261 7 Animal Waste and Air Quality Problems Yes…we are next to the hog farm, and to tell you the truth, I don’t know what in the world we are goin a do. It’s not so bad now but when the wind changes and they turn on the fans it is very bad. My husband suffers from it a good deal. In the house we have nine special air conditions and six air puriers runnin all the time, so it’s not too awful, but outside, when the wind is right, your eyes just ame up and your throat hurts. That’s why I only ask fty dollars a month for the apartment. Otherwise it would be two hundred. So if you can stand the hog farm it’s a good deal. Do you have a tendency to asthma? (Proulx, 2002, p. 309) Some years ago our family took a trip across the Midwest to visit relatives in Iowa, and for thousands of miles along the way we saw virtually no animal life except feedlots full of cattle—surely the most unappetizing sight and smell I’ve encountered in my life (and my life includes some years of intimacy with diaper pails). And we saw almost no plant life but the endless elds of corn and soybeans required to feed those pathetic penned beasts. Our kids kept asking, mile after mile, “What used to be here?” (Kingsolver, 2002, p. 119–120) 7.1 INTRODUCTION There are more than 1 million livestock and poultry farms in the United States. About one-third of these farms raise animals in conned areas, qualifying them as animal feed operations (AFOs) (USDA, 1999). Airborne contaminants (air emissions) and odor have always been associated with livestock and poultry production. With the trend toward larger and more-concentrated production sites, however, gases, dust, and odors are rapidly becoming important issues for animal producers. “Even though very little evidence is available on the impact of airborne contaminants and odor from livestock operations on human health, the increasing intolerance of odors and the economic importance of animal agriculture have resulted in an urgent need for all stakeholders to nd adequate solutions” (NWPS-18, 2002, P. 1). This chapter addresses the beef, dairy, swine, and poultry (broiler, laying hens, and turkey) sectors only. These animal sectors comprise the majority of animals raised in connement in the United States; the smaller animal sectors (sheep, horses, goats, mules, rabbits, ducks, and geese) are not covered here because they do not generate emissions of the same magni - tude as other animal sectors. As previously mentioned, and as dened by the U.S. Environmental Protection Agency (USEPA, 40 CFR 122.23), an AFO is a facility where: (1) livestock or poultry are conned and fed for a total of 45 days or more in any 12-month period and (2) vegetative cover of any signicance (crops, vegetative forage growth, or post harvest residues) is lacking. To be considered an AFO, the same animals do not have to be conned for 45 days, the 45 days do not have to be consecutive, and the 12-month period does not have to correspond to a calendar year. The stipulation of the absence of 7098.indb 261 4/25/07 5:31:25 PM © 2007 by Taylor & Francis Group, LLC 262 Environmental Management of Concentrated Animal Feeding Operations (CAFOs) vegetative cover of any signicance intentionally excludes operations where animals are main- tained on pasture or rangeland. An AFO includes the connement facility, manure management systems, and the manure application site. Key term: The USEPA Ofce of Water uses the term concentrated animal feeding operation (CAFO) to designate AFOs that are point sources subject to the National Pollutant Discharge Elimi - nation System (NPDES) permit system. Currently, 40 CFR 122.23 denes a CAFO as an AFO that connes 1,0000 animal units (AU) or more at any one time or that is designated as a CAFO on a case-by-case basis (according to 40 CFR 122.23). Key term: Animal unit (AU) is a unit of measure used to compare different animal species. This text uses the denition of animal unit developed by the USEPA Ofce of Water (66 FR 2960-3138): 1 cattle excluding mature dairy and veal cattle; 0.7 mature dairy cattle; 2.5 swine weighing over 55 lb; 10 swine weighing 55 lb or less; 55 turkeys; 1000 chickens; and 1 veal calf. 7.2 AIR EMISSIONS FROM FEEDLOT OPERATIONS AFOs emit gaseous and particulate substances. The primary mechanism for release of gaseous emissions is microbial decomposition of manure. The release of particulate matter is derived from the entrainment of feeds, dry manure, soil, and other material caused by movement of animals in both indoor and outdoor connement. As previously mentioned, in this text, manure is dened as any combination of fecal matter, urine, and other materials that are mixed with manure (bedding material, waste feeds, wash water). Manure can be in a solid, slurry, or liquid state (surface liquids from storage facilities). Decomposition and the formation of these gaseous compounds begin imme - diately at excretion and continue until the manure is incorporated into the soil. Therefore, the sub - stances generated and the subsequent rates of emission depend on a number of variables, including the species of animal, feeding practices, type of connement facility, type of manure management system, and land application practices. Animals also directly emit some of the gaseous substances mentioned above as a result of nor - mal metabolic processes such as respiration. However, these emissions were not included in this text, given that they are uncontrollable (Alexander, 1977; Brock & Madigan, 1998; Tate, 1995). 7.2.1 general CharaCTeriSTiCS of aniMal feeDing oPeraTionS An AFO has a connement facility, a system for manure management (storage and in some cases stabilization), and a land application site. Because of different methods of connement and asso - ciated manure management, no typical AFO is identied. Variances depending on animal type, regional climatic conditions, business practices, and preferences of the operator impact the design and operation of an AFO. However, the combinations of connement and waste management sys - tems that are most commonly used in each sector of animal agriculture are identied in this section. We present a general overview of AFOs below. 7.2.1.1 Confinement A connement facility may be a totally enclosed structure with full-time mechanical ventilation, a partially enclosed structure with or without mechanic ventilation, an open paved lot, or an open unpaved lot. Method of connement, which varies among and within the animal species, probably is the most signicant factor affecting emissions, because it inuences ventilation and method of manure handling and disposal. Whether manure is handled as a solid, liquid, or slurry inuences if microbial degradation occurs aerobically or anaerobically, and thus the substances generated. Key term: Aerobic means occurring in the presence of free oxygen or capable of living or growing in the presence of free oxygen, such as aerobic bacteria. 7098.indb 262 4/25/07 5:31:25 PM © 2007 by Taylor & Francis Group, LLC Animal Waste and Air Quality Problems 263 Key term: Anaerobic means occurring in the absence of free or dissolved oxygen or capable of liv- ing and growing in the absence of oxygen, such as anaerobic bacteria. 7.2.1.2 Manure Management System A manure storage facility may be an integral part of the connement facility or located adjacent to the connement facility. When manure is handled as a solid, storage may be within the connement facility or in stockpiles that may or may not be covered. For liquid or slurry manure handling sys - tems, manure may be stored in an integral tank, such as a storage tank under the oor of a conne - ment building, or ushed to an external facility, such as a pond or an anaerobic lagoon. Emissions from storage tanks and ponds differ those from anaerobic lagoons, which are designed for manure stabilization. Stabilization is the treatment of manure to reduce volatile solids and control odor prior to application to agricultural land. The use of the term “stabilization” rather than “treatment” is intended to avoid the implication that stabilized animal manure can be discharged to surface water or groundwater. 7.2.1.3 Land Application Currently, almost all livestock and poultry manure is applied to cropland or pastures for ultimate disposal. The method of applying manure can affect emissions. Emissions from manure applied to the soil surface and not immediately incorporated are higher than those from manure that is imme - diately incorporated by disking or plowing. Injection, which is possible with manures handled as liquids or slurries, also reduces emissions. Conversely, the use of irrigation for the land application of liquid manure increases emissions of gaseous pollutants because of the increased opportunity for volatilization. Key term: Irrigation is application of water and liquid wastes to land for agricultural purposes. Key term: Slurry is manure with a total solids concentration of between approximately 5% to 15%. Slurries with a total solids concentration of less than 10% are pumpable. Above a total solids con - centration of 10%, slurries are semisolids with a negligible angle of repose and can be scraped but not stacked for storage. Table 7.1 presents an overview of the most common methods of connement and manure man - agement for large operations. These different combinations affect the relative magnitudes of emis - sions from each operation. TABLE 7.1 Common Types of Animal Confinement and Manure Management Systems Species Animal confinement Typical type of manure management systems Broilers Enclosed building Integral with connement, or open or covered stockpiles Turkeys Enclosed building Integral with connement, or open or covered stockpiles Layers (dry manure) Enclosed building Integral with connement Layers (ush systems) Enclosed building Ponds and anaerobic lagoons Swine Enclosed building Integral with connement, or tanks, ponds, or anaerobic lagoons Dairy Enclosed building and open lots Anaerobic lagoons, tanks and ponds, and uncovered stockpiles Veal Enclosed building Integral with connement, or tanks, ponds, or anaerobic lagoons Beef Open lots Uncovered stockpiles Source: USEPA (2001). 7098.indb 263 4/25/07 5:31:26 PM © 2007 by Taylor & Francis Group, LLC 264 Environmental Management of Concentrated Animal Feeding Operations (CAFOs) 7.2.2 SubSTanCeS eMiTTeD A number of factors affect the emission of gases and particulate matter from AFOs. Most of the substances emitted are the products of microbial processes that decompose the complex organic constituents in manure. The microbial environment determines which substances are generated and at what rate. In this section, we describe the chemical and biological mechanisms that affect the formation and release of emissions. Table 7.2 summarizes the substances that can be emitted from different operations with an AFO. Although all AFOs share the same three common elements (connement faculties, manure management system, and land application site), the differences in production and manure manage - ment practices both among and within the different animal sectors result in different microbial environments and therefore different emission potentials. Several factors affect the emissions of ammonia, nitrous oxide, methane, carbon dioxide, volatile organic compounds (VOCs), hydrogen sulde, particulate matter, and odors. TABLE 7.2 Substances Potentially Emitted from Animal Feeding Operations Animal sector Operations PM a Hydrogen sulfide Ammonia Nitrous oxide Methane VOCs CO 2 Broilers, turkeys, layers (dry) Connement X X X Manure storage and treatment X X X Land disposal X X X X Layers (liquid) Connement X X X X X X X Manure storage and treatment X X X X X X Land disposal X X X X X Swine (ush) Connement X X X X X Manure storage and treatment X X X X X Land disposal X X X X X Swine (other 1 ) Connement X X X X X Manure storage and treatment X X X X X X Land disposal X X X X X Dairy (ush) Connement X X X X X Manure storage and treatment X X X X X Land disposal X X X X X Dairy (scrape) Connement X X X X X Manure storage and treatment X X X X X Land disposal X X X X X Dairy (drylot) Connement X X X X X X Manure storage and treatment X X X X X X Land disposal X X X X X X Veal Connement X X X X X Manure storage and treatment X X X X X Land disposal X X X X X X Beef Connement X X X X X X Manure storage and treatment X X X X X X Land disposal X X X X X X Source: USEPA (2001). Note: PM = particulate matter, as total suspended particulate; VOC = volatile organic compounds; CO 2 = carbon dioxide a Other includes pit storage, pull plug pits, and pit recharge systems 7098.indb 264 4/25/07 5:31:26 PM © 2007 by Taylor & Francis Group, LLC Animal Waste and Air Quality Problems 265 7.2.2.1 Ammonia Ammonia is produced as a by-product of the microbial decomposition of the organic nitrogen com - pounds in manure. Nitrogen occurs as both unabsorbed nutrients in manure and as either urea (mam - mals) or uric acid (poultry) in urine. Urea and uric acid hydrolyze rapidly to form ammonia and are emitted soon after excretion. The formation of ammonia continues with the microbial breakdown of manure under both aerobic and anaerobic conditions. Because ammonia is highly soluble in water, ammonia accumulates in manures handled as liquids and semisolids or slurries but volatizes rap - idly with drying from manures handled as solids. Therefore, the potential for ammonia volatization exists wherever manure is present, and ammonia is emitted from connement buildings, open lots, stockpiles, anaerobic lagoons, and land application from both wet and dry handling systems. Key term: Anaerobic bacterium are bacteria that do not require the presence of free or dissolved oxygen. Key term: An anaerobic lagoon is a facility used to stabilize livestock or poultry manure using anaerobic microorganisms to reduce organic compounds to methane and carbon dioxide. The volatilization of ammonia from any AFO can be highly variable depending on total ammonia concentration, temperature, pH, and storage time. Emissions depend on how much of the ammonia-nitrogen in solution reacts to form ammonia versus ionized ammonium (NH 4 + ), which is nonvolatile. In solution, the partitioning of ammonia between the ionized (NH 4 + ) and unionized (NH 3 ) species is controlled by pH and temperature. Under acidic conditions (pH values of less than 7.0), ammonium is the predominate species, and ammonia volatilization occurs at a lower rate than at higher pH values. However, some ammonia volatilization occurs even under moderately acidic conditions. Under acidic conditions, ammonia that is volatized is replenished because of the con - tinual reestablishment of the equilibrium between the concentrations of the ionized and unionized species of ammonia in solution following volatilization. As pH increases above 7.0, the concentra - tion of ammonia increases, as does the rate of ammonia volatilization. The pH of manures handled as solids can be in the range of 7.5 to 8.5, which results in fairly rapid ammonia volatilization. Manure handled as liquids or semisolids tend to have lower pH. Because of its high solubility in water, the loss of ammonia to the atmosphere is more rapid when drying of manure occurs. However, little difference in total ammonia emissions occurs between solid and liquid manure handling systems if liquid manure is stored over extended periods prior to land application. 7.2.2.2 Nitrous Oxide Nitrous oxide also can be produced from the microbial decomposition of organic nitrogen com - pounds in manure. Unlike ammonia, however, nitrous oxide is emitted only if nitrication occurs and is followed by denitrication. Nitrication is the microbial oxidation of ammonia to nitrites and nitrates and requires an aerobic environment. Denitrication most commonly is a microbially medi - ated process by which nitrites and nitrates are reduced under anaerobic conditions. The principal end product of denitrication is dinitrogen gas (N 2 ). However, small amounts of nitrous oxide as well as nitric oxide also can be generated under certain conditions. Therefore, for nitrous emissions to occur, the manure must rst be handled aerobically (dry) and then anaerobically (wet). Key term: Denitrication is the chemical or biological reduction of nitrate or nitrite with molecular nitrogen (N 2 ) as the primary end product. Other possible end products are nitrous oxide (N 2 O) and nitric oxide (NO). Key term: Nitrication is the microbially mediated biochemical transformation by oxidation of ammonium (NH 4 + ) to nitrite (NO 2 – ) or nitrate (NO 3 – ). 7098.indb 265 4/25/07 5:31:26 PM © 2007 by Taylor & Francis Group, LLC 266 Environmental Management of Concentrated Animal Feeding Operations (CAFOs) Nitrous oxide emissions are most likely to occur from unpaved drylots for dairy and beef cattle and at land application sites, the sites most likely to have the necessary conditions for both nitri - cation and denitrication. At these sites, the ammonia nitrogen that is not lost by volatilization is adsorbed on soil particles and subsequently oxidized to nitrite and nitrate nitrogen. Emissions of nitrous oxide from these sites depends on two primary factors. The rst is drainage. In poorly drained soils, the frequency of saturated conditions, and thus anaerobic conditions necessary for denitrication, are higher than for well-drained soils. Conversely, the opportunity for leaching of nitrite and nitrate nitrogen through the soil is higher in well-drained soils, and the conversion to nitrous oxide is less. Therefore, poorly drained soils enhance nitrous oxide emissions. The second factor is plant uptake of ammonia and nitrate nitrogen. Manure that is applied to cropland outside of the growing season has more available nitrogen for nitrous oxide emissions, as does manure that is applied at higher than agronomic rates. Key term: Drylots are open feedlots sloped or graded from 4% to 6% to promote drainage away from the lot to provide consistently dry areas for cattle to rest. Drylots may be paved, unpaved, or partially paved. At most operations, the manure application site is the principal source of nitrous oxide. How - ever, if manure is applied correctly and at agronomic rates, little if any increase should occur in nitrous oxide emissions relative to emissions from application of inorganic commercial fertilizers. 7.2.2.3 Methane Methane is a product of the microbial degradation of organic matter under anaerobic conditions. The microorganisms responsible, known collectively as methanogens, decompose and convert carbon (cellulose, sugars, proteins, fats) in manure and bedding materials into methane and carbon dioxide. Because anaerobic conditions are necessary, manures handled as a liquid or slurry emit methane. Manures handled as solids generally have a low enough moisture content to allow adequate diffu - sion of atmospheric oxygen to preclude anaerobic activity or permit the subsequent oxidation of any methane generated. Methane is insoluble in water. Thus, methane volatilizes from solution as rapidly as it is generated. Concurrent with the generation of methane is the microbially mediated production of carbon dioxide, which is only sparingly soluble in water. Therefore, methane emissions are accompanied by carbon dioxide emissions. The mixture of these two gases is commonly referred to as biogas. The relative fractions of methane and carbon dioxide in biogas vary depending on the population of methanogens present. Under conditions favorable for the growth of methano - gens, biogas normally are between 60% and 70% methane and 30% to 40% carbon dioxide. If, however, the growth of methanogens is inhibited, the methane fraction of biogas can be less than 30%. Key term: Biogas is a combustible mixture of methane and carbon dioxide produced by the bacte- rial decomposition of organic wastes under anaerobic conditions. It may be used as a fuel. The principal factors affecting methane emissions are the amount of manure produced and the portion of the manure that decomposes anaerobically, which depends on the biodegradability of the organic fraction and the management of manure. When manure is stored or handled as a liquid (anaerobic lagoons, ponds, tanks, or pits), it decomposes anaerobically and produces a signicant quantity of methane. Anaerobic lagoons are designed to balance methanogenic microbial activity with organic loading and, therefore, produce more methane than ponds or tanks. The organic con - tent of manure is measured as volatile solids. When manure is handled as a solid (in open feedlots or stockpiles), it tends to decompose aerobically and little or no methane is produced. Likewise, manure application sites are not likely sources of methane because the necessary anaerobic condi - tions generally do not exist, except when soils become saturated. In addition, because methane 7098.indb 266 4/25/07 5:31:27 PM © 2007 by Taylor & Francis Group, LLC Animal Waste and Air Quality Problems 267 is insoluble in water, any methane generated during liquid storage or stabilization treatment is released immediately and is not present when manure is applied to cropland. 7.2.2.4 Carbon Dioxide Carbon dioxide is a product of the microbial degradation of organic matter under both aerobic and anaerobic conditions. Under aerobic conditions, carbon dioxide and water are the end-products, with essentially all of the carbon emitted as carbon dioxide. Under anaerobic conditions, carbon dioxide is one of the products of the microbial decomposition of organic matter to methane. Under these conditions, carbon dioxide is formed as a by-product of the decomposition reactions involving complex organic compounds that contain oxygen. Thus, carbon dioxide is emitted under both aero - bic and anaerobic conditions and occurs wherever manure is present. Land application sites emit carbon dioxide from the decomposition of manorial organic matter by soil microorganisms. Although AFOs emit carbon dioxide, the emissions do not contribute to a net long-term increase in atmospheric carbon dioxide concentrations. The carbon dioxide from animal manures is a release of carbon sequestered by photosynthesis during the past 1 to 3 years at most. Thus, the carbon diox - ide emitted is part of a cycling of carbon from the atmosphere to crops to animals and back into the atmosphere over a relatively short time period. 7.2.2.5 Volatile Organic Compounds VOCs are formed as intermediate metabolites in the degradation of organic matter in manure. Under aerobic conditions, any VOC formed are rapidly oxidized to carbon dioxide and water. Under anaerobic conditions, complex organic compounds are degraded microbially to volatile organic acids and other VOCs, which in turn are converted to methane and carbon dioxide by methanogenic bacteria. When the activity of the methanogenic bacteria is not inhibited, virtually all VOCs are metabolized to simpler compounds, and the potential for VOC emissions is nominal. However, the inhibition of methane formation results in a buildup of VOCs in the manure and ultimate volatiliza - tion to the air. Inhibition of methane formation typically is caused by low temperatures or exces - sive loading rates of volatile solids in a liquid storage facility. Both of these conditions create an imbalance between populations of the microorganisms responsible for the formation of VOCs and methanogenic bacteria. Therefore, VOC emissions are minimal from properly designed and oper - ated stabilization processes (such as anaerobic lagoons) and the associated manure application site. In contrast, VOC emissions are higher from storage tanks, ponds, overloaded anaerobic lagoons, and associated land application sites. The specic VOC emitted varies depending on the solubility of individual compounds and other factors (including temperature) that affect solubility. 7.2.2.6 Hydrogen Sulfide and Other Reduced Sulfur Compounds Hydrogen sulde and other reduced sulfur compounds are produced as manure decomposes anaero - bically. The two primary sources of sulfur in animal manures are the sulfur amino acids contained in feed and inorganic sulfur compounds, such as copper sulfate and zinc sulfate, which are used as feed additives to supply trace minerals and serve as growth stimulants. Although sulfates are used as trace mineral carriers in all sectors of animal agriculture, their use is more extensive in the poultry and swine industries. A possible third source of sulfur in some locations is trace minerals in drinking water. Hydrogen sulde is the predominant reduced sulfur compound emitted from AFOs. Other emit - ted compounds include methyl mercaptans, dimethyl sulde, dimethyl disulde, and carbonyl sul - de. Small quantities of other reduced sulfur compounds are likely to be emitted as well. Under anaerobic conditions, any excreted sulfur that is not in the form of hydrogen sulde is reduced microbially to hydrogen sulde. Therefore, manures managed as liquids or slurries are potential sources of hydrogen sulde emissions. The magnitude of hydrogen sulde emissions is a 7098.indb 267 4/25/07 5:31:27 PM © 2007 by Taylor & Francis Group, LLC 268 Environmental Management of Concentrated Animal Feeding Operations (CAFOs) function of liquid phase concentration, temperature, and pH. Temperature and pH affect the solu- bility of hydrogen sulde in water, which increases at pH values above 7. Therefore, as pH shifts from alkaline to acidic (pH < 7), the potential for hydrogen sulde emissions increases (Snoeyink & Jenkins, 1980). Under anaerobic conditions, livestock and poultry manures are acidic, with pH values ranging from 5.5 to 6.5. Key term: pH is the negative logarithm of the hydrogen ion concentration. The pH scale ranges from 0 to 14. Values below 7 are considered acidic; those above, alkaline. Under aerobic conditions, any reduced sulfur compounds in manure are oxidized microbially to nonvolatile sulfate, and emissions of hydrogen sulde are minimal. Therefore, emissions from connement facilities with dry manure handling systems and dry manure stockpiles should be negligible, if adequate exposure to atmospheric oxygen to maintain aerobic conditions occurs. Any hydrogen sulde that is generated in dry manure generally is oxidized as diffusion through aerobic areas occurs. In summary, manure storage tanks, ponds, anaerobic lagoons, and land application sites are primary sources of hydrogen sulde emissions whenever sulfur is present in manure. Conne - ment facilities with manure ushing systems that use supernatant from anaerobic lagoons also are sources of hydrogen sulde emissions. Key term: Supernatant is the liquid fraction above settled solids in a lagoon or storage tank. 7.2.2.7 Particulate Matter In this text, the authors consider particulate matter (PM) as PM10 and PM2.5. PM 10 is commonly dened as airborne particles with aerodynamic equivalent diameters (AEDs) less than 10 µm. The number refers to the 50% cut diameter in a Federal Reference Method PM 10 sampler where par - ticles of 10 µm AED are collected at 50% efciency (62 Fed. Reg. 38651-38701). Similarly, PM2.5 refers to the particles that are collected in a Federal Reference Method PM2.5 sampler, which has a 50% cut diameter of 2.5 µm (62 Fed. Reg. 38651-38701). Key term: Particulate matter (PM) is any airborne, nely divided solid or liquid matter with an aerodynamic diameter less than or equal to 100 µm. For this text, PM means total suspended par - ticulate (TSP), except where noted specically as PM 10. Key term: Aerodynamic equivalent diameter (AED) is the diameter of a sphere (in µm) of unit density (1 g/cm 3 ) that has the same terminal settling velocity in air as the particle of interest (a 1 µm AED particle has 1000 times the volume of a 0.1 µm AED particle). The AED refers to an individ - ual particle. The AED of PM is critical to its health and radiative effects. PM 2.5 can reach and be deposited in the smallest airways (alveoli) in the lungs, whereas larger particles tend to be deposited in the upper airways of the respiratory tract (National Research Council [NRC], 2002). Sources of PM emissions include feed, bedding materials, dry manure, unpaved soil surfaces, animal dander, and poultry feathers. Therefore, connement facilities, dry manure storage sites, and land application sites are potential PM emission sources. The relative signicance of each source depends on three interrelated factors: (1) the type of animal being raised, (2) the design of the connement facility being used, and (3) the method of manure handling. The National Ambient Air Quality Standards (NAAQS, pronounced “knacks”) currently regu - late concentrations of PM with a mass median diameter of 10 µm of less (PM 10). Studies have shown that particles in the smaller size fractions contribute most to human health effects. The cur - rent PM 10 standard may be replaced by a standard for PM 2.5. A PM 2.5 standard was published in 1997, but has not been implemented pending the results of ongoing litigation. The particle size distribution of PM emitted from AFOs has not been well-characterized. Virtu - ally all of the emissions studies to date have measured total suspended particulate or did not report 7098.indb 268 4/25/07 5:31:28 PM © 2007 by Taylor & Francis Group, LLC Animal Waste and Air Quality Problems 269 the test method used. Particle size distribution data was found only for beef feedlots. In one study, ambient measurements of PM 10 and PM 2.5 (using 5 hour sample collection periods) were taken downwind (15 to 61 m) of three cattle feedlots in the Southern Great Plains (Sweeten et al., 1998). In this study, PM 10 was measured as 20% to 40% of TSP (depending on the measurement method used), and PM 2.5 was 5% of TSP. No studies were found of particle size distribution from conne - ment buildings. Based on the emission mechanisms at AFOs, one would expect to nd that: (1) PM from AFOs would have varying particle size distributions depending on the animal sector, method of connement, and type of building ventilation used and (2) the PM emitted would include PM 10 and a lesser fraction of PM 2.5. In addition to direct emissions, PM 2.5 can be secondarily formed in the atmosphere from emissions of ammonia. If sulfur oxides or nitrogen oxides are present in the air, ammonia is converted to ammonium sulfate or ammonium nitrate, respectively. No information is available at this time to quantify the emissions of secondarily formed PM 2.5. All connement facilities are sources of PM emissions. However, the composition of these emissions vary. The only constant constituent is animal dander and feather particles from poultry. For poultry and swine, feed particles constitute a signicant fraction of PM emissions because the dry, ground feed grains and other ingredients used to formulate these feeds are inherently dusty. Pelleting of feeds reduces, but does not eliminate, dust and PM emissions. Dried forages also gener - ate PM, but most likely to a lesser degree. Silages, which have relatively high moisture content, tend to generate less PM than do other types of feed. Because veal calves are fed a liquid diet, feed does not contribute to particle emissions from veal operations. The mass of PM emitted from totally or partially enclosed connement facilities, as well as the particle size distribution, depend on type of ventilation and ventilation rate. Particulate matter emissions from naturally ventilated buildings are lower than those from mechanically ventilated buildings. Mechanically ventilated buildings emit more PM at higher ventilation rates. Therefore, connement facilities located in warmer climates tend to emit more PM because of the higher ven - tilation rates needed for cooling. While connement facilities for dairy and beef cattle typically are all naturally ventilated, facilities for poultry, swine, and veal are mechanically ventilated for all or at least part of the year. When mechanical ventilation is used for only part of the year, it is used during the coldest and hot - test months, with natural ventilation used during the remainder of the year. Open feedlots and storage facilities for dry manure from broilers, turkeys, laying hens in high rise houses, dairy drylots, and beef cattle drylots also are potential sources of PM. These sites are intermittent sources of PM emissions, because of the variable nature of wind direction and speed and precipitation. Thus, the moisture content of the manure and the resulting emissions are highly variable. The PM emissions from covered manure storage facilities depend on the degree of expo - sure to wind. Key term: A feedlot is a concentrated, conned animal or poultry growing operation for meat, milk, or egg production, or stabling, in pens or houses, wherein the animals or poultry are fed at the place of connement and crop or forage growth or production is not sustained in the area of conned and is subject to 40 CFR 412. Key term: Broilers are chickens of either sex specically bred for meat production and marketed at approximately 7 weeks of age. Key term: A hen is a mature female chicken. 7.2.2.8 Odors Generally, odor is not a problem until the neighbors complain. In the not-too-distant past, agricul - tural activities were isolated, rural activities with few neighbors, and those neighbors were also agriculturally based. Thus, agricultural operations that produced odors in these settings, those hav - ing few neighbors, consequently had few, if any, complaints. With the expansion of urban centers 7098.indb 269 4/25/07 5:31:28 PM © 2007 by Taylor & Francis Group, LLC 270 Environmental Management of Concentrated Animal Feeding Operations (CAFOs) (suburbia, exurbia), however, many formerly isolated agricultural operations have been squeezed from all directions by new construction and new neighbors. Odors that were not previously offen - sive because of lack of neighbors now have become irritating to the point of complaint—and com - plain these new, urban neighbors do. Odor generated from an AFO is not the result of a distinct compound but rather is is the result of a large number of contributing compounds. Schiffman et al. (2001) identied 331 odor-causing compounds in swine manure. The principal compounds responsible for noxious odors are hydrogen sulde, ammonia, and VOCs. The VOCs that contribute to odors are volatile acids (acetic, propionic, formic, butyric, and valeric), indole, phenols, volatile amines, methyl mercaptans, and skatole. Most of the odorous compounds are products of anaerobic digestion or organic compounds. Therefore, the potential for odors is greater at operations with liquid manure management systems. In liquid systems, odors can be produced from storage pits, ponds, and land application. Properly designed and operated anaerobic lagoons should have relatively low odors, but odors can be pro - duced under two conditions: (1) in the spring and fall, when sudden temperature changes can upset the microbial balance or (2) if the lagoon is overloaded with volatile solids. Drylots can produce odors whenever warm, wet conditions produce transient anaerobic conditions. Odors also can be caused by decaying animals, if the carcasses are stored too long prior to disposal. Important point: Land application of manure from livestock and poultry facilities is a frequent source of odor complaints from neighbors (the public). 7.2.3 SuMMary of faCTorS affeCTing eMiSSionS To summarize Section 7.2.2, emissions from AFOs depend on manure characteristics and manure management. Manure excreted by each type of animal has specic characteristics (nitrogen content, moisture content). These characteristics, however, can be altered depending on how the manure is collected, stored, and land applied. The potential for generating emissions from manure manage - ment systems used for the beef, dairy, swine, and poultry sectors depends on several factors. The potential for PM emissions depends on whether the manure is handled in a wet or dry state. The potential for gaseous emissions generally depends on: (1) the presence of an aerobic or anaerobic microbial environment, (2) the precursors present in the manure (for example, sulfur), (3) pH of the manure, and (4) time and temperature in storage, which primarily affect mass emitted. The effect of each of these factors on emission is summarized in Table 7.3 and described next. • TABLE 7.3 Pollutant Precursors Substance emitted Wet manure handling Dry manure handling pH High temperature Manure residence time Precursors Ammonia > 7.0 X X Nitrogen Nitrous oxide X Nitrogen Hydrogen sulde X < 7.0 X X Sulfur Methane X X X Carbon VOCs X X X Carbon Particulate matter* X Source: USEPA (2001a). * Total suspended particulate. Fine particles (PM 2.5) in the form of ammonium sulfate and ammonium nitrate can be sec- ondarily formed in the atmosphere from ammonia emissions, if sulfur oxides or nitrogen oxides are present in the air. 7098.indb 270 4/25/07 5:31:28 PM © 2007 by Taylor & Francis Group, LLC [...]... 10, 673 10,329 10, 673 10, 673 9,640 10, 673 10,329 10, 673 10,329 10, 673 10, 673 10,329 10, 673 10,329 10, 673 25,6 67 Cumulative Producede 10, 673 18, 974 27, 791 37, 019 45 ,75 6 53,560 59 ,72 3 60, 676 53,593 41,036 25,596 24,215 10, 673 19,195 27, 558 458,600 Consumedf Methane Emitted (kg)g 2,028 1,856 1,445 904 2,869 4,165 9 .72 0 17, 412 23,230 26,113 11 ,71 0 7, 111 1,8 07 2,310 1,3 27 108, 679 973 891 694 434 1, 377 1,999... = 23 lb N AU-yr AU-yr © 20 07 by Taylor & Francis Group, LLC 70 98.indb 277 4/25/ 07 5:31:32 PM 278 Environmental Management of Concentrated Animal Feeding Operations (CAFOs) This converts to an emission factor for dairy flush houses of 28 lb NH3/AU yr The other instances where emissions information were translated from one animal species to another are shown in the following calculations 7. 4.2.1.2.1 ... short-term emissions are influenced by the type of manure application method used The second phase is the release from the soil that occurs over a longer period as a result of the microbial breakdown of substances in the applied manure © 20 07 by Taylor & Francis Group, LLC 70 98.indb 271 4/25/ 07 5:31:29 PM 272 Environmental Management of Concentrated Animal Feeding Operations (CAFOs) 7. 3.1 Short-Term... 61.3 57. 1 46 .7 0. 17 0.15 0.15 0.16 0.33 0.41 0.58 0 .78 0 .76 0.49 0.30 0.24 0.14 13,352 13,352 12,060 13,352 12,921 13,352 12,921 13,352 13,352 12,921 13,352 12,921 13,352 1 57, 206 10,681 10,681 9,648 10,681 10,3 37 10,681 10,3 37 10,681 10,681 10,3 37 10,681 10,3 37 10,681 125 ,76 4 24,421 30,949 35,846 41,236 44,936 40,915 34,548 25, 170 16,204 14,205 10,681 17, 779 24,112 336,583 4,153 4 ,75 1 5,292 6,6 37 14 ,70 2... methane potential of the waste (Bo) For swine, Bo is equal to 0.48 m3 methane/kg VS (Table 7. 9) = 900 kg VS consumed multiplied by 0.48 m3 methane/kg VS = 432 m3 methane = 289 kg methane (assuming a density of 0. 67 kg/m3 © 20 07 by Taylor & Francis Group, LLC 70 98.indb 2 87 4/25/ 07 5:31:42 PM 288 Environmental Management of Concentrated Animal Feeding Operations (CAFOs) Tables 7. 11 and 7. 12 show the calculations... T1B 4/25/ 07 5:31:44 PM Source: USEPA (2001a) © 20 07 by Taylor & Francis Group, LLC 293 Beef Animal Waste and Air Quality Problems Table 7. 16 Summary of Virtual Farms 294 Environmental Management of Concentrated Animal Feeding Operations (CAFOs) Table 7. 17 Summary of Beef Emission Factors Emission Source Emission Number of Average/Median Factor Range Emission Emission Factor Substance (lb/yr-AU) Factors... 290.4 17. 2 63.0 0.33 13,352 10,681 10,681 3,521 1,690 November 285 .7 12.6 54.6 0.21 12,921 10,3 37 17, 4 97 3 ,75 8 1,804 December January February March April May June July August September October November December Sumh 283.2 282 .7 281.8 282 .7 290.3 292.8 300.2 299.9 294.8 289.5 289.5 2 87. 1 281.3 10.1 9.0 8.6 9.5 17. 1 19.6 23.6 27. 1 26.8 21 .7 16.3 14.0 8.2 50.2 48.2 47. 5 49.1 62.8 67. 3 74 .5 80 .7 80.2 71 .0... knowledge of fundamental microbial and emission mechanisms © 20 07 by Taylor & Francis Group, LLC 70 98.indb 273 4/25/ 07 5:31:29 PM 274 Environmental Management of Concentrated Animal Feeding Operations (CAFOs) Section 7. 4.4 presents the emission factors and the annual emissions from the virtual farms To provide a perspective on these results, Section 7. 4.5 compares the virtual farm emissions to the amount of. .. anaerobic lagoons based on a fraction of the potential methane emissions being converted to VOCs, using the methodology and information presented in Section 7. 4.2.5 © 20 07 by Taylor & Francis Group, LLC 70 98.indb 295 4/25/ 07 5:31:45 PM 296 Environmental Management of Concentrated Animal Feeding Operations (CAFOs) Table 7. 20 Summary of Emissions from Veal Virtual Farms (tons/year-500 AU farm) Virtual ID Emission... 70 98.indb 279 4/25/ 07 5:31:36 PM 280 Environmental Management of Concentrated Animal Feeding Operations (CAFOs) Excreted_N = 0 .74 lb N 11.5 lb LW 105 days 2 cycles 55 turkeys × × × × = 98.3 lb N AU-yr day ·1000 lb LW turkey hen cycle yr AU For toms: Excreted_N = 0 .74 lb N 16.8 lb LW 133 days 2 cycles 55 turkeys × × × × = 182 lb N AU-yr day ·1000 lb LW turkey tom cycle yr AU The average of toms and . = 142 lb N AU-yr lb N AU-yr× =0 16 23. 70 98.indb 277 4/25/ 07 5:31:32 PM © 20 07 by Taylor & Francis Group, LLC 278 Environmental Management of Concentrated Animal Feeding Operations (CAFOs) This. emissions is a 70 98.indb 2 67 4/25/ 07 5:31: 27 PM © 20 07 by Taylor & Francis Group, LLC 268 Environmental Management of Concentrated Animal Feeding Operations (CAFOs) function of liquid phase. absence of 70 98.indb 261 4/25/ 07 5:31:25 PM © 20 07 by Taylor & Francis Group, LLC 262 Environmental Management of Concentrated Animal Feeding Operations (CAFOs) vegetative cover of any signicance