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71.
Evaluation of factors influencing soluble microbial product in submerged MBR through hybrid ASM model 总被引:1,自引:0,他引:1
Fangyue Li Joachim Behrendt Knut Wichmann Ralf Otterpohl 《Frontiers of Environmental Science & Engineering in China》2009,3(2):226-235
In this study, a mathematical model was established to predict the formation of the soluble microbial product (SMP) in a submerged
membrane bioreactor. The developed model was calibrated under the reference condition. Simulation results were in good agreement
with the measured results under the reference condition. The calibrated model was then used in the scenario studies to evaluate
the effect of three chosen operating parameters: hydraulic retention time (HRT), dissolved oxygen concentration, and sludge
retention time (SRT). Simulation results revealed that the SMP dominated the soluble organic substances in the supernatant.
The scenario studies also revealed that the HRT can be decreased to 1 h without deteriorating the effluent quality; dissolved
oxygen concentration in the reactor can be kept at 2–3 mg/L to maintain the effluent quality, reduce the content of SMP, and
minimize operating costs; the optimal SRT can be controlled to 10–15 d to achieve complete nitrification process, less membrane
fouling potential, and acceptable organic removal efficiency. 相似文献
72.
Gritta Veit-Köhler Marleen De Troch Mateja Grego Tania Nara Bezerra Wendy Bonne Guy De Smet Christina Folkers Kai Horst George Chen Guotong Rudy Herman Rony Huys Nikolaos Lampadariou Jürgen Laudien Pedro Martínez Arbizu Armin Rose Michaela Schratzberger Sybille Seifried Paul Somerfield Jan Vanaverbeke Edward Vanden Berghe Magda Vincx Borut Vriser Leen Vandepitte 《Marine Biology》2010,157(8):1819-1835
A large-scale database concerning benthic copepods from the Arctic, Baltic Sea, North Sea, British Isles, Adriatic Sea and Crete was compiled to assess species richness, biodiversity, communities, ecological range size and biogeographical patterns. The Adriatic showed the highest evenness and the most species-rich communities. Assemblages from the North Sea, British Isles, Baltic and Crete had a lower evenness. The British Isles were characterised by impoverished communities. The ecological specificity of copepod species showed two diverging trends: higher specificity of species in more diverse assemblages was observed in the Adriatic, North Sea and Baltic. A uniformly high species specificity disregarding sample diversity was found on Crete and in the British Isles. Benthic copepod communities showed distinct patterns that clearly fit the predefined geographical regions. Communities were distinguishable and β-diversity was found to be high around Europe, indicating a high species turnover on the scale of this investigation. The British Isles and the North Sea were found to be faunistic links to the Baltic and the Arctic. 相似文献
73.
A universal method to assess the potential of phosphorus loss from soil to aquatic ecosystems 总被引:2,自引:0,他引:2
Pöthig Rosemarie Behrendt Horst Opitz Dieter Furrer Gerhard 《Environmental science and pollution research international》2010,17(2):497-504
Background, aim, and scope
Phosphorus loss from terrestrial to the aquatic ecosystems contributes to eutrophication of surface waters. To maintain the world's vital freshwater ecosystems, the reduction of eutrophication is crucial. This needs the prevention of overfertilization of agricultural soils with phosphorus. However, the methods of risk assessment for the P loss potential from soils lack uniformity and are difficult for routine analysis. Therefore, the efficient detection of areas with a high risk of P loss requires a simple and universal soil test method that is cost effective and applicable in both industrialized and developing countries. 相似文献74.
Agricultural land use has shifted towards more intensified production because the prices of agricultural products have increased
during the past years. Just a few years ago, voluntary area set-aside was a lucrative alternative in some regions. But nowadays,
land is re-cultivated again, inter alia with biomass crops. Consequently, this affects the soil and nutrient balances in agriculture.
The global changes on the world markets influence agricultural production and thus the water cycle at the regional scale.
In this paper, the regional developments and policy alternatives are discussed for the Elbe River Basin. The paper concludes
that on average, no substantial effects of nitrogen surpluses are expected for the Elbe River Basin due to a continuing decline
in animal herds. However, at the county level, nitrogen surpluses are likely to exceed the maximum threshold of 60 kg nitrogen
per hectare (stipulated in the German Fertiliser Regulation) due to regional concentrations of animal production. A halving
of the threshold to 30 kg per hectare shows that the marginal costs of nitrogen surplus reduction regionally exceeded 10 Euros
per kilogram nitrogen. 相似文献
75.
Research and field experience from the past 15 years has allowed remediation professionals to purposefully design injection‐based remediation systems with a high potential for success. Industry professionals can now claim a number of achievements that were unthinkable just a few years ago: (1) we have demonstrated that maximum contaminant levels (MCLs) can be achieved for multiple contaminants; (2) we have successfully targeted dense nonaqueous‐phase liquid (DNAPL) source zones; (3) we have expanded our understanding of injection hydraulics to treat large plumes; and (4) we have collected sufficient data on rates of treatment to be more predictive regarding outcomes. The next decade will continue to evolve the design and execution of these types of systems for application to more complex problems. At this point on the timeline, questions regarding the mechanisms of treatment have largely been addressed, allowing a shift in focus to operational enhancements. Specific operational insights arising from the body of work to date that arguably will continue to shape and influence the design and execution of injection‐based remediation systems include: (1) the fact that delivery does not always equal distribution, (2) treatment optimization requires aquifer tuning, and (3) life‐cycle costs can be reduced with remedy‐optimized investigation. The number of examples that support these concepts and their ramifications to future technology refinement is already increasing, demonstrating how the refinements that can be made around these areas of focus will enhance our ability to effectively tackle larger and more complicated plumes, and do so with maximum efficiency. © 2011 Wiley Periodicals, Inc. 相似文献
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Begg Katherine Van der Horst Dan 《Mitigation and Adaptation Strategies for Global Change》2004,9(2):181-200
The European Union EU project PROBASE hasexplored a range of possible multi projectstandardised benchmarks as a way ofencouraging projects under Joint Implementation (JI) and the Clean Development Mechanism (CDM)by minimising transaction costs. The aim ofthis paper is to examine the environmentalintegrity of the use of standardisedbaselines and to explore the role ofadditionality. The environmental integritydepends on the uncertainty in emissionreductions, which was estimated bygenerating scenario baselines and comparingthese with the standardised baselines. Thishas allowed a comparison of selected multiproject baselines with the envelope ofuncertainty on the reductions. The projectsincluded a range of electricity supply,heat sector, cogeneration and methane(CH$_{4}$) projects in different countries. Theanalysis showed that the key uncertaintieswere in the technology fuel selection inthe baseline, the continued additionalityof the project emission reductions,uncertainties in some project emissions(e.g. spinning reserve emissions for wind)and data uncertainties. The effect on theestimation of reductions was in the range±12% to ±46% for the electricityprojects and from ±19% to ±57%for the heat and Combined Heat and Power CHP sector projects.Comparison with the envelope of uncertaintyfor the range of projects showed that multiproject electricity sector baselines whichhave been weighted or use high technologyperformance benchmarks (e.g. Organization for Economic Cooperation and Development OECD)can provide conservative estimates buttheir general nature can lead to variationsbetween countries. We would recommend thatthe country-specific context must be takeninto account so that standardised baselinesfor the electricity sector are generated onthe basis of country specificcharacteristics, the project type, andwhether it provides new or existing demand.The conservative scenario produced shouldthen be weighted. Whereas weightings havebeen applied to account for uncertaintiesor to bias towards renewables, we havesuggested a weighting factor of 25% on theelectricity baseline for large projectsbased on an analysis of the effect ofnon-additionality on emission reductionuncertainty. For heat projects, theappropriate benchmark is a technology/fuelbenchmark which is deemed relevant for theheat sector in that (part of the) country.Again we suggest that a weighted sectorbaseline is required to take account of theuncertainties. These recommendations applyto large projects only for a 10-yearcrediting lifetime. 相似文献
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