Using canonical correspondence analysis (CCA), relationships were investigated between plant species composition and flooding characteristics, heavy metal contamination and soil properties in a lowland floodplain of the Rhine River. Floodplain elevation and yearly average flooding duration turned out to be more important for explaining variation in plant species composition than soil heavy metal contamination. Nevertheless, plant species richness and diversity showed a significant decrease with the level of contamination. As single heavy metal concentrations seemed mostly too low for causing phytotoxic effects in plants, this trend is possibly explained by additive effects of multiple contaminants or by the concomitant influences of contamination and non-chemical stressors like flooding. These results suggest that impacts of soil contamination on plants in floodplains could be larger than expected from mere soil concentrations. In general, these findings emphasize the relevance of analyzing effects of toxic substances in concert with the effects of other relevant stressors.     

煤气废水中有机化合物的生物去除特征

好氧/缺氧/好氧生物处理系统是一种新型煤气废水二级处理工艺,该工艺通过改变微生物的生化环境,充分发挥各单元对有机化合物的降解功能,强化了有机化合物总体去除效果.主要采用气相色谱/质谱联用(GC/MS)测试方法,分析对比煤气废水进水及其系统各单元出水中有机化合物的成分,结合生物降解的特点,评价各单元对有机化合物的去除效果...     

淀粉-g-丙烯酸/凹凸棒土复合物制备及其吸附废水中NH_4~＋-N性能

采用反相乳液聚合法以凹凸棒土为原料,合成了新型NH4＋-N吸附剂淀粉-g-丙烯酸/凹凸棒土,并进行了氨氮吸附对比实验。结果表明：凹凸棒土氨氮单位吸附量为4.243 mg/g;淀粉-g-丙烯酸/凹凸棒土氨氮单位吸附量为5.301 mg/g,吸附能力比未改性的凹凸棒土提高了25%。淀粉-g-丙烯酸/凹凸棒土的氨氮吸附过程比凹凸棒土更符合Freundlich等温吸附模型。随着pH、温度的升高,凹凸棒土和淀粉-g-丙烯酸/凹凸棒土对NH4＋-N吸附量逐渐增大。     

壳聚糖的物理/化学改性及其对含酚废水的处理

将壳聚糖物理改性为球形颗粒,然后在微波辐射下,球形壳聚糖与柠檬醛接枝反应,再与NaBH4还原反应,制备一种新型环保材料--物化改性壳聚糖.采用红外光谱仪(IR)、X衍射仪(XRD)、电子显微镜(SEM)和比表面测定及孔径分析仪(BET)结构表征改性壳聚糖.通过含酚制药废水的动态小柱吸附实验,研究了时间、柱高和出水流速等...     

V/Ce共掺杂TiO2光催化降解甲醛的实验研究

采用溶胶凝胶法制备了不掺杂、V 掺杂、Ce掺杂、V/Ce共掺杂纳米TiO₂光催化剂,并将其分别负载于瓷砖上,利用X射线衍射分析（XRD）和扫描电镜分析（SEM）技术对薄膜样品的结构和形貌进行了表征。通过对甲醛的降解实验评价光催化剂的光催化活性。实验结果表明,光催化剂的负载量、共掺杂离子的掺杂量、掺杂配比、煅烧温度影响纳米TiO₂的光催化活性。V/Ce共掺杂TiO₂光催化剂产生了协同效应,其光催化活性优于纯TiO₂和单掺杂TiO₂样品。     

O3氧化结合化学吸收同时脱硫脱硝的动力学及热力学研究

构建了O3氧化多种污染物的反应机制,并对O3氧化SOx、NOx过程进行动力学模拟,然后利用热力学原理计算出Ca(OH)2和CaCO3湿法烟气同时脱硫脱硝吸收反应达到平衡时SOx和NOx的分压力.结果表明,Ca(OH)2作吸收剂湿法烟气同时脱硫脱硝比CaCO3作吸收剂效果好,而且两者几乎100％地去除烟气中的SOx和NO...     

盐城市区环境空气污染原因分析及对策建议

通过对盐城市区建成空气自动监测站来的数据分析,简要说明了盐城市区环境空气质量下降的原因,并提出了改善城市大气污染的建议措施。     

A hybrid method for quasi-three-dimensional slope stability analysis in a municipal solid waste landfill

Limited space for accommodating the ever increasing mounds of municipal solid waste (MSW) demands the capacity of MSW landfill be maximized by building landfills to greater heights with steeper slopes. This situation has raised concerns regarding the stability of high MSW landfills. A hybrid method for quasi-three-dimensional slope stability analysis based on the finite element stress analysis was applied in a case study at a MSW landfill in north-east Spain. Potential slides can be assumed to be located within the waste mass due to the lack of weak foundation soils and geosynthetic membranes at the landfill base. The only triggering factor of deep-seated slope failure is the higher leachate level and the relatively high and steep slope in the front. The valley-shaped geometry and layered construction procedure at the site make three-dimensional slope stability analyses necessary for this landfill. In the finite element stress analysis, variations of leachate level during construction and continuous settlement of the landfill were taken into account. The "equivalent" three-dimensional factor of safety (FoS) was computed from the individual result of the two-dimensional analysis for a series of evenly spaced cross sections within the potential sliding body. Results indicate that the hybrid method for quasi-three-dimensional slope stability analysis adopted in this paper is capable of locating roughly the spatial position of the potential sliding mass. This easy to manipulate method can serve as an engineering tool in the preliminary estimate of the FoS as well as the approximate position and extent of the potential sliding mass. The result that FoS obtained from three-dimensional analysis increases as much as 50% compared to that from two-dimensional analysis implies the significance of the three-dimensional effect for this study-case. Influences of shear parameters, time elapse after landfill closure, leachate level as well as unit weight of waste on FoS were also investigated in this paper. These sensitivity analyses serve as the guidelines of construction practices and operating procedures for the MSW landfill under study.     

Environmental assessment of garden waste management in the Municipality of Aarhus, Denmark

An environmental assessment of six scenarios for handling of garden waste in the Municipality of Aarhus (Denmark) was performed from a life cycle perspective by means of the LCA-model EASEWASTE. In the first (baseline) scenario, the current garden waste management system based on windrow composting was assessed, while in the other five scenarios alternative solutions including incineration and home composting of fractions of the garden waste were evaluated. The environmental profile (normalised to Person Equivalent, PE) of the current garden waste management in Aarhus is in the order of −6 to 8 mPE Mg⁻¹ ww for the non-toxic categories and up to 100 mPE Mg⁻¹ ww for the toxic categories. The potential impacts on non-toxic categories are much smaller than what is found for other fractions of municipal solid waste. Incineration (up to 35% of the garden waste) and home composting (up to 18% of the garden waste) seem from an environmental point of view suitable for diverting waste away from the composting facility in order to increase its capacity. In particular the incineration of woody parts of the garden waste improved the environmental profile of the garden waste management significantly.