Understanding Livestock Odors Ron Sheffield Animal Waste Extension Specialist

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Understanding Livestock OdorsRon
SheffieldAnimal Waste Extension Specialist
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Odors from Livestock Facilities
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Odors from Livestock Facilities

• Highly emotional issue
• Rural development
• Economic importance of livestock industry
• Only after we understand the problem can we work
  towards acceptable solutions.

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Olfaction-Sense of Smell

• Complex
• Evokes a reaction
• Humans detect gt 10,000 odors
• Mixtures of gases
• Able to detect extremely low concentrations

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Conception of Odors and Smells

• Describe a childhood odor memory
• What is your favorite odor? Why?
• Describe your most unusual odor memory

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Breathing vs. Sniffing
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Normal Olfactory Sensitivity
Ansomic Condition
Hypersensitive Condition
Population Detecting Odor ()
Normal Sense of Smell
Odor Concentration
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How are odors produced?

• By-products of microbial degradation of manure
  and organic matter
• Uncontrolled anaerobic conditions
• Highly dependent on the amount and type of
  microbial activity

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Manure Decomposition

• Over 80 to 200 different gasses identified
• Manure gasses related to anaerobic decomposition
• Ammonia (NH3)
• Methane (CH4)
• Hydrogen sulfide (H2S)
• Odorants
• volatile fatty acids
• Dust and other particulate matter

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Manure Gasses

• Hydrogen Sulfide
• Methane
• colder climates, poor ventilation, anaerobic
  decomposition of stored manure
• Ammonia (NH3)
• dominates in warmer climates
• anaerobic by-product
• compounded by recycling of lagoon effluent for
  waste handling

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Dust

• Sources
• Feed
• Dried Manure
• Dander (dead skin)
• Hair
• Other particulate matter
• viral, bacterial, and fungal agents
• endotoxin, glucans
• Dual role as possible odorant and odor carrier

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Odor and Gas Emissions

• Parameters that effect odor and microbe
  production
• moisture content
• temperature
• pH
• oxygen concentrations
• environmental conditions (season, wind patterns)

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Manure Gases

• Nose detection at low levels
• Hydrogen Sulfide (H2S)
• Nose detection at high level
• Methane (CH4)
• Some gases may have a compounding odor effect

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Odor Emission Sources

• Livestock buildings
• Manure storage units
• Land application sites
• Method of land application
• Feed storage
• Mortality storage or disposal units

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Odor Sources

• Background odor
• buildings
• lagoons or storage ponds
• Seasonal variations in odor
• Short-term odors
• agitation
• land application / spray irrigation

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Odor and Gas Emissions

• Can be controlled through design and management
• ventilation system
• management and housekeeping practices
• waste management system
• waste application system

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Odor Chemistry

• Odorous Compounds
• Aliphatic (fatty) Acids
• Amines
• Ammonia
• Aromatics
• Sulfur (inorganic and organic)

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Compounds Produced through Anaerobic
Decomposition

• Methane
• Carbon Dioxide
• Carbon Monoxide
• Ammonia
• Hydrogen Sulfide
• Acetic, Propionic, Butyric Acids
• Cadaverine and Putresine - bacterial breakdown of
  amino acids

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Osmophores

• Odors are caused by this group of radicals
• CHO- Aldehydes
• CH2OH- Carbinols
• CO-2 Carbonyls
• COOH- Carboxyls
• OH- Hydroxyl compounds
• SH- Sulphydryls

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Osmophores

• Odor/smell is due to the presence of different
  molecules
• C2H5OH Ethyl Alcohol, sweet-smelling
• C3H5OH Allyl Alcohol, irritating smell
• C9H19OH Nonyl Alcohol, offensive smell

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Oxygen Transfer

• Replacement of oxygen by sulfur
• Non-odorous compounds
• H2O Water
• H2O2 Hydrogen Peroxide
• CO2 Carbon Dioxide
• Compounds become odorous
• H2S Hydrogen Sulfide
• H2S2 Hydrogen Persulfide
• CS2 Hydrogen Disulfide

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Biochemical Oxidation

• Proteins, amino acids carbohydrates are
  plentiful energy source for bacteria
• Aerobic or anaerobic process
• Bacteria transfer oxygen from compounds to a
  hydrogen acceptor
• 2NO3- 12H N2 6H2O
• CO2 8H CH4 2H2O
• SO4 10H H2S 4H2O (odorous)

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Purple Sulfur Bacteria - PSB

• Biochemical Oxidation in Anaerobic Lagoons in NC
  and southern US
• Purple lagoon color
• Photosynthetic bacteria
• Use H2S as an electron acceptor instead of O2 and
  NO3
• Reduces emission of sulfur compounds and sulfur
  based odors

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Photosynthesis
Oxygenic Green plants, algae, cyanobacteria
Anoxygenic Purple, green and Heliobacteria
Sun
Light-dependent reactions (photophosphorylation)
ATP
H2S
Dark reaction (CO2 fixation)
CO2
Carbohydrates
H2O is electron donor
H2S is electron donor
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Anaerobic Lagoons

• Studies have been inconclusive relating
  environmental conditions to the presence of PSB
  in lagoons
• loading rate (TS, VS, NH3, SO4)
• class of animals
• Temperature
• Lagoon start-up procedures

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Odors and Gases

• Odor Intensity
• measure of detection sensed by the nose
• Gas Concentration
• actual concentration of gas in the air
• The relationship between odor intensity and gas
  concentration is different for each gas

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Gas vs Odor Measurement

• Gas
• Identify individual gases
• Measure concentrations
• Odor - Olfactometry
• Analyze mixture
• Correlates with odor
• Uses human sense of smell

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Gas Measurement

• Instantaneous
• Integrated average
• Precision detection limit

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Gas Measurement

• Patches
• Tubes - Indicator Diffusion
• Jerome meter - H2S
• Electronic Sensors
• GC / Mass Spectrometer

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Odor Intensity
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Odor Intensity vs. Gas Concentration

• Weak positive correlation's for some gases
• Ammonia (NH3)
• Hydrogen Sulfide (H2S)
• Example
• High odor intensities indicate high gas
  concentrations of NH3 and H2S
• However, high gas concentrations do not
  necessarily indicate a high odor intensity

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Odor Transport

• Difficult to document the impact area of gases
• Transmitted via air currents
• wind direction
• wind speed
• weight of gas
• adsorption to dust particles

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Terrain Influence on Dispersion
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Dust Lagoon Interaction Related to Odor
Transport
Dust
Odorous Compounds
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Limits to Measuring Odors

• Changes in weather or micrometeorological
  conditions
• temperature, humidity, inversions
• Odor emissions change with time
• Wind speed and direction
• A snap-shot in time may not reflect the
  conditions an hour/day before or after a
  measurement

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Technologies to Control Odor

• Prevent odor generation
• Capture or destroy odors before any release to
  the atmosphere
• Dispersion or disguise of odors

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Odor Prevention Technologies

• Anaerobic treatment
• Aeration or Oxidation
• Feed additives
• Manure pit or lagoon additives
• pH control

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Technologies to Capture Odors

• Manure storage covers
• synthetic
• organic mats
• Biofilters
• Biomass filters
• Washing walls

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Technologies to Disperse Odors

• Site Selection
• Ventilation Design
• Vegetated Wind Breaks
• Windbreak Walls
• Stacks or Chimneys
• Perfumes
• Masking Agents

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