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 ConferenceDenver, Co, April 3, 2013
Outline
• Background
• Objectives of the study
• Materials and Methods
• Results
• Summary & Conclusions
Waste-2-Worth ConferenceDenver, Co, April 3, 2013
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.
Waste-2-Worth ConferenceDenver, Co, April 3, 2013
Methods and Materials: AD site plan
AD Mixing tank
Lagoons
Composting vessel
Manure from Dairy
Liquid effluent
Solids separation
Solids/compost
GeneratorRoom
Waste-2-Worth ConferenceDenver, Co, April 3, 2013
Methods and Materials: AD site
AD
Receiving/mixing tank
Primary lagoon
Composting drums
Liquid effluent tank
Solids/liquid separator
Electricity generator
Waste-2-Worth ConferenceDenver, Co, April 3, 2013
Methods and Materials: Manure application
28 ft
125
ft
Broadcasted Non-AD
Injected non-AD
Injected AD
Broadcasted Non-AD
Broadcasted Non-AD
Injected AD
Injected AD
Injected non-AD
Injected non-AD
Broadcasted AD
Broadcasted AD
Broadcasted AD
Drag hose applicator
Chamber in place
Evacuated vials
Manure application plan/strategy in the plots
Waste-2-Worth ConferenceDenver, Co, April 3, 2013
Methods and Materials: Lagoon measurements
Floating chamber
Chambers’ access
Photoacoustic gas analyzer (INNOVA model 1412)
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Methods and Materials: Lagoon and Land Application Simulations in the lab.
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Methods and Materials: Odor samples
AD
Receiving/mixing tank
Influent
Liquid effluent tank
Separator
Effluent
Waste-2-Worth ConferenceDenver, Co, April 3, 2013
• Air samples were collected in 10-L Tedlar bags.
• At: Raw manure, influent, effluent, and separated liquid.
• Samples shipped immediately to the lab for odor analyses by a trained odor panel (Overnight).
• Dynamic Dilution Forced-choice Olfactometer.
Results: Land application (field studies)
R² = 0.97
R² = 0.94
R² = 0.92
R² = 0.95
0
2
4
6
8
10
0 15 30 45 60
CH
4C
once
ntra
ion
(ppm
)
Time (minutes)
AD-Broadcast:
NonAD-Injection:
AD-Injection:
NonAD-Broadcast:
R² = 0.99
R² = 0.97
R² = 0.97
R² = 0.99
0
200
400
600
800
0 15 30 45 60
CO
2C
once
ntra
tion
(ppm
)
Time (minutes)
AD-Broadcast:
NonAD-Injection:
AD-Injection:
NonAD-Broadcast:
R² = 1.00
R² = 0.99
R² = 0.93
R² = 1.00
0
0.5
1
1.5
2
2.5
0 15 30 45 60
N2O
Con
cent
rati
on (p
pm)
Time (minutes)
AD-Broadcast:
NonAD-Injection:
AD-Injection:
NonAD-Broadcast:
Waste-2-Worth ConferenceDenver, Co, April 3, 2013
Results: Land application – emissions (field studies)
0 2 4 6 8 10 12 140
1000
2000
3000
4000
5000
6000
AD-Broadcast
NonAD-Injection
AD-Injection
NonAD-Broadcast
Time (day)
CH
4 E
mis
sion
s (µ
g/kg
-VS
)
0 2 4 6 8 10 12 140
500
1000
1500
2000AD-BroadcastNonAD-InjectionAD-InjectionNonAD-Broadcast
Time (day)
CO
2 E
mis
sion
(m
g/kg
-VS
)
0 2 4 6 8 10 12 140
2000
4000
6000
8000AD-BroadcastNonAD-InjectionAD-InjectionNonAD-Broadcast
Time (day)
N2O
Em
issi
on (
µg/
kg-T
AN
)
Waste-2-Worth ConferenceDenver, Co, April 3, 2013
Results: Land application – Ammonia emissions (field vs. studies)
Waste-2-Worth ConferenceDenver, Co, April 3, 2013
0
20
40
60
80
0 100 200 300 400 500
NonAD-B NonAD-I
AD-B AD-I
Cum
mul
ativ
eN
H3
emis
sion
(m
g)Time (h)
0
300
600
900
1200
1500
0 1 2 3 4 5 6 7
AD-I NonAD-I
AD-B NonAD-B
Time (day)
Cu
mm
ula
tive
NH
3em
issi
on
(p
pm
)
Field studies
Note the higher ammonia loss from non-AD surface applied manure – contrary to what one would anticipate or expect!
Lab simulation studies
Results: Lagoon GHG Emissions
0
10
20
30
April-May July September November
AD nonAD
CH
4(m
g/m
2 /m
in)
0
30
60
90
April-May July September November
AD
nonAD
CO
2(m
g/m
2 /m
in)
Waste-2-Worth ConferenceDenver, Co, April 3, 2013
0
5
10
15
20
April-May July September November
AD nonAD
N2O
(µg/
m2 /
min
)
Results: Lagoon NH3 Emissions
0
0.3
0.6
0.9
1.2
April-May July September November
AD nonAD
NH
3(m
g/m
2 /m
in)
Waste-2-Worth ConferenceDenver, Co, April 3, 2013
0
400
800
1200
1600
2000
0 5 10 15 20 25
Cu
mm
ula
tive
NH
3 em
issi
on (m
g)
Time (Day)
RM
AD Influent
AD Effluent
AD Liquid Effluent
Field studies
Lab simulated studies
AD effluent liquid after separation – probably huge volatilization or loss occurs during solids-liquid separation process.
Results: Odor Analyses
Waste-2-Worth ConferenceDenver, Co, April 3, 2013
Intensity 6-point scale: • 1—very weak• 2—weak”• 3—distinct• 4—strong• 5—very strong• 6—extremely
strong
Hedonic tone a nine-point scale:“-4:extremely unpleasant to “0 or neutral”) to “+4:extremely pleasant”
0
1500
3000
4500
6000
Water (Control) Raw Manure AD Influent AD Effluent AD Liquid Effluent
OU
E/m
3
0.0
1.0
2.0
3.0
4.0
Water (Control) Raw Manure AD Influent AD Effluent AD Liquid Effluent
Inte
nsi
ty
-5.0
-4.0
-3.0
-2.0
-1.0
0.0Water
(Control)Raw Manure AD Influent AD Effluent AD Liquid
Effluent
He
do
nic
To
ne
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!
Waste-2-Worth ConferenceDenver, Co, April 3, 2013
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 ConferenceDenver, Co, April 3, 2013
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