Modeling Oxidizing Scrubbers for Odor Control

Overcamp, Thomas J.

doi:10.1021/es9711167

Cited by 16 publications

(22 citation statements)

References 6 publications

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“…Reaction rates ranging from 4 × 10 4 to 3 × 10 8 (L/mol/sec) are required to achieve rapid removal in wet scrubbers. 4 Although no specific kinetic data are available for the VOCs reported in this work, benzaldehyde, a representative aldehyde previously reported in rendering emissions, has a reported reaction rate of less than 3 × 10 -4 (L/mol/sec at pH 8) with ClO 2 , compared with 5 × 10 5 L/mol/sec (pH 8) for 2-methyl-1-propanethiol. 6 Wet scrubber simulations resulted in removal efficiencies ranging from 10 to 15% for methanethiol and 50-70% for butanal (i.e., mass transfer Table 5.…”

Section: Discussionmentioning

confidence: 84%

“…However, kinetic data specific to the VOCs generated in the rendering industry are lacking, without which optimal scrubber design is impractical. 4 Kinetic data suggest that typical oxidizing agents used in wet scrubbers (e.g., ClO 2 and ozone) do not react or react slowly with many of the VOCs in rendering plant waste gases. 5,6 Reaction rates ranging from 4 × 10 4 to 3 × 10 8 (L/mol/sec) are reportedly required to achieve rapid removal in wet scrubbers.…”

Section: Discussionmentioning

confidence: 99%

“…5,6 Reaction rates ranging from 4 × 10 4 to 3 × 10 8 (L/mol/sec) are reportedly required to achieve rapid removal in wet scrubbers. 4 Benzaldehyde, a representative aldehyde periodically measured in rendering emissions, 7 has a reported reaction rate of less than 3 × 10 -4 (L/mol/sec) with ClO 2 . 6 Similarly, ozone reacts rapidly with reduced sulfur compounds (e.g., >2 × 10 5 L/mol/sec for ethylmercaptan) but very slowly with aldehydes (e.g., 2.5 L/mol/sec for propanal).…”

Section: Discussionmentioning

confidence: 99%

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Wet Scrubber Analysis of Volatile Organic Compound Removal in the Rendering Industry

Kastner

Das

2002

Journal of the Air & Waste Management Association

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The promulgation of odor control rules, increasing public concerns, and U.S. Environmental Protection Agency (EPA) air regulations in nonattainment zones necessitates the remediation of a wide range of volatile organic compounds (VOCs) generated by the rendering industry. Currently, wet scrubbers with oxidizing chemicals are used to treat VOCs; however, little information is available on scrubber efficiency for many of the VOCs generated within the rendering process. Portable gas chromatography/mass spectrometry (GC/MS) units were used to rapidly identify key VOCs on-site in process streams at two poultry byproduct rendering plants. On-site analysis was found to be important, given the significant reduction in peak areas if samples were held for 24 hr before analysis. Major compounds consistently identified in the emissions from the plant included dimethyl disulfide, methanethiol, octane, hexanal, 2-methylbutanal, and 3-methylbutanal. The two branched aldehydes, 2-methylbutanal and 3-methylbutanal, were by far the most consistent, appearing in every sample and typically the largest fraction of the VOC mixture.A chlorinated hydrocarbon, methanesulfonyl chloride, was identified in the outlet of a high-intensity wet scrubber, and several VOCs and chlorinated compounds were identified in the scrubbing solution, but not on a consistent basis. Total VOC concentrations in noncondensable gas streams ranged from 4 to 91 ppmv. At the two plants, the odor-causing compound methanethiol ranged from 25 to 33% and 9.6% of the total VOCs (v/v). In one plant, wet scrubber analysis using chlorine dioxide (ClO 2 ) as the oxidizing agent indicated that close to 100% of the methanethiol was removed from the gas phase, but removal efficiencies ranged from 20 to 80% for the aldehydes and hydrocarbons and from 23 to 64% for total VOCs. In the second plant, conversion efficiencies were much lower in a packed-bed wet scrubber, with a measurable removal of only dimethyl sulfide (20-100%). INTRODUCTIONPoultry rendering operations convert organic wastes (feathers, offal, dead birds, blood, hatchery byproducts, etc.) to products such as feed additives and fertilizer. In poultry rendering operations, feathers are typically hydrolyzed in batch mode at 140-150 ºC (276-345 kPa) for 20-45 min to breakdown the keratin, 1 and the meat byproducts or offal are typically treated at 121-135 ºC (172-517 psig) with varying residence times depending on the mode of operation, batch or continuous. 2,3 In some cases, the hydrolyzed feathers are then combined with offal and dried. In both of these steps, volatile organic compounds (VOCs) are generated, some of which are odorous. Overhead vapors from the feather hydrolyzer and driers are passed through condensers to remove some VOCs. The noncondensable gases typically are passed through wet scrubber units to remove the VOC fraction not removed in the condensers.

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Section: Discussionmentioning

confidence: 84%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Wet Scrubber Analysis of Volatile Organic Compound Removal in the Rendering Industry

Kastner

Das

2002

Journal of the Air & Waste Management Association

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“…However, there is a general lack of kinetic data specific for the VOCs generated in the rendering industry, without which optimal scrubber design is impractical. 3 Kinetic data indicate that typical oxidizing agents used in wet scrubbers (eg ClO 2 and ozone or O 3 ) do not react or react slowly with many of the compounds in rendering plant waste gases. 4 -6 Reaction rate constants ranging from 4 × 10 4 to 3 × 10 8 (L mol −1 s −1 ) are reportedly required to achieve rapid removal in wet scrubbers.…”

Section: Introductionmentioning

confidence: 99%

“…4 -6 Reaction rate constants ranging from 4 × 10 4 to 3 × 10 8 (L mol −1 s −1 ) are reportedly required to achieve rapid removal in wet scrubbers. 3 Recent kinetic analysis indicated that ClO 2 does not react with hexanal and 2-methylbutanal over a wide range of pH and temperatures. 5 Similarly, ozone rapidly reacts with reduced sulfur compounds (eg…”

Section: Introductionmentioning

confidence: 99%

Comparison of chemical wet scrubbers and biofiltration for control of volatile organic compounds using GC/MS techniques and kinetic analysis

Kastner

Das

2005

J of Chemical Tech & Biotech

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Increasing public concerns and EPA air regulations in non-attainment zones necessitate the remediation of volatile organic compounds (VOCs) generated in the poultry-rendering industry. Wet scrubbers using chlorine dioxide (ClO 2 ) have low overall removal efficiencies due to lack of reactivity with aldehydes. Contrary to wet scrubbers, a biofilter system successfully treated the aldehyde fraction, based on GC/MS analysis of inlet and outlet streams. Total VOC removal efficiencies ranged from 40 to 100% for the biofilter, kinetic analysis indicated that the overall removal capacity approached 25 g m −3 h −1 , and aldehyde removal efficiency was significantly higher compared with chemical wet scrubbers. Process temperatures monitored in critical unit operations upstream from the biofilter varied significantly during operation, rising as much as 30• C within a few minutes. However, the outlet air temperature of a high intensity scrubber remained relatively constant at 40• C, although the inlet air temperature fluctuated from 50 to 65• C during monitoring. These data suggest a hybrid process combining a wet scrubber and biofilter in series could be used to improve overall VOC removal efficiencies and process stability.

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Mechanistic Modeling of Pollutant Removal, Temperature, and Evaporation in Chemical Air Scrubbers

et al. 2016

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Chemical air scrubbers reduce the concentration of water-soluble components such as ammonia from the outgoing ventilation air through absorption in water, followed by chemical conversions and removal of the end products. A mechanistic model for a countercurrent air scrubber was set up. Mass balances for ammonia, hydrogen sulfide, nitrous oxide, and methane were implemented, as well as the water mass balance and heat balances. The model was validated against experimental data from a conventional fattening pig housing facility. The effect of influent characteristics, design parameters, and control handles on the removal efficiency, the temperature profile, and the water evaporation rate were investigated through simulation. The model was able to describe the behavior of a countercurrent chemical air scrubber.

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Modeling Oxidizing Scrubbers for Odor Control

Cited by 16 publications

References 6 publications

Wet Scrubber Analysis of Volatile Organic Compound Removal in the Rendering Industry

Wet Scrubber Analysis of Volatile Organic Compound Removal in the Rendering Industry

Comparison of chemical wet scrubbers and biofiltration for control of volatile organic compounds using GC/MS techniques and kinetic analysis

Mechanistic Modeling of Pollutant Removal, Temperature, and Evaporation in Chemical Air Scrubbers

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