Ammonia Released from Broiler houses Zifei Liu, Lingjuan Wang, David - - PowerPoint PPT Presentation
A Review of Emission Models of Ammonia Released from Broiler houses Zifei Liu, Lingjuan Wang, David Beasley Department of Biological and Agricultural Engineering, North Carolina State University Biological & Agricultural Engineering 1
Zifei Liu, Lingjuan Wang, David Beasley Department of Biological and Agricultural Engineering, North Carolina State University
Biological & Agricultural Engineering 1
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Ammonia as an air pollutant (Four major impacts)
Soil acidification
(Nitrification processes)
Eutrophication
(Excess N deposition)
Aerosol formation
(Fine particle precursor)
Health impact
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Ammonia emissions from animal production
Animal Production 80% Human activities 10% Cropping Activities 10%
Air Emissions from Animal Feeding Operations: Current Knowledge, Future Needs, National Research Council (NRC) of The National Academies of Science, 2003 Consent agreements with USEPA, 2005
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Broiler litter NH3 NH3
Broiler house
Ammonia in broiler house: affect bird performance Ammonia emissions: the primary concern for regulatory reporting under CERCLA
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Estimation of Emission Rates form broiler houses
Wide variations have been found Seasonal conditions Regional conditions House design Management practices Litter properties … Quantifying of ammonia emission rates from broiler houses: a complex process
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1. To calculate site-specific emissions, using the local design and operating parameters. 2. To quantify and evaluate the effectiveness of the various control strategies 3. To simulate seasonal and geographic variations in ammonia emission factors
Three major objectives of emission models
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Emission models
Mechanistic models Sub-models Empirical models Inverse dispersion models Mass balance models Process based models N-mass flow models
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Scientific basis of ammonia emissions from broiler litter
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Mass transfer flux equation Emission flux = Km (C g, 0 – C g, ∞ )
Air velocity Temperature Surface roughness Air density Air viscosity Kh C l, 0 Kd pH Generation & diffusion of TAN in litter Temperature Litter moisture Litter N content Microbial & enzymatic activities Temperatur e
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Factors that may affect ammonia emissions from broiler litter
– Residence time – Air velocity
– Diet – litter age – bird age
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Emissions = A [TAN] H* r-1
A : the area of exposed manure [TAN] : concentration of TAN H* : effective Henry’s constant r : mass transfer resistance
(Pinder et al., 2004)
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Emission rates = Q (Chouse - Cout) Q : ventilation rate Chouse: concentration of NH3 in house air Cout : concentration of NH3 in outside air
(Zhang et al., 2006)
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Ventilation sub-models
(Hutchings et al., 2006; Zhang et al., 2005; Koerkamp et al., 1998)
maintain the indoor temperature at a target value suitable for the animal species. Outside temperature Sensible heat production of the animals Ventilation rate Thermal energy models
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N-excretion sub-models
(Zhang et al., 2006)
production and characteristics were used as the basis for developing the manure and N excretion model. Type and growth stage of animals Feed factors Animal productivity Animal management practices N excretion
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(Carr et al.,1990 ) Ammonia concentration in house Litter pH Litter temperature Litter moisture content Air temperature RH Litter moisture content
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(Gates et al., 2004; Wheeler et al., 2004) Bird age Emission rates
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Flow diagram of nitrogen input and output of broiler house
Broiler house Bird Litter Feed Water Finished bird Used litter Leachate Ammonia emission Other gases
(NRC, 2003; Burns et al., 2003; Keener and Zhao, 2006)
Input Output
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(Siefert et al., 2004; Faulkner, et al., 2006) Emission rates Downwind concentration Dispersion plume models Inverse dispersion models
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(Mukhtar et al. 2004; Zhang et al., 2005; Kohn et al., 1997). )
emissions from AFO as a whole and consider each of the processes occurring on a typical farm, and calculates the resulting ammonia emissions from each.
Housing Storage Land application
AFO
NH3 NH3 NH3 NH3
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(Mukhtar et al. 2004; Zhang et al., 2005; Kohn et al., 1997). )
enterprise are likely to be more important for some emissions than for others. Development of a process-based model would enable system analysis and simulation for determining critical control points for emissions
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(Reidy, et al. 2006)
used in the national ammonia emission inventory calculations and manure policy analysis in Europe. Housing Storage Land application
NH3 NH3 NH3
TAN TAN TAN
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(Reidy, et al. 2006)
rapid and easy estimation of the consequences of upstream emission on downstream emissions. It has been adopted to calculate the interaction between abatement techniques at various stages of manure management.
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to fit different objectives for the estimation.
as geographical resolution of ammonia emission models to meet the requirement of recent chemical transport modeling .
Summary and future directions
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Characterization of management factors and litter conditions are not well documented and they have not been adequately incorporated into current mechanistic models. Much work remains to be done because of the number of variables in practice. Further evaluation of these variables is needed for enhanced understanding of the wide variation in ammonia emission rates.
it would be valuable to expand research in well-controlled test facilities and evaluate model components individually or in designed combinations.
Summary and future directions
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