山地城市合流污水特细砂粒径特征及分布

对山地城市合流污水特细砂粒径特征参数及分布研究的结果表明,晴、雨天合流污水细砂平均粒径D(3,4)均小于250μm,且含量高,属于特细砂;新旧城区排水体制、山地地貌、降雨强度、雨前晴天数、用地性质、水土流失等因素均会对山地城市合流污水特细砂粒径特征和分布等造成影响。涪陵污水处理厂进水含砂量高达183.9 mg/L,平均粒径为182.6μm,粒径偏小,超出沉砂池有效去除范围;大量特细砂进入曝气池后,堵塞管道、磨损设备等,给污水处理厂运行带来一系列不利影响。     

镇江市典型合流管网旱天污水排放规律

为给镇江市合流制污水管网(简称合流管网)系统的改造提供参考依据,选择镇江市内一条具有代表性的合流管网,并从2010年7月至2011年3月(2月除外,4次/周)对管网中5个采样点的生活污水水质进行旱天监测。结果表明,生活污水中COD、SS、TP、NH3-N浓度在不同月份之间具有明显的变化差异,并且波动幅度较大,冬、春季生活污水中COD浓度皆高于夏、秋季;居民混合区排出的生活污水中污染物浓度显著高于其他4个采样点。     

山地城市污水特细砂除砂系统目标粒径确定

三峡库区重庆段污水处理厂长期受污水特细砂影响;污水中特细砂平均粒径仅182.6μm,而传统沉砂池通常以粒径大于200μm砂粒去除率来衡量沉砂池除砂效果;参考国外传统除砂设备性能参数估算特细砂总去除率仅为51.2%,若考虑砂水分离器效率等因素,则实际去除率更低。基于重庆"特细砂"的粒径分布特征、除砂效率理论计算分析认为,特细砂除砂装置的设计研发时,除砂粒径分界点或目标粒径为100μm,并以粒径≥100μm细砂去除率来衡量沉砂池的除砂效果,能保证粒径分布曲线中70%~95%的特细砂得到有效去除,能满足污水处理厂对特细砂的去除要求。     

基于瓦斯燃烧余热利用的煤矸石快速风化成土

基于瓦斯燃烧的余热利用,对煤矸石进行高频率的干湿/冷热交替处理,加速煤矸石结构风化粉化,提升风化产物的保墒-透气-蓄肥等土壤学性能。结果表明煤矸石在50℃下经30次干湿/冷热交替后粒径显著下降,粗砂(5～10 mm)比例下降43%,细砂(<1 mm)含量上升35%,持水率可达12.78%,达到砂土持水标准,持水率、微粒含量、毛管孔隙度与循环次数呈正比;颗粒粉化主要受矿物溶出产生溶蚀裂隙、矿物重构并干燥产生盐结晶强化裂隙涨裂,以及黏土矿物的不均匀性膨胀/收缩的影响;风化产物种植紫花苜蓿,发芽率在80%以上,发芽时间、茎长等优于低扰动样品。本研究结果可为瓦斯与煤矸石的能源化、资源化协同利用提供参考。     

杀虫剂十氯酮的多介质环境行为模拟

应用EQC模型模拟十氯酮在多介质环境中的归宿和迁移通量.结果表明:土壤是十氯酮最大的贮存库,在稳态平衡条件下,残留率达到95.0%;在稳态非平衡条件下,十氯酮单独排放到水体,有37.5%残留在于排放的水体中,其在大气的浓度水平和质量分布均很低,在沉积物中的质量则来自于水体向沉积物的沉降迁移;十氯酮主要通过水体的水平迁移和土壤的厌氧降解输出;十氯酮的主要界面迁移过程是大气向土壤的迁移,其次是水体向沉积物的沉降和大气向水体的迁移.     

菖蒲人工湿地对城市生活污水的净化研究

分别研究了土壤、粉煤灰和土壤及粉煤灰3种基质构建的菖蒲模拟人工湿地系统对城市生活污水的净化效果,并探讨了进水流量对城市生活污水净化效果的影响。结果表明,用粉煤灰基质构建的菖蒲模拟人工湿地系统的TP、TN、NH4+-N、浊度净化效果最佳,去除率最高,分别可达99.7%、85.8%、99.5%、99.3%;用粉煤灰和土壤基质构建的菖蒲模拟人工湿地系统的COD净化效果最佳,去除率最高,可达83.2%。因此,菖蒲人工湿地系统对城市生活污水的净化能力强,尤其适合广大中小城市生活污水的处理,具有极其广阔的应用与推广前景。     

污泥果肥利用中重金属迁移特征研究

为了厦门城市污泥的安全利用,将石渭头污水处理厂污泥经过好氧堆肥后施用于柚子树,对重金属元素在土壤、树叶及果肉中的迁移特征进行了研究。结果表明：Cd在土壤中的富集能力强;重金属元素从土壤向树叶迁移累积能力比向果肉的大得多,污泥肥料不能用于叶类食用植物的施用;Cr向树叶、Ni向果肉的迁移累积能力强;泥肥的施用加重了土壤中Cd的污染,提高了Cr向树叶、Ni向果肉的迁移能力;污泥果肥利用需降低Ni的浓度,对污泥中含量较高的Cu、Zn、Ni、Cr和Cd需进行跟踪检测。     

三峡库区垃圾污染现状及治理技术

如何搞好三峡库区的生态环境保护已成为全世界关注的课题，介绍了库区生活垃圾污染现状，并根据库区生活垃圾的特性及当地的经济发展和自然条件，对三峡库区生活垃圾的综合治理进行了系统研究，建议三峡库区垃圾实行分类收集，系统地将城区生活垃圾的管理、收集、运输和处理等各个环节有机结合起来，逐步建立起高效完善的现代化城市生活垃圾管理体系。重点介绍了准好氧垃圾卫生填埋技术和CBS（Cental Bilolgical System）城市生活垃圾高效菌种堆肥技术，秭归、巴东等烧煤区生活垃圾含无机物成分较高，建议选用准好氧填埋技术；涪陵、开县、忠县等燃气区生活垃圾有机物成分较高，已具备一定的资源化价值，高效菌种CBS堆肥技术在燃气区具有广阔的前景。     

山阴地区浅层沉积物中砷的分布特征及吸附行为

本文通过室内实验的方法,对山阴高砷地下水地区不同浅层沉积物中砷的分布特征及吸附行为进行了研究。结果表明：研究区内饮用水浓度高,病情重。浅层承压含水层中的砷含量平均值为290 mg/kg,在17.4～22.7 m段的平均值达643 mg/kg,22.7～25.8 m段的平均值为115 mg/kg,25.8 m以下的平均值为212 mg/kg。As（Ⅲ）、As（Ⅴ）在4种沉积物表面上的动力学吸附过程均符合Lagergren模型,相关系数达0.9以上。沉积物对As（Ⅴ）的吸附速率较As（Ⅲ）快,但As（Ⅲ）在沉积物中的吸附比As（Ⅴ）稳定。4种含水层介质对As（Ⅲ）、As（Ⅴ）的吸附速率依次为粘土〉亚粘土〉粉砂〉中砂。吸附动力学吸附过程符合二级速率方程。Freundlich方程和Langmuir方程对As（Ⅲ）、As（Ⅴ）的吸附过程拟合性最佳,相关系数均在0.95以上。沉积物对As（Ⅲ）吸附的最佳pH在7～8范围内,As（Ⅴ）吸附的最佳pH在5～6左右。此外,沉积物对砷的吸附性能主要受沉积物颗粒大小、矿物成分等因素综合作用的影响,而非各组分吸附砷的简单加和。     

乡镇企业有机废水对稻田生态的影响

城市生活污水、制糖及食品加工废水均为有机污水。有机污水危害水稻症状为:贪青、茎杆徒长、无效分叶多、易倒伏、烂根、籽粒不饱满、米质下降等。危害机理是氮素过多引起的和随着土壤还原所带来的生理性障碍。减少污染物进入稻田的数量和节水栽培使土壤氧化、促使土壤中有机物的分解是防治有机废水危害稻田的有效措拖。     

不同措施在防治山地果园水土流失及面源污染中的应用研究

通过施用生物毯、生物带和秸秆覆盖3种措施,模拟人工降雨,测定山地果园的水土流失量,比较不同措施在防治山地果园水土流失中的效果.结果表明,在降雨强度为1.33 mm/min时,与对照相比生物毯和秸秆覆盖能减少50%以上的氮磷流失量,生物带减少氮磷流失量也达到30%以上;在降雨强度为2.33 mm/min时,秸秆覆盖防治水土流失的效果最好;在高降雨强度(2.33mm/min)时,各种措施防治效果降低,但效果仍然明显,对磷的防治效果好于对氮的防治效果,与对照相比生物毯能减少44.5%的磷流失量.山地果园水土流失相当严重,施用生物毯和秸秆覆盖能有效防治山地果园的面源污染.     

土霉素在4种人工湿地基质上的吸附-解吸特性

为了研究土霉素在人工湿地基质床中的行为机制,本实验采用批量平衡方法研究了壤土、煤灰渣、粗砂和细砂等4种人工湿地基质材料对土霉素的吸附、解吸特性。结果表明,土霉素在人工湿地基质材料上的吸附可分为前4小时的快速吸附阶段和之后的慢速吸附阶段,14 h后达到吸附平衡,这一吸附平衡时间明显低于一般人工湿地系统的水力停留时间。可以认为,土霉素在人工湿地中有足够的时间吸附于基质层上,其吸附量的大小主要取决于基质材料的性质。土霉素在4种基质材料上的等温吸附实验表明,吸附等温线均呈非线性,用Freundlich方程能较好地对吸附数据进行非线性拟合。在4种人工湿地基质材料中,煤灰渣对土霉素的吸附作用最强,通过Freundlich方程拟合的吸附容量参数(KF)为280.2;其次为壤土,KF值为129.3;粗砂和细砂的吸附作用较弱,KF值分别为53.2和64.5。人工湿地基质材料对土霉素的吸附能力主要与基质有机质含量、粘粒含量、Fe2O3含量、阳离子交换量和Al2O3含量呈正相关。土霉素在4种人工湿地基质材料上的解吸均存在滞后现象,相对于壤土和煤灰渣,吸附于粗砂和细砂上的土霉素更容易被解吸下来。     

Fine and coarse aerosol composition in an urban setting: A case study in Beijing,China

Components of the near-ground urban aerosol in Beijing, China, which are derived from natural and pollution sources, have been identified by means of PIXE analysis of particle size fractionated samples and relationships among the concentrations of 18 elements. Samples were collected in city center and outlying suburban and rural locations on five days in July and December 1980. The panicle size distributions of most elements were bimodal, with a gradual progression from mainly coarse mode Ca, Ti and Al to mainly fine mode S, As, and Br. Pb, Zn and Cu occurred mainly in fine particles and were apparently pollutants derived from the combustion of coal and other fuels, but not gasoline. Fine particle Cr, Mn and Fe concentrations were especially high on one July day and may have derived from a pulse of industrial air pollution. Si concentrations were singularly high in ultra-fine particles as if from the condensation of high temperature vapors from coal combustion. Coarse particles in the city center were apparently from local surface dust raised by vehicle traffic, and they were enriched in Pb, Zn and Cu compared to a rural location, suggesting a significant degree of city soil contamination by fine pollution aerosol fallout over time.     

Hydrocarbon pollution fixed to combined sewer sediment: a case study in Paris

Over a period of two years (2000-2001), sediment samples were extracted from 40 silt traps (STs) spread through the combined sewer system of Paris. All sediment samples were analysed for physico-chemical parameters (pH, organic matter content, grain size distribution), with total hydrocarbons (THs) and 16 polycyclic aromatic hydrocarbons (PAHs) selected from the priority list of the US-EPA. The two main objectives of the study were (1) to determine the hydrocarbon contamination levels in the sediments of the Paris combined sewer system and (2) to investigate the PAH fingerprints in order to assess their spatial variability and to elucidate the PAH origins. The results show that there is some important inter-site and intra-site variations in hydrocarbon contents. Despite this variability, TH and PAH contamination levels (50th percentile) in the Parisian sewer sediment are estimated at 530 and 18 microg g(-1), respectively. The investigation of the aromatic compound distributions in all of the 40 STs has underlined that there is, at the Paris sewer system scale, a homogeneous PAH background pollution. Moreover, the study of the PAH fingerprints, using specific ratios, suggests the predominance of a pyrolytic origin for those PAHs fixed to the sewer sediment.     

Cost optimization of integrated wastewater drainage and treatment systems

This paper presents the cost optimization of an urban drainage and wastewater treatment system. The mixed sewer urban drainage (including combined sewer overflows and retention basins), the activated sludge wastewater treatment plant (WWTP), and the permissible loading of the receiving water were optimized simultaneously by the nonlinear programming approach. For this purpose, the integrated optimization model OPTIMALWWT was developed. The economic objective function of the defined investment and operational costs is subjected to rigorous design and ecological constraints. A practical example of the cost optimization of an existing urban drainage and WWTP, located in Slovenia, is presented to demonstrate the efficiency of the proposed method. For each of the two different design approaches, three different optimization cases were carried out for three different technological alternatives. As a result, the optimal technological process was finally selected for the reconstruction of the system, as a result of its suitable costs and operational safety.     

Deposition velocities to Sorbus aria, Acer campestre, Populus deltoides X trichocarpa 'Beaupré', Pinus nigra and X Cupressocyparis leylandii for coarse, fine and ultra-fine particles in the urban environment

Trees are effective in the capture of particles from urban air to the extent that they can significantly improve urban air quality. As a result of their aerodynamic properties conifers, with their smaller leaves and more complex shoot structures, have been shown to capture larger amounts of particle matter than broadleaved trees. This study focuses on the effects of particle size on the deposition velocity of particles (Vg) to five urban tree species (coniferous and broadleaved) measured at two field sites, one urban and polluted and a second more rural. The larger uptake to conifers is confirmed, and for broadleaves and conifers Vg values are shown to be greater for ultra-fine particles (Dp < 1.0 microm) than for fine and coarse particles. This is important since finer particles are more likely to be deposited deep in the alveoli of the human lung causing adverse health effects. The finer particle fraction is also shown to be transported further from the emission source; in this study a busy urban road. In further sets of data the aqueous soluble and insoluble fractions of the ultra-fines were separated, indicating that aqueous insoluble particles made up only a small proportion of the ultra-fines. Much of the ultra-fine fraction is present as aerosol. Chemical analysis of the aqueous soluble fractions of coarse, fine and ultra-fine particles showed the importance of nitrates, chloride and phosphates in all three size categories at the polluted and more rural location.     

Size-resolved trace metal characterization of aerosols emitted by four important source types in Switzerland

In central Switzerland five types of emission sources are mainly responsible for airborne trace metals: traffic, industrial plants burning heavy oil, resuspension of soil particles, residential heatings and refuse incineration plants. The particulate emissions of each of these source types except refuse incineration were sampled using Berner impactors and the mass and elemental size distributions of Cd, Cu, Mn, Pb, Zn, As and Na determined.Cd, Na and Zn are not characteristic for any of these source types. As and Cu, occurring in the fine particle fractions are characteristic for heavy oil combustion, Mn for soil dust and sometimes for heavy and fuel oil combustion and Pb for traffic aerosols. The mass size distributions of aerosols originating from erosion and abrasion processes show a maximum mass fraction in the coarse particle range larger than about 1 μm aerodynamic equivalent diameters (A.E.D.). Aerosols originating from combustion processes show a second maximum mass fraction in the fine particle range below about 0.5μm A.E.D.Scanning electron microscopy combined with an EDS analyzer was used for the morphological characterization of emission and ambient aerosols.     

U-series disequilibria in a groundwater flow route as an indicator of uranium migration processes

U-series data relating to groundwater, fracture coatings and the adjoining rock matrix in a groundwater flow system at the Palmottu natural analogue site was examined. The aim was to obtain an experimental reference for migration modelling in a transport section defined within the flow system. The U-series reference obtained turned out to be a very useful tool for fine tuning the flow route and for migration mechanism considerations. The U-series data are well in line with other interpretations of the migration system.     

Assessment of aided phytostabilization of copper-contaminated soil by X-ray absorption spectroscopy and chemical extractions

Field plots were established at a timber treatment site to evaluate remediation of Cu contaminated topsoils with aided phytostabilization. Soil containing 2600 mg kg⁻¹ Cu was amended with a combination of 5 wt% compost and 2 wt% iron grit, and vegetated. Sequential extraction was combined with extended X-ray absorption fine structure (EXAFS) spectroscopy to correlate changes in Cu distribution across five fractions with changes in the predominant Cu compounds two years after treatment in parallel treated and untreated field plots. Exchangeable Cu dominated untreated soil, most likely as Cu(II) species non-specifically bound to natural organic matter. The EXAFS spectroscopic results are consistent with the sequential extraction results, which show a major shift in Cu distribution as a result of soil treatment to the fraction bound to poorly crystalline Fe oxyhydroxides forming binuclear inner-sphere complexes.     

Heavy metal distribution in an urban wetland impacted by combined sewer overflow

The heavy metal content and distribution in an urban wetland affected by combined sewer overflow (CSO) discharge during dry conditions was evaluated. Metals identified in the CSO discharge were also measured upstream and downstream of the CSO. Metals were detected in the acid-extractable fraction of the wetland sediments and the roots of Phragmites australis plants. Sediment from the banks of a pool created by the CSO, and from a clay bed upstream were found to be moderately contaminated with Cu, Pb and Zn. Micro X-ray fluorescence (μ-XRF) of Phragmites roots from the CSO banks showed a correlation in the spatial distribution of Fe and Mn, attributed to the formation of mineral plaques on the root surface. Micro X-ray absorption near edge spectroscopy (μ-XANES) revealed that Cu and Zn were complexed with the organic ligands phytate and cysteine. The findings indicated that continuous discharge from the CSO is a source of heavy metals to the wetland. Metals bound to sediments are susceptible to remobilization and subsequent transport, whereas those associated with Phragmites roots may be more effectively sequestered. These observations provide insight into the behavior of heavy metals in urban areas where CSOs discharge into wetlands.