Tuesday, October 7, 2008

ODORS

Odor
Has insignificant effects on the global or national environment
Has major effects on the local environment
Nearest dwelling
Greatest source of nuisance complaints
Operations % of nuisance complaints from odor
Swine 95
Broiler 75
Layer 66
Beef feedlots 50
Sources
Animal buildings and lots
Manure treatment and storage
Land application
Silage
Feed processing
Dead animal disposal
Difficult to define, quantify, and control
Odor composed of 331 compounds in manure
30 compounds most common in swine manure

Most objectionable compounds in manure
Odor threshold
___Class___ ___Compound___ ____Smell_____ ____ppm____ Substrate
Volatile fatty Butyric acid Rancid butter .001 Carbohydrate
Acids Isobutryic acid Rancid butter - Protein
Caproic acid - - Carbohydrate
Isocaproic acid - - Protein
Valeric acid Putred fecal - Carbohydrate
Isovaleric acid Stinky feet - Protein
Propionic acid Intense vinegar 20.0 Carbohydrate
Phenylpropionic acid - - Protein
Lauric acid - - Carbohydrate
Acetic acid Vinegar 1.0 Carbohydrate
Ammonia and Ammonia Acrid 46.8 Protein
Amines Amines
Putrescine Rotting flesh - Protein
Cadaverine Rotting flesh - Protein
Trimethyl amine - .00021 Protein
Trimethyl pyrazine - - Protein
Tetramethly pyrazine - - Protein
Indoles and Indole Intense fecal - Protein
Phenols Skatole Nauseating fecal - Protein
Phenol - .005 Protein
Ethyl phenol - - Protein
p-Cresol Major odor in swine manure .001 Protein



Measurement of odor
Gas measurement
Air samples are collected and analyzed for specific, individual gaseous compounds
Measured with:
Patches
Indicator tubes
Meters
Electronic sensors
Gas chromatograph/mass spectrometer
Advantages
Accurate measure of individual gases
Allows for specific numeric standards
Useful for measuring gaseous compounds with specific health effects
Limitations
Manure odor is not associated with any single compound

Olfactometry
Odors are measured by a trained panel of humans
May be measured
On location
Scentometer
Field sniffer
In laboratory
Dynamic, triangular forced-air olfactometer
Characteristics to describe odor
Concentration
Detection threshold
Volume of normal air needed to dilute odor sample to
the point where the difference is detected by 50% of the panel members
Recognition threshold
Volume of normal air needed to dilute an odor sample to the point that the panel can recognize the compound
Intensity
Describes the strength of the odor relative to different concentrations of n-butanol
Persistence
Amount of air needed to dilute air around a livestock unit to the point where the odor is not smelled

Hedonic tone
Measurement of the unpleasantness of an odor
Scale of measurement is 1 to 10
Character descriptors
A description of the smell
Advantages
There is a direct correlation between odor and the sense of smell
Measures the complete mixture of gases
Limitations
Olfactometry is subjective
Imprecise
Difficult to regulate

Health effects of odors
Within buildings
Toxicity of two compounds
Ammonia
Hydrogen sulfide
Ammonia
Concentrations, ppm Exposure ________Effects____________
20 - Decreased disease resistance
50 < 1 day Eye and throat irritation
Severe cough
100 6 weeks Impaired pulmonary function
<150 < 1 day Scarring of upper and lower airway
500 30 min Sore nose and throat
<1000 - Irritation of upper respiratory
tract
>4000 - Severe damage to upper and
and lower respiratory tract
5000 < 30 min Death
Smells at 50 ppm


Hydrogen sulfide
Most dangerous of gases
Colorless
Can be smelled at 1 ppm, but concentrations > 150 ppm inhibits smell
Makes H2S particularly dangerous
Requires monitoring equipment
Gas is heavier than air
Concentrates in pits and holding tanks
Dangerous when agitated
Acute toxicity
Concentration, ppm Exposure Human effects Swine effects
100 > 1 hr Eye and nose irritation None
200 1 hr Headache, dizziness -
375 4 hr - Pulmonary edema
500 30 min Nausea, excitement, -
insomia
>500 - Severe pulmonary edema -
1000 - Unconsiousness, Spasms, convulsions
death cyanosis, death

Chronic toxicity
Occurs at long-term exposure at 300 ppm
Symptoms
Asthma, bronchitis, sinusitis, hay fever, progressive loss of lung function, chronic obstructive pulmonary disease

Effects of H2S on lungs are uniform throughout the respiratory tract
Particularly damaging to deep pulmonary structures, causing edema
Toxicity effects
Binds mitochondrial cytochrome oxidase
Blocks oxidative phosphorylation and ATP production
Causes build up of lactic acid in body
Neurophysiological abnormalities
Impaired balance
Impaired hearing
Impaired memory
Impaired mood
Impaired intellectual function
Workplace limit
10 ppm H2S

Community effects
Response to NH3, H2S, and VOCs
Symptoms
Headache
Runny nose
Sore throat
Coughing
Diarrhea
Burning eyes
Negative mood (Tension, depression, anger, fatigue, confusion)
Odor recommendations
Based on dilution ratio of clean air:air from livestock operation
Odor shall not exceed a 7:1 dilution at a residence in two periods/day for more than 7 days per year
Odor shall not exceed a 15:1 dilution at the property line for one period/day for more than 14 days per year
Factors affecting odor complaints
Frequency of problem
86% of farmers tolerate neighbor’s odor if problem occurs > 2 days/year
50% of farmers tolerate neighbor’s odor if problem occurs > 10 days/year
Intensity of problem
Duration of problem
Offensiveness of odor
Relations with neighbors (Time of residence, previous contact)
Odor plume (Direction, topography)


Origin of livestock odor
Odor compound
Large intestine Carbohydrates Protein
(Starch, cellulose) Volatile fatty acids
(Acetic, Propionic, Butyric acids;
may be absorbed or excreted)

H2S and mercaptans
(Passed as gas)
Other amines, phenols, and
indoles (Absorbed from LI &
excreted in urine)

Manure Carbohydrates
(Secondary Volatile fatty acids and alcohols Protein
fermentation Lactic acid
greater at: Butyric acid
Manure pH > 4.5;
High manure moisture; NH3, H2S, mercaptans, branched
High ambient temperatures) chain VFAs (Isobutyric, Isovaleric), CH4
Amines (Putrescine, Cadaverine),
Phenols (Phenol, p-Cresol),
Indoles (indole, Skatole)

Air Emissions increased with increased temperature, moisture, humidity, agitation,
dust, pH, wind, surface exposure

Livestock management to reduce odors
Reduce excessive protein feeding
Reducing protein swine diets from 18 to 14% reduced odor components by 40 to 86%
Nonruminants
Balance essential amino acids to create ideal dietary protein with crystalline amino acids
Use multi-phase and split-gender feeding
Avoid safety margins in protein feeding
Use genetically lean pigs
Use growth promoters
Minimize feed waste
Ruminants
Supply only enough ruminally degraded protein to meet the NH3 needs of the rumen bacteria
Beyond the microbial NH3 needs, meet animal’s metabolizable protein needs with ruminally undegrade protein sources or crystalline amino acids
Use phase feeding of beef feedlot or dairy cows
Control feed wastes
Reduce sulfur in mineral supplements
Can reduce odor by 40%
Utilize salts other than sulfates or sulfides for trace minerals

Increase cellulose or other nonstarch polysaccharides in swine diets
Causes bacteria in large intestine to incorporate NH3 into microbial protein
Reduces NH3 by as much as 35%
Ingredients to add:
Soy hulls
Sugar beet pulp
Distillers grains
Mask odor with other odors
Garlic powder has been used for poultry
Feeding sarsaponin
Extracted from yucca plant
Inhibits urease
Feeding zeolites
Minerals that have cation exchange capacity
Binds odor compounds
Reduce dust from animals’ skin
Increase quality of dietary fat
Feed adequate zinc

Management of livestock facilities to manage manure odor
Frequent cleaning of wet manure and feed from facilities
Manure standing for more than 5 days will cause considerable offensive odor
Use bedded systems
Odor seems less offensive than liquid systems
Addition of organic matter from bedding reduces odor
Reduce dust within and outside buildings
Approaches
Frequent cleaning
Spraying vegetable oils
Reduce NH3 and H2S by 30%
Spray once daily
Use a medium droplet size
Problem with oily facilities
Installation of wet scrubbers
Wetted pads 3 to 5’ in front of ventilation fans
Traps dust with some NH3, H2S, and NOx
Effectiveness on odors?
Use of chemical additives
Alum (K Al(SO4)) will reduce some NH3 emissions

Use Biofiltration
A system that uses aerobic bacteria to degrade gaseous odors from ventilated air
Process
Aerobic bacteria
VOC & inorganic gases CO2 + H2O + Mineral salts +
Microbial biomass
Fiber mat serves as media
Shredded wood and compost (50:50)
Shredded wood and soil (50:50)
Straw and compost
Less effective during periods of high ventilation
Can be difficult to control vegetation and rodents


Use Biomass filters
Walls of corn stalks, corn cob or other materials placed immediately outside ventilation fans
Effects
Reduces dust by 52 – 83%
Reduces odor by 43 – 90%


Use windbreak walls
Walls placed 10 – 20 ft downwind from ventilation fans
Effects
Settle dust near barn
Disperses odor plume upward to increase dilution












Use natural windbreaks
Rows of trees or other vegetation
Effects
Trap dust
Aids in dispersion and dilution of odor
Provides a visual barrier

Management of manure storage to limit odor
Aerobic treatment
Liquid manure
Air is pumped into liquid manure
Should oxidize odor-causing chemicals
Difficult to mix enough O2 to be effective
Solid manure
Composting
Requirements
Appropriate moisture (50%)
Adequate C:N ration (>20:1)
Aerobic conditions (Frequent mixing)
Temperature (130oF for 3 days)
Oxidizes odor and incorporates N-containing compounds into microbial protein
Effects
Reduces odor by 75% in 2 weeks


Management of anerobic lagoons
Complete anerobic digestion is effective at limiting odors
















Odors can be controlled if:
Loading rate is slow and uniform enough to allow balance of bacteria producing VFAs or CH4
Allows development of purple sulfur-oxidizing bacteria
Metabolize VOCs
Reduce amines
A purple or pink color of lagoon is desirable


Factors affecting odors in lagoons
High loading rates
Excess animal numbers
Inadequate dilution water
Windy conditions
Disturbs surface
Timing of agitation and pumping for application
Should be done on clear, sunny days when warm air causes odors to rise and disperse
Early spring turnover
Odor problems increase as bacterial action begins to increase digesting nutrients that were incompletely metabolized over winter

Use covers over storage facilities
Covers over manure structures
Rigid covers
Concrete, wood, fiberglass, plastic
Materials must be noncorrosive
Flexible covers
Tarp over manure with a blower
Floating covers
Natural
Crust floating on top of manure
Artificial organic
Straw, chopped corn stalks, wood shavings
Artificial
Polystyrene foam, air-filled clay balls, geotextile
Effectiveness
Provides a barrier between liquid manure and the atmosphere
Provides aerobic media to all microbes to degrade odor compounds
Limitations
Straw will only last from 2 weeks to 6 months


Anerobic digesters
Produce methane for biogas
Reduce odors by 70 – 80%
Additives
Biological
Microbial additives
Cultures added to degrade odor compounds
Effectiveness?
Chemical
Oxidizers and pH control
Limited effectiveness
Masking agents
Volatile compounds that smell pleasant
Sprayed on or above manure
May separate from manure downwind
Absorbents and Adsorbents
Activated carbon, zeolite, bentonite, or sphagnum moss
Effectiveness?
Antimicrobial oils
Includes plant oils like thymol and carvacol
Inhibit microbial degradation of manure during anerobic storage, but degrade in aerobic conditions after application
Preserves nutrients and reduces odor emissions
Still in research
Economics?

Natural windbreaks
Creates a visual barrier
Filters, disperses and dilutes odor
Separation of manure solids and liquid
Can be mechanical or gravity
Separates urea in urine from urease in feces
Effects
Reduces NH3
Reduces odor by 50%

Manure application management to control odors
Manure odor problems are directly proportional to the surface area for emissions
The area of manure application is the greatest source of manure odor
Factors affecting manure odor during application
Form of manure
Earthen basin > Below barn pit > Anerobic lagoon > Solid > Compost
Lagoon management
Lagoon should be large enough to leave a permanent pool to stabilize microbial population
Apply in June through fall
Odors reduced when microbes are most active
Dilute manure with water liberally
2 – 3 parts H2O : 1 part manure
Test for salt and NH3 concentration
Stop lagoon feeding 2 weeks before pumping
Allows bacteria the opportunity to degrade odor
Application method
Injection of manure into soil
Most effective at preventing odors
Surface application with incorporation
Must be done immediately after application

If surface applying liquid manure by irrigation make sure to:
Set sprayer for large droplets
Reduce droplet surface area
Adequately dilute manure with clean water
2:1
Monitor wind direction
Shut down if wind blows towards neighboring residences
Monitor wind spead
Shut down if wind speed exceeds 5 mph
Prevents dilution of odor

Consideration of neighbors as a method to control manure odor nuisance complaints
Siting of operation and fields for manure application
Major tool to limit odor nuisance complaints
Considerations
Distance
Odors decreases exponentially with distance
Distances (Required to use the Master Matrix)
> Residences
>¼ mile from buildings
>750 ft from manure application-Surface applied
> Residential development
>1 mile from buildings
>750 ft from manure application-Surface applied
Topography
Don’t build uphill from residences
Prevailing winds
Don’t build so residences are downwind of the prevailing winds
Especially during the spring
Building orientation
Short side of livestock facility should be perpendicular to the neighbor’s residence





Timing of manure application
Tell neighbors when you plan to spread manure
Select days when wind is blowing away from neighbors
Avoid spreading manure on weekends, holidays, or on days when neighbors have a social event planned
Facility maintenance
Maintain buildings and grounds around facilities
Mow grass
Control weeds
Proper dead animal disposal
Avoid spilling manure on roads

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