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النتائج 171 - 180 من 424
Elemental Mercury Control by Novel Oxidant and Sorbent in an Entrained-Flow System
2008
Lee, Sang-Sup | Lee, Joo-Youp | Keener, Tim C
An entrained-flow system has been designed and constructed to simulate in-flight mercury capture by sorbents in ducts of coal-fired utility plants. The test conditions of 1.5 s residence time, 140°C temperature, 4.5 ppbv inlet Hg⁰ concentration, and 0-20 lb/MMacf sorbent injection rates were chosen to simulate conditions in the ducts. Novel oxidants developed in previous fixed-bed tests and novel sorbents derived from the novel oxidants were tested for their Hg⁰ capture in the entrained-flow system to examine the possibility of using those sorbents in a full-scale system. Darco-FGD and Darco Hg-LH served as benchmark sorbents with which mercury control capability of the novel oxidants and novel sorbents could be compared. The test results showed that the novel oxidants have remarkable Hg⁰ oxidation capability, and the novel sorbents showed a better performance in Hg⁰ removal than Darco Hg-LH.
اظهر المزيد [+] اقل [-]Sources and Mass Flows of Xenobiotics in Urban Water Cycles--an Overview on Current Knowledge and Data Gaps
2008
Bester, K | Scholes, L | Wahlberg, C | McArdell, C. S
In this study, several emerging compounds of concern in waste water are identified and discussed in relation to data available on their sources and mass flows in urban waters. In most western European situations, the highest contributions to the mass flow of xenobiotics to the urban water cycle stems from household and services applications (e.g. personal care compounds, pharmaceuticals, steroid hormones, flame retardants, fluorinated detergents etc.) as well as building and constructing environments (e.g. flame retardants, plasticizers, UV-blockers and biocides). The contribution from industrial point sources such as incineration industries e.g. coal, tar, steel and gas production (such as PAHs, PCBs, dioxins, etc.) and chemical industries are decreasing in relevance in terms of input and are hence currently of more local relevance only. In relation to identified compounds, this paper considers current data availability and its use in a range of management strategies for the mitigation or controlling of xenobiotics 'at source'. However it also identifies major knowledge gaps relating to the behaviour and fate of organic pollutants in various sectors of the urban water cycle including stormwater management, bank- and soil infiltration as well as underground and soil passage of polluted waters. It is also discussing the major sources of a range of current day urban pollutants. The paper considers the sources of emerging pollutants in a qualitative way.
اظهر المزيد [+] اقل [-]Flows of Active Pharmaceutical Ingredients Originating from Health Care Practices on a Local, Regional, and Nationwide Level in Germany--Is Hospital Effluent Treatment an Effective Approach for Risk Reduction?
2008
Schuster, A | Hädrich, C | Kümmerer, K
Pharmaceuticals are designed to be bioactive and therefore are among the most important chemical compounds manufactured. In recent years pharmaceuticals have been detected in a range of environment compartments, with concerns raised that they may impose a risk to both humans and environmental organisms. To support informed management of any associated risks, knowledge about their substance flows is indispensable. However, little is known about sources and attributable substance flows with regard to the use of human pharmaceuticals. Often data available on a national level are used to judge local or regional situations and to calculate expected concentrations. In this paper, computations on the use of active pharmaceutical ingredients (APIs) of drugs used in human medicine at the local, regional and national levels were conducted. Different data sources were used and raw-data were scaled up- or downwards and compared. Results of this analysis indicated that hospitals are, by far, minor sources of pharmaceuticals to the aquatic environment in comparison to non-point emissions from households. Differences in flows at the local, regional and national scales are also identified.
اظهر المزيد [+] اقل [-]Source Analysis and Hazard Screening of Xenobiotic Organic Compounds in Wastewater from Food-Processing Industries
2008
Maya-Altamira, L | Eriksson, E | Baun, A
In this study we present and apply a methodology for identifying environmentally hazardous compounds in food industry wastewaters (FIW). The methodology comprises a source analysis and a hazard screening of xenobiotic organic compounds based on environmental distribution, persistence, bioaccumulation, and toxicity in aqueous and solid phases. This approach was applied to four selected FIW representing fish, pork meat, and vegetable production. Included in this approach was an analytical-chemical screening of 137 xenobiotic organic compounds showing that 13 compounds and groups of compounds could be detected in the FIW composite samples. The combined source analysis revealed that 161 xenobiotic organic compounds could potentially be present in these four FIW. The main sources were raw materials and their processing, but also packaging and cleaning of the production facility contributed to the total number of compounds potentially present. Using the hazard screening procedure it was found that 29 and 102 compounds should be considered for further hazard assessment in the aqueous and solid phases, respectively. It is important to note that 12% of the 161 compounds could not be evaluated for environmental hazards due to lack of inherent data on degradability, toxicity, and bioaccumulation. Furthermore, for 91% of the compounds no information was found on anaerobic biodegradability. The presented procedure contributes with a systematic source analysis and a ranking of the xenobiotic organic compounds that could cause environmental concern. In this way the procedure can provide guidance to operators and decision makers on handling options for wastewater streams in food processing industries.
اظهر المزيد [+] اقل [-]Material Flows in Sweden 2004
2008
Carlsson, Arvid | Palm, V | Sörme, L | Wadeskog, A
This paper presents and discusses the method and results of account for material flows in Sweden for the year 2004. The results show that it is possible to compile material flow data from existing sources in the Swedish statistical system. By using the European classification system of goods, the Combined Nomenclature, as the basic unit of the data collection, both data collection and aggregation into material flow categories were made possible. Although these data exist in the statistical system, they are not easily available for the scientific community. This is due to several reasons, such as the aggregation of data in the system of statistics not corresponding to the material flow account structure and the fact that data on import and export of materials are organised differently than data for domestic extraction. Almost 50% of the material flows in Sweden are flows of minerals, mainly construction minerals followed by iron ores. Most of the extracted iron ores are exported. In comparison with other European countries this generates a unique situation with Sweden as the only net exporter of iron ores. The flow of biomass in terms of wood is also considerable (26% of the Swedish material flows in 2004). The domestic material consumption (inflow) per capita in 2004 was 8 tonnes minerals, 6 tonnes biomass and almost 3 tonnes of fossil fuels. Of the material flows of fossil fuels petroleum and natural gas dominates with 90%.
اظهر المزيد [+] اقل [-]Shipboard Measurements of Nitrogen Dioxide, Nitrous Acid, Nitric Acid and Ozone in the Eastern Mediterranean Sea
2008
Večeřa, Zbyněk | Mikuška, Pavel | Smolík, Jiří | Eleftheriadis, Kostas | Bryant, Charlotte | Colbeck, I (Ian) | Lazaridis, Mihalis
Measurements of nitrogen dioxide, nitrous and nitric acids as well as ozone were made using newly developed instrumentation onboard the research vessel Aegeon in the Aegean Sea between 25th-29th July 2000. Typical nitrogen dioxide concentrations observed aboard the boat were 4-6 ppb (v/v) with a broad maximum of 20-30 ppb (v/v). Ozone concentrations typically ranged between 40 and 80 ppb (v/v). Mixing ratios of both nitric and nitrous acids in the ambient air of the Aegean Sea were mainly below 50 ppt (v/v). The data also showed a number of short pollution episodes with rapid changes in the concentration of reactive nitrogen compounds [nitrogen dioxide maximum up to 164 ppb (v/v), nitric acid maximum up to 12 ppb (v/v), nitrous acid maximum up to 2.7 ppb (v/v)] and ozone [maximum up to 88 ppb (v/v)]. These episodes were correlated with pollution plumes originating from boats upwind, at short distance, from the R/V Aegeon. The measurements revealed the importance of nitrous and nitric acids for the transport of nitrogen to marine biota in busy ship lanes.
اظهر المزيد [+] اقل [-]Groundwater Pollution of the Quaternary Aquifer in Northern United Arab Emirates
2008
Al-Hogaraty, Eslam A. | Rizk, Zeinelabidin S. | Garamoon, Hassan K.
Natural conditions and human activities have caused serious quality degradation of the Quaternary aquifer in the north of the United Arab Emirates (UAE). The aquifer within Ajman City is unconfined, receiving limited recharge (12 542 m³/day) from the east and large pollutants flux (4,800 m³/day) from land surface. Field survey and laboratory analyses revealed anomalies in groundwater salinity (TDS), total hardness (TH), dissolved oxygen (DO), cations (Ca²⁺, Mg²⁺, Na⁺ and K⁺), anions ( [graphic removed] , [graphic removed] , Cl⁻ and [graphic removed] ) and trace elements (Fe, Pb, Cd and Cr), which can be correlated to point and non-point pollution sources. Concentrations of trace elements are more responsive to anthropogenic sources than natural ones. High Fe and Pb levels were measured close to the untreated sewage disposal site, while high Cd and Cr contents were observed near hospitals and clinics. Iso-concentration maps of salinity and major ions, in addition to hydrochemical profiles were used to define the seawater-groundwater interface in Ajman City. The potentiometric surface map of the Quaternary aquifer within the study area shows that groundwater flows from the east towards the Arabian Gulf in the west. The proposed landfill site is suitable because it lies within a topographic low, receiving groundwater flow from all directions.
اظهر المزيد [+] اقل [-]Cosolvent-enhanced Desorption and Transport of Heavy Metals and Organic Contaminants in Soils during Electrokinetic Remediation
2008
Maturi, Kranti | Reddy, Krishna R.
Numerous sites are contaminated with both heavy metals and polycyclic aromatic hydrocarbons (PAHs) and the technologies to treat such mixed contaminants are very limited. Electrokinetic remediation has the potential to remediate mixed contaminants in soils, including low permeability soils; however, the efficiency of this technology depends on the extracting solution employed. Previous studies on electrokinetic remediation have focused on the removal of heavy metals and organic compounds when they exist individually in clayey soils. In the present study, the feasibility of using cosolvents to enhance the electrokinetic removal of PAHs from clayey soils in the presence of heavy metals is investigated. A series of laboratory electrokinetic experiments was conducted using kaolin soil spiked with phenanthrene and nickel at concentrations of 500 mg/kg each to simulate typical field mixed contamination. Experiments were performed using n-butylamine (cosolvent) at concentrations of 10 and 20% and deionized water, each mixed with 0.01 M NaOH solution and circulated at the anode to maintain alkaline conditions. A periodic voltage gradient of 2 VDC/cm in cycles of 5 days on and 2 days off was applied in all the tests. During the initial stages when the soil pH was low, nickel existed as a cation and electromigrated towards the cathode. However, as the soil pH increased due to hydroxyl ions generated at the cathode and also flushing of high pH n-butylamine solution from the anode, nickel precipitated with no further migration. Phenanthrene was found migrating towards the cathode in proportion to the concentration of n-butylamine. The extent of phenanthrene removal was found to depend on both the electroosmotic flow and the concentration of n-butylamine, but the presence of nickel did not influence the transport and removal of phenanthrene.
اظهر المزيد [+] اقل [-]Detection and Quantification of Human Adenoviruses in Surface Waters by Nested PCR, TaqMan Real-Time PCR and Cell Culture Assays
2008
Muscillo, M. | Pourshaban, M. | Iaconelli, M. | Fontana, S. | Di Grazia, A. | Manzara, S. | Fadda, G. | Santangelo, R. | La Rosa, G.
Adenoviruses are emerging pathogens which may represent new indicators of microbial water quality. In the present study, environmental samples of seawater, estuarine water, and influents of sewage treatment plants underwent both standard bacteriological and viral analyses (adenovirus identification, typing and quantification) in order to evaluate the role of surface water contamination as a possible vehicle for the transmission of adenovirus, and the relevance of adenoviruses as an additional tool in water quality assessment. Qualitative PCR methods were used for the detection and typing of adenoviruses. This was done through the sequencing and phylogenetic analysis of segments of the hexon- and fiber-coding regions of the viral genome. Subsequently, quantitative PCR assays based on TaqMan probe hydrolysis technology were used to assess virus concentrations in environmental samples. Results showed a widespread presence of adenovirus in the environment, even in the absence of bacterial indicators, confirming the relevance of evaluating these viruses as possible indicators of viral contamination of water.
اظهر المزيد [+] اقل [-]Carbon Monoxide in Ouagadougou, Burkina Faso - A Comparison between Urban Background, Roadside and In-traffic Measurements
2008
Lindén, Jenny | Thorsson, Sofia | Eliasson, Ingegärd
Spatial variations of Carbon Monoxide (CO) are examined in the urban environment of Ouagadougou, Burkina Faso. Focus is given on the variations between urban background, roadside and in-traffic measurements. Results show significant differences between the three methods where average in-traffic values were 2-3 times higher than average roadside values and 10-12 times higher than average background values. During traffic congestions these differences extended up to 6 and 20 times respectively. Results are discussed in relation to human exposure assessments and WHO guidelines.
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