M. R. Midgett

Evaluation of canisters for measuring emissions of volatile organic air pollutants from hazardous waste incineration

Regulation to control air emissions of toxic organic compounds require the collection and analysis of effluent gas from low level sources such as hazardous waste incinerators. The standard SW-846 Method specifies the use of Tenax and Tenax/charcoal adsorbent traps for collection of volatile organics from incinerators. This study evaluates passivated stainless steel canisters as an alternative to adsorbent traps to eliminate some of the problems associated with adsorbent sampling. Initially the stability of 18 nonpolar, volatile organic compounds was determined in Summa-treated stainless steel canisters with greater than 100 ppmv HCl and saturated with water vapor. All 18 components were stable for a two-week period; however, an interference caused a 10-fold increase in the FID response of trichloroethylene, toluene, and chlorobenzene. No interference of the ECD response was found for any of the 11 compounds detected with the ECD including trichloroethylene. A pilot scale incinerator was sampled using canisters, and the destruction efficiency of 1,1,1-trichloroethane was determined at a concentration of less than 0.5 ppbv while determining 1,1-dichloroethylene, the major product of incomplete combustion, at a concentration of 8000 ppbv from the same sample.

A tedlar bag sampling system for toxic organic compounds in source emission sampling and analysis

The Atmospheric Research and Exposure Assessment Laboratory (AREAL) of the US Environmental Protection Agency at Research Triangle Park, North Carolina, has studied the Tedlar bag for the applicability of this material in sampling different organic compounds and has designed a Tedlar Bag Sampling System which reduces the sampling rate from 1-1.5 L/min to 50 mL/min to make the sample volume more manageable. This new, smaller version of the original Tedlar bag sampling system was designed to meet the following criteria: It must hold a negative pressure of 10 in. of water to extract emission air samples from a negative-pressure stack; The bag must be visible so that the operator can see it inflate during sampling; It must be small enough to be easily handled; and It must not show any bias compared to the standard sampling system which collects the samples at a much higher rate. This system was designed at AREAL and tested in the field side by side with the conventional large bag sampling system for possible bias of the small bag in sampling.

Chromium analysis at a ferrochrome smelter, a chemical plant and a refractory brick plant

Techniques were developed to sample and analyze the Cr content of particulate samples with emphasis on determining the concentration of the carcinogen Cr/sup +6/. Cr/sup +6/ is extracted to alkaline solution and analyzed colorimetrically. Residual particles are extracted with acid solution to remove soluble Cr/sup +3/, which is determined by atomic absorption spectrometry. This methodology was tested on samples from three diverse types of sources: a ferrochrome smelter, a chemical plant, and a refractory brick plant. Identical quadruplicate samples were collected to determine accuracy and precision of the collection and analysis procedures, and extraction of Cr/sup +6/ and Cr/sup +3/. A statistical analysis revealed that the precision of Cr/sup +6/ analysis is comparable to that of the particulate mass determination. The stability of Cr/sup +6/ in particulate form and in solution was determined. Size resolved particulate samples were collected to determine the particle size versus the Cr/sup +6/ content. At the ferrochrome smelter and the chemical plant the majority of the Cr/sup +6/ was contained in the respirable particles. The accuracy and completeness of the chemical methods employed were verified by neutron activation analysis, x-ray photoelectron spectroscopy, and scanning electron microscopy-energy dispersive x-ray analysis.

A new audit method for EPA reference method 6

A simple, inexpensive, and accurate method for evaluating and/or auditing sampling and analytical phases of the EPA Source Reference Method 6 was developed. The method uses a known amount of a chemical compound in the form of a tablet or pill (or placed in a capsule) to generate sulfur dioxide quantitatively by reaction with an acid. The reaction takes place in a compact glass impinger system that can be taken to the field. The S02 generated in test runs was collected and analyzed using the Method 6 procedure. The SO2 generation was quantitative and recoveries were found to be 94 ± 5 %. The time to complete the reaction was less than 15 min at a flow rate of 1 L/min, but the recommended sampling time was 45 min. The tablets prepared gravimetrically were found to be stable over a sixmonth period. The interlaboratory results obtained showed close agreement with the expected concentrations based on calculations from the stoichiometric reaction. The estimates of repeatability (or within-laboratory precision) ...

An Assessment of the Long-Term Performance of Gas Continuous Emission Monitoring Systems

A field test program was conducted to evaluate the long-term performance of several gas continuous emission monitoring systems (CEMS).* This paper presents the results gathered on the long-term accuracy and calibration drift characteristics of ten CEMS installed at scrubber-controlled, coal-fired power plants. The program involved periodic accuracy audits and a review of available calibration drift data for selected CEMS. Accuracy audit results show that both SO2 and NOx CEMS are capable of providing accurate data on a long-term basis. However, frequent audits are necessary in order to verify the performance of an individual CEMS. The results of the calibration drift data evaluation show that despite infrequent occurrences of excessive drift, CEMS operated with a significant bias for extended time periods simply because corrective action was not taken in a timely manner.

Validation of an Audit Material for EPA Method 6B

A simple audit material for EPA Method 6B was developed in a compressed gas cylinder and validated at three different laboratories. The audit mixture of CO2 (10 percent) and SO2 (250 ppm) in a balance gas of nitrogen prepared in aluminum cylinders was found to be stable over a 1-year period. The interlaboratory results obtained for the audit mixture using EPA Method 6B procedures showed reasonable agreement (SO2 and CO2 are within 7.5 percent and 5.3 percent, respectively) with EPA-measured concentrations except in one case, which was probably due to some contamination in the laboratory. A second audit material which uses chemical reactions to generate SO2 and CO2 was also developed. However, this approach was discontinued because it was difficult to simultaneously generate ppm levels of SO2 and percent levels of CO2 by chemical reactions in the field.

A New Audit Technique for EPA Method 25

A simple, inexpensive, and accurate technique for evaluating or auditing the sampling, recovery, and analytical phases of EPA Source Reference Method 25 has been developed. The technique involves spiking a U-shaped stainless steel cartridge containing Tenax® with known quantities of selected organic compounds and thermally desorbing them at temperatures from 160°C to 180°C to generate organic vapors quantitatively. The major advantages of this technique are that no other measurement methods can be used to determine the generated organic concentrations in lieu of Method 25; and that the cartridge can easily be taken to the field for evaluation. The organic compounds generated in test runs are collected and analyzed using the Method 25 procedure. The generation of organics is quantitative and recoveries were found to be 100 ± 10%. The time required for desorption of the majority of organics is generally less than forty-five minutes at a flow rate of 100 mL/min; however, based on laboratory experience the re...

Field validation of EPA proposed method 108 for measurement of inorganic arsenic emissions from stationary sources

The U.S. Environmental Protection Agency’s proposed Method 108 for measurement of inorganic arsenic emissions from stationary sources has been evaluated both in the laboratory and in the field. Field studies, which are the focus of this paper, Included determination of the precision of the sampling method using concurrent dual or quad sampling trains in the measurement of inorganic arsenic emissions from a copper smelter plant and a glass manufacturing plant. Results of the field tests indicate that the precision was 3.85 % at the glass plant and 15.7% at the copper smelter. Considering the sampling sites and the variability of process operations, these results Indicate an acceptable degree of precision.

EPA Reference Method 25 - laboratory evaluation and field testing

EPA Reference Method 25 for measurement of total gaseous nonmethane organics as carbon in source emissions was evaluated in the laboratory and through field testing. Laboratory evaluation included development and testing of a nonmethane organic analyzer. In addition, a series of tests was performed on the condensate trap recovery system. The tests involved evaluation of two different condensate trap recovery system designs. The first design was very similar to the Federal Register design and the second design was a modified system for minimizing interference from trapped carbon dioxide. Field testing of the method was performed at two different printing plants. Both plants used carbon bed adsorption for solvent recovery and control of VOC emissions. Samples were collected from the inlet and outlet streams of adsorption units at both plants. In addition to Method 25 samples, Method 18 samples were collected for analysis by gas chromatography with flame ionization detection. The results of all the laboratory and field test samples are described.

A Manual Method for Measurement of Reduced Sulfur Compounds

A manual method for measuring reduced sulfur compounds in kraft pulp mill and sulfur recovery plant emissions was evaluated. The method involves removing SO/sub 2/ from the gas stream (if present) with a citric acid-potassium citrate buffer that passes reduced sulfur compounds; thermal oxidation of all reduced sulfur compounds to SO/sub 2/; collection of the SO/sub 2/ in H/sub 2/O/sub 2/; and a titrimetric analysis of the H/sub 2/O/sub 2/ for SO/sub 4//sup 2 -/. A heated filter removes alkaline particulate matter that would produce a negative interference if absorbed by the buffer. When used at kraft pulp mills, the method agrees closely with Reference Method 16, provided that nonregulated reduced sulfur compounds, such as carbonyl sulfide, are not present in the emissions. At sulfur recovery plants, nonregulated reduced sulfur compounds, such as thiophene, are likely to be present in the emissions and will produce a positive bias in the results obtained with this method. The precision of the method ranges from 1 to 7% relative standard deviation.