Progress on Pit Foaming(what we know, what we don’t know, what we’re doing)

2015 Iowa Pork Congress

Dan Andersen, PhDSteve Hoff, PhD

Dept. of Ag & Biosystems EngineeringIowa State University

Brian Kerr, PhDSteve Trabue, PhD

USDA-ARS National Center for Agriculture and the EnvironmentAmes, Iowa

January 28, 2015

Objectives for Today

Update on IPPA-funded Pit Foaming Research

Summarize Results

Precautionary Measures

Overall Foaming Requirements

Three-phase Process:

1. Gas generation (i.e. methane, hydrogen sulfide),

2. Surface tension reduction (surfactants; bio- or otherwise),

3. Bubble support structure (i.e. small fibers).

H2S

CH4

CH4

CH4

H2S

H2S

A surfactant causes surface to“elasticize”

Gases otherwise naturallyescaping at very low concentrations are trapped

Foam supported by bacteriaor fine fibers or ??

Photo courtesy of Dr. Larry Jacobson, UMN

Foam Creeping Through Slats (4 ft of foam case)

In-field Foaming

Foam Into Animal Occupied Zone

Photo courtesy of Dave Preisler, MPB;Dr. Larry Jacobson, UMN

Curious Nature of Foaming

Has occurred in one pit of side-by-side roomswith equalizing channel.

Commonly found in one barn of multi-barn siteswith common genetics, feed, management, etc.

Attempts at correlating foaming vs non-foamingbarns with multiple factorshas been elusive.

Photo courtesy of Dr. Larry Jacobson, UMN

IPPA Funded Research Project

GOAL: Finding and Correctingthe Mechanisms of Foaming

Photo courtesy of Dr. Larry Jacobson, UMN

IPPA Funded Research Effort

Multi-state effort (ISU, UMN, UILL) involving 20+ academicprofessionals with expertise in manure management,chemistry, microbiology, feed rations, and digestibility

$1M investment over three years (we are finishing YR2)

Project managed by Iowa State University

Our team is working diligently to solve this problem

Multi-state Research Collaboration

• Feed trials

• Chemical composition

analysis

• Methane production

• Foaming potential

testing

ISU/USDA-ARS UMN

• Extensive producer

survey

• Microbial analysis

• Foaming potential

testing

UILL

• Organize all manure

sampling and

distribution

• Microbial analysis

Dan AndersenBrian KerrSteve Trabue

Chuck ClantonLarry JacobsonBo HuBrian Hetchler

Rich Gates, Angela Kent, Laura Pepple

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.

Hypotheses - Mechanism

(1) Increased prevalence of foaming is due to increased biogas/methane production from the manure

(2) Elevated concentrations of surface active agents in foaming manures are causing greater gas capture

(3) Foam is being stabilized by small particles/proteins

(4) Differing physical, chemical, and biological properties are related to dietary inputs.

Hypotheses - Microbial

• Brief Background

• ARISA & Sequencing

• Site, Management, and Environmental Factor Database

• Objective 1 – Microbial community differences

• Objective 2 – Identify relevant microbes using sequencing

• Objective 3 – Use relational database with Obj’s 1 and 2

• Methanogen Sequencing

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

Sample Summary: Cases

CLASSIFICATIONINTEGRATORA INTEGRATOR

B#OFSAMPLES #OFSAMPLES

NON-FOAMING 250 183

FOAMING 255 362

NOTTREATED 178 163TREATED 327 362

PREVIOUSPUMPOUT 24 18FALL2012 337 460

SPRING2013 142 38FALL2013 2 9

CASE1(FOAMING) 115 76CASE2(NON-FOAMING) 85 258CASE3(TRANSITION) 157 111CASE4(UNSTABLE) 148 80

TOTAL 505 525

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-SBM + FIBER 6.2% EE 63% (37%) 8,889 2,297 (+35%) 28%

13.8% NDF 68% (32%) 17,112 7,889 (+85%) 55%

17% CP 85% (15%) 9,881 1,976 (+25%) 17%

46% Carbon 87% (13%) 23,291 7,597 (+48%)

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.

Dietary Tidbits

• Averaged across 3 trials in our metabolism/tank studies, high fiber diets increased manure carbon by approximately 40%.

• Intact fats are less digestible than ‘added’ fats (e.g., 65% versus 85%, respectively).

• We do not know any interactive effects between fiber and lipid type, or between fiber and lipid level.

• On average, grinding to a finer particle size, 374 vs 631 m, improved FAT, FIBER, CP, and C digestibility by 30, 8, 3, and 3%, respectively. In general, finer grinding improves digestibility of low-digestible ingredients more than high-digestible ingredients.

• DDGS of 340 μm exhibited an FAT digestibility of 75% compared to 57% for DDGS of 650 μm

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

How do you study the gas phase?

MPRL

L ∗ day=(Methane %

1100)(Biogas Produced mL + Vheadspace) × ρmanure(

gmL)

Mass of sample g × incubation period(minutes)×1440 minutes

day

Methane Production Rates

• Methane production rate was higher in foaming barn than non-foaming barns.

• Why?

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?

Quantity of Food?

0

2

4

6

8

10

12

A B C D

Tota

l Sol

ids

(%)

Sample Depth

Foaming Non-FoamingA

DE

B C

A A

0

1

2

3

4

5

6

7

8

9

A B C D

Vola

tile

Solid

s (%

)

Sample Depth

Foaming Non-FoamingA

CD

BB

A A

Quality of Food?

• Difference between foaming and non-foaming, but non-foaming is better and driven by VFA’s

• More solids deeper in the manure, but quality of those solids is lower

Microbial Data – What your looking at

Microbial Differences?

• Foaming and non-foaming sites have distinct microbial communities

• Sequencing Data

Microbial Richness (Diversity)

Integrator A Integrator B

So which microbes are these?

• Differences in relative abundance of dominant taxa are associated with

foaming—but no new microbes.

0%

2%

4%

6%

8%

10%

12%

14%

16%

18%

20%

non.foaming

foaming

So can these microbes be related to management practices?

So what is influencing these microbes?

Integrator B

Is this related to functionality?

Integrator B

So do they like a certain food better?

What about surfactants?

Difference between F and NF – driven by VFA concentrations

Difference between B and C&D driven by ??? (oil/long chain fatty acids)

What is role of particles/proteins?

Surfactant should drive capacity to foam

Generally small differences in ability of manure to foam.

What stabilizes foam?

0

1

2

3

4

5

6

7

8

9

A B C D

Vola

tile

Sol

ids

(%)

Sample Depth

Foaming Non-FoamingA

CD

BB

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)

Foam is really stable

0

200

400

600

800

1000

1200

1400

1600

1800

A B C D

Foa

m H

alf-

Lif

e (M

inut

es)

Sample Depth

Foaming

Non-Foaming

AB B B BB

The foam stays wet - viscous

0

2

4

6

8

10

12

Foam Foaming Manure Non-FoamingManure

Visc

osity

(cP)

As Is

Centrifuged

Filtered

A

BB

a

b b1

2 2

Its not just the solids, something else is giving us viscosity in the foam.

-sugar, oil, lipopolysaccharides, proteins? Microbial goo

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

Frac

tion

of P

artic

les F

inne

r

Particle Size (um)

Foam

Foaming Manure

Non-foaming Manure

0

20

40

60

80

100

120

140

160

180

200

Foam Foaming Manure Non-foamingManure

Aver

ag P

artic

le S

ize (u

m)

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

Frac

tion

of P

arti

cles

in

Size

Cla

ss

Particle Size (μm)

C-SBM-C C-DDGS-C

C-SH-C C-SBM-F

C-DDGS-F C-SH-F

Greater percent of particles were fine silt particles from inoculated manure (p < 0.05) & courser grind (p = 0.1254)

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.

So Proteins then?

0

5000

10000

15000

20000

25000

30000

35000

40000

Foam Foaming ManureNon-foaming Manure

Prot

ein

Cone

nt (u

g/m

L) As Is

CentrifugedA

B

B

aa

a

So remove proteins, stop foam?

• Removal of protein strongly reduces foaming capability and stability

What’s holding the proteins together?Total Carbohydrates

mg

g-1 m

anur

e

0.0

0.5

1.0

1.5

2.0

2.5 Foam

Foam Manure C

Non-Foam Manure C

Total Hemicellulose

g g-1

man

ure

0

200

400

600

800

1000

Foam

Foam Manure C

Non-Foam Manure C0.977

0.7980.783

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

Precautionary Measures

Any attempt to break-up foam WILL releaseexplosive levels of methane. Therefore….

1. All ignition sources OFF (i.e. pilot lights, welding),2. Set ventilation at 30 cfm/pig space minimum,

- Use open curtains if ≥ 10 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

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 ≥ 10 mph

But NOT

Curtains Open, Calm ConditionsReliance on Fans

Precautionary Measures (NPB)

http://www.pork.org/filelibrary/November2009%20PCRSE.pdf

Precautionary Measures (ISU)

http://www.agronext.iastate.edu/immag/

Precautionary Measures (UMN)

http://www1.extension.umn.edu/agriculture/manure-management-and-air-quality/

Questions, comments, discussion?