Chapter 5. Air Pollution

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<ul><li><p>Pollutants: Sources, Effects, andDispersion Modeling </p><p>5.1SOURCES, EFFECTS, AND FATE OFPOLLUTANTS Sources of Air Pollution </p><p>Point, Area, and Line Sources Gaseous and Particulate Emissions Primary and Secondary Air Pollut-</p><p>ants Emission Factors Emission Inventories Nationwide Air Pollution Trends </p><p>Effects of Air Pollution Economic Losses Visible and Quantifiable Effects Biodiversity Deterioration of Exposed Materials Health Effects Atmospheric Effects Rainfall Quality </p><p>Tropospheric OzoneA Special Prob-lem</p><p>Brief Synopsis of Fate of AirPollutants </p><p>Effects of Wind Speed and Direc-tion </p><p>Effects of Atmospheric Turbulence Effects of Atmospheric Stability Effects of Topography on Air</p><p>Motion Other Factors </p><p>5.2VOCs AND HAPs EMISSION FROM CHEMICALPLANTS Emission Points </p><p>Process Point Sources Process Fugitive Sources Area Fugitive Sources </p><p>Classification of VOCs and HAPs </p><p>5.3HAPs FROM SYNTHETIC ORGANIC CHEMICALMANUFACTURING INDUSTRIES Hazardous Organic NESHAP </p><p>Process Vents Storage Vessels Transfer Operations Wastewater Solid Processing </p><p>Toxic Pollutants </p><p>5.4ATMOSPHERIC CHEMISTRY Basic Chemical Processes </p><p>Catalytic Oxidation of SO2Photochemical Reactions </p><p>Particulates Long-Range Planning </p><p>5.5MACRO AIR POLLUTION EFFECTS Acid Rain Effects </p><p>Effects on Forests Effects on Soil </p><p>5Air PollutionElmar R. Altwicker | Larry W. Canter | Samuel S. Cha | Karl T.Chuang | David H.F. Liu | Gurumurthy Ramachandran | Roger K.Raufer | Parker C. Reist | Alan R. Sanger | Amos Turk | Curtis P.Wagner</p><p>1999 CRC Press LLC</p></li><li><p>Effects on Groundwater Effects on Surface Water Effects on Materials Effects on Health </p><p>Losses in Stratospheric Ozone Layer Global Warming </p><p>Ecological Impact Impact on Water Resources Impact on Agriculture Impact on Air Quality Impact on Human Health </p><p>5.6METEOROLOGY Wind </p><p>Scales of Air Motion Wind Rose Turbulence </p><p>Lapse Rates and Stability Lapse Rates Stability Inversions </p><p>Precipitation Topography </p><p>Land-Sea Breeze Mountain-Valley Winds Urban-Heat-Island Effect </p><p>5.7METEOROLOGIC APPLICATIONS IN AIRPOLLUTION CONTROL Air Pollution Surveys Selection of Plant Site Allowable Emission Rates Stack Design </p><p>5.8ATMOSPHERIC DISPERSION MODELING The Gaussian Model </p><p>Plume Characteristics Dispersion Coefficients Stability Classes Wind Speed </p><p>Plume Rise and Stack Height Considera-tions </p><p>Plume Rise Briggs Plume Rise Downwash Tall Stacks </p><p>Computer Programs for Dispersion Model-ing </p><p>Guideline Models Model Options Screening and Refined Models </p><p>Simple and Complex Terrain Urban and Rural Classification Averaging Periods Single and Multiple Sources Type of Release Additional Plume Influences Meteorology Other Models </p><p>Mobile and Line Source Modeling CALINE3 Model CAL3QHC Model BLP Model </p><p>Air Quality </p><p>5.9EMISSION MEASUREMENTS Planning an Emissions Testing Pro-</p><p>gram Analyzing Air Emissions </p><p>Stack Sampling Air Toxics in Ambient Air Equipment Emissions </p><p>Monitoring Area Emissions Direct Measurements Indirect Methods </p><p>5.10AIR QUALITY MONITORING Sampling of Ambient Air </p><p>Sampling Method Selection General Air Sampling Problems </p><p>Gas and Vapor Sampling Collection in Containers or Bags Absorption Adsorption Freeze-Out Sampling </p><p>Particulate Matter Sampling Filtration Impingement and Impaction Electrostatic Precipitation Thermal Precipitators </p><p>Air Quality Monitoring Systems Purpose of Monitoring Monitoring in Urban Areas Sampling Site Selection Static Methods of Air Monitoring </p><p>Manual Analyses Instrumental Analyses </p><p>Sensors Data Transmission </p><p>1999 CRC Press LLC</p></li><li><p>1999 CRC Press LLC</p><p>Data Processing Portable and Automatic Analyzers </p><p>5.11STACK SAMPLING Pitot Tube Assembly </p><p>Installation Operation </p><p>Two-Module Sampling Unit Heated Compartment Ice-Bath Compartment </p><p>Operating or Control Unit Sampling for Gases and Vapors </p><p>5.12CONTINUOUS EMISSION MONITORING Requirements System Options </p><p>In Situ Systems Extractive Systems System Selection </p><p>Continuous Emission Monitors Location of Systems Maintenance of Systems </p><p>5.13REMOTE SENSING TECHNIQUES Open-Path Optical Remote Sensing</p><p>Systems Instrumentation </p><p>Bistatic Systems Unistatic Systems Limitations </p><p>Pollutants: Minimization andControl </p><p>5.14POLLUTION REDUCTION Raw Material Substitution Process Modification Marketing Pollution Rights Demand Modification Gas Cleaning Equipment </p><p>5.15PARTICULATE CONTROLS Control Equipment Particulate Size Other Factors </p><p>5.16PARTICULATE CONTROLS: DRYCOLLECTORS 336Gravity Settling Chambers </p><p>Cyclones Gas Flow Patterns Tangential Gas Velocity Radial and Axial Gas Velocity Modeling Gas Flows Collection Efficiency Pressure Drop Dust Loading Cyclone Design Optimization </p><p>Filters Fiber Filters Fabric Filters (Baghouses) </p><p>5.17PARTICULATE CONTROLS: ELECTROSTATICPRECIPITATORS Corona Generation Current-Voltage Relationships Particle Charging </p><p>Field Charging Diffusion Charging </p><p>Migration Velocity ESP Efficiency </p><p>Dust Resistivity Precipitator Design </p><p>5.18PARTICULATE CONTROLS: WETCOLLECTORS General Description Scrubber Types </p><p>Spray CollectorsType I Impingement on a Wetted SurfaceType</p><p>II Bubbling through Scrubbing Liquid</p><p>Type III Scrubbers Using a Combination of</p><p>Designs Factors Influencing Collection</p><p>Efficiency Contacting Power Rule Use of the Aerodynamic Cut Diam-</p><p>eter Determination of dac as a Function of</p><p>Scrubber Operating Parameters </p><p>5.19GASEOUS EMISSION CONTROL Energy Source Substitution Process Modifications </p><p>Combustion Control Other Modifications </p><p>Design Feature Modifications Modified Burners Burner Locations and Spacing </p></li><li><p>Tangential Firing Steam Temperature Control Air and Fuel Flow Patterns Pressurized Fluidized-Bed Com-</p><p>bustion Pollution Monitoring </p><p>5.20GASEOUS EMISSION CONTROL: PHYSICAL ANDCHEMICAL SEPARATION Absorption </p><p>Absorption Operations Commercial Applications </p><p>Condensation Adsorption </p><p>Adsorption Isotherm Adsorption Equipment Adsorber Design </p><p>Chemical Conversion VOCs Hydrogen Sulfide Nitrogen Oxides </p><p>5.21GASEOUS EMISSION CONTROL: THERMALDESTRUCTION Overview of Thermal Destruction </p><p>Thermal Combustion and Incinera-tion </p><p>Flaring Emerging Technologies </p><p>Source Examples Petroleum Industry Chemical Wood Pulping Landfill Gas Emissions Rendering Plants </p><p>Combustion Chemistry Stoichiometry Kinetics </p><p>Design Considerations Thermal Incinerators Flares Emerging Technologies </p><p>Conclusions </p><p>5.22GASEOUS EMISSION CONTROL: BIOFILTRATION Mechanisms Fixed-Film Biotreatment Systems Applicability and Limitations </p><p>Fugitive Emissions: Sources andControls </p><p>5.23FUGITIVE INDUSTRIAL PARTICULATEEMISSIONS Sources Emission Control Options </p><p>Process Modification Preventive Measures Capture and Removal </p><p>5.24FUGITIVE INDUSTRIAL CHEMICALEMISSIONS Sources Source Controls </p><p>Valves Pumps Compressors Pressure-Relief Devices Sampling Connection Systems Open-Ended Lines Flanges and Connectors Agitators </p><p>5.25FUGITIVE DUST Sources Prevention and Controls </p><p>Wind Control Wet Suppression Vegetative Cover Chemical Stabilization </p><p>Odor Control </p><p>5.26PERCEPTION, EFFECT, ANDCHARACTERIZATION Odor Terminology </p><p>Threshold Intensity Character Hedonic Tone </p><p>Human Response to Odors and OdorPerception </p><p>Sensitization, Desensitization, andTolerance of Odors </p><p>Odor Mixtures Other Factors Affecting Odor Percep-</p><p>tion Odor and Health Effects </p><p>1999 CRC Press LLC</p></li><li><p>1999 CRC Press LLC</p><p>5.27ODOR CONTROL STRATEGY Activated Carbon Adsorption Adsorption with Chemical Reaction Biofiltration Wet Scrubbing Combustion Dispersion </p><p>Indoor Air Pollution </p><p>5.28RADON AND OTHER POLLUTANTS Radon </p><p>Source and Effects Radon Detection Radon Control Techniques </p><p>Other Indoor Pollutants Source and Effects Control Techniques </p><p>5.29AIR QUALITY IN THE WORKPLACE Exposure Limits Occupational Exposure Monitoring </p><p>Color Change Badges Color Detector (Dosimeter) Tubes Other Monitoring Techniques </p><p>MSDSs </p></li><li><p>Air pollution is defined as the presence in the outdoor at-mosphere of one or more contaminants (pollutants) inquantities and duration that can injure human, plant, oranimal life or property (materials) or which unreasonablyinterferes with the enjoyment of life or the conduct of busi-ness. Examples of traditional contaminants include sulfurdioxide, nitrogen oxides, carbon monoxide, hydrocarbons,volatile organic compounds (VOCs), hydrogen sulfide,particulate matter, smoke, and haze. This list of air pol-lutants can be subdivided into pollutants that are gases orparticulates. Gases, such as sulfur dioxide and nitrogen ox-ides exhibit diffusion properties and are normally formlessfluids that change to the liquid or solid state only by acombined effect of increased pressure and decreased tem-perature. Particulates represent any dispersed matter, solidor liquid, in which the individual aggregates are larger thansingle small molecules (about 0.0002 mm in diameter) butsmaller than about 500 micrometers (mm). Of recent at-tention is particulate matter equal to or less than 10 mmin size, with this size range of concern relative to poten-tial human health effects. (One mm is 1024 cm).</p><p>Currently the focus is on air toxics (or hazardous airpollutants [HAPs]). Air toxics refer to compounds that arepresent in the atmosphere and exhibit potentially toxic ef-fects not only to humans but also to the overall ecosys-tem. In the 1990 Clean Air Act Amendments (CAAAs),the air toxics category includes 189 specific chemicals.These chemicals represent typical compounds of concernin the industrial air environment adjusted from workplacestandards and associated quality standards to outdoor at-mospheric conditions.</p><p>The preceding definition includes the quantity or con-centration of the contaminant in the atmosphere and itsassociated duration or time period of occurrence. This con-cept is important in that pollutants that are present at lowconcentrations for short time periods can be insignificantin terms of ambient air quality concerns.</p><p>Additional air pollutants or atmospheric effects thathave become of concern include photochemical smog, acid</p><p>rain, and global warming. Photochemical smog refers tothe formation of oxidizing constituents such as ozone inthe atmosphere as a result of the photo-induced reactionof hydrocarbons (or VOCs) and nitrogen oxides. This phe-nomenon was first recognized in Los Angeles, California,following World War II, and ozone has become a majorair pollutant of concern throughout the United States.</p><p>Acid rain refers to atmospheric reactions that lead toprecipitation which exhibits a pH value less than the nor-mal pH of rainfall (the normal pH is approximately 5.7when the carbon dioxide equilibrium is considered).Recently, researchers in central Europe, severalScandinavian countries, Canada, and the northeasternUnited States, have directed their attention to the poten-tial environmental consequences of acid precipitation.Causative agents in acid rain formation are typically as-sociated with sulfur dioxide emissions and nitrogen oxideemissions, along with gaseous hydrogen chloride. From aworldwide perspective, sulfur dioxide emissions are thedominant precursor of acid rain formation.</p><p>Another global issue is the influence of air pollution onatmospheric heat balances and associated absorption orreflection of incoming solar radiation. As a result of in-creasing levels of carbon dioxide and other carbon-con-taining compounds in the atmosphere, concern is growingthat the earths surface is exhibiting increased temperaturelevels, and this increase has major implications in shiftingclimatic conditions throughout the world.</p><p>Sources of Air PollutionAir pollutant sources can be categorized according to thetype of source, their number and spatial distribution, andthe type of emissions. Categorization by type includes nat-ural and manmade sources. Natural air pollutant sourcesinclude plant pollens, wind-blown dust, volcanic eruptions,and lightning-generated forest fires. Manmade sources in-clude transportation vehicles, industrial processes, powerplants, municipal incinerators, and others.</p><p>1999 CRC Press LLC</p><p>Pollutants: Sources, Effects, andDispersion Modeling</p><p>5.1SOURCES, EFFECTS, AND FATE OF POLLUTANTS</p></li><li><p>POINT, AREA, AND LINE SOURCES</p><p>Source categorization according to number and spatial dis-tribution includes single or point sources (stationary), areaor multiple sources (stationary or mobile), and line sources.Point sources characterize pollutant emissions from in-dustrial process stacks and fuel combustion facility stacks.Area sources include vehicular traffic in a geographicalarea as well as fugitive dust emissions from open-air stockpiles of resource materials at industrial plants. Figure 5.1.1shows point and area sources of air pollution. Included inthese categories are transportation sources, fuel combus-tion in stationary sources, industrial process losses, solidwaste disposal, and miscellaneous items. This organizationof source categories is basic to the development of emis-sion inventories. Line sources include heavily travelledhighway facilities and the leading edges of uncontrolledforest fires.</p><p>GASEOUS AND PARTICULATEEMISSIONS</p><p>As stated earlier, air pollution sources can also be catego-rized according to whether the emissions are gaseous orparticulates. Examples of gaseous pollutant emissions in-clude carbon monoxide, hydrocarbons, sulfur dioxide, andnitrogen oxides. Examples of particulate emissions includesmoke and dust emissions from a variety of sources. Often,an air pollution source emits both gases and particulatesinto the ambient air.</p><p>PRIMARY AND SECONDARY AIRPOLLUTANTS</p><p>An additional source concept is that of primary and sec-ondary air pollutants. This terminology does not refer tothe National Ambient Air Quality Standards (NAAQSs),nor is it related to primary and secondary impacts on airquality that result from project construction and opera-</p><p>tion. Primary air pollutants are pollutants in the atmos-phere that exist in the same form as in source emissions.Examples of primary air pollutants include carbon monox-ide, sulfur dioxide, and total suspended particulates.Secondary air pollutants are pollutants formed in the at-mosphere as a result of reactions such as hydrolysis, oxi-dation, and photochemical oxidation. Secondary air pol-lutants include acidic mists and photochemical oxidants.In terms of air quality management, the main strategiesare directed toward source control of primary air pollu-tants. The most effective means of controlling secondaryair pollutants is to achieve source control of the primaryair pollutant; primary pollutants react in the atmosphereto form secondary pollutants.</p><p>EMISSION FACTORS</p><p>In evaluating air quality levels in a geographical area, anenvironmental engineer must have accurate informationon the quantity and characteristics of the emissions fromnumerous sources contributing pollutant emissions into theambient air. One approach for identifying the types andestimating the quantities of emissions is to use emissionfactors. An emission factor is the average rate at which apollutant is released into the atmosphere as a result of anactivity, such as combustion or industrial production, di-vided by the level of that activity. Emission factors relatethe types and quantities of pollutants emitted to an indi-...</p></li></ul>