Degradation of recalcitrant organic contaminants by solar photocatalysis.

Biological pre-treated landfill leachates of Djebel Chakir contains some macromolecular organic substances that are resistant to biological degradation. The aim of the present work is to assess the feasibility of removing refractory organic pollutants in biological pre-treated landfill leachate by solar photocatalyse process. Leachate pollutant contents are studied to assess their contribution to leachate pollution and their treatability by solar photocatalyse process. Phenol is chosen as model of pollutants, to evaluate its removal and the efficiency of the photocatalytic system. The experiments were carried out in suspended photocatalytic reactor, using TiO2 Degussa P25, under sunlight illumination (UV-A: 15-31 W/cm2). Under optimum operational conditions, applied to single reactant (phenol), the system presents a TOC removal of 90% (the degradation follows a first-order kinetic). Based on the TOC removal, the results shows that the degradation of biological pre-treated leachate follows a zero-order kinetic. After 5 h of sunlight exposure, 74% of COT is removed. The TOC removal is the best without any correction of the pH and at the TiO2 concentration of 2.5 g/L. The photocatalytic degradation of organic contaminants as well as the formation and disappearance of the by-products were followed by GC/MS. The solar photocatalysis processes induce several modifications of the matrix leading to more biodegradable forms: all the remaining and new compounds generated after the biological pre-treatment of leachate are degraded and other types of organics appear, mainly carboxylic acid, aliphatic hydrocarbons and phtalic acids.     

Removal of trace organic chemical contaminants by a membrane bioreactor

Emerging wastewater treatment processes such as membrane bioreactors (MBRs) have attracted a significant amount of interest internationally due to their ability to produce high quality effluent suitable for water recycling. It is therefore important that their efficiency in removing hazardous trace organic contaminants be assessed. Accordingly, this study investigated the removal of trace organic chemical contaminants through a full-scale, package MBR in New South Wales, Australia. This study was unique in the context of MBR research because it characterised the removal of 48 trace organic chemical contaminants, which included steroidal hormones, xenoestrogens, pesticides, caffeine, pharmaceuticals and personal care products (PPCPs). Results showed that the removal of most trace organic chemical contaminants through the MBR was high (above 90%). However, amitriptyline, carbamazepine, diazepam, diclofenac, fluoxetine, gemfibrozil, omeprazole, sulphamethoxazole and trimethoprim were only partially removed through the MBR with the removal efficiencies of 24-68%. These are potential indicators for assessing MBR performance as these chemicals are usually sensitive to changes in the treatment systems. The trace organic chemical contaminants detected in the MBR permeate were 1 to 6 orders of magnitude lower than guideline values reported in the Australian Guidelines for Water Recycling. The outcomes of this study enhanced our understanding of the levels and removal of trace organic contaminants by MBRs.     

Use of comprehensive two-dimensional gas chromatography for the broad screening of hazardous contaminants in urban wastewaters.

The list of priority chemicals included in various regulations such as the European Water Framework Directive, as well as the list of hazardous contaminants identified in the aquatic environment, are increasing at an accelerated pace. Therefore, there is a need for broad spectrum methods capable of simultaneously determining hundreds, if not thousands, of contaminants. For the analysis of non-polar or semi-polar contaminants, comprehensive two-dimensional gas chromatography (GC x GC) is more powerful than conventional gas chromatography thanks to a separation on two different stationary phases. This paper reports the use of GC x GC for a broad screening of hazardous contaminants in an urban wastewater plant. Comparison between the raw and treated wastewater has been carried out using a semi-quantitative approach. A variety of drugs, personal care products, pesticides, carcinogens and compounds toxic for reproduction, were identified. Most of these compounds were removed or decreased by this wastewater treatment plant. Preliminary results from this single plant will need to be confirmed by a more extensive study before drawing conclusions on the removal efficiency of 2D-GC amenable compounds.     

Development of adsorbent for the simultaneous removal of organic and inorganic contaminants from aqueous solution

In this study, a modified adsorbent, alginate complex beads, was prepared and applied to the removal of mixed contaminants from wastewater. The alginate complex beads were generated by the immobilization of powdered activated carbon and synthetic zeolites onto alginate gel beads, which were then dried at 110 °C for 20 h until the diameter had been reduced to 1 mm. This dry technique increased the hardness of the adsorbent to assure its durability and application. The adsorption onto the alginate complex beads of organic and inorganic compounds, as target contaminants, was investigated by performing both equilibrium and kinetic batch experiments. From the adsorption isotherms, according to the Langmuir equation, the alginate complex bead was capable of effectively removing benzene, toluene, zinc and cadmium. From kinetic batch experiments, the removal efficiencies of benzene, toluene, zinc and cadmium were found to be 66.5, 92.4, 74.1 and 76.7%, respectively, for initial solution concentrations of 100 mg L(-1). The results indicated that the adsorbent developed in this study has the potential to be a promising material for the removal of mixed pollutants from industrial wastewater or contaminated groundwater.     

Transfer of hydrophobic contaminants in urban runoff particles to benthic organisms estimated by an in vitro bioaccessibility test.

An in vitro bioaccessibility test was applied for assessing the transfer of polycyclic aromatic hydrocarbons (PAHs) present in road dust, into benthic organisms living in a receiving water body. The road dust is supposed to be urban runoff particles under wet weather conditions. Sodium dodecyl sulfate (SDS) solution was used as a hypothetical gut fluid. Pyrene, fluoranthene and phenanthrene were the main PAH species in the SDS extractable fraction of road dust, as well as the whole extract. Benzo(ghi)perylene showed relatively low concentrations in the SDS extract in spite of a high concentration in the original dust. The PAH composition in benthic organisms (polychaetes) did not correspond with that of the surrounding sediment and the PAHs detected were also detected in high concentrations in the SDS extract of road dust. When testing the toxicity of the extracted contaminants by a standardised algal toxicity test, SDS extracts of a detention pond sediment showed higher toxicity than the pore water of the corresponding sediment. Sediment suspension showed a comparative toxicity with 0.1% SDS extract. From the results, the in vitro bioaccessibility test seems more suitable to evaluate the exposed contaminants than the traditional organic solvent extraction method and the SDS extracted fraction is applicable to toxicity tests reflecting the digestive process.     

长江干流主要城市江段微量有机物污染分析

微量有机物对地面水体产生的污染已较普遍,为了解其在长江干流水体中的污染状况与特征,对长江干流主要城市江段水、底质和鱼体中的微量有机污染物进行了检测,根据检测结果,分析和阐述了其微量有机污染物的种类、含量水平及分布特征,并引用美国“多介质环境目标值”评价方法进行了综合评价,结果表明：长江干流主要城市江段水体已普遍受到微量有机物污染,共鉴定出有机物12类308种,主要污染物种为烷烃类、多环芳烃类和脂类;鱼体中微量有机污染物含量普遍高于底质中,而底质中又高于水中;大中型综合工业城市江段污染较为严重,对健康和生态的总环境影响度较大,应引起有关方面的重视。     

The characteristics and measuring technique of refractory dissolved organic substances in urban runoff.

It is considered that refractory dissolved organic substances have caused an increase in the COD concentration in Lake Biwa in recent years. We investigated the organic matter in the first flush of stormwater runoff from a road in the watershed area of the lake, and studied the possibility of improvement in the water environment from that aspect. After percolating the stormwater through soil, we analyzed organic substances fractionated by using GPC-TC. And we examined the effect of removal of organic substances by comparing the peak height before and after percolation. In the result of the experiments, we found that soil infiltration reduced the refractory dissolved organic substance and we successfully designed a system for a simple and easy experimental facility to treat urban runoff.     

Priority organic pollutants in the urban water cycle (Toulouse, France)

Application of the European Water Framework Directive requires Member States to have better understanding of the quality of surface waters in order to improve knowledge of priority pollutants. Xenobiotics in urban receiving waters are an emerging concern. This study proposes a screening campaign of nine molecular species of xenobiotics in a separated sewer system. Five sites were investigated over one year in Toulouse (France) using quantitative monitoring. For each sample, polycyclic aromatic hydrocarbons, polychlorinated biphenyls, nonylphenols, diethelhexylphthalate, linear alkylbenzene sulphonates, methyl tert-butylether, total hydrocarbons, estradiol and ethinylestradiol were analysed. Ground, rain and roof collected water concentrations are similar to treated wastewater levels. Run-off water was the most polluted of the five types investigated, discharged into the aquatic environment. The wastewater treatment plant reduced xenobiotic concentrations by 66% before discharge into the environment. Regarding environmental quality standards, observed concentrations in waters were in compliance with standards. The results show that xenobiotic concentrations are variable over time and space in all urban water compartments.     

A larval medaka (Oryzias latipes) acute toxicity assay combined with solid-phase extraction to efficiently determine the toxicity of organic contaminants in river water.

Using a larval medaka (Oryzias latipes) acute toxicity assay combined with solid-phase extraction, we proposed a method for efficiently determining the fish toxicity of organic contaminants in river water. Organic toxicants were 10, 20, 50 and 100-fold concentrated from 4 L of the sample with adsorption cartridges. The lethal effect was observed by exposing every ten individuals of 48-72 h old larval medaka to 20 mL of each solution for 48h. The median lethal concentration rate (LCR50) was used as an indicator for the toxicity. With the developed toxicity test method, more than seven times difference was found in the LCR50 of the river water samples. LCR50 distribution profiles were compared with 125 samples in two typical rivers. The result revealed a lower toxicity level in the mainstream than in the confluences, and a lower toxicity level in Sagami River than in Ayase River. LCR50 proved unique as a toxicity indicator, which was impossible to speculate from the conventional water quality indicator of the dissolved organic carbon concentration. As an effective screening test for priority settings, the method can help us with an efficient planning for the environmental investigation and management.     

撒融雪剂除冰对桥梁破损的影响

撒融雪剂除冰引起的钢筋锈蚀是北方跨河桥梁结构破坏的重要原因。通过对北京市通州区的一些跨河桥梁的氯化物含量的测试,初步探讨了造成该地区桥梁钢筋锈蚀的主要原因,并从设计方面提出解决问题的办法。     

非线性Stokes波浪场中污染物输移扩散研究

本文讨论了二阶Stokes非线性波浪作用下流体微团的平动和变形对污染物输移及混合扩散的影响,推导了相关公式,得出了波浪场作用下污染物输移及混合扩散的基本规律,为进一步研究波浪场中的纵向离散系数提供了一定的理论依据。建立了基于有限元方法(FEM)的对流扩散数学模型．对理论推导的结果进行了验证。研究结果表明：在非线性波浪场中．污染物的混合扩散除了受漂移速度影响外,具有明显各向异性的特征。     

城市生活污水中的污染物分类及处理性评价

以城市生活污水为对象,通过长期取样和试验分析,研究了水中SS,COD,BOD,总磷,总氮等代表性污染物的存在形态和分布规律。以0.45μm作为溶解物和悬浮物界限尺寸的分析结果表明,城市生活污水中的SS,约65％的COD,60％的BOD,50％的磷和20％的氮均以悬浮物的形态存在,这部分污染物很容易通过沉淀或混凝沉淀的方法有效去除。在研究基础上提出的评价方法和污染物分类及处理性评价模式图有助于污水处理方法的合理选择。     

Polycyclic aromatic hydrocarbons and metals in snow along a highway.

Snow quality and its variations due to distance from the road were studied. Also, how the snow quality changes over time during the melting period was discussed. Snow samples were collected at three occasions during the winter of 2004. The samples were taken along a highway in the Lule? region, Sweden, with an average daily traffic load of 9200 vehicles. Snow samples were taken perpendicular to the road and at different distances. The snow samples were analysed for metals and polycyclic aromatic hydrocarbons (PAH). Also, weather parameters such as temperature, precipitation, and wind speed and wind direction were measured. The highest total metal and PAH concentrations were found at the sample site closest to the road and at the end of the season. Before the melting period started, 42-57% of the total amount of metals and PAH were found in the first 1 m of the snow pack. This information could be valuable when one is discussing how to achieve sustainable snow-handling management.     

城市湿地在城市水环境建设中的开发利用

随着社会的发展和人民生活水平的提高,城市的环境改善更加被关注.城市湿地作为城市生态基础设施的重要组成部分,具有调蓄雨洪、补充地下水、降污净水、调节小气候、改善生态环境、为市民提供休闲娱乐场所等重要功能.     

Removal of trace contaminants using molecularly imprinted polymers.

This work was conducted to study the potential of molecularly imprinted polymers (MIPs) for the removal of oestradiol at trace concentrations (1 ppm-1 ppb). An MIP synthesised with 17beta-oestradiol as template was compared to non-imprinted polymers (NIP) synthesised under the same conditions but without template, a commercial C18 extraction phase and granulated activated carbon. At 1 ppb oestradiol was recovered by 98 +/- 2% when using the MIP, compared to 90 +/- 1, 79 +/- 1, and 84 +/- 2% when using the NIP, a C18 phase, or granulated activated carbon, respectively. According to these levels, the MIP was capable of producing an effluent with a quality 5-10 times higher than the other materials. The same levels of oestradiol recovery were achieved with the MIP when supplying 17beta-oestradiol at 0.1 ppm. Phenolic compounds added as interferences bound less to the MIP than to the NIP, confirming the selectivity of the MIP. Oestradiol biodegradation was also demonstrated at high concentrations (50 ppm), showing the pollutants can be safely destructed after being enriched by molecular extraction. This study demonstrates the potential of molecular imprinted polymers as a highly efficient specific adsorbent for the removal of trace contaminants.     

Water vending in urban Sudan

Water vendors, selling water door‐to‐door from donkey carts, are an important source of domestic supply in low‐income urban areas in Sudan, as in other developing countries. A study of the demand for this service showed that it was of negligible elasticity, with no evidence of direct control of the price by a monopoly or cartel. It follows that the price of water paid by the poor could be greatly reduced by increased availability of water to the vendors or of credit for the purchase of donkeys and carts.     

城市雨洪模型在天津市区排水分教计算中的应用

针对天津市城区产汇流特性，在充分论证和经过验区检验的基础上，引进美国雨洪管理模型（SWMW），详细地进行了市区二级河道的排涝模拟与计算，并计算了市区有关控制断面的出流过程。     

城市雨洪模型在天津市区排水分析计算中的应用

针对天津市城区产汇流特性 ,在充分论证和经过验区检验的基础上 ,引进美国雨洪管理模型 (SWMW) ,详细地进行了市区二级河道的排涝模拟与计算 ,并计算出市区有关控制断面的出流过程     

利用桃汛洪水冲刷降低潼关高程试验效果分析

在对2006年黄河桃汛洪水万家寨调水试验基本情况介绍的基础上,主要分析了三门峡水库相关各站洪水、水库运用和库区冲淤等情况,并对桃汛洪水对潼关高程和渭河尾闾段壅水和冲淤情况进行了分析,认为冲刷对降低潼关高程有一定作用,对渭河尾闾段无明显影响,进而提出了桃汛试验的不足和改进方向。     

城市雨洪多功能调蓄技术

在城市雨水排放系统中建造雨水多功能调蓄设施既可以减少雨水资源的流失,有效地利用城市雨水、削减洪峰流量、缓解城市水涝,又可以高效率地利用宝贵的土地资源,为城市创造优美的景观、改善城市生态环境。简略地论述这种设施在国外的应用情况,并以北京为例,讨论了多功能雨水调蓄措施在北京和我国其他城市的推广应用情况。