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1.

Background

Sorting and disposal of waste are the last steps in the “lifetime” of a product. If products are contaminated with chemicals assessed to be hazardous for man or environment, waste management has the role of a vacuum cleaner in substance chain management working in two different ways: The hazardous compounds have to be properly separated from potential secondary resources in sorting processes. If this is not possible, those products have to be disposed safely. Starting from the experiences collected with some chemicals banned, the tools used for phasing out these chemicals from the technosphere are studied with respect to their influence on the contamination of the environment.

Results

Even if a dangerous substance has been banned, it is further used in a number of products. In the cases presented here, the substances were banned for further use. In the case of CFCs, the substitutes used have partially also been substituted because of adverse effects. Besides the prohibition of use of hazardous substances, numerous other regulations were issued to reduce unsafe handling and minimize emissions into the environment. It turned out that waste management cannot correct mistakes which already happened “upstream” in the product chain. The control of point sources works quite successfully, whereas today the overwhelming emissions stem from diffuse sources, partially caused by unsafe waste management procedures.

Conclusions

Though there are no complete balances for both groups of compounds serving as examples, some conclusions can be drawn based on the experiences collected. Hazardous compounds may be separated successfully from used products or waste,
  • If they are mostly used in industry and not in households,
  • if they can be identified as part of certain products,
  • if their concentration in these products is rather high,
  • if technical problems come up when they contaminate secondary raw materials,
  • if there is international support for proper waste management.
  相似文献   

2.
The development of criteria for the comparative assessment of technologies and substances beyond the toxicological approach and the development of an integrated pattern of criteria is still at the beginning. The criteria presented here for integrating the precautionary principle into the substance and technology assessment have to be further operationlised and completed, in the same way as the criteria which have been discussed and developed within the framework of
  • - the poisoning and pollutant paradigm
  • - the equilibrium paradigm
  • - the sustainability and “Mitwelt” paradigm
  • - the energy and the general technology assessment debate.
  • The resolution of the criteria has to be improved and their range (which is certainly limited) has to be explored more precisely. The application of the criteria should never occur mechanically. Technology assessment and substance assessment are not only scientific, but essentially social and, hence, discursive processes. It is not so much the assessment of individual substances which should be in the center of the debate, but rather the comparative assessment of competing techniques, substances and substancerelated development pathways (see vonGleich andRubik, 1966 as a first approach to assess the environmental effects of old and new materials). According to the example of the energy strategies, only the development of competing strategies in the substance field could create the necessary prerequisites for a broad public discourse and thus for a democratisation of the basic substancerelated policy decisions. This discourse is a duty which science and economy have toward society.  相似文献   

    3.
    The development of criteria for the comparative assessment of technologies and substances beyond the toxicological approach and the development of an integrated pattern of criteria is still at the beginning. The criteria presented here for integrating the precautionary principle into the substance and technology assessment have to be further operationalised and completed, in the same way as the criteria which have been discussed and developed within the framework of
  • - the poisoning and pollutant paradigm
  • - the equilibrium paradigm
  • - the sustainability and “Mitwelt” paradigm
  • - the energy and the general technology assessment debate.
  • The resolution of the criteria has to be improved and their range (which is certainly limited) has to be explored more precisely. The application of the criteria should never occur mechanically. Technology assessment and substance assessment are not only scientific, but essentially social and, hence, discursive processes. It is not so much the assessment of individual substances which should be in the center of the debate, but rather the comparative assessment of competing techniques, substances and substancerelated development pathways (see vonGleich andRubik, 1966 as a first approach to assess the environmental effects of old and new materials). According to the example of the energy strategies, only the development of competing strategies in the substance field could create the necessary prerequisites for a broad public discourse and thus for a democratisation of the basic substancerelated policy decisions. This discourse is a duty which science and economy have toward society.  相似文献   

    4.
    For the time being, simple and reliable methods which permit the imaging of the complex topography of contaminant plumes in groundwater are missing. The conventional methods for the punctual determination of contaminant concentrations cannot fulfill this demand. To successfully implement and utilize. Natural Attenuation, these deficits have to be overwhelmed. The detectors described in the following represent only part of the probing device system the authors have developed; it shall enable their user to image different aspects of plume topography and its time dependent change by monitoring within the undisturbed groundwater aquifer in groundwater measuring levels:
  • ? relative freights of contaminants and trace contaminants by passive samplers [4] and
  • ? redox milieu parameters by detectors.
  • The detectors offer multi-purpose, tape-like probing devices of unlimited length. They are charged with a defined reserve of reactive substances. During monitoring actions, the derector tape hangs vertically stretched by a weight preferably covering from the top to the bottom of the whole water column. During the reaction period, the detector may be relaunched for repeated visual inspection. The colour changes of the detectors enable the identification of a row of parameters in the vertically (depth-) oriented profile by unbroken optical/visually perceivable imaging:
  • ? Position of Redox potential thresholds for Mn-IV-Mn-II, Fe-III-Fe-II, Sulfate-Sulfide
  • ? Position of ochre precipitation and iron-sulfide precipitation horizons
  • ? Relative freights of the sum of substances effecting reduction (period until defined oxidant reserve has been reduced)
  • ? Relative freights of the sum of substances effecting iron-sulfide oxidation (period until defined reductant reserve has been reduced)
  • ? Position of dissolved iron-II ions containing horizons
  • ? Position of dissolved hydrogen-sulfide ions/hydrogen-sulfide containing horizons
  • ? Relative freights of iron-II ions (period until defined oxidant reserve has been reduced)
  • ? Relative freights of hydrogen-sulfide ions/hydrogen-sulfide (period until defined oxidant reserve has been reduced). Furthermore, the detectors are also suitable for the examination of waters even of great depth, as for example artificial or natural lakes, sea and ocean basins.
  •   相似文献   

    5.
    Ecotoxicological investigations focus on biological systems and their response to chemically induced stress. Experimental techniques are much more developed than deterministic dynamic modelling. In this methodological contribution a technique is presented, based on lattice theory. This technique, also calledHasse diagram technique, allows data analysis with respect to comparative evaluation. Hasse diagrams are used
  • ? to suggest a possible measure of microbial diversity,
  • ? to analyze dependencies between phospholipid fatty acids and simple geochemical parameters on an ordinal scale and
  • ? to visualise complex results of interactions of humic substances with xenobiotics.
  •   相似文献   

    6.

    Background and aim

    Air pollution caused by oxidized and reduced nitrogen is distributed over wide areas of Europe at a high level. As an alternative or complement to physical measurements and modelling calculations, biomonitoring with plants provides techniques to assess amounts and effects of pollution from oxidized and reduced nitrogen compounds (depositions and concentrations). Many of the previously implemented techniques are based on well-proven standardised methods, e.g. documented in VDI guidelines, modified more or less for a biomonitoring of atmospheric nitrogen pollution. This paper gives a review of the techniques for a biomonitoring of atmospheric nitrogen pollution, their possibilities as well as their limitations.

    Main features

  • -diversity of the ground vegetation
  • -nitrogen accumulation in vascular plants
  • -exposure of vascular plants
  • -mapping of epiphytic lichens, bryophytes and algae
  • -nitrogen accumulation in lichens and bryophytes
  • -exposure of lichens and bryophytes
  • Results and Discussion

    Important response parameters are nitrogen concentrations in plant tissue (shoot, needle, leave) and biodiversity of plant species. These responses of vascular plants in many cases are influenced by other local varying conditions, in particular the soil. The exposure of vascular plants over a short period provides a standardised quantification of the total atmospheric nitrogen input in a model ecosystem. The enrichment of nitrogen in the plant tissue of bryophytes and lichens from the ground vegetation is closely correlated with the amount of nitrogen deposition. The diversity of epiphytic lichens and the response of exposed Hypogymnia physodes is more sensitive to ammonia than to nitrous oxide, whereas with the diversity of epiphytic bryophytes or the abundance of algae no significant correlation with atmospheric N pollution were found.

    Conclusions

    Some bioindication techniques provide a causeeffect related, partly standardised biomonitoring of nitrogen pollution. In some cases varying experiences with some biomonitors like the biodiversity of the ground vegetation, exposure of lichens, moss bags and grass cultures stress the need for more research in this subject.  相似文献   

    7.

    Aim and Scope

    This study was aimed at evaluating environmental effects of tar-oil impregnated (tanalized) tree stakes using simple and efficient biotests to obtain results of its ecological impacts during the tar-oil breakdown in the stake.

    Results

    1. Soil respiration was measured in-situ as an indication of soil microbial activity in two field trials. Soil respiration was measured in a 20 year-old apple orchard at various distances from the tar-oil impregnated tree stakes and also on soil mixed with chippings from pine stakes with tar-oil impregnation of different ages.
    2. Cress germination tests were employed to evaluate tar-oil phytotoxicity in a field and laboratory trial. Cress was seeded close to tree stakes in the same 20 year-old apple orchard and germination rates related to tar oil-impregnation. Cress was also seeded in trays in sand mixed with pine chippings from stakes with tar-oil impregnation of different ages.
    3. The portion of the carcinogenic benzoapyrene (BaP) ranged between 0.0015% in freshly tar-oil impregnated to 0.4% in tar-oil impregnated 20-year old trees stakes, i.e. irrespective of the overall PAK concentration and its degradation.
    4. Kinetic analysis using DIXON plots showed a 50% breakdown of overall PAHs after ca. 2.7 years, i.e. km or Ki values of less than 3 years.

    Conclusion

    Germination tests of cress and endogenous seeds as well as soil respiration proved sensible indicators of the phytotoxicity and ecotoxicity of tar-oil impregnated tree stakes in fruit orchards. Soil respiration proved particularly sensitive to tar-oil ageing. Its combination with kinetic inhibition models resulted in parameters suitable for the interpretation of results.  相似文献   

    8.
    Risk assessment of chemicals requires comprehensive data material, which often is not available. To provide substitutes for the lacking experimental ecotoxicological and physico-chemical data, a software-system (SAR-System) has been developed comprising more than 90 estimation models for relevant endpoints. The approach is based on quantitative structure-activity relationships (QSAR). Two major aspects characterize the SAR-System:
    1. The implemented models were tested for their validity and application range.
    2. The QSARs are accessible by a menu-driven programme package.
    The following endpoints are included: Thysico-Chemical Data: 1-Octanol/water-partition-coefficient log Pow, vapour pressure, water solubility, pKa-value, boiling point Biological Data: Toxicity towards fish, daphnia, tetrahymenae, algae, bacteria and mammals, mutagenicity. Distribution: soil sorption, bioconcentration, Henry-Constant, Mackay (Level I). Degradation: photodegradation, biodegradability.  相似文献   

    9.

    Goal, Scope and Background

    Worldwide energy requirements are constantly increasing. Rising prices and the necessity to secure the future energy supply have led the decision-makers in politics and economy to focus on the more intensive use of their own resources. Before the background of possible climatic effects caused by the use of fossil energies, the use of renewable resources as primary energies, with its narrow C-circulation, have gained in importance, particularly in terms of economic aspects. The production of biogas is of specific interest here. It is a sensible ecological investment and a solid source of income for our agriculture.

    Material and Methods

    The operator uses a complex biological system in a plant with high investment costs. An economic operation is only possible if the process parameters are optimized and the properties of the substrates and the co-ferments are known. For the important determination of the blogas potential, we present an efficient and robust system, which is easy to handle and low cost, that has been developed by the LHL and LLH at the Eichhof. This procedure enables one to make statements on the implementation dynamics and is also suited to judge the fermentation process depending on the size of particles, as the co-ferments are used in a practice-oriented consistency.

    Results

    With the described fermentation apparatus you can not only assess the potential development of biogas and methane, but also the process of fermentation. The sum-graphs determined allow one to make conclusions on the implementation dynamics and, thus, on the optimization of the process. The advanced equipment makes it possible to determine the process of fermentation and the gas yield under different retention times and digester loads. The determination of the potential of the biogas and also the evaluation of the continuous fermentation are related to a specific correction factor won from the standard.

    Discussion

    A prerequisite for economic process management is the knowledge of the attainable gas yield and the fermentation process of substrates and co-ferments. A precise calibration is the quality basis for the results achieved with this method, as is the case with other fermentation tests as well. For the tests, a highly homogeneous substrate, which guarantees a continuous biological activity in the digesters, ought to be used. The possibility of determining optimum retention times and digester loads with this equipment makes costly tests with a full scale reactor unnecessary.

    Conclusions

    All tests run demonstrated that the fermentation apparatus originally developed to determine the biogas yield is absolutely suited to also assess the impact of different digester loads and retention times.

    Recommendations

    The problem of the suitability and the potential of different materials, the optimum reactor performance and the combination of different processes of energy generation from renewable but also conventional resources will increaseingly become the focus of laboratory tests. The following subjects have to be taken into account:
  • - Testing different materials on their suitability
  • - Evaluation security of common and new co-ferments
  • - Guidelines for mixtures to optimize reactor performance
  • - Mixtures of different substrates and co-ferments available to a particular operator (also with the help of simulation models)
  • - Processing changing quantity proportions of plants won from a rotation of crops altered for energy generation
  • - Other parameters like pre-fermentation, particle size and fer mentation supplements.
  • Perspective

    These tests with a high practical relevance are supposed to contribute to a reliable method of producing biogas, in order to optimize the yield of gas production, but also to find a calibration of less costly procedures like those involving Near Infrared Spectroscopy (NIRS).  相似文献   

    10.

    Object and Background

    Production and use of substances and formulations can result in exposures on humans and the environment. In October 2003, the European Commissions presented a proposal for the registration, evaluation, assessment and restriction of chemicals (REACH). Assessment of exposures will become an essential element of REACH for certain substances. For many manufacturers and users of substances and formulations these tasks are new. Pilot projects to REACH have shown so far that solutions and instruments for these tasks which meet the requirements of real life situations have yet to be developed.

    Discussion and Conclusions

    Within the REACH proposal, exposure scenarios are a main element of the chemical safety assessment. This article outlines the contents of exposure scenarios. It reflects experiences with exposure scenarios and discusses possibilities of standardization. It covers exposure steps/categories and possibilities to build product groups. Non-branch specific types of exposure situations are an important element of exposure scenarios. Therefore, exposure steps/categories should be contained in exposure scenarios. Nevertheless, these elements structure only a specific part of the information contained in exposure scenarios. Hence they cannot replace exposure scenarios. Exposure categories do not reveal the uses, the processes and the activities connected with the intended use of substances. These information are important parts of a complete exposure scenario. They are the basis for the following step of risk characterisation. In addition, they provide the necessary transparency regarding the use patteern of substances.  相似文献   

    11.
    This paper reviews the environmental problems associated with the coal-mining industry on the Yorkshire coalfield. The main environmental problems are identified as being caused by:
    1. The need to dispose of large quantities of colliery waste or ‘spoil’, in an environmentally acceptable manner.
    2. Derelict and despoiled land, including the problems caused by the re-working of old tips for their coal content.
    3. Opencast coal mining.
    4. Subsidence.
    5. Transportation of coal and coal waste.
    These problems are reviewed in the context of the role of coal in meeting the United Kingdom's energy needs and the framework of environmental control within which the coal-mining industry has to operate. Particular stress is laid on the fact that the Yorkshire coalfield, as with the majority of coalfields, is an old one with a legacy of inherited dereliction. Whilst modernisation of the mining industry is proceeding there have not been parallel developments put in hand to cope with the changing nature of the environmental problems resulting from the modernisation of the industry. Particular stress is placed on the need to dispose of the greatly increased quantities of spoil now being produced.  相似文献   

    12.

    Background, Aim and Scope

    Many environmental pollutants are slowly degrading (persistent) and very mobile. They are semivolatile, i.e. they are partitioned between the environmental media of soil, water and air, and undergo long-range transport. The combined action of climate and substance properties determines the distributions and fate of these substances, among them as the persistent organic pollutants (POPs), other pesticides and industrial chemicals.

    Main Features

    Multicompartment chemistry-transport models are under development in order to study environmental exposure models.

    Results

    The investigation of transport and fate of some POPs on the global scale has emphasized the significance of historically explicit and geo-referenced simulations for substance distributions, persistence and long-range transport potential. Apart from the substance properties, it is the regional climate which is most important. This was illustrated by studies into the regional cycling of DDT and γ-HCH in selected tropical and extra-tropical regions.

    Discussion

    The isolation of individual steps of subsequent cycles of emission, transport and deposition (a so-called grasshopper effect) in model experiments shows the potential to elucidate the complex superposition of substance properties and environmental conditions, variable in time and space.

    Conclusions

    The results suggest that the grasshopper effect enhances the long-range transport potential, but is not required to explain an accumulation in polar regions (at least for γ-HCH).

    Perspectives

    A number of relevant scientific questions should be addressed by exposure modelling.  相似文献   

    13.
    Through their use of energy and materials, universities cause a great deal of environmental pollution which could be reduced considerably by an effective choice of organizational and technical measures. There are some examples for environmental protection measures at several universities, but a professional environmental management system (EMS) for universities with a systematic approach to reduce the consumption of resources is lacking. At the University of Osnabrück, the basis for an EMS applicable for a university has been developed for the first time in Germany and the use of this system can also be transferred to other universities. The EMS is composed of ten building blocks, for example, alteration of the administration’s organizational structure, adoption of environmental guidelines, analysis of the energy and material flows which result in an eco-balance, an environmental program or measures to inform the staff and to help to involve them in environmental management. Over the next months, these ten building blocks will gradually be implemented at the University of Osnabrück. Five articles will provide an overview about the EMS developed for the University of Osnabrück as a whole and will describe parts of the material and energy flow analysis, and the planned environmental information system.
  • Part I: An Environmental Management Model for Universities: From Environmental Guidelines to the Involvement of Employees
  • Part II: The Energy Balance of the University of Osnabrück: Analysis of the Energy Flows and Conclusions
  • Part III: The Traffic Balance of the University of Osnabrück: Calculation of the Environmental Pollution which is caused by the University’s Commuters and Business Trips
  • Part IV: A Concept of Waste Reduction for the University of Osnabrück: Constructing the Waste Balance and Measures to Inform and Involve the Staff
  • Part V: The Planned Environmental Information System of the University of Osnabrück: Concept and Integration into the Management Information System
  •   相似文献   

    14.
    15.
    The scope of anaerobic metabolism of Sipunculus nudus L. was assessed from the maximal activities of some enzymes of the intermediary metabolism and from the concentration of some metabolites accumulated during enhanced muscular activity and during prolonged experimental hypoxia.
    1. Maximal enzyme activities demonstrate that the scope of anaerobic glycolysis, as indicated by maximal activities of glycogen phosphorylase (0.84 U g-1 fresh wt), far exceeds the aerobic capacity, which is assumed not to surpass the activity of succinate dehydrogenase (0.09 U g-1 fresh wt). Three pyruvate reductase activities (alanopine-, strombine- and octopine dehydrogenase) can possibly terminate anaerobic glycolysis.
    2. During muscular activity, energy is provided by the degradation of phospho-L-arginine and by anaerobic glycolysis. Octopine is the major endproduct during functional anaerobiosis while the formation of strombine is less pronounced.
    3. During exposure to a nitrogen atmosphere, several anaerobic endproducts are found to accumulate. Anaerobic glycolysis is terminated by strombine synthesis. This opine accumulates in concentrations much higher than octopine. In addition the concentrations of succinate, propionate and acetate are found to increase in tissues, and/or in the coelomic fluid and the incubation water.
    4. The relative contribution of energy by the different anaerobic metabolic pathways are estimated during functional and environmental hypoxia.
      相似文献   

    16.
    For the two biosphere-reserves of Schorfheide-Chorin and Spreewald in the Federal State of Brandenburg, Germany, we designed a concept for a monitoring program of ecosystems which is feasible and inexpensive, and whose methodical development is transferable to other large-scale protected areas. Beside the statistical analysis of hard GIS data, we systematically used additional criteria such as naturalness, scarcity and special management, a based on expert knowledge. Thus, after an inventory of the existing ecosystems, we selected the ecosystems to be monitored from the different ecosystem groups (i.e. woods and forests, fens, lakes, rivers, arable land and grasslands) based on the following four criteria:
    1. dominance,
    2. naturalness,
    3. nation-wide scarcity and
    4. special management.
    We then combined the selected ecosystems with their relevant forms of landuse to so-called ecosystem-landuse-complexes, which reflect the natural conditions as well as the human impact in the biosphere reserves. This paper presents the selection of the ecosystem landuse complexes to be monitored. Thus, for both biosphere reserves, we obtained 32 ecosystem landuse complexes in woods and forests, 32 in fens, 53 in lakes, 7 in rivers, 23 in grasslands and 20 in arable land.  相似文献   

    17.
    The reclamation of tailing that is toxic to vegetation (phytotoxic) was the subject of laboratory and field research. Using trona tailing as an example of phytotoxic waste, research identified three areas that may be critical to reclamation:
  • establishment and maintenance of a capillary barrier to prevent upward migration of plant toxicants into the plant-rooting zone;
  • water drainage or evaporation to prevent or control water accumulation within the tailing;
  • soil requirements for revegetation.
  • A pilot reclamation program was developed in which a 20-cm layer of coarse gravel formed a capillary barrier between phytotoxic tailing and overlying material. To maintain the integrity of the capillary barrier, a 20-cm layer of fine gravel was applied to the coarse gravel surface; soil was then applied to the fine gravel surface. A zone of shallow soil was used to allow water, which collected during the late winter, to evaporate from the tailing during the dry summer. Soil depth requirements were assessed by measuring the response of shrubs and grasses to increasing soil depth.  相似文献   

    18.
    This article discusses the evaluative criteria which are applied for the assessment of contaminated soils. Guide values for materials in the soil (reference values, test values and action levels). Such guide values can be derived based upon either functional or constitutional criteria. The leachate from the soil must be analyzed for noxious materials in order to ensure the conservation of both ground- and surface-waters. Furthermore, existing concepts and drafts for evaluating soil contamination are discussed. The great diversity of the 37 regulatory publications for evaluating soil contamination is due to 1. different purposes these guidelines are aimend at, and 2. varying philosophies with regard to the degree of safety which is considered to be acceptable:
    1. The approach of the LAGA (Länderarbeitsgemeinschaft Abfall-German federal cooperative for waste regulation) is to merely avert dangerous effects of polluted land rather than to take precautionary measures.
    2. The approach of the state of Baden-Württemberg is to combine precautionary activities and defensive procedures in one scheme with the technical and financial feasibility as criteria for the final decision.
    A summary of the valid legislation is discussed, based on the specific regulatory works of the individual German states:
  • - The federal soil protection act and the directives based on it
  • - Inherent problems with deriving test values from basic toxicological data as well as the question of a tolerable cancer risk level
  • The procedure of linking the test values with a concrete danger to health that was designed for the federal soil protection act is discussed and compared with an alternative procedure. A presentation is given of the LABO (Länderarbeitsgemeinschaft Bodenschutz — German federal and state cooperative on soil conservation) utilization concept for soils: The use of test values for assessing soil materials with regard to particular utilization goals. The article quotes the ?Guideline for monitoring the success in soil cleanup operations” as compiled by the GDCh working group on ?Environmental chemistry and ecotoxicology” (1996). This guideline provides a review of the evaluatory concepts applied in the German states of Hamburg, North Rhine-Westphalia, Brandenburg, Rhineland-Palatinate, Hessen, Baden-Württemberg, as well as those of the German federal cooperative for waste regulation (LAGA). The respective procedures and specifications of Holland, Canada, the USA are also noted in this guideline.  相似文献   

    19.

    Background

    Aim and Scope. Implementation of the European Union White Paper on chemicals policy shall provide more safety and more transparency in chemicals use. In the past, when assessing existing commercial substances there was often a lack of information in the fields of application of the chemicals and the exposures arising in those contexts. The White Paper therefore calls for ‘shared responsibility’. Processors and commercial users of substances are to be involved much more closely in the risk evaluation process than has hitherto been the case. They are to provide data on substance applications and exposures, and, to some extent, they are also to carry out exposure assessments and risk assessments themselves. By analysing case studies, the paper highlights the consequences of this approach.

    Results and Discussion

    Fear has often been voiced that these new tasks will completely overburden small and medium-sized enterprises. It is assumed that many chemicals are no longer available for smallvolume applications, as — for cost reasons — producers do not include these applications in their registration. The wording of the White Paper is not precise enough to be able to appraise the costs that will be associated with the required intensified communication. In this situation, it is essential to analyse prototypical substances and their applications in order to gain an improved understanding of the principle of shared responsibility.

    Conclusions

    The concrete study of several product chains has shown that the flow of information required between producers and users is very likely feasible within the context of the REACH system. For the producers of chemicals, the intensified communication will presumably make it simpler to procure information in the fields of application and exposures. However, in order to avoid users being overburdened, it will be important that registration requirements and focuses are shaped in a manner doing justice to practical realities. Users will need to undertake community-wide efforts on an industry federation and branch level. In this context, the protection of company know-how also needs to be ensured.

    Recommendation and Outlook

    In practice, implementation of the principle of shared responsibility can lead to intensified communication among the producers and users of chemicals. This can greatly facilitate exposure assessments and risk assessments. There is a need to develop manageable procedures that can also be implemented by small and medium-sized enterprises. Numerous proposals have been made in this context, and extensive reference material is now available.  相似文献   

    20.
    All Australian coal for export is washed — that is, the low-grade high-ash material is separated out and disposed of at the washery site. The coarse rejects are generally placed in embankments and the tailings are pumped into settling ponds. These methods of waste disposal can create environmental problems. In addition, they represent a significant energy loss, because about one-third of the waste material is combustible and is thus a potentially valuable source of energy. Laboratory studies at the CSIRO Division of Fossil Fuels at North Ryde, New South Wales, have shown that energy can be successfully recovered from washery wastes by the process of fluidized-bed combustion. A pilot fluidized-bed combustor, with a capacity of 2 tonnes/hour, is undergoing prolonged trial at the Clutha washery near Camden, New South Wales, in a joint project between the Joint Coal Board and CSIRO. The results from the pilot plant tests have provided the basis for a conceptual design and feasibility study for a full-scale tailings treatment plant. This study has indicated that fluidized-bed combustion:
    1. offers an environmentally attractive and economically competitive alternative to the disposal of tailings in settling ponds, and
    2. can be used to generate large quantities of energy from the wastes, reducing the energy lost in coal washing from around 16% to 6% of the coal mined.
      相似文献   

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