ABSTRACT Membrane collection surfaces, developed and patented by researchers at Ohio University, were used to replace steel plates in a dry electrostatic precipitator (ESP). Such replacement facilitates tension-based rapping, which shears the adhered particle layer from the collector surface more effectively than hammer-based rapping. Tests were performed to measure the collection efficiency of the membranes and to quantify the potential improvements of this novel cleaning technique with respect to re-entrainment. Results indicate that even semiconductor materials (e.g., carbon fibers) collect ash nearly as efficiently as steel plates, potentially indicating that collection surface resistivity is primarily dictated by the accumulated ash layer and not by the underlying plate conductivity. In addition, virtually all sheared particles separated from the collecting membranes fell within the boundary layer of the membrane, indicating extremely low potential for re-entrainment. 相似文献
To increase U.S. petroleum energy independence, the University of Texas at Arlington (UT Arlington) has developed a direct coal liquefaction process which uses a hydrogenated solvent and a proprietary catalyst to convert lignite coal to crude oil. This sweet crude can be refined to form JP-8 military jet fuel, as well as other end products like gasoline and diesel. This paper presents an analysis of air pollutants resulting from using UT Arlington's liquefaction process to produce crude and then JP-8, compared with 2 alternative processes: conventional crude extraction and refining (CCER), and the Fischer-Tropsch process. For each of the 3 processes, air pollutant emissions through production of JP-8 fuel were considered, including emissions from upstream extraction/production, transportation, and conversion/refining. Air pollutants from the direct liquefaction process were measured using a LandTEC GEM2000 Plus, Draeger color detector tubes, OhioLumex RA-915 Light Hg Analyzer, and SRI 8610 gas chromatograph with thermal conductivity detector. According to the screening analysis presented here, producing jet fuel from UT Arlington crude results in lower levels of pollutants compared to international conventional crude extraction/refining. Compared to US domestic CCER, the UTA process emits lower levels of CO2-e, NOx, and Hg, and higher levels of CO and SO2. Emissions from the UT Arlington process for producing JP-8 are estimated to be lower than for the Fischer-Tropsch process for all pollutants, with the exception of CO2-e, which were high for the UT Arlington process due to nitrous oxide emissions from crude refining. When comparing emissions from conventional lignite combustion to produce electricity, versus UT Arlington coal liquefaction to make JP-8 and subsequent JP-8 transport, emissions from the UT Arlington process are estimated to be lower for all air pollutants, per MJ of power delivered to the end user.
Implications: The United States currently imports two-thirds of its crude oil, leaving its transportation system especially vulnerable to disruptions in international crude supplies. At current use rates, U.S. coal reserves (262 billion short tons, including 23 billion short tons lignite) would last 236 years. Accordingly, the University of Texas at Arlington (UT Arlington) has developed a process that converts lignite to crude oil, at about half the cost of regular crude. According to the screening analysis presented here, producing jet fuel from UT Arlington crude generates lower levels of pollutants compared to international conventional crude extraction/refining (CCER). 相似文献
An aerostat-borne instrument and sampling method was developed to characterize air samples from area sources, such as emissions from open burning. The 10 kg battery-powered instrument system, termed “the Flyer”, is lofted with a helium-filled aerostat of 4 m nominal diameter and maneuvered by means of one or two tethers. The Flyer can be configured variously for continuous CO2 monitoring, batch sampling of semi-volatile organic compounds (SVOCs), volatile organic compounds (VOCs), black carbon, metals, and PM by size. The samplers are controlled by a trigger circuit to avoid unnecessary dilution from background sampling when not within the source plume. The aerostat/Flyer method was demonstrated by sampling emissions from open burning (OB) and open detonation (OD) of military ordnance. A carbon balance approach was used to derive emission factors that showed excellent agreement with published values. 相似文献
The environmental fate and effects of pioglitazone prescribed for the treatment of type 2 diabetes were evaluated in an environmental risk assessment following the European Medicines Agency (EMA) "Guideline on the Environmental Risk Assessment of Medicinal Products for Human Use"; EMEA/CHMP/SWP/4447/00. A predicted environment concentration (PEC) for surface water was estimated at 0.023μgL(-1), (action limit of 0.01μgL(-1)) triggering a comprehensive battery of laboratory evaluations. Pioglitazone and its major metabolites were determined not to significantly adsorb to sewage solids, were not persistent in the aquatic environment, did not bioaccumulate and were non-toxic to aquatic organisms. Pioglitazone does not pose an unacceptable risk to groundwater supplies, with concentrations not anticipated to be a risk to aquatic organisms or human drinking water supplies. Pioglitazone does not pose a risk of secondary poisoning. 相似文献
Introduction: Driving under the influence (DUI) citations are still a serious concern among drivers aged 16–20 years and have been shown to be related to increased risk of fatal and nonfatal crashes. A battery of laws and policies has been enacted to address this concern. Though numerous studies have evaluated these policies, there is still a need for comprehensive policy evaluations that take into account a variety of contextual factors. Previous effort by this research team examined the impact of 20 minimum legal drinking age–21 laws in the state of California, as they impacted alcohol-related crash rates among drivers under 21 years of age while at the same time accounting for alcohol and gas taxes, unemployment rates, sex distribution among drivers, and sobriety checkpoints. The current research seeks to expand this evaluation to the county level (San Diego County). More specifically, we evaluate the impact of measures subject to county control such as retail beverage service (RBS) laws and social host (SH) laws, as well as media coverage, city employment, alcohol outlet density, number of sworn officers, alcohol consumption, and taxation policies, to determine the most effective point of intervention for communities seeking to reduce underage DUI citations.
Methods: Annual DUI citation data (2000 to 2013), RBS and SH policies, and city-wide demographic, economic, and environmental information were collected and applied to each of the 20 cities in San Diego County, California. A structural equation model was fit to estimate the relative contribution of the variables of interest to DUI citation rates.
Results: Alcohol consumption and alcohol outlet density both demonstrated a significant increase in DUI rates, whereas RBS laws, SH laws, alcohol tax rates, media clusters, gas tax rates, and unemployment rates demonstrated significant decreases in DUI rates.
Conclusions: At the county level, although RBS laws, SH laws, and media efforts were found to contribute to a significant reduction in DUI rates, the largest significant contributors to reducing DUI rates were alcohol and gas taxation rates. Policy makers interested in reducing DUI rates among teenagers should examine these variables within their specific communities and consider conducting community-specific research to determine the best way to do so. Future efforts should be made to develop models that represent specific communities who are interested in reducing DUI rates among drivers aged 16–20 years. 相似文献
Abstract: Total Maximum Daily Load (TMDL) implementation generates benefits and costs from water quality improvements, which are rarely quantified. This analysis examines a TMDL written to address bacteria and aquatic‐life‐use impairments on Abrams and Opequon Creeks in Virginia. Benefits were estimated using a contingent valuation survey of local residents. Costs were based on the number and type of best management practices (BMPs) necessary to achieve TMDL pollution reduction goals. BMPs were quantified using watershed‐scale water quality simulation models (Generalized Watershed Loading Function and Hydrological Simulation Program‐FORTRAN). Based on our projections, the costs to achieve TMDL induced pollution reduction goals outweigh the estimated benefits. Benefit‐cost ratios ranged between 0.1 and 0.3. 相似文献
Putrajaya Wetlands in Malaysia, a 200ha constructed wetland system consisting of 24 cells, was created in 1997-1998 to treat surface runoff caused by development and agricultural activities from an upstream catchment before entering Putrajaya Lake (400ha). It was designed for stormwater treatment, flood control and amenity use. The water quality improvement performance of a section of the wetland cells is described. The nutrient removal performance was 82.11% for total nitrogen, 70.73% for nitrate-nitrogen and 84.32% for phosphate, respectively, along six wetland cells from Upper North UN6 to UN1 from April to December 2004. Nutrient removal in pilot scale tank systems, simulating a constructed wetland and planted with examples of common species at Putrajaya, the Common Reed Phragmites karka and Tube Sedge Lepironia articulata, and the capacity of these species to retain nutrients in above and below-ground plant biomass and substrate is reported. The uptake of nutrients by the Common Reed and Tube Sedge from the pilot tank system was 42.1% TKN; 28.9% P and 17.4% TKN; 26.1% P, respectively. The nutrient uptake efficiency of the Common Reed was higher in above-ground than in below-ground tissue. The results have implications for plant species selection in the design of constructed wetlands in Malaysia and for optimizing the performance of these systems. 相似文献
Due to environmental concerns and regulatory initiatives, electronics manufacturers are replacing the tin/lead solder commonly used on printed wire boards (PWBs) with alternative solders. To determine the potential waste management impacts of the alternative solders versus the tin/lead solder, two leaching tests on PWBs manufactured with five alternative types of solder were performed: the toxicity characteristic leaching procedure (TCLP) and the synthetic precipitation leaching procedure (SPLP). These tests are commonly used in the US regulatory community to assess pollutant leachability in different disposal scenarios. The article discusses the application and limitations of these tests. The five types of solders investigated were 63Sn/37Pb, 99.3Sn/0.7Cu, 95.5Sn/4Ag/0.5 Cu, 96Sn/2.5Ag/1Bi/0.5Cu, and 42Sn/1Ag/57Bi. The leaching tests were conducted on four PWB sections, each with a unique configuration and solder density. The largest lead concentrations were observed from the PWBs containing Sn/Pb solder, with concentrations exceeding the hazardous waste toxicity characteristic (TC) in TCLP leachates. Silver, the other regulated element used in the solders, was rarely detected, with none of the samples exceeding the TC limit for silver. High copper concentrations were observed and were determined to result from the PWB itself, not from the copper-containing solders. 相似文献
A jet resonance-enhanced multiphoton ionization (REMPI) monitor was tested on a hazardous-waste-fired boiler for its ability
to determine concentrations of polychlorinated dibenzodioxins and dibenzofurans (PCDDs/Fs). Jet REMPI is a real-time instrument
capable of highly selective and sensitive (from parts per billion to parts per trillion) detection of a broad range of aromatic
compounds, including a number of air toxic compounds. The PCDD/F toxic equivalency (TEQ) value was derived from a predetermined
correlation (R2 = 0.74) with monochlorobenzene (MClBz). This relationship was applied to nine subsequent jet REMPI on-line measurements of
MClBz and parallel, standard extractive sampling for PCDD/F TEQ. For high waste-firing rates, with a range of PCDD/F TEQ values
between 3.9 and 6.0 ng TEQ/m3, the TEQ values predicted by jet REMPI had a relative difference of 26% with the standard EPA Method 23 results. At low waste-firing
rates (0.9–1.6 ng TEQ/m3), the relative difference increased to 219%. This limited testing shows that jet REMPI has promise as an on-line diagnostic
monitor, providing feedback on the effects on PCDD/F emissions of operating parameter changes such as fuel feed interruptions
or air pollution control failures. 相似文献
We connected a cellular, dynamic, spatial urban growth model and a semi-distributed continuous hydrology model to quantitatively predict streamflow in response to possible future urban growth at a basin scale. The main goal was to demonstrate the utility of the approach for informing public planning policy and investment choices. The Hydrological Simulation Program-Fortran (HSPF) was set up and calibrated for the Kishwaukee River basin in the Midwestern USA and was repeatedly run with various land use scenarios generated either by the urban growth model (LEAMluc) or hypothetically. The results indicate that (1) the land use scenarios generated by LEAMluc result in little changes in total runoff but some noticeable changes in surface flow; (2) the argument that low flows tend to decrease with more urbanized areas in a basin was confirmed in this study but the selection of indicators for low flows can result in misleading conclusions; (3) dynamic simulation modeling by connecting a distributed land use change model and a semi-distributed hydrological model can be a good decision support tool demanding reasonable amount of efforts and capable of long-term scenario-based assessments. 相似文献