Manure Gasses: Hydrogen Sulfide and Your Safety - Dr. Dan Andersen, Iowa State University, from the 2016 Iowa Pork Congress, January 27-28, Des Moines, IA, USA. More presentations at http://www.swinecast.com/2016-iowa-pork-congress

1. Manure Gasses:
Hydrogen Sulfide and Your Safety

2. • Sulfur concentration
– 10 years ago about 3 lb/1000 gallons
– Currently about 10 lbs/ 1000 gallons
• Increase risk of high H2S
• High farm-to-farm variation
Manure

3. Evaluating H2S during agitation

4. Evaluating H2S during agitation

5. Evaluating H2S during agitation

6. Barn Monitoring
0
100
200
300
Curtains up, ~43
cfm/hd
Curtains up, ~15
cfm/hd
Endwall curtain
down, ~15 cfm/hd
Endwall curtain
down, ~43 cfm/hd
Endwall curtain
down, ~43 cfm/hd
Curtains up,
agitator splashing,
~43 cfm/hd
Barn 2 - H2S leaving fans (ppm)
SE Fan SC Fan SW Fan WS Fan WN Fan NE Fan NW Fan

7. • Employee monitoring
• Barn ventilation
• Be vigilant of conditions
What should you do?

8. • GasAlertMax XT II (Honeywell)
• BW Honeywell GasAlert Clip Extreme
GA24XT-H
• BW Honeywell GasAlert Micro Clip XL 4-Gas
Monitor
• Draeger Pac 3500 H2S Monitor
• RAE Systems ToxiRAE II
Monitoring

9. • Verify all fans are working prior to pumping
• Check that air inlets open
• Place a tarp over pump-out to help protect
applicator
• Communicate with farmer and crew
• Listen for pig distress
Pumping Ventilation Tips

10. Think about your surroundings

11. • High concentrations of H2S can result from
manure agitation and pumping
• Never enter a facility while agitation is
occurring
• Be aware and alert, dangerous condition can
develop quickly
Summary

12. Photo courtesy of Dr. Larry Jacobson, UMN
Foam Creeping Through Slats (4 ft of foam case)
Progress on Pit Foaming
Foam Into Animal Occupied Zone
Photo courtesy of Dave Preisler, MPB;
Dr. Larry Jacobson, UMN

13. Theory
• Biogas
Generation of methane, CO2 and
hydrogen sulfide.
• Surfactants
Materials that significantly
change the surface tension.
• Stabilizer
Increases the stability of foam
bubbles, like small fibers and
other hydrophobic particles.

14. Manure Sampling SOP
A
B
C
D
foam/crust
transition
slurry
sludge
Samples were collected from discrete depths
in the manure storage pit.
Samples from 2 Integrators
Over 60 Sites
Generated more than 2000 manure samples

15. Why Foam? Why Now?
Diet composition and particle size effects on nutrient excretion
Diet ID Diet Composition
Digestion/Excretion
Coefficient Output, kg1
Output
difference, kg
Estimated C
Equivalence, kg2
C-SBM 4.6% EE 63% (37%) 6,592
7.0% NDF 66% (34%) 9,223
17% CP 88% (12%) 7,905
45% Carbon 91% (9%) 15,694
C-35%DDGS 6.2% EE 63% (37%) 8,889 2,297 (+35%) 1,746 (28%)
13.8% NDF 68% (32%) 17,112 7,889 (+85%) 3,550 (55%)
17% CP 85% (15%) 9,881 1,976 (+25%) 1,047 (17%)
46% Carbon 87% (13%) 23,291 7,597 (+48%) 6,343
1Output based upon 310 kg feed/pig from wean-to-finish and 1,250 pigs/barn.
2Lipid = 76% carbon; Protein = 53% carbon; Fiber = 45% carbon.

16. Diets in Practice:
More C in manure, more methane potential

17. Methane Production Rates
• Methane production rate was higher in foaming barn than non-foaming barns.
• Why?

18. What would cause this difference?
• Quantity of carbon inputs?
• TS, VS, VFA
• Source of carbon?
• BMP, VFA
• Differences in microbes?
• Degraders, methanogens, sulfate reducers
• Microbial community structure
• Response to different carbon substrates?
• Differences in pathways/response to substrate?

19. Microbial Data – What your looking at

20. Microbial Differences?
• Foaming and non-foaming
sites have distinct microbial
communities
• Sequencing Data

21. So which microbes are these?
• Differences in relative abundance of dominant taxa are associated with
foaming
0%
2%
4%
6%
8%
10%
12%
14%
16%
18%
20%
non.foaming
foaming

22. So what is influencing these microbes?

23. Is this related to functionality?

24. What stabilizes foam?
0
1
2
3
4
5
6
7
8
9
A B C D
VolatileSolids(%)
Sample Depth
Foaming Non-FoamingA
C
D
B
B
A A
• What did we notice about samples that stabilized
• Solids rich, but finer looking solids, not big chunks
• Liquid drained more slowly from the foam
• Sort of set up, with solids in bubble matrix
• Good foams grey/brown (protein), bad foams were white/clear (fats/oils)

25. Foam is really stable
0
200
400
600
800
1000
1200
1400
1600
1800
A B C D
FoamHalf-Life(Minutes)
Sample Depth
Foaming
Non-Foaming
A
B B B BB

26. The foam stays wet - viscous
0
2
4
6
8
10
12
Foam Foaming Manure Non-Foaming
Manure
Viscosity(cP) As Is
Centrifuged
Filtered
A
B
B
a
b b
1
2 2
Its not just the solids, something else is giving us viscosity in the foam.
-sugar, oil, lipopolysaccharides, proteins? Microbial goo

27. but… Particles hold it together
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
0.01 0.1 1 10 100 1000
FractionofParticlesFinner
Particle Size (um)
Foam
Foaming Manure
Non-foaming Manure
0
20
40
60
80
100
120
140
160
180
200
Foam Foaming Manure Non-foaming
Manure
AveragParticleSize(um)

28. Does diet influence these particles?
0.00
0.04
0.08
0.12
0.16
0.20
0.0 0.3 2.0 16.0 128.0 1,024.0
FractionofParticlesin
SizeClass
Particle Size (μm)
C-SBM-C C-DDGS-C
C-SH-C C-SBM-F
C-DDGS-F C-SH-F
Feed Particle Size
(μm)
Manure Particle Size
(μm)
Coarse Grind 631 238
Fine Grind 374 138
Greater percent of particles were fine silt particles from inoculated manure (p < 0.05), courser grind (p = 0.1254),
and fiber source (p < 0.05)
(soybean meal > DDGS > soy hulls)

29. If you add these particles will make foam?
Yes…. But they have to interact with proteins
Add moving particles from foaming manure to non-
foaming manure will make it foam.

30. So Proteins then?
0
5000
10000
15000
20000
25000
30000
35000
40000
Foam Foaming ManureNon-foaming Manure
ProteinConent(ug/mL)
As Is
Centrifuged
A
B
B
a
a
a

31. So Proteins then?
0
5000
10000
15000
20000
25000
30000
35000
40000
Foam Foaming ManureNon-foaming Manure
ProteinConent(ug/mL)
As Is
Centrifuged
A
B
B
a
a
a

32. So remove proteins, stop foam?
• Removal of protein strongly reduces foaming capability and stability
Sample Original High temperature
Denature (80oC)
Low temperature
incubate (35oC)
Proteinase digestion
(35oC + enzyme)
Foaming
capability
(ml)
Lasting
time
(min)
Foaming
capability
(ml)
Lasting
time
(min)
Foaming
capability
(ml)
Lasting
time
(min)
Foaming
capability
(ml)
Lasting
time
(min)
1A 450 20 75 0.5 450 25 50 0.5
1B 75 1 60 0.5 30 0.5 35 0.5
2A 450 5 125 1 450 15 30 0.5
2B 25 0 20 0 20 0 20 0

33. What’s holding the proteins together?
Total Carbohydrates
mgg-1
manure
0.0
0.5
1.0
1.5
2.0
2.5 Foam
Foam Manure C
Non-Foam Manure C
Total Hemicellulose
gg-1
manure
0
200
400
600
800
1000
Foam
Foam Manure C
Non-Foam Manure C0.977
0.798
0.783

34. So what do we know now?
• High fiber feed ingredients have reduced nutrient digestibility increasing
levels of C reaching the pit.
• Efficiencies in both the processing of these new C inputs and
fermentation of fatty acid material have resulted in increased levels of
methane production.
• Higher levels of methane production have resulted in separation (i.e.,
translocation) and concentration of biological material into a foam layer.
• The foam layer itself showed unique characteristics:
• Solids Enriched with Fine Particles (Proteins)
• Enhanced Foam Stability
• Higher Total Carbohydrates
• Liquid is viscous

35. Precautionary Measures
 Any attempt to break-up foam WILL release
explosive levels of methane. Therefore….
1. All ignition sources OFF (i.e. pilot lights, welding),
2. Set ventilation at 30 cfm/space minimum,
- Use open curtains if ≥ 5 mph wind, OR,
- Use fans* + ceiling inlets if calm
3. Make sure ceiling inlets operational,
4. Vacate barn, then finally,
5. Foam/pit can be disturbed.
* In a 1000-hd barn, equates to 2-48” or 3-36” or 6-24” fans

36. Ventilation Strategies
(1000-hd Finisher)
6-24” fans or 3-36” fans or 2-48” fans
+ operational ceiling inlet system +
curtains closed
OR
Curtains Open with Wind of ≥ 5 mph
But NOT
Curtains Open, Calm Conditions
Reliance on Fans

37. Ventilation Dilution Time
1,000-hd finisher
0
100,000
200,000
300,000
400,000
500,000
600,000
700,000
800,000
0 1 2 3 4 5 6 7 8 9 10 11
MethaneConcentration(ppm)
Ventilation Time (min)
V=30,000 cfm V=60,000 cfm V=90,000 cfm
2 min at 90,000 cfm
3 min at 60,000 cfm
6 min at 30,000 cfm
Trapped methane in foam measured at 70% or more
LELCH4=5.1% (51,000 ppm)

38. Precautionary Measures (NPB)
http://www.pork.org/filelibrary/November2009%20PCRSE.pdf

39. Precautionary Measures (ISU)
http://www.agronext.iastate.edu/immag/

40. Precautionary Measures (UMN)
http://www1.extension.umn.edu/agriculture/manure-management-and-air-quality/

41. Questions, comments, discussion?