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971.
Life cycle assessment is emerging as a powerful tool in the evaluation of the environmental impact of manufacturing processes. This paper describes a general methodology for the life cycle analysis of manufacturing processes taking into account the flexibility and decision-making potential of knowledge base systems. Emphasis is placed on on-site waste minimisation and associated sustainability characteristics in relation to environmental impact assessment and process improvement. The ensuing software model is applied with some success to an initial study of pulp and paper manufacture. 相似文献
972.
Liu Hong Yan Yixin Wang Wenyan Yu Yongyong 《Frontiers of Environmental Science & Engineering in China》2007,1(1):67-72
This work aims to explore a procedure to improve biological wastewater treatment efficiency using low intensity ultrasound.
The aerobic activated sludge from a municipal wastewater treatment plant was used as the experimental material. Oxygen uptake
rate (OUR) of the activated sludge (AS) was determined to indicate the changes of AS activity stimulated by ultrasound at
35 kHz for 0–40 min with ultrasonic intensities of 0–1.2 W/cm2. The highest OUR was observed at the ultrasonic intensity of 0.3 W/cm2 and an irradiation period of 10 min; more than 15% increase was achieved immediately after sonication. More significantly,
the AS activity stimulated by ultrasound could last 24 h after sonication, and the AS activity achieved its peak value within
8 h after sonication, or nearly 100% higher than the initial level after sonication. Therefore, to improve the wastewater
treatment efficiency of bioreactors, ultrasound with an intensity of 0.3 W/cm2 could be employed to irradiate a part of the AS in the bioreactor for 10 min every 8 h.
Translated from Environmental Science, 2005, 26(4): 124–128 [译自: 环境科学] 相似文献
973.
云南洱海沉积物--水界面铁、锰的分布和迁移特征 总被引:11,自引:0,他引:11
洱海是一永久性含氧湖泊。对洱海沉积物中铁、锰的分布特征进行了分析,说明洱海沉积物中铁的循环比锰微弱的多,铁氧化物的还原作用受到了溶解氧和锰氧化物的双重控制。输入沉积物中的铁大部分都保存于沉积物中。锰氧化物的还原虽然也受到溶解氧的制约,但其还原作用仍很激烈,所以锰对环境的敏感程度比铁高,沉积物中的铁具有环境记录意义,而锰不具有环境记录意义。 相似文献
974.
975.
介绍了产品全生命周期和循环经济的概念,提出了产品的资源循环模型。对干电池全生命周期的生命过程及阶段进行了划分,并分析了于电池的材料组成,提出了可应用于实践的干电池回收循环利用模型,计算出3种类型回收材料各自所占比重,为我国干电池回收业提供了决策理论和实践指导。 相似文献
976.
Issues and challenges for forest-based carbon-offset projects: A case study of the Noel Kempff climate action project in Bolivia 总被引:1,自引:0,他引:1
Brown S. Burnham M. Delaney M. Powell M. Vaca R. Moreno A. 《Mitigation and Adaptation Strategies for Global Change》2000,5(1):99-121
The Noel Kempff Climate Action Project in Bolivia, nowin its third year, is breaking ground to establishcredible and verifiable methods to quantify greenhousegas (GHG) benefits of land-use change and forestry (LUCF)projects. Developed under the United Nations FrameworkConvention Climate Change (FCCC) Activities ImplementedJointly pilot phase, the project conserves naturalforests that would otherwise have been subjected tocontinued logging and future agricultural conversion.Carbon (C) monitoring began with a C inventory of theproject area in 1997. The total amount of C in theproject area was 118 Tg (Tg = 1012g) ± 4%(95% confidence interval). Periodic monitoring ofrelevant C pools (occurring in 1999 and every 5 yrthereafter) occurs over the 30-year life of theproject to establish the difference between thewith-project and projected without-project scenarios. Permanent sample plots were established both insidethe project area to monitor changes in C pools overtime and in a proxy logging concession near theproject area to determine changes in C pools inforests that have been impacted by logging. Ground-based monitoring is complemented by datacollection on forest industry trends and land-usechange patterns. Remote sensing was used to developa vegetation stratification map of the area, and workis ongoing to investigate the potential application ofdual-camera aerial videography to improve theefficiency of monitoring over time. 相似文献
977.
978.
1IntroductionAerosolsplayanimportantroleinclimatechange,airquality,aciddeposition,visibilityreduction,andcloudproceses.Theyar... 相似文献
979.
产品生命周期评价体系探讨 总被引:7,自引:1,他引:7
生命周期评价(LCA)是一个相对罗新的概念,理论上生命周期评价具有将环境质量融入决策过程的特点,生命周期评价是对产品和过程相关的环境干扰进行定量分析和评估的方法,本文介绍了LCA的要领和内容,探讨了LCA的技术框架和实施方案,并着重介绍LCA的核心--影响分析的主人指标,提出了LCA有待发展完善的方面。 相似文献
980.
L. M. Risse B. Y. Liu M. A. Nearing 《Journal of the American Water Resources Association》1995,31(1):147-159
ABSTRACT: Since the trend in infiltration modeling is currently toward process-based approaches such as the Green-Ampt equation, more emphasis is being placed on methods of determining appropriate parameters for this approach. The SCS curve number method is an accepted and commonly used empirical approach for estimating surface runoff, and is based on numerous data from a variety of sources. The time and expense of calibrating process-based infiltration parameters to measured data are often prohibitive. This study uses curve number predictions of runoff to develop equations to estimate the “baseline” hydraulic conductivities (Kb) for use in the Green-Ampt equation. Curve number predictions of runoff were made for 43 soils. Kb values in the Water Erosion Prediction Project (WEPP) model were then calibrated so that the annual runoff predicted by WEPP was equal to the curve number predictions. These calibrated values were used to derive an equation that estimated Kb based on the percent sand, percent clay, and cation exchange capacity of the soil. Estimated values of Kb from this equation compared favorably with measured values and values calibrated to measured natural runoff plot data. WEPP predictions of runoff using both optimized and estimated values of Kb were compared to curve number predictions of runoff and the measured values. The WEPP predictions using the optimized values of Kb were the best in terms of both average error and model efficiency. WEPP predictions using estimated values of Kb were shown to be superior to predictions obtained from the curve number method. The runoff predictions all tended to be biased high for small events and low for larger events when compared to the measured data. Confidence intervals for runoff predictions on both an annual and event basis were also developed for the WEPP model. 相似文献