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831.
During the second half of the 20th century, the Ganga River ecosystem has been continuously altered by several ongoing anthropogenic
processes, accommodating multi-dimensional pressure due to increase of nearly four-fold human population. For solution of
any environmental issues of the river, the Earth System Science approach is required to have maximum socio-economic benefits
to millions of people living in Indian and Bangladesh. A bibliography containing more than 250 references on environmental
studies of the Ganga River was prepared to preserve its ecosystem by providing the baseline support in this regard. 相似文献
832.
Organic pollutants in compost and digestate. Part 1. Polychlorinated biphenyls, polycyclic aromatic hydrocarbons and molecular markers 总被引:1,自引:0,他引:1
Brändli RC Bucheli TD Kupper T Furrer R Stahel WA Stadelmann FX Tarradellas J 《Journal of environmental monitoring : JEM》2007,9(5):456-464
In Europe, 9.3 x 10(6) t(dry weight (dw)) of compost and digestate are produced per year. Most of this is applied to agricultural land, which can lead to considerable inputs of organic pollutants, such as polychlorinated biphenyls (PCB) and polycyclic aromatic hydrocarbons (PAH) to soil. This paper presents an inventory of the pollutant situation in source-separated composts, digestates and presswater in Switzerland by a detailed analysis of over 70 samples. PCB concentrations ( summation PCB 28, 52, 101, 118, 138, 153, 180) were significantly higher in urban (median: 30 microg kg(-1)dw, n = 52) than in rural samples (median: 14 microg kg(-1)dw, n = 16). Together with low concentrations in general, this points to aerial deposition on compost input material as the major contamination pathway. Enantiomeric fractions of atropisometric PCB were close to racemic. Median PAH concentration was 3010 microg kg(-1)dw( summation 15PAH, n = 69), and one quarter of the samples exhibited concentrations above the relevant Swiss guide value for compost (4000 microg kg(-1)dw). The levels were influenced by the treatment process (digestate > compost), the season of input material collection (spring-summer > winter > autumn), the particle size (coarse-grained > fine-grained), and maturity (mature > less mature). The main source of PAH in compost was pyrogenic, probably influenced mainly by liquid fossil fuel combustion and some asphalt abrasion, as suggested by multiple linear regression. This study, together with a companion paper reporting on other organic contaminates including emerging compound classes, provides a starting point for a better risk-benefit estimation of the application of compost and digestate to agricultural soil in Switzerland. 相似文献
833.
Harrad S Robson M Hazrati S Baxter-Plant VS Deplanche K Redwood MD Macaskie LE 《Journal of environmental monitoring : JEM》2007,9(4):314-318
The environmentally prevalent polybrominated diphenyl ether (PBDE) #47 and polychlorinated biphenyls (PCBs) #28 and #118 were challenged for 24 hours with a novel biomass-supported Pd catalyst (Bio-Pd(0)). Analysis of the products via GC-MS revealed the Bio-Pd(0) to cause the challenged compounds to undergo stepwise dehalogenation with preferential loss of the least sterically hindered halogen atom. A mass balance for PCB #28 showed that it is degraded to three dichlorobiphenyls (33.9%), two monochlorobiphenyls (12%), and biphenyl (30.7%). The remaining mass was starting material. In contrast, while PCB #118 underwent degradation to yield five tetra- and five trichlorinated biphenyls, no less chlorinated products or biphenyl were detected, and the total mass of degraded products was 0.3%. Although the Bio-Pd(0) material was developed for treatment of PCBs, a mass balance for PBDE #47 showed that the biocatalyst could prove a potentially useful method for treatment of PBDEs. Specifically, 10% of PBDE #47 was converted to identifiable lower brominated congeners, predominantly the tribrominated PBDE #17 and the dibrominated PBDE #4, 75% remained intact, while 15% of the starting mass was unaccounted for. 相似文献
834.
For the south central U.S., lower tropospheric ozone pollution has been a persistent and challenging problem. This paper provides long-term trends analyses of the ozone and precursor monitoring data collected over the past 20 years in four south central U.S. cities. The results of these analyses should be useful to air quality scientists, managers, planners, and modelers in assessing the effectiveness of ozone pollution control strategies being implemented or being planned for the future. Results of the data analyses show that all areas have monitored significant decreases in ozone and precursor concentrations over the past 20 years, especially in El Paso, Texas. Continuing challenges include the reduction of the percentage of time that monitors record 8 hour ozone concentrations over the U.S. 8 hour ozone standard, and the future control of highly reactive volatile organic compounds. 相似文献
835.
Wen-Cheng Liu Jan-Tai Kuo Chih-Chieh Young Ming-Ching Wu 《Environmental Modeling and Assessment》2007,12(3):201-211
Numerical models are often used to evaluate the potential impact of human alternation of natural water bodies and to help
the design of the alternation to mitigate its impacts. In the past decade, three-dimensional hydrodynamic and reactive transport
modeling has matured from a research subject to a practical analysis technology. This paper presents a practical study in
which a three-dimensional hydrodynamic and water quality model [hydrodynamic eutrophication model (HEM-3D)] was applied to
determine the optimal location for treated wastewater discharged from marine outfall system in the Keelung harbor and the
adjacent coastal sea. First, model validation was conducted with respect to surface elevation, current, and water quality
variables measured in the Keelung harbor station and its coastal sea. The overall performance of the model was in qualitative
agreement with the available field data. The model was then used to evaluate several scenarios of the locations from marine
outfall system. Based on model simulation results, a location at the northeast of Ho-Ping Island was recommended for adoption
because the environmental impact is smaller than any other alternative.
相似文献
Wen-Cheng LiuEmail: |
836.
Pyrolysis of mixtures of sewage sludge and manure: a comparison of the results obtained in the laboratory (semi-pilot) and in a pilot plant 总被引:1,自引:0,他引:1
A pilot-scale pyrolysis process was carried out for the treatment of a mixture of two types of waste, sewage sludge and cattle manure, comparing the results with others obtained under laboratory conditions (semi-pilot scale). The aim of this study was to obtain the energetic valorization of the products. Owing to the specific characteristics of the plant, two products were obtained from the process: gas and carbonized solid. As no liquid fraction was obtained, the gas fraction is a greater percentage made up of both condensable and non-condensable compounds, which were obtained separately at the laboratory scale. The pilot plant was designed so that the gases produced by thermolysis were burnt continuously in a combustion chamber, while the carbonized fraction was fed in batches for co-combustion. To determine composition and combustion ability, the gas and solid products from the pilot process were characterized by chromatographic analysis of the gaseous fraction and chemical analysis and programmed-temperature combustion of the carbonized solid. The composition of the combustion gases, rich in light hydrocarbons, and the carbon present in the carbonized fraction enable the energetic valorization of these products. The combustion gases were subjected to a cleaning process and their composition analysed twice: before and after the gas cleaning treatment. The study led to a positive assessment of the possible use of the process products as fuel, provided that the combustion gases are treated. As most of the sulphur and chlorine from the original waste are mainly concentrated in the solid fraction, the use of char as a fuel will depend on the effectiveness of clean-up techniques for combustion gases. During gas cleansing, neutralizing with sodium bicarbonate proved effective, especially for the acidic compounds HCl, HF and SO(2). 相似文献
837.
Because of the stringent pollutant emission standards introduced with the European Union guidelines for waste incineration, it is very important to optimize the flue gas cleaning systems which are able to result in a low environmental impact according to the emission limits. In this paper a thermochemical model has been proposed for the simulation of the flue gas cleaning system of an RDF incineration plant. The model simulates the operation of the flue-gas treatment section and the combustion section by using a simplified approach. The combustion includes the grate incinerator and the post-combustion chamber, while the cleaning section includes the NO(x) reduction process (urea injection) and the scrubbing of SO(2) and HCl (Ca(OH)(2) as sorbent). The modelling has been conducted by means of ASPEN PLUS code. The simulation results have been validated with the operating data. The model proposed by the authors can be a useful tool in both evaluating the efficiency of the gas cleaning system by verifying the environmental pollution of an incinerator power plant in nominal operating conditions and in forecasting the efficiency of the cleaning system in off-design operating conditions. 相似文献
838.
This work presents an analysis on the suitability of mechanical biological treatment of municipal solid waste in South America, based on two previous experimental investigations carried out in two different countries. The first experiment was performed for determining the mass and volume reduction of MSW in the province of Concepción (Chile). The implemented bench-scale process consisted of a manual classification and separation stage, followed by an in-vessel biological degradation process. The second experiment consisted of a full-scale experiment performed in the city of Estrela (Brazil), where the existing municipal waste management facility was adapted to enhance the materials sorting and separation. Expressed in wet weight composition, 85.5% of the material input in the first experiment was separated for biological degradation. After 27 days of processing, 60% of the initial mass was reduced through degradation and water evaporation. The final fraction destined for landfilling equals 59% of the total input mass, corresponding to about 50% of the initial volume. In the second experiment, the fraction destined to landfill reaches 46.6% of the total input waste mass, whilst also significantly reducing the total volume to be disposed. These results, and the possible recovery of material streams suitable for recycling or for preparing solid recovered fuels, are the main advantages of the studied process. 相似文献
839.
Performance results obtained from a 6200 ton demonstration-scale anaerobic bioreactor, constructed on the Pacara Pintada Landfill in Tucumán, Argentina, are described. The operational aspects over a 30-month period for the Tucumán bioreactor demonstrate the ability to maintain the bioreactor in the mesophilic range, with the result that the generation and collection of the biogas has been maintained at accelerated rates with a rate constant of approximately 0.5 year(-1). Field measurements of metal concentrations in leachate indicated significant attenuation over time. Refuse subsidence, measured over a 28-month period, ranged from 4% to 19%, with an average of 11% subsidence across the Tucumán cell. 相似文献
840.
Life cycle assessment of a national policy proposal - the case of a Swedish waste incineration tax 总被引:1,自引:0,他引:1
At the core of EU and Swedish waste policy is the so-called waste hierarchy, according to which waste should first be prevented, but should otherwise be treated in the following order of prioritisation: reuse, recycling when environmentally motivated, energy recovery, and last landfilling. Some recent policy decisions in Sweden aim to influence waste management in the direction of the waste hierarchy. In 2001 a governmental commission assessed the economic and environmental impacts of introducing a weight-based tax on waste incineration, the purpose of which would be to encourage waste reduction and increase materials recycling and biological treatment. This paper presents the results of a life cycle assessment (LCA) of the waste incineration tax proposal. It was done in the context of a larger research project concerning the development and testing of a framework for Strategic Environmental Assessment (SEA). The aim of this paper is to assess the life cycle environmental impacts of the waste incineration tax proposal, and to investigate whether there are any possibilities of more optimal design of such a tax. The proposed design of the waste incineration tax results in increased recycling, but only in small environmental improvements. A more elaborate tax design is suggested, in which the tax level would partly be related to the fossil carbon content of the waste. 相似文献