Fine Paniculate Removal and S02 Absorption with a Two Stage Wet Scrubber

This paper includes results from pilot plant studies and early field demonstration units and a discussion of the application of the limestone wet scrubbing process to a low sulfur syb-butuminous coal. This latter application required the development of a hybrid two stage scrubber to enable collection of the fine particulate matter as well as removal of a significant amount of the sulfur dioxide.     

Microwave Process for Volatile Organic Compound Abatement

ABSTRACT

The CHA Corporation has completed the U.S. Air Force Phase II Small Business Innovation Research program to investigate the feasibility of using a novel microwave-based process for the removal and destruction of volatile organic compounds (VOCs) in effluents from noncombustion sources, such as paint booth ventilation streams. Removal of solvents by adsorption, followed by the regeneration of saturated granular activated carbon (GAC) by microwave energy, was achieved in a single fixed-bed reactor. Microwave regeneration of the fixed-bed-saturated carbon restored the original GAC adsorption capacity. After 20 adsorption/regeneration cycles, the adsorption capacity dropped from 13.5 g methyl ethyl ketone (MEK)/100 g GAC to 12.5 g MEK/100 g GAC. During microwave regeneration of the GAC fixed bed, the concentrated desorbed paint solvent was oxidized by passing the solvent mixture through a fixed bed of an oxidation catalyst mixed with silicon carbide in a microwave reactor. A 98% oxidation efficiency was consistently achieved from the oxidation of VOCs in the microwave catalytic reactor.     

Continuous Monitoring of FGD Wet Scrubber Corrosion

This article describes an electrochemical corrosion monitoring system developed in England that offers utilities the capability of continuously measuring power plant corrosion activity for a wide range of operating conditions.     

Assessment of Control Strategies for Reducing Volatile Organic Compound Emissions from the Polyvinyl Chloride Wallpaper Production Industry in Taiwan

Abstract

This study attempts to assess the effectiveness of control strategies for reducing volatile organic compound (VOC) emission from the polyvinyl chloride (PVC) wallpaper production industry. In Taiwan, methyl ethyl ketone, TOL, and cyclohexanone have comprised the major content of solvents, accounting for ～113,000 t/yr to avoid excessive viscosity of plasticizer dioctyl phthalate (DOP) and to increase facility in working. Emissions of these VOCs from solvents have caused serious odor and worse air quality problems. In this study, 80 stacks in five factories were tested to evaluate emission characteristics at each VOC source. After examining the VOC concentrations in the flue gases and contents, the VOC emission rate before treatment and from fugitive sources was 93,000 and 800 t/yr, respectively. In this study, the semiwet electrostatic precipitator is recommended for use as cost-effective control equipment.     

Incineration Techniques for Control of Volatile Organic Compound Emissions

A review of incineration techniques for control of volatile organic compound emissions is presented in two consecutive issues o/JAPCA. Part I presented an overview of the process including fundamentals and design considerations. Both thermal and catalytic incinerators were considered. Part IIpresents capital and annual operating cost estimates for both thermal and catalytic incinerator systems based on information received from a number of equipment manufacturers.     

Determination of Source Contributions to Ambient Volatile Organic Compound Concentrations in Berlin

ABSTRACT

During three measuring campaigns in June, July, and August 1996, volatile organic compound (VOC) concentrations were measured at a rural background site, a city residential site, and a street site in Berlin. In addition, samples were taken near relevant sources of VOCs. The meaurements covered the volatile hydrocarbons in the range C₁-C₁₄ and included aldehydes and ketones. Samples were taken at four characteristic periods of 2 hr/day: during the night, during the early morning rush hour, at midday, and during the evening rush hour. An assessment of the contribution of emission categories to the observed concentrations was made with the chemical mass balance (CMB) modelling technique.

The VOC concentrations at the residential area and at the street site in the inner city were, respectively, a factor of 3 and 7 above the background concentration. Traffic exhaust contributed approximately 80-90% of the non-methane hydrocarbon (NMHC) concentration in the inner city and approximately 60% at the background area. Evaporative losses of motor fuel are estimated to account for approximately 7% at all sites. Natural gas leakage also contributed significantly to the observed VOC concentrations: in the inner city approximately 510% and at the background area approximately 30%. The measurements also showed a contribution of smaller sources, such as dry cleaning, use of solvents, and bio-genic emissions. However, the contribution of these sources to the total observed concentrations at the sites is estimated to be very small.     

Economic Study of the Tunable Electron Beam Plasma Reactor for Volatile Organic Compound Treatment

ABSTRACT

A tunable electron beam generated plasma system has been developed for selective cold plasma treatment of dilute concentrations (1-3,000 ppm range) of hazardous compounds in gaseous waste treatment. This system, referred to as the Tunable Hybrid Plasma (THP), has shown a high degree of efficiency and effectiveness in both laboratory and field tests. Decomposition energy requirements are in the 100 eV per molecule range for treatment of carbon tetrachloride and 10 eV for treatment of trichloroethylene.

A cost comparison has been made between the Tunable Hybrid Plasma (THP) technology and three conventional technologies used for emission control of volatile organic compounds (VOCs): granular activated carbon, thermal incineration, and catalytic oxidation. In addition to its environmentally attractive features, THP technology has the potential to be lower cost than other technologies over a range of concentrations and flow rates. Cost projections for the THP system for decomposition of trichloroet-hylene are around 50 cents/lb for initial concentrations in the few hundred ppm range and flow rates of 5,000 cfm or greater and around $1/lb for 1,000 cfm flow rates. Cost projections for carbon tetrachloride and trichloroethane decomposition using the THP technology are several dollars per pound. The costs for THP treatment are generally significantly lower than costs for use of granular activated carbon and are also quite competitive with costs for thermal incineration and catalytic oxidation.     

Inter-Urban Comparison of Ambient Volatile Organic Compound Concentrations in U.S. Cities

Airborne particulate matter from three ferrous foundries was sampled in granulometric fractions and analyzed by scanning electron microscopy with energy dispersive X-ray analysis (SEM-EDXA), X-ray photoelectron spectroscopy (XPS) and secondary ion mass spectrometry (SIMS) to determine morphology and qualitative bulk and surface chemical compositions. Cluster and principal components analyses (PCA) were used as an aid for interpretation of results. A clear pattern of composition as a function of size emerges; in particular, trace metals accumulate in fine particles and volatile species on the surface of these. Chemical composition changes are also related to daily schedules where applicable: trace metals appear during pouring operations, silicon is generated during mold making and unmolding. Cluster and PCA greatly ease examination of data and offer pictorial representations of results; in particular, the chemical composition versus particle size relationship is very neatly illustrated by PCA graphs.     

Pilot Study of Enclosed Thermal Soil Aeration for Removal of Volatile Organic Contamination

During the winter and spring of 1986 sandy soils contaminated with volatile organic chemicals were successfully treated during a pilot study of an enclosed thermal soil aeration process at the McKin Superfund site in Gray, Maine. Excavated soil containing up to 3310 ppm of trichloroethylene (TCE) was fed into a large rotating drum and mixed at 300°F. Aerated soil was then solidified with cement and water and returned to the on-site excavation location. Exhausted air from the enclosed aeration process was treated in a baghouse, a scrubber, and a vapor phase carbon bed prior to atmospheric release. Continuous air monitoring for organic vapors and particulates took place at the site perimeter and for organic vapors at onsite locations. Techniques to minimize uncontrolled volatilization of organic chemicals from the soil during excavation and aeration and to control dust emissions were implemented. Results of this pilot study indicate that concentrations of volatile organic contaminants routinely were reduced to nondetectable levels and achieved site-specific soil performance targets established by the U.S. Environmental Protection Agency. The pilot study was conducted by Canonie Environmental Services Corporation and funded by private companies under order from EPA.     

The Missoula Valley Semivolatile and Volatile Organic Compound Study: Seasonal Average Concentrations

Abstract

The city of Missoula is located in a high mountain valley (elevation 3200 ft) in western Montana and contains one of the largest populations in the entire Rocky Mountain Region completely enclosed by mountains. During the 2000/2001 Missoula Valley Sampling Program, ambient levels of 61 semivolatile organic compounds (SVOCs) and 54 volatile organic compounds (VOCs) were originally quantified before refining the analytical program to 28 of the most prominent SVOCs and VOCs found in the Missoula Valley airshed. These compounds were measured over 24-hr periods at two locations throughout an entire year. This study provides the first, comprehensive appraisal of the levels of SVOCs and VOCs measured simultaneously throughout all four seasons at two locations in the Missoula Valley, including those levels measured during the 2000 Montana wildfire season. Generally, SVOC levels were comparable between both sides of the Missoula Valley. However, there were nearly double the amount of VOCs measured at the more urban Boyd Park site compared with the rural Frenchtown sampling site, a result of the greater number of automobiles on the eastern side of the Valley. SVOCs and VOCs were measured at their highest levels of the sampling program during the winter. Forest fire smoke samples collected during the summer of 2000 showed significant increases in SVOC phenolic compounds, including phenol, 2-methylphenol, 4-methylphenol, and 2,4-dimethylphenol. Although there were modest increases in some of the other SVOCs and VOCs measured during the fire season, none of the increases were as dramatic as the phenolics.     

Performance of a Pilot-Scale Biotrickling Filter in Controlling the Volatile Organic Compound Emissions in a Furniture Manufacturing Facility

Abstract

A 0.75-m³ pilot-scale biotrickling filter was run for over 1 yr in a Spanish furniture company to evaluate its performance in the removal of volatile organic compounds (VOCs) contained in the emission of two different paint spray booths. The first one was an open front booth used to manually paint furniture, and the second focus was an automatically operated closed booth operated to paint pieces of furniture. In both cases, the VOC emissions were very irregular, with rapid and extreme fluctuations. The pilot plant was operated at an empty bed residence time (EBRT) ranging from 10 to 40 sec, and good removal efficiencies of VOCs were usually obtained. When a buffering activated carbon prefllter was installed, the system performance was improved considerably, so a much better compliance with legal constraints was reached. After different shutdowns in the factory, the period to recover the previous performance of the biotrickling reactor was minimal. A weekend dehydration strategy was developed and implemented to control the pressure drop associated with excessive biomass accumulation.     

Interlaboratory Study of a Test Method Measuring Total Volatile Organic Compound Content of Consumer Products

Abstract

Consumer products are potentially significant sources of volatile organic compounds (VOCs), which are precursors to the formation of ozone in photochemical smog. To address the problem of ozone formation in ambient air, the U.S. Environmental Protection Agency (EPA) has been involved in the development of test methods for measuring the VOC content of consumer products. This paper describes results of an interlaboratory study to estimate the repeatability (precision of analyses performed by a single laboratory) and reproducibility (precision of analyses performed by different laboratories) of the consumer products’ VOC measurement method based on EPA Method 24 (for VOCs in surface coatings).

The mean method repeatability was 2.7 wt % VOC, and the mean method reproducibility was 4.8 wt % VOC. Method repeatability ranged from 0.2 to 4.4 wt % VOC, and reproducibility ranged from 0.6 to 11.9 weight percent VOC. The precision of the VOC method for consumer

products is similar to the precision of EPA Method 24 for surface coatings.     

Removal of Volatile Organic Compounds at Extreme Shock-Loading Using a Scaled-Up Pilot Rotating Drum Biofilter

Abstract

A pilot-scale rotating drum biofilter (RDB), which is a novel biofilter design that offers flexible flow-through configurations, was used to treat complex and variable volatile organic compound (VOC) emissions, including shock loadings, emanating from paint drying operations at an Army ammunition plant. The RDB was seeded with municipal wastewater activated sludge. Removal efficiencies up to 86% and an elimination capacity of 5.3 g chemical oxygen demand (COD) m^?3 · hr^?1 were achieved at a filter-medium contact time of 60 sec. Efficiency increased at higher temperatures that promote higher biological activity, and decreased at lower pH, which dropped down to pH 5.5 possibly as a result of carbon dioxide and volatile fatty acid production and ammonia consumption during VOC degradation. In comparison, other studies have shown that a bench-scale RDB could achieve a removal efficiency of 95% and elimination capacity of 331 g COD m^?3 · hr^?1. Sustainable performance of the pilot-scale RDB was challenged by the intermittent nature of painting operations, which typically resulted in 3-day long shutdown periods when bacteria were not fed. This challenge was overcome by adding sucrose (2 g/L weekly) as an auxiliary substrate to sustain metabolic activity during shutdown periods.     

Determination of Volatile Organic Compounds in the Atmosphere Using Two Complementary Analysis Techniques

ABSTRACT

During a preliminary field campaign of volatile organic compound (VOC) measurements carried out in an urban area, two complementary analysis techniques were applied to establish the technical and scientific bases for a strategy to monitor and control VOCs and photochemical oxidants in the Autonomous Community of the Basque Country. Integrated sampling was conducted using Tenax sorbent tubes and laboratory analysis by gas chromatography, and grab sampling and in situ analysis also were conducted using a portable gas chromatograph. With the first technique, monocyclic aromatic hydrocarbons appeared as the compounds with the higher mean concentrations. The second technique allowed the systematic analysis of eight chlorinated and aromatic hydrocarbons. Results of comparing both techniques, as well as the additional information obtained with the second technique, are included.     

Preparation of Activated Carbons from Raw and Biotreated Agricultural Residues for Removal of Volatile Organic Compounds

ABSTRACT

Activated carbons with diverse physical and chemical properties were produced from four agriculture residues, including raw barley husk, biotreated barley husk, rice husk, and pistachio shell. Results showed that with adequate steam activation (30–90 min, 50% H₂O_(g)/50% N₂), activated carbons with surface areas between 360 and 950 m² g^?1 were developed. Further increases in the activation time destroyed the pore structure of activated carbons, which resulted in a decrease in the surface area and pore volume. Biotreated agricultural residues were found to be suitable precursors for producing mesoporous activated carbons. The oxygen content of activated carbons increased with increasing activation time. Results from X-ray photoelectron spectroscopy examination further suggested that H₂O molecules react with the carbon surface, enhancing the deconvoluted peak area of carbonyl and carboxyl groups. Equilibrium adsorption of toluene indicated that the adsorption capacities increased with an increase in the inlet toluene concentration and a decrease in temperature. The adsorption isotherms were successfully fitted with Freundlich, Langmuir, and Dubinin– Radushkevich equations. Activated carbons derived from agricultural residues appear to be more applicable to adsorb volatile organic compounds at a low concentration and high-temperature environment.

IMPLICATIONS This paper presents data on the preparation of activated carbons from agricultural residues, especially the waste from biohydrogen generation. Experimental results indicated that with proper carbonization and steam activation, activated carbons with diverse characteristics can be produced from various agricultural residues. The resulting activated carbons effectively adsorb toluene. This work provides useful information for reutilization of these agricultural residues, helping in decreasing the cost of biological waste treatment and providing a cost-effective alternative to conventional adsorbent production and application.     

Source Location and Characterization of Volatile Organic Compound Emissions at a Petrochemical Plant in Kaohsiung,Taiwan

Abstract

This paper elucidated a novel approach to locating volatile organic compound (VOC) emission sources and characterizing their VOCs by database and contour plotting. The target of this survey was a petrochemical plant in Linyan, Kaohsiung County, Taiwan. Samples were taken with canisters from 25 sites inside this plant, twice per season, and analyzed by gas chromatography–mass spectrometry. The survey covered 1 whole year. By consolidated into a database, the data could be readily retrieved, statistically analyzed, and clearly presented in both table and graph forms. It followed from the cross‐analysis of the database that the abundant types of VOCs were alkanes, alkenes/dienes, and aromatics, all of which accounted for 99% of total VOCs. By contour plotting, the emission sources for alkanes, aromatics, and alkenes/dienes were successfully located. Through statistical analysis, the database could provide the range and 90% confidence interval of each species from each emission source. Both alkanes and alkene/dienes came from tank farm and naphtha cracking units and were mainly composed of C₃–C₅ members. Regarding aromatics, benzene, toluene, and xylenes were the primary species; they were emitted from tank farm, aromatic units, and xylene units.     

Incineration Techniques for Control of Volatile Organic Compound Emissions Part I. Fundamentals and Process Design Considerations

A review of incineration techniques for control of volatile organic compound emissions is presented in two consecutive issues of JAPC A. Part I presents an overview of the process including fundamentals and design considerations. Both thermal and catalytic incincerators are considered. Part II will present capital and annual operating cost estimates for both thermal and catalytic incinerator systems based on information received from a number of equipment manufacturers.     

Total Volatile Organic Compounds in the Urban Environment of Delhi

ABSTRACT

Total volatile organic compounds (TVOCs) in the urban ambient environment of Delhi were monitored from November 1994 to June 1995 at 13 sites using an inexpensive and a manual-labor-intensive sample collection procedure in want of sophisticated equipment. The results of the study show appreciable levels of TVOCs in the ambient environment of Delhi. The amount of TVOCs in the ambient environment was found to vary between 3 and 42 ppmv and exhibited wide temporal and seasonal variations. On a diurnal cycle, TVOC levels mostly peaked at 9:00 a.m., which coincided with the peak traffic hour. TVOC buildup in the urban atmosphere has serious implications for air quality through the formation of highly toxic oxidants. The results of this preliminary study make out a strong case for a regular monitoring of TVOCs in the urban environment of Delhi.     

Removal of Volatile Aliphatic Hydrocarbons in a Soil Bioreactor

Soil removal of propane, isobutane and n-butane from a waste air stream was evaluated in the laboratory and in a prototype soil bioreactor. Laboratory investigations indicated first-order kinetics and the potential to degrade light aliphatic hydrocarbons and trichlorethylene, a compound ordinarily resistant to aerobic biological treatment. The predicted behavior of the bioreactor, based on laboratory studies, agreed closely with the actual behavior of the Reid system. The prototype bioreactor reduced the hydrocarbon concentrations in the air by at least 90percent with a residence time of 15 minutes and a pressure drop of 85 cm of water. The bioreactor functioned well through a range of temperatures, 12°C to 24°C.     

难降解有机污染物湿法氧化处理技术

综述了湿法氧化的原理,介绍了Fenton组合技术和TiO2光催化氧化等氧化技术,并对应用前景作了展望.