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121.
Louis Theodore Joseph Reynolds 《Journal of the Air & Waste Management Association (1995)》2013,63(12):1215-1218
This paper addresses a common operation and maintenance problem encountered with sectionalized electrostatic precipitators—bus section failure. ESPs are normally designed to meet a specific minimum collection efficiency in order to comply with emission standards; the loss of several bus sections may cause the unit to be out of compliance. In this paper, the effect of bus section failure on precipitator performance is analyzed. The study is presented in two parts. First, a simplified procedure to estimate the effect of bus section failure on the overall collection efficiency is developed. An illustrative example is presented to demonstrate the use of the technique. Secondly—and this is the main thrust of this study—the technique is extended to include calculations on whether a unit is out of compliance due to the failure of a given number of bus sections. This development clearly shows that this latter effect can only be expressed in terms of a probability. Two additional examples, based on a field unit using actual test data, complement the presentation and illustrate this probability calculation. 相似文献
122.
Joseph A. Laszlo 《Journal of Polymers and the Environment》1998,6(2):73-78
Quaternized, crosslinked sugarcane bagasse can adsorb anionic dyes from textile wastewater. Disposal of dye-saturated adsorbent by composting or land application would require that modifications made to the bagasse do not interfere with its decomposition. The impact of quaternization and crosslinking on bagasse biodegradability was examined. Bagasse in varying states of modification was mixed with soil and monitored for carbon dioxide evolution for four weeks at 27°C. After subtracting the amount of carbon evolved from control soil samples, the net carbon evolved from the bagasse samples was determined and used as a measure of their extent of biodegradation. Biodegradability decreased in the order: bagasse (approx. 60% degraded after four weeks) > quaternized bagasse > quaternized, epichlorohydrin-crosslinked bagasse > quaternized, methylene-bis-acrylamide-crosslinked bagasse > epichlorohydrin-crosslinked bagasse (less than 5% degraded). Crosslinking severely impacted biodegration, probably by preventing the penetration of (hemi)cellulytic and lignolytic enzymes into the interior of the modified bagasse particles. It is concluded that the biodegradability of quaternized, crosslinked bagasse is too low for composting or land application. 相似文献
123.
Amir P. Nejadhashemi Joseph M. Sheridan Adel Shirmohammadi Hubert J. Montas 《Journal of the American Water Resources Association》2007,43(3):744-756
Abstract: Evaluating the relative amounts of water moving through the different components of the hydrological cycle is required for precise management and planning of water resources. An important aspect of this evaluation is the partitioning of streamflow into surface (quick flow) and base‐flow components. A prior study evaluated 40 different approaches for hydrograph‐partitioning on a field scale watershed in the Coastal Plain of the Southeastern United States and concluded that the Boughton’s method produced the most consistent and accurate results. However, its accuracy depends upon the proper estimation of: (1) the end of surface runoff, and (2) the fraction factor (α) that is function of many physical and hydrologic characteristics of a watershed. Proper identification of the end of surface runoff was accomplished by using a second derivative approach. Applying this approach to 12 years of separately measured surface and subsurface flow data from a field scale watershed (study area) proved to be accurate for 87% of the time. Estimation of the α value was accomplished in this study using two steps: (1) alpha was fitted to individual hydrographs: and, (2) a regression equation that determines these alpha values based on climatological factors (e.g., rainfall, evapotranspiration) was developed. Using these strategies improved the streamflow partitioning method’s performance significantly. 相似文献
124.
Gordon Mcgranahan Joseph Leitman Charles Surjadi 《Journal of Environmental Planning and Management》1998,41(4):505-518
Understanding neighbourhood conditions can play an important role in urban environmental management, especially when environmental services are lacking and new approachesare being debated. This paper describes and evaluates three research methods for assessing some of the environmentalproblems facing low income households and communities: (1) broad spectrum household surveys; (2) participatory rapid assessment; and (3) contingent valuation. As part of the study upon which this paper is based, the techniques were applied on a small scale in Jakarta. The paper finds that each technique can provide important and often complementaryinsights. The broad spectrum survey is particularly suitable to broad based planning, participatory appraisal to NGO initiatives and contingent valuation to utility pricing decisions. 相似文献
125.
126.
Sources and Transport of Phosphorus to Rivers in California and Adjacent States,U.S., as Determined by SPARROW Modeling 下载免费PDF全文
Joseph Domagalski Dina Saleh 《Journal of the American Water Resources Association》2015,51(6):1463-1486
The SPARROW (SPAtially Referenced Regression on Watershed attributes) model was used to simulate annual phosphorus loads and concentrations in unmonitored stream reaches in California, U.S., and portions of Nevada and Oregon. The model was calibrated using de‐trended streamflow and phosphorus concentration data at 80 locations. The model explained 91% of the variability in loads and 51% of the variability in yields for a base year of 2002. Point sources, geological background, and cultivated land were significant sources. Variables used to explain delivery of phosphorus from land to water were precipitation and soil clay content. Aquatic loss of phosphorus was significant in streams of all sizes, with the greatest decay predicted in small‐ and intermediate‐sized streams. Geological sources, including volcanic rocks and shales, were the principal control on concentrations and loads in many regions. Some localized formations such as the Monterey shale of southern California are important sources of phosphorus and may contribute to elevated stream concentrations. Many of the larger point source facilities were located in downstream areas, near the ocean, and do not affect inland streams except for a few locations. Large areas of cultivated land result in phosphorus load increases, but do not necessarily increase the loads above those of geological background in some cases because of local hydrology, which limits the potential of phosphorus transport from land to streams. 相似文献
127.
128.
Yellow starthistle (Centaurea solsitialis L.) is an invasive weed that creates problems for the management of Idaho's rangelands. A bioeconomic approach combined with an input-output economic model is used to estimate direct and secondary economic costs of the weed in relation to its interference with agricultural and non-agricultural benefits that rangelands provide. Direct economic costs of the infestations were estimated to be of 8.2 million '05 dollars per year, and secondary costs of 4.5 million '05 dollars per year, for a total of 12.7 million '05 dollars; agricultural related economic impacts accounted for 79% of this total cost, and non-agricultural for 21%. 相似文献
129.
Daniel J. Bain Erin M. Copeland Marion T. Divers Marijke Hecht Kristina G. Hopkins Justin Hynicka Michael Koryak Mary Kostalos Lisa Brown Emily M. Elliott Joseph Fedor Michele Gregorich Brady Porter Brenda Smith Christopher Tracey Margaret Zak 《Journal of the American Water Resources Association》2014,50(6):1608-1621
Urban stream restoration continues to be used as an ecological management tool, despite uncertainty about the long‐term sustainability and resilience of restored systems. Evaluations of restoration success often focus on specific instream indicators, with limited attention to the wider basin or parallel hydrologic and geomorphic process. A comprehensive understanding of urban stream restoration progress is particularly important for comparisons with nonurban sites as urban streams can provide substantial secondary benefits to urban residents. Here, we utilize a wide range of indicators to retrospectively examine the restoration of Nine Mile Run, a multi‐million dollar stream restoration project in eastern Pittsburgh (Pennsylvania, USA). Examination of available continuous hydrological data illustrates the high cost of failures to incorporate the data into planning and adaptive management. For example, persistent extreme flows drive geomorphic degradation threatening to reverse hydrologic connections created by the restoration and impact the improved instream biotic communities. In addition, human activities associated with restoration efforts suggest a positive feedback as the stream restoration has focused effort on the basin beyond the reach. Ultimately, urban stream restoration remains a potentially useful management tool, but continued improvements in post‐project assessment should include examination of a wider range of indicators. 相似文献
130.
Anjel Stough-Hunter Kristi S. Lekies Joseph F. Donnermeyer 《Environmental management》2014,54(6):1306-1319
Little research has considered how residents’ perceptions of their local environment may interact with efforts to increase environmental concern, particularly in areas in need of remediation. This study examined the process by which local environmental action may affect environmental concern. A model was presented for exploring the effects of community-based watershed organizations (CWOs) on environmental concern that also incorporates existing perceptions of the local environment. Survey data were collected from area residents in two watersheds in southwestern Pennsylvania, USA, an area affected by abandoned mine drainage. The findings suggest that residents’ perceptions of local water quality and importance of improving water quality are important predictors of level of environmental concern and desire for action; however, in this case, having an active or inactive CWO did not influence these perceptions. The implications of these findings raise important questions concerning strategies and policy making around environmental remediation at the local level. 相似文献