National Academies Press: OpenBook

Air Emissions from Animal Feeding Operations: Current Knowledge, Future Needs (2003)

Chapter: Appendix F: Ammonia Emissions from Manure Storage

« Previous: Appendix E: Animal Units
Suggested Citation:"Appendix F: Ammonia Emissions from Manure Storage." National Research Council. 2003. Air Emissions from Animal Feeding Operations: Current Knowledge, Future Needs. Washington, DC: The National Academies Press. doi: 10.17226/10586.
×

F
Ammonia Emissions from Manure Storage

The production of ammonia from animal manure via mineralization of organic nitrogen on the kth day of storage can be predicted using the following equation:

TMTAN,k = ΓNi · N0i · NCFjk · WSij · CAF,

where

TMTAN,k =

production of total ammoniacal nitrogen (TAN) from manure storage on the farm in grams per day on the kth day of storage;

Ni =

total nitrogen excreted by animal i in grams per day;

N0i =

maximum TAN production potential of the manure from animal i in grams per grams of total nitrogen;

NCFjk =

nitrogen conversion factor for manure storage j, for k days of storage time, which represents the extent to which the N0 is realized (note: 0 ≤ NCF ≤ 1);

WSij =

fraction of waste of animal i handled in manure storage j;

CAF =

climate adjustment factor for the farm, which represents the extent to which N0 is realized under climatic conditions (e.g., temperature and rainfall) on the farm (note: 0 ≤ CAF ≤ 1).

Quantitative information on the production of ammonia in animal manure is scarce in the literature. Zhang et al. (1994) developed equations for predicting the production rate of ammonia in swine manure storage as a function of time and depth in the manure. However, their study did not account for the influence of

Suggested Citation:"Appendix F: Ammonia Emissions from Manure Storage." National Research Council. 2003. Air Emissions from Animal Feeding Operations: Current Knowledge, Future Needs. Washington, DC: The National Academies Press. doi: 10.17226/10586.
×

different temperatures, manure solid content, and oxygen content. More research is needed to develop accurate prediction models for quantifying the production rate of ammonia due to mineralization of organic nitrogen in different types of manure management systems.

Once ammonia (NH3) is generated in animal housing or manure storage, its emission from the manure to the atmosphere is controlled by the aqueous chemistry of NH3 in the manure and the convective mass-transfer mechanism at the manure surface. The pH, manure temperature, air temperature, wind velocity, and relative humidity are major factors affecting the emission process. The pH controls the partitioning of ammonia between NH3 and NH4+ (ammonium ion) in the water. The emission rate of ammonia from manure on the kth day can be calculated using the following mass-transfer equation,

where M is g/m2, 86,400 is the number of seconds in a day, KL is the mass transfer coefficient in meters per second, F is the fraction factor for free ammonia in total ammonia and has a value of 0-1, and [TAN]k is the concentration of total ammoniacal nitrogen in milligrams per liter after k days. F can be determined as a function of pH and ionization constant (Ka) of ammonia in water, using the following equation:

Ka is a function of water temperature (Taq, kelvin) as shown in the following equation:

It has been found by researchers that the Ka in wastewater has a different value from that in water (Zhang et al., 1994; Liang et al., 2002). The Ka in animal manure (Ka,m) is 25-50 percent of the Ka in water, depending on the characteristics of manure, such as its solids content.

KL is the convective mass-transfer coefficient and [TAN] is the concentration of total ammoniacal nitrogen at the manure surface. If the stratification of NH3 in the manure is negligible, [TAN] can be assumed to be the concentration in the bulk liquid. For any given day k, [TAN]k can be calculated by the concentra-

Suggested Citation:"Appendix F: Ammonia Emissions from Manure Storage." National Research Council. 2003. Air Emissions from Animal Feeding Operations: Current Knowledge, Future Needs. Washington, DC: The National Academies Press. doi: 10.17226/10586.
×

tion at the end of previous day, [TAN]k−1, and the ammonia generated on the kth day (TMTAN,k, grams) divided by the volume (V, cubic meters) of the liquid manure in storage, as shown below:

[TAN] k = [TAN]k−1 + TMTAN,k /V.

The mass-transfer coefficient KL is a function of manure temperature, air temperature, wind velocity, and relative humidity. Various equations for KL are available in the literature. However, most of them were developed using controlled experiments by means of convective mass-transfer chambers, and have not been well validated using field-scale experiments. More research is needed to calibrate and validate them. An example is given below is based on the two-film theory.

AMMONIA MASS-TRANSFER COEFFICIENT

The mass-transfer coefficient for ammonia as derived from the two-film theory (Whitman, 1923) is given as follows:

where KL is the overall mass-transfer coefficient in meters per second, KH is Henry’s law constant (dimensionless) calculated as a function of water temperature (Taq, kelvin),

and and are mass-transfer coefficients (meters per second) through gaseous and liquid films, respectively, at the interface of water and air, and are related to the diffusivities (square meters per second) of ammonia and water in air ( and ), and of ammonia and oxygen in water ( and ):

Suggested Citation:"Appendix F: Ammonia Emissions from Manure Storage." National Research Council. 2003. Air Emissions from Animal Feeding Operations: Current Knowledge, Future Needs. Washington, DC: The National Academies Press. doi: 10.17226/10586.
×

where u8 is the wind velocity (meters per second) at 8 m above the water surface. The diffusivities are calculated using the following equations:

where M is the molecular weight (grams per mole), Ta and Taq are the air and water temperatures (kelvin), and v is the molecular diffusion volume (cubic centimeters per mole).

Suggested Citation:"Appendix F: Ammonia Emissions from Manure Storage." National Research Council. 2003. Air Emissions from Animal Feeding Operations: Current Knowledge, Future Needs. Washington, DC: The National Academies Press. doi: 10.17226/10586.
×

SYMBOL DEFINITIONS, UNITS

KL

Overall mass-transfer coefficient of ammonia, cm/h

KH

Henry’s coefficient, dimensionless

Mass-transfer coefficient of ammonia in liquid phase, cm/h

Mass-transfer coefficient of ammonia in gas phase, cm/h

Mass-transfer coefficient of oxygen in liquid phase, cm/h

Mass-transfer coefficient of water in gas phase, cm/h

u8

Wind speed at 8-m height, m/s

uz

Wind speed at an anemometer height z, m/s

z0

Roughness height, m

P

Atmospheric pressure, atm

NH3 diffusion coefficient in air, m2/s

H2O diffusion coefficient in air, m2/s

O2 diffusion coefficient in water, m2/s

NH3 diffusion coefficient in water, m2/s

Mair

Molecular weight of air (average), g/mol (29)

Molecular weight of NH3, g/mol (17)

Molecular weight of H2O, g/mol (18)

v)air

Air molecular diffusion volume, 20.1 cm3/mol

NH3 molecular diffusion volume, 14.9 cm3/mol

Ta

Air temperature, K, mg/l

[TAN] k

Total ammoniacal concentration at the manure surface on the kth day of storage

Taq

Water (manure) temperature, K

Suggested Citation:"Appendix F: Ammonia Emissions from Manure Storage." National Research Council. 2003. Air Emissions from Animal Feeding Operations: Current Knowledge, Future Needs. Washington, DC: The National Academies Press. doi: 10.17226/10586.
×
Page 217
Suggested Citation:"Appendix F: Ammonia Emissions from Manure Storage." National Research Council. 2003. Air Emissions from Animal Feeding Operations: Current Knowledge, Future Needs. Washington, DC: The National Academies Press. doi: 10.17226/10586.
×
Page 218
Suggested Citation:"Appendix F: Ammonia Emissions from Manure Storage." National Research Council. 2003. Air Emissions from Animal Feeding Operations: Current Knowledge, Future Needs. Washington, DC: The National Academies Press. doi: 10.17226/10586.
×
Page 219
Suggested Citation:"Appendix F: Ammonia Emissions from Manure Storage." National Research Council. 2003. Air Emissions from Animal Feeding Operations: Current Knowledge, Future Needs. Washington, DC: The National Academies Press. doi: 10.17226/10586.
×
Page 220
Suggested Citation:"Appendix F: Ammonia Emissions from Manure Storage." National Research Council. 2003. Air Emissions from Animal Feeding Operations: Current Knowledge, Future Needs. Washington, DC: The National Academies Press. doi: 10.17226/10586.
×
Page 221
Next: Appendix G: Regulatory Action Levels by Selected Atmospheric Pollutant »
Air Emissions from Animal Feeding Operations: Current Knowledge, Future Needs Get This Book
×
Buy Paperback | $67.00 Buy Ebook | $54.99
MyNAP members save 10% online.
Login or Register to save!
Download Free PDF

Air Emissions from Animal Feeding Operations: Current Knowledge, Future Needs discusses the need for the U.S. Environmental Protection Agency to implement a new method for estimating the amount of ammonia, nitrous oxide, methane, and other pollutants emitted from livestock and poultry farms, and for determining how these emissions are dispersed in the atmosphere. The committee calls for the EPA and the U.S. Department of Agriculture to establish a joint council to coordinate and oversee short - and long-term research to estimate emissions from animal feeding operations accurately and to develop mitigation strategies. Their recommendation was for the joint council to focus its efforts first on those pollutants that pose the greatest risk to the environment and public health.

  1. ×

    Welcome to OpenBook!

    You're looking at OpenBook, NAP.edu's online reading room since 1999. Based on feedback from you, our users, we've made some improvements that make it easier than ever to read thousands of publications on our website.

    Do you want to take a quick tour of the OpenBook's features?

    No Thanks Take a Tour »
  2. ×

    Show this book's table of contents, where you can jump to any chapter by name.

    « Back Next »
  3. ×

    ...or use these buttons to go back to the previous chapter or skip to the next one.

    « Back Next »
  4. ×

    Jump up to the previous page or down to the next one. Also, you can type in a page number and press Enter to go directly to that page in the book.

    « Back Next »
  5. ×

    Switch between the Original Pages, where you can read the report as it appeared in print, and Text Pages for the web version, where you can highlight and search the text.

    « Back Next »
  6. ×

    To search the entire text of this book, type in your search term here and press Enter.

    « Back Next »
  7. ×

    Share a link to this book page on your preferred social network or via email.

    « Back Next »
  8. ×

    View our suggested citation for this chapter.

    « Back Next »
  9. ×

    Ready to take your reading offline? Click here to buy this book in print or download it as a free PDF, if available.

    « Back Next »
Stay Connected!