This study evaluated the potential air quality impacts of anaerobic digestion (AD) of dairy manure. Researchers measured greenhouse gas emissions, odor, ammonia, and other pollutants from lagoons storing digested and non-digested manure. They also measured emissions from land application of digested and non-digested manure applied by different methods. Results showed AD manure produced significantly lower emissions of methane and carbon dioxide but higher ammonia emissions from lagoons. Land application of non-AD manure resulted in higher emissions of methane, carbon dioxide, and ammonia compared to AD manure. While AD improved odor intensity, ammonia emissions during manure storage require further investigation.

1. Potential Air Quality Impacts of Anaerobic Digestion of
Dairy Manure
Washington State University:
H.S. Joo, P.M. Ndegwa, J.H. Harrison, E. Whitefield, S.
Fei, X. Wang, G. Neerackal
Purdue University:
A.J. Heber, J.Q. Ni
Waste-2-Worth Conference
Denver, Co, April 3, 2013

2. Outline
• Background
• Objectives of the study
• Materials and Methods
• Results
• Summary & Conclusions
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3. Background
• This study is funded under NRCS-CIG program to
demonstrate the impact of anaerobic digestion (AD) of dairy
manure on air quality during effluent storage and/or
subsequent manure application on land.
• Motivation: The environmental benefits of AD has been
shown in research but adoption of the technology is still low.
• Interests:
• Odor and VOCs emissions,
• Greenhouse gases (GHGs) emissions,
• NH3 and H2S emissions.
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4. Methods and Materials: AD site plan
Composting
Solids separation vessel
Manure from
Dairy
Solids/compost
Generator Liquid
Room effluent
AD Mixing
tank
Lagoons
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Denver, Co, April 3, 2013

5. Methods and Materials: AD site
Electricity
generator
Solids/liquid
separator
AD
Composting
drums
Receiving/mixing tank
Liquid
effluent
tank
Primary
lagoon
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6. Manure application plan/strategy in the plots
Methods and Materials: Injected
AD
Injected
AD
Injected
AD
Manure application
Drag hose applicator Broadcasted Broadcasted Broadcasted
Non-AD Non-AD Non-AD
Broadcasted Broadcasted Broadcasted
AD AD AD
125 ft
Injected Injected
Injected
non-AD non-AD
non-AD
28 ft
Evacuated vials
Chamber in place
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7. Methods and Materials:
Lagoon measurements
Photoacoustic gas analyzer
(INNOVA model 1412)
Floating chamber Chambers’ access
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8. Methods and Materials: Lagoon
and Land Application Simulations in the lab.
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9. Methods and Materials: Odor samples
•Air samples were collected
in 10-L Tedlar bags.
Effluent
Separator •At: Raw
AD manure, influent, effluent, a
Influent nd separated liquid.
Receiving/mixing
Liquid effluent tank •Samples shipped
tank
immediately to the lab for
odor analyses by a trained
odor panel (Overnight).
•Dynamic Dilution Forced-
choice Olfactometer.
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10. Results: Land application (field studies)
10 800
AD-Broadcast: R² = 0.97 AD-Broadcast: R² = 0.99
CO 2 Concentration (ppm)
CH 4 Concentraion (ppm)
8 NonAD-Injection: R² = 0.94 NonAD-Injection: R² = 0.97
600
AD-Injection: R² = 0.92 AD-Injection: R² = 0.97
6 NonAD-Broadcast: R² = 0.95 NonAD-Broadcast: R² = 0.99
400
4
200
2
0 0
0 15 30 45 60 0 15 30 45 60
Time (minutes) Time (minutes)
2.5
AD-Broadcast: R² = 1.00
N 2 O Concentration (ppm)
2 NonAD-Injection: R² = 0.99
AD-Injection: R² = 0.93
1.5 NonAD-Broadcast: R² = 1.00
1
0.5
0
0 15 30 45 60
Time (minutes)
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11. 2000
AD-Broadcast
NonAD-Injection
CO2 Emission (mg/kg-VS)
Results: Land application –
AD-Injection
1500
NonAD-Broadcast
emissions (field studies) 1000
6000
CH4 Emissions (µg/kg-VS)
500
5000
AD-Broadcast
4000 0
NonAD-Injection
0 2 4 6 8 10 12 14
AD-Injection Time (day)
3000
NonAD-Broadcast
2000 8000
AD-Broadcast
NonAD-Injection
N2O Emission (µg/kg-TAN)
1000 AD-Injection
6000 NonAD-Broadcast
0
0 2 4 6 8 10 12 14
4000
Time (day)
2000
0
0 2 4 6 8 10 12 14
Time (day)
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12. Results: Land application – Ammonia
emissions (field vs. studies)
1500
Field studies 80
Lab simulation studies
Cummulative NH3 emission
1200
Cummulative NH 3 emission
60
AD-I NonAD-I
900 AD-B NonAD-B NonAD-B NonAD-I
AD-B AD-I
(mg)
(ppm)
40
600
20
300
0 0
0 1 2 3 4 5 6 7 0 100 200 300 400 500
Time (day) Time (h)
Note the higher ammonia loss from non-AD surface applied
manure – contrary to what one would anticipate or expect!
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13. 20
AD nonAD
15
Results: Lagoon GHG Emissions
N2 O (µg/m2 /min)
10
5
30
0
April-May July September November
CH4 (mg/m2 /min)
AD nonAD
20 AD
90
nonAD
CO2 (mg/m2 /min)
10 60
30
0
April-May July September November
0
April-May July September November
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14. Results: Lagoon NH3 Emissions
1.2 Field studies
0.9
NH 3 (mg/m2 /min)
AD nonAD
2000 Lab simulated studies
RM
Cummulative NH3 emission (mg)
0.6 AD Influent
1600
AD Effluent
AD Liquid Effluent
0.3 1200
800
0
April-May July September November 400
AD effluent liquid after separation – 0
probably huge volatilization or loss occurs 0 5 10 15
Time (Day)
20 25
during solids-liquid separation process.
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15. 6000
4500
OUE/m3
3000
Results: Odor Analyses 1500
0
Water (Control) Raw Manure AD Influent AD Effluent AD Liquid
Effluent
4.0
3.0
Intensity 6-point
Intensity
scale:
2.0
1.0 •1—very weak
•2—weak‖
0.0
Water (Control) Raw Manure AD Influent AD Effluent AD Liquid •3—distinct
Effluent
•4—strong
Hedonic tone a 0.0 •5—very strong
nine-point scale:
Water Raw Manure AD Influent AD Effluent AD Liquid
(Control) Effluent •6—extremely
―-4:extremely strong
-1.0
unpleasant to ―0 or
Hedonic Tone
-2.0
neutral‖) to
―+4:extremely
-3.0
pleasant‖ -4.0
-5.0
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16. Summary & Conclusions
• Emission of CO2 was much higher from non-AD manure compared with AD
manure. Injection of manure did not seem to play a major part on CO2
emissions.
• CH4 emission was also much higher from non-AD manure compared with AD
manure. Injection of non-AD manure increased emissions of CH4.
• N2O emissions were slightly higher from non-AD manure compared with AD
manure. Injection of either AD or non-AD manure did not seem to affect
emissions of N2O.
• Although AD manure had more TAN, NH3 emissions were highest in surface
applied non-AD manure!
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17. Summary & Conclusions
• GHG emissions from the anaerobic lagoon holding AD manure, during
all four seasons, were significantly lower than from the anaerobic
lagoon with non-AD manure.
• In contrast, the reverse was observed with NH3 emissions. This was
also confirmed via lab simulation studies.
• While odor concentration (DT) increased some going through the
digester, the intensity and hedonic tone improved.
• AD of dairy manure prior to its storage and land application
demonstrate significant environmental benefits (GHGs, odor, NH3).
• Potential liability - increased NH3 emissions during storage.
Waste-2-Worth Conference
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18. Our sponsors
Questions?
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