Demonstration of a high field electrostatically enhanced venturi scrubber on a magnesium furnace fume emission

A 566 m³/m (20,000 acfm) permanent installation demonstration system, consisting of the Air Pollution Systems' High Intensity Ionizer and a variable throat venturi scrubber (called the Scrub-E) has been installed on a magnesium recovery furnace. The furnace produces submicron fume particles of MgO, MgCl₂, and ZrCl₄. The system is designed to demonstrate the effectiveness of the High Intensity Ionizer versus high venturi pressure drop on the furnace emissions. The High Intensity Ionizer array operates stably at field strengths of 10–15 kV/cm and at velocities in excess of 18 m/sec (60 fps) while maintaining high charging efficiencies. The report covers the system design, technology, applications, and project developments. An Environmental Protection Agency proposed charged droplet Scrub-E is also discussed covering the design, technology, and proposed demonstration program.     

Application of slipstreamed air pollution control devices on waste-as-fuel processes

The recovery of energy from the combustion of municipal solid wastes is becoming an attractive alternative as landfill space becomes scarce and the availability of fossil fuels decreases. Particulate emissions from “waste-as-fuel” processes, however, may differ significantly in chemical and physical properties from particulate emissions produced by firing only coal. Such differences can affect the design and operation of air pollution control equipment. Presented in this paper are the results of a 2-month test program at Ames, Iowa, with a mobile electrostatic precipitator (ESP) and a mobile scrubber supplied by the U.S. Environmental Protection Agency (EPA), Industrial Environmental Research Laboratory (IERL), Research Triangle Park. PEDCo Environmental, Inc., and Acurex Corporation jointly conducted the test program to examine the effect of burning refuse-derived fuel (RDF) on particulate and heavy metal control efficiencies. The mobile ESP was used only as a primary control device, whereas the mobile scrubber was tested both upstream and downstream of the existing full-scale ESP. This paper also presents a status report on a PEDCo test program with a pilot fabric filter at Ames.     

High velocity fabric filtration for control of coal-fired boilers

As a follow-up to a pilot study, a full scale investigation of applying high velocity fabric filtration to coal-fired boiler fly ash control was conducted. Two filter systems were separately applied to two 60,000 lb/h coal-fired boilers. Performance evaluations conducted over the course of a year included total mass removal efficiency and fractional efficiencies. One filtration system employed Teflon felt as the filter media while the second system employed Gore-Tex, a Polytetrofluorethylene (PTFE) laminate on PTFE woven backing. During the course of the year, a limited number of glass felt and woven glass bags were introduced into the house containing Gore-Tex. As a separate option, the second system was outfitted entirely with woven glass bags. Preliminary results indicate acceptable performance at air-to-cloth ratio of 6 to 1. Future plans call for utilizing one of the baghouse systems for SO₂ removal.     

Mutagenic and carcinogenic potency of extracts of diesel and related environmental emissions: Study design, sample generation, collection, and preparation

A major diesel emissions research program has been initiated by the U.S. Environmental Protection Agency to assess the human health risk associated with increased use of diesel automobiles. This program is intended to establish the mutagenic and carcinogenic potency of complex organics associated with diesel particles as well as comparative particle-bound organics from other environmental emissions for which human epidemiological data are available. The mobile source samples selected for this study were collected from a heavy-duty diesel engine, a series of light-duty diesel passenger cars, and a gasoline catalyst automobile. The comparative source samples incorporated into the study were cigarette smoke condensate, coke oven emissions, roofing tar emissions, and benzo(a)pyrene. The samples were tested using three mutagenic assays and four carcinogenic assays as prescribed by a test matrix. This report describes the study design, particle generation, and sample collection and preparation. A brief summary of the bioassays is also included.     

Mutagenic and carcinogenic potency of extracts from diesel related environmental emissions: Simultaneous morphological transformation and mutagenesis in BALB/c 3t3 cells

Particulate extracts from six different environmental emission sources were assayed for genotoxic activity in mouse BALB/c 3T3 clone A31-1 cells. All compounds were tested simultaneously for both transforming and mutagenic (induction of ouabain-resistance) potential with and without exogenous metabolic activation in the form of a 9000 × g postmitochondrial hepatic supernatant fraction from Aroclor-1254 induced Fischer 344 rats. Dichloromethane particulate extracts from the exhaust of two light duty diesel engines (Oldsmobile and Nissan), one heavy duty diesel engine (Caterpillar) and one late model gasoline engine (Mustang II) were assayed in an identical manner to particulate extracts from the emissions of a roofing tar pot and a coke oven. No clear dose-dependent responses were observed, but several of the samples showed significant transforming and mutagenic activity. A qualitative ranking system showed the activity of these particulate extracts for either mutagenesis or transformation was: coke oven = Mustang II gasoline engine > Nissan diesel engine > roofing tar. Particulate extracts from the Oldsmobile diesel engine and the Caterpillar diesel engine showed essentially no activity.     

An elemental rationing technique for assessing concentration data from a complex water system

Water samples have been collected at the surface and bottom layers at 51 locations throughout Chesapeake Bay. The suspended particulate and dissolved fractions of these samples have been analyzed for Cd, Ce, Co, Cu, Fe, Mn, Mo, Ni, Pb, Sc, Sn, Th, U, and Zn using neutron activation analysis and atomic absorption spectrometry. Special chemical procedures were used to preconcentrate the elements of interest in the dissolved samples and separate them from the salt water matrix. The elemental concentrations observed in the dissolved samples were evaluated by direct comparison to those found in coastal seawater; however, the elemental concentrations in the particulate samples (mass per volume of water) were strongly influenced by the total amount of particulate material suspended in the water at time of collection. A double normalization procedure was used to calculate crustal enrichment factors for each sample, and these enrichment factors provided both a means to observe sample-to-sample variations, and also allowed a crude comparison with the natural levels occurring in the earth's crust.     

Fertility and air pollution: Some empirical findings

This paper attempts to explain regional differences in fertility rates in the standard metropolitan statistical areas of the United States through socioeconomic factors and air pollution. An important feature of this study is that it uses the most recent data pertaining to a homogeneous sample of observations within a country rather than using data for different countries. Statistical results suggest that given other factors, fertility and the level of air pollution have an inverse relationship. This quantitative effect is statistically significant but the absolute impact is rather low. Our results also suggest that an increase in the level of income, relative education of females, temperature, and the availability of physicians would in the long run reduce fertility rates in the urban areas of the United States.     

Health effects of oxidants

Oxidants of significance to human health include ozone, nitrogen dioxide, and peroxyacetylnitrate. All of these compounds are involved in complex photochemical reactions which makes quantification and prediction of their individual health effects difficult. Ozone causes trauma to lung tissues and interferes with enzyme systems in the lungs and other tissues causing a broad range of symptoms. Measurable health impacts can occur at concentrations as low as 390 μg/m³. Acute effects of ozone exposure are reversible at normal urban concentrations (80–120 μg/m³). A special problem of concern, however, is increased susceptibility to infectious diseases contracted through the lungs. Nitrogen dioxide also causes trauma to lung tissues and interferes with enzyme systems. Measurable impacts can occur at concentrations as low as 100 μg/m³, but recovery is rapid and it is not known whether repeated exposures at this level have cumulative effects or predispose the lungs to permanent damage. Chronic exposure of laboratory animals to higher nitrogen dioxide levels can cause emphysema-like conditions and reduction in resistance to respiratory infection. Epidemiological studies of children in houses with gas stoves confirm the finding of reduced resistance to respiratory infection. The U.S. EPA estimates that health effects may occur in young children exposed to concentrations in excess of 280 to 560 μg/m³ one-hour average. These concentrations occur routinely in houses having gas stoves. Peroxyacetylnitrate is a powerful eye irritant in photochemical smog. Other health effects are similar to those of ozone, but less important because of the relatively low concentrations of this pollutant compared to other oxidants.     

An appraisal of emissions control requirements in the California South Coast Air Basin

The purpose of this study is to evaluate the effect of reductions of reactive organic gases (ROG) and NO_x emissions on short-term O₃ and NO₂ concentrations and annual average NO₂ concentrations in the California South Coast Air Basin. Short-term air quality predictions were obtained by applying the Systems Applications Airshed Model to summer O₃ and autumn NO₂ episodes. Effects of emission controls on annual NO₂ concentrations were estimated using CDM and a new parcel tracking model NOXTRAK. Results for the summer O₃ episode indicate that ROG emission reduction in an effective means for reducing peak O₃ concentrations. NO_x emission reduction imposed in addition to ROG emission reductions are counterproductive in reducing peak O₃ concentrations. The modeling results also suggest that attainment of the 1-h federal O₃ standard requires ROG emission reductions on the order of 80% from 1987 levels. Results for the autumn NO₂ episode indicate that NO_x emission reductions approximating those recommended in a proposed Air Quality Management Plan (about 22%) will result in only small (about 5%) reductions in the peak NO₂ concentrations. ROG emission reduction may be more effective than NO_x emission reduction in reducing the peak NO₂ concentration. For the episode studied, a reduction of 36% in ROG emissions is estimated to result in a reduction in peak NO₂ concentrations commensurate with that required to attain the 1-h state NO₂ standard. Model calculations also indicate that the federal NO₂ standard may not be meet by 1987 at one or two stations, but may blosely approached.     

Trends in environmental education for biodiversity conservation in Costa Rica

Costa Rica is internationally recognized for its abundant biodiversity and being a leader in the promotion of education strategies for biodiversity conservation. We interviewed staff from 16 institutions developing key environmental communication, education, and participation projects for biodiversity conservation in the country. Through content analysis, hierarchical cluster analysis and Chi-square tests, we examined the characteristics of the projects carried out by these institutions and developed a typology of four categories derived from six variables: primary audience, content, project purpose, location, scale, and facility. Then, we designed a conceptual model describing the integration of conservation and economic development in the educational projects. We found two key approaches related to this integration: vision of nature protection which aims to inform audiences of ecological concepts and focuses on schoolchildren and vision of sustainability which engages adult audiences and is management-oriented. Education for community-based environmental management may serve as a good example of educational projects which integrate conservation and economic development, implementing a vision of sustainability.