Field Reliability of the Orsat Analyzer

Results from four field based collaborative tests and from one laboratory based collaborative test of the Orsat analytical procedure are discussed. The results from the five collaborative tests demonstrate that routinely using Orsat data to convert particulate emissions from combustion sources to the reference conditions of 50 % excess air and 12% carbon dioxide may introduce sizeable errors in the corrected particulate loading. Ways to improve the Orsat apparatus and increase the reliability of the data are suggested.

Also reported are the results from field and laboratory studies on the reliability of using individual carbon dioxide and oxygen analyzers of the Fyrite* type to determine stack gas molecular weight. The laboratory study, which was done using three cylinders containing mixtures of carbon dioxide, oxygen, carbon monoxide, and nitrogen of known concentration, determined that these analyzers give carbon dioxide and oxygen analyses of sufficient reliability to yield accurate molecular weights. The results of the field studies, which were done on actual flue gas samples, also support this conclusion.     

Ambient Ozone Concentration Patterns among Eastern U.S. Urban Areas Using Factor Analysis

Data on dally maximum ozone concentrations measured at ambient air monitoring stations operated by state and local air pollution control agencies in the Eastern United States were analyzed using principal factor analysis. Four orthogonal factors representing O₃ formation potentials were derived using the statistical package SPSS; these factors accounted for over two-thirds of the variations in 1978 summer O₃ levels at 21 urban-oriented stations. The analysis confirmed that O₃ variations are similar among stations within defined geographical areas; this confirmation supports the widely held theory that ambient O₃ formations are reglonwlde. The analysis suggested that trends analysis for determining general progress in improving O₃ air quality should be based on aggregate statistics from clusters of monitors rather than from a single monitoring station within areas associated with the derived factors.     

Revised Air Quality Surveillance Requirements for State Implementation Plans

The National Ambient Air Quality Monitoring Program is carried out by state and local air pollution control agencies in support of their State Implementation Plans (SIP’s). The current EPA regulations which specify the characteristics of these state monitoring programs are undergoing change as a result of a comprehensive review by an independent work group. These revised regulations, which are described in the paper, are intended to improve the quality, timeliness, and usability of the data generated by the states for all data users. In addition, the revised regulations seek to bring about; (a) national consistency in monitoring site locations through standardized siting procedures; (b) improved network operations by means of a minimum quality assurance program; (c) reduced network inflexibility through an annual network review process; and (d) reduced data reporting through changed data reporting procedures.     

Statistical Comparisons between Teleradiometer-Derived and Slide-Derived Visibility Parameters

An automated scanning densitometer system developed to estimate visibility-related parameters from photographic slides was tested in comparison to similar teleradiometric measurements. Parameters such as target-sky contrast, visual range, atmospheric light extinction coefficient, and plume and layered contrast can be estimated using this system; however, only target-sky radiance ratios and standard visual ranges were compared. More than 1600 concurrent densitometer and teleradiometer data pairs from eight National Park Service air quality and visibility monitoring locations in the western United States were analyzed using the techniques of correlation, linear regression, average bias and difference calculation, and cumulative frequency distribution generation. Correlation coefficients were good, especially with middle-range camera vistas around 50 km distant. Regression slopes approached unity with intercepts near zero. Average bias introduced into the determination of radiance ratios from slides ranged from near zero to 6 percent, depending on target distance. Standard visual range data distributions compared favorably at the low end with some minor differences at the high end.     

Soil Bed System for Control of Rendering Plant Odors

Biofilter technology has been applied recently to treating rendering odors. Soil beds are one class of biofilter but as yet have not been used for this application. Although wet scrubbers have been a traditional method of odor control, their capital and operating costs are impacting more severely. Soil bed systems are less expensive to install and operate.

A soil bed system was installed at a rendering plant in Arizona and has been in operation since September 1983. The soil bed treats 1100 m³/h (650 cfm) of cooker noncondensables with a surface area of 420 m²(4500 ft²). The pressure drop across the soil bed is 5 cm (2 in.) of water. Odor sensory testing with the MTRI forced-choice triangle dynamic olfactometer indicates an odor removal efficiency of 99.9 percent is obtained with the soil bed. Soil bed odor removal efficiency is equivalent to or superior than that for incineration or scrubbing of high intensity odors from the rendering process. Recent experience during this past winter indicates a soil bed is a viable method for operation in a northern climate with severe winter weather conditions. Also, monitoring of the leachate from a soil bed indicated no contamination.     

Performance Characterization and Optimization of the AgNO3-Filter/FMA Fluorimetric Method for Atmospheric H2S Measurements

This sensitive, albeit precarious, method for measuring ppb-ppt (V/V) concentrations of H₂S was examined for various sources of potential error within the procedure. Filter preparation, filter storage, filter extraction, fluorimetric reagent stabilities, matrix differences between standards and samples, and possible interferences from other sulfur-containing compounds were separately studied for their effects on the analytical performance of the method. The overall method showed no Interference from SO₂, CS₂, COS, CH₃SH, CH₃SCH₃, and SO₄ ^-2. To minimize bias and obtain a reliable estimate of precision, the method should be calibrated with H₂S standards rather than liquid bisulfide standards. The measurement precision is a function of the quantity of H₂S collected as Ag₂S and/or AgSH on the impregnated filters. Because of the method’s linear dynamic range, sufficient air should be sampled to achieve filter loadings of 15 to 35 ng S/filter. A quality control method based on fluorescein mercuric acetate (FMA) is presented that ensures data quality while reducing the otherwise frequent need for fluori-metric calibration.     

Sizing and Costing of fabric Filters Part II: Costing Considerations

This is the second of a two-part article that reviews baghouse filtration theory, presents size estimating methods, and gives costing procedures for a variety of baghouse types and sizes. Part I of the article discussed theory and sizing; this part presents costing. Information is given for estimating total capital investment including separate costs for the bare baghouse (five types), bags, and, where needed, cages and Venturis. Factors are given for installation and for indirect costs. Direct and indirect annual costs are discussed. An example problem is given. The material in this article is taken primarily from the EAB Control Cost Manual.