deep–pit foaming control - namic - home · agricultural engineering and animal science, a...

Deep–Pit Foaming Control Tuesday, July 23, 2013, 10:20 a.m.

Dr. Chuck Clanton, P.E. Faculty Member University of Minnesota St. Paul, Minn. Chuck Clanton has been on the faculty at the University of Minnesota in the Department of Bioproducts and Biosystems Engineering since 1980. He has research and classroom teaching appointments. His interests are in environmental issues dealing with animal agriculture, more specifically in water quality issues such as nutrient management, land application of manure, and water quality beneath manure storages and in air quality issues such as odors, gas emissions, GHG, and variability in measuring. He is a member of the American Society of Agricultural and Biological Engineers, the National Society of Professional Engineers, the Minnesota Society of Professional Engineers, and American Society of Animal Scientists. Chuck is a licensed professional engineer in Minnesota and he holds bachelor’s degrees in agricultural engineering and animal science, a master’s degree in agricultural engineering from the University of Nebraska, and a doctorate from the University of Minnesota. Session Description: Foaming on the manure surface in deep-pit barns is not a new phenomenon, but until recently spontaneous foaming was rare. Foaming incidence has increased significantly since 2008 and concerns over the potential hazards posed by foam have risen accordingly. This session will provide a better understanding of the agricultural sector on preventing fires, explosions, and animal building loss.

Top Three Session Ideas Tools or tips you learned from this session and can apply back at the office.

1. ______________________________________________________________________

2. _______________________________________________________________________

3. ________________________________________________________________________

Deep-Pit Foaming Control Session Outline

Overview

• Review Swine Buildings o Ventilation is Complex o Mechanical System o Natural, Curtain Sides o Biosecurity

• Foaming Needs • Brewery Industry • Beer & Manure Club

Problem

• Foam • Foam Destruction • Questions

Producer Survey, Fall 2010

• History – Manure Deep-Pit Foaming • Common Foaming Situations • Producer Survey

Producer Survey, Fall 2012

• Pumping Frequency • Pit Additives for Non-Foaming Issues • Unpleasant Smell in Drinking Water • To Reduce Foam – Commonly Used Pit Additives • How Often Do You Check Your Pits? • Preliminary Statistical Tests • Flash Fire or Explosion (13 Producers) • Questions

Deep-Pit Manure Sampling

• Sampling Standardization Causative Factors (Minnesota)

• Lab Summary • Manure Compositional Change • Foaming Index • FI Results When Added Immediately

o One Week o Four Weeks

• Current Lab Research – Summary • Long-Chain Fatty Acids – Propose Feeding Trials • Questions

Gas, Liquid, Physical Phase System (Iowa) • ISU – Pit Foaming Results • Outline • Short Chain Volatile Fatty Acids • Gas Phase • Methane Production Rate • Methane Fluxes • Foaming Capacity • Diet Tank Projects • Summary • Questions

Microbial Ecology Evaluation (Illinois)

• Microbial Analysis Methods • ARISA Revealed Dominant Population in Foam • ARISA Revealed Dominant Population in Slurry • Microbial Communities Differ Among Foaming and Non-Foaming Samples • Microbial Richness is Reduced in Foaming Sites • Current Site Management and Environmental Factors Being Collected and Stored in

Project Database • Differences in Microbial Communities Were Correlated with Management Factors • Higher Methane Production is Correlated with Foam Production • Summary • Questions

Field Study – Monensin

• Foaming – Bloat • Experimental Procedure • Site A – Rumensin • Site D - Rumensin • Site C – Boat Guard • Safety – Rumensin

o Human Handling o Swine o Environmental o Playing the What if Game o Half Life in Soil

• Regulations – Rumensin • Bottom Line

o Rumensin-90 – Preventative o Remensin-90 – Active Foam

• Questions Producer Recommendations

• Check Pits Weekly • Proper Ventilation • Eliminate Sparks • Minimum 12 Inches Headspace Above Manure • Agitation/Pumping Manure • No Rooster Tailing

Future Research Direction

• Multiple State/Multi-Year Project • Repeat Producer Survey • Tie/Predict Foaming Based on on-Farm Factors • Feeding Trials Targeting Dietary Components

Q & A

Deep-Pit Foaming Control

NAMIC Agricultural Risk Inspection School

July 23, 2013

Bloomington, MN

• Problem

• Producer survey, fall 2010


• Deep-pit manure sampling

• Causative factors (Minnesota)

• Gas, liquid, physical phase system (Iowa)

• Microbial ecology evaluation (Illinois)

• Field study—Monensin

• Producer recommendations

• Future research direction

2013 NAMIC Agricultural Risk Inspection School - Clanton Page 1 of 54

Review swine buildings

• Ventilation is complex

– Multiple, variable speed fans

– Based on pig size & weather



• Mechanical system




• Mechanical system

• Natural, curtain sides


• Biosecurity

– Time

– Species


Foaming needs

• Biogas generation – CH4, CO2, H2S

• Surfactants – Decrease surface tension

• Stabilizer – Increases bubble stability– Filamentous bacteria– Small fiber– Other hydrophobic particles

Brewery industry


BM Club

BM Club

• Beer & Manure Club


• Problem





• Solid, liquid, gas phase system (Iowa)





Foam


Foam destruction


Questions

• Problem











History—manure deep-pit foaming

• 2004 Flash fires and foaming – Ignored

• 2009 summer/fall– Barn explosions

– Flash fires

• Pit foaming related

Common foaming situations

• Same farm– One pit or barn foams

– Others don’t foam

• Problem over time (1-2 yr)– Once established, very fast growing

• Sensitive trigger


Producer survey

• 28% of producers, 26% of pits foam– Limited to upper Midwest

– Isolated other locations

Producer survey

• 28% of producers, 26% of pits foam• No clue as to cause—facilities

– Building (room) type, size, or age– Type of waterer (nipple/cup) or

feeder (dry/wet-dry)– Room cleaning technique– Pit additives or pumping frequency– Genetics– Diet– Management


Producer survey

• 28% of producers, 26% of pits foam

• No clue as to cause—manure character– Manure crust presence

– pH

– Solids content

– Nutrients

– Strength—COD

– Lipid (fat) content (maybe)

• Problem











2012‐2013 Manure Foam Survey

• 34 questions, seven categories

– Different questions

• Bigger geographical area

• Problem still exists

Survey Results• Total 225 surveys

– Iowa (80.0%)

– Illinois (8.9%)

–Missouri (4.9%)

–Minnesota (3.1%)

–Michigan (2.2%)

– Indiana (0.9%)

• Total 88 counties

50 counties in IA

IA80.0%

IL8.9%

MN3.1%

IN0.9%

MO4.9%

MI2.2%

50 counties in IA


Survey Results

• 24% foam was present

• 58.7% producers had at least one foaming pit

• 13 producers had an explosion or a flash fire caused by manure foam:

– 5.8% of all producers

– 9.8% of producers with at least one foaming pit

Survey Results

Pumping frequency

– Once a year: 54.2%

– Twice a year: 43.6

– Three times a year: 2.2%

• Foaming farm owners pumped twice a year more often

Foaming Non‐foaming

Once a year 52.3% 57.0%

Twice a year 46.2% 39.8%

Three times a year 1.5% 3.2%


Survey Results

Pit additives for non‐foaming issues

• Additives used to reduce foam and additives used for non‐foaming issues sometimes overlapped

• 70% of the non‐foaming and 62% of the foaming farm owners did not use a pit additive

Pit additives Foaming Non‐foaming

No 62.1% 69.9%

Yes 37.9% 30.1%

Survey Results

Unpleasant smell in drinking water

– 87.6% no

– 12.4% yes

Unpleasant smell Foaming Non‐foaming

No 83.3% 93.5%

Yes 16.7% 6.5%


Survey ResultsTo reduce foam

Commonly used pit additives:RumensinCoban 90Pit chargerPit digesterKnock-down

MOC#7Profit pro

Digest O BacFoam eliminator

Defoamer

Action taken Response %

Used pit additive(s) 45.5%

Nothing 36.4%

Agitated manure 20.5%

Sprayed water 9.1%

Used feed additive(s) 7.6%

Pumped manure out 5.3%

Added mineral or vegetable oil

3.8%

Other 2.3%

Added diesel fuel 1.5%

Survey Results

How often do you check your pits? Response %

Once a week 37.1%

Once a month 32.6%

Twice a year 12.9%

Twice a month 12.1%

Never 4.5%

Once a year 0.8%


Survey ResultsPreliminary statistical tests

p‐value

Pumping freq. 0.48

Depth 0.42

Solid content 0.09

pH 0.25

Pit additive 0.27

Cleaning 0.3

p‐value

DDGS ave 0.40

DDGS max 0.43

Antibiotic 0.25

Fat 0.26

Unpleasantsmell

0.03

Flash fire or explosion (13 producers)What was the state of the barn? Response %

Rooms empty 76.9%

Rooms full 15.4%

Rooms partially full 7.7%

What was happening in the barns? Response %

Repair work 61.5%

Manure agitated/pumped 30.8%

Rooms being washed 15.4%Ventilation level Response %

More than minimal 46.2%

Minimal 38.5%

None 15.4%


Questions

Fishing for ideas

Educated guess


• Problem










Sampling Standardization

• Layer A– foam or crust only

• Layer B– transition

• Layer C– slurry

• Layer D– sludge layer


• Problem











Lab summary

• Bacteria screening• Differences in species

• Differences in communities

Manure compositional change

Total Solids Percent

Organic Nitrogen%DM

Total Nitrogen%DM

Ammonia Nitrogen%DM

Foaming layer

9.0 0.42 0.88 0.46

Foamingliquid

5.2 0.25 0.71 0.45

Total Solids %

Organic Nitrogen%DM

Total Nitrogen%DM

Ammonia Nitrogen%DM

Foaming layer 9.0 0.42 0.88 0.46

Foaming liquid 5.2 0.25 0.71 0.45

Non‐foaming liquid

5.3 0.23 0.74 0.51


Foaming Index

FI results when added immediately

A: digested manureB: raw manure


One week

0

2

4

6

8

10

12

14

16

18

Control Yeastextract

Corn oil DDGS VFA Tracemetals

Fo

amin

g I

nd

ex Non-foamingdigested manure

Seeded digestedmanure

Non-foaming rawmanure

Seeded rawmanure

Four weeks

0

10

20

30

40

50

60

70

80

90

Control Yeastextract

Corn oil DDGS VFA Tracemetals

Fo

amin

g i

nd

ex Non-foamingdigested manure

Seeded digestedmanure

Non-foaming rawmanure

Seeded rawmanure


Current lab research—summary

• Surface oil addition– Short-term benefit

– Long-term bigger problem• Better carbon balance


• Surface oil addition

• No real impact– Yeast extract

– DDGS

– VFA

– Trace metals



• Surface oil addition

• No real impact– Yeast extract

– DDGS

– VFA – Glycerol – short chain

– Oleic acid – long chain

– Trace metals

0

10

20

30

40

50

60

70

80

90

Control Glycerol Oleic Acid Glycerol + OleicAcid

Fo

amin

g In

dex


0

5

10

15

20

25

30

35

40

45

50

0.0 0.1 0.2 0.3 0.4 0.5

Fo

am i

nd

ex

Oleic acid, ml/L

PalmiticAcid

StearicAcid

OleicAcid

LinoleicAcid

Sum of four fatty acids

Foaming 651 1652 1707 148 4147

Non-foaming 426 898 671 77 2048

Long‐chain fatty acids


PalmiticAcid

StearicAcid

OleicAcid

LinoleicAcid


Foaming 651 1652 1707 148 4147

Non-foaming 426 898 671 77 2048

Propose feeding trials

Long‐chain fatty acids

Questions


• Problem





• Gas, liquid, physical phase system (Iowa)





ISU ‐ Pit Foaming Results

Gas, Liquid, and Physical phase system approach to foaming


Outline• Three‐Phase System Approach

• Field Data

– Temperature and pH

• Solids Phase

– Total Solids and Volatile Solids

• Liquid Phase

– Viscosity, Surface Tension, Density

– Volatile Fatty Acid Analysis

• Gas Phase

– Methane Production Rate

– Biochemical Methane Potential

• Foaming Capacity and Stability57

Short Chain Volatile Fatty Acids

– Statistical differences by surface condition, no difference in strata, but highest concentration tended to occur at the surface

– In general foaming barns had lower VFA, possibly converted to methane more efficiently 58

0

2000

4000

6000

8000

10000

12000

14000

16000

OCT NOV DEC

Total VFA Concentration

(μg/g)

Sampling Month

Foaming

Non‐Foaming

A

AA A

B

B


Gas Phase• Biochemical Methane Potential Assay

– Month was the only significant factor in the statistical model, but strata and surface condition were nearly statistically significant

– Data could suggest that foaming barns are more efficient digesters as more potential has been consumed 59

Methane Production Rate

– Statistically significant differences between samples from foaming barns and non‐foaming barns

– No differences between month or strata before temperature corrections

60

0.00

0.05

0.10

0.15

0.20

0.25

0.30

OCT NOV DEC JAN FEB MAR APR


(L/L slurry‐day)

Sampling Month

Foaming

Non‐Foaming

A

AA

AA A

A

B

BB

B B BB

0.00

0.05

0.10

0.15

0.20

0.25

B C D


(L/L slurry‐day)

Stratum

Foaming

Non‐Foaming


Methane Fluxes

– Temperatures corrected to in situ pit temperature via empirical curve developed in separate study

– Average corrected MPR for facility by depth61

0

20

40

60

80

100

120

140

160

180

200

Oct Nov Dec Jan Feb March April

Metha

ne Flux (L/m

2 ‐day) Foaming

Non‐foaming

Foaming CrustA

A

AA

AA

A

BB

B BB B C B

Foaming Capacity

– In general, foaming barns had a higher capacity index than non‐foaming barns, and more stratified variation

– Increasing trend by month is counterintuitive, but may indicate a surfactant suspended in the foam layer itself

62

0

50

100

150

200

250

OCT NOV DEC JAN

Foaming Capacity Index

Sampling Month

Foaming

Non‐Foaming

A A

A

AA

B B

B

0

20

40

60

80

100

120

140

160

180

B C D

Foaming Capacity Index

Stratum

Foaming

Non‐FoamingA

B

B

B

B

B


Diet Tank Projects

• Feeding trials

• Protein and carbohydrates/fiber

Diet Tank Projects

• Foam testing, after thought

– Get experience in testing & analysis of foam

• No consistent statistical differences


Summary

Foaming pits:

• Produced methane faster

• Greater biological processing

• Lower VFA

• Higher LCFA

• Greater foam capacity

Questions


• Problem










Microbial Ecology Evaluation

of Foam Production


Microbial analysis methods

ARISA Revealed Dominant Population in Foam

• Population 785 was enriched in the foam layer of foaming samples


ARISA Revealed Dominant Population in Slurry

• Population 791 was dramatically enriched in the manure slurry at foaming sites

Microbial communities differ among foaming and non‐foaming samples

• Distinct microbial communities were observed in foaming and non‐foaming samples

• Across many sites and sampling dates, we see consistently different communities in foaming and non‐foaming samples

NMDS based on ARISA from consistently foaming and non-foaming samples, B layer only Each point represents a sampleDistance represents dissimilarityANOSIM R = 0.565, p<0.001


Microbial richness is reduced in foaming sites

• Significantly fewer microbial populations are detected in the foaming slurry Based on ARISA from consistently foaming

and non-foaming samples

Current site, management, and

environmental factors being collected and stored in project

database


Differences in microbial communities were correlated with management factors

• Higher fiber, methane production, and depth are associated with foaming samples.

Correspondence analysis based on ARISA from consistently foaming and non-foaming samplesDistance represents dissimilarity in community compositionArrows represent potential explanatory variablesB layer only

Higher methane production is correlated with foam production• Consistently foaming sites had significantly higher methane production rates foaming non-foaming

MPR data from Dan Andersen


Summary

• There are community differences

• Within communities, there are microbial population differences

• On‐farm characteristics affect populations, dietary fiber & manure depth

• Foaming correlated to methane production

Questions


• Problem










Foaming ↔ Bloat

• Borrowed from beef production

• Rumensin– Alters biochemistry pathway in rumen

• Increased volatile fatty acids

• Decreased methane

• Bloat Guard– Reduces frothy bloat in grazing cattle


Experimental procedure

• Added Rumensin-90 directly to the pit– Similar rates to feeding

• Rates / 100,000 gal manure– 0 lbs (control)

– 2.5 lbs

– 5.0 lbs

– 10.0 lbs

Experimental procedure

• Rumensin-90

• Added Bloat Guard– Rumensin-90 (control @ 5 lbs)

– 60 lbs

– 100 lbs


0

5

10

15

20

25

30

Preapplication 3-wk post

Fo

am d

epth

(in

ch)

Sampling period

Site C--Boat GuardRumensin

BG 60

BG 100A

BG 100B

Application

Safety - Rumensin

• Human handling– Causes eye burns

– Allergic skin reaction

– Harmful if swallowed

– Respiratory tract irritation

• Swine– Lethal if enough consumed

– 0.1 lb product per 100 lbs liveweight


Safety - Rumensin

• Environmental– Toxicity to fish

– LC50 for 96 hr• Lethal concentration 50% of population

– Rainbow trout: 9.0 mg/L

– Bluegill sunfish: 16.6 mg/L

Safety - Rumensin

• Environmental– Rainbow trout: 9.0 mg/L

• Playing the what if game– 5 lb / 100,000 gal

– 50% reduction in pit

– 6000 gallons / acre; 10% runoff

– 1 inch rain; 75% runoff

– 0.018 mg/L (0.2%)


Safety - Rumensin

• Environmental– Rainbow trout: 9.0 mg/L

• Playing the what if game

• Half life in soil– 7 days

Regulations - Rumensin

• FDA – None, not being fed

• MPCA– No official statement

• MDA– Non-Pesticide


Bottom line

• Rumensin-90—Preventive – 1-2 lbs after pumping pits

Bottom line

• Rumensin-90—Preventive

• Rumensin-90—Active foam– Suggest 5 lbs / 100,000 gallons

• Lower rate (< 5 lbs) may work – Take additional material

– Longer period

– About 10-14 days to see response• Maybe 30 days


Bottom line

• Rumensin-90—Preventive

• Rumensin-90—Active foam– Interaction with other pit additives

– No clue

Questions


• Problem










Swine producer recommendations

• Check pits weekly

• Foam present

– Treat

– Pump manure




• Proper ventilation

• Emergency backup generation

• Never shut off

– Even when empty




• Eliminate sparks

– Cigarettes, cigars, pipes, etc.

– Sparking switches / motors

– Pilot lights

– Welding / grinding






• Minimum 12 inches headspace above manure





• Agitation / pumping manure

– Max ventilation

• All fans are on

• Curtains wide open, > 10 mph wind

– No humans

– No animals






• No rooster tailing

• Problem











Research direction

• Continue multiple state

– Iowa

– Illinois

– Minnesota

• Multi‐year project

Research direction

• Multiple state / Multi‐year project

• Repeat producer survey

– Late 2014 / early 2015

– Compare 2010 & 2012


Research direction



• Tie / predict foaming based on on‐farm factors

Research direction



• Tie / predict foaming based on on‐farm factors

• Feeding trials targeting dietary components

– Long‐chain fatty acids

– Fiber

– Combination / interaction


Questions


Swine Manure Deep-Pit Foaming Control for Preventing Flash Fires and Explosions

Chuck Clanton, Ph.D., PE

Bioproducts and Biosystems Engineering University of Minnesota

St. Paul, Minn. 612-625-9218 [email protected]

Presentation at the 2013 Agricultural Risk Inspection School

National Association of Mutual Insurance Companies July 23-25, 2013 Bloomington, Minn.

In 2004, two flash fires occurred in west-central Minnesota, where a blue flame moves across the manure surface in swine deep-pits. In 2009, several swine finishing units experienced flash fires with two explosions. It was an abnormally cold winter and producers had reduced ventilation rates to conserve heat. In some cases, they had completely shut down the ventilation during changeover between pig groups. A producer survey determined that about 25% of the finishing barns in the upper Midwest have the potential to produce explosive conditions and flash fires. The information presented here is a summary of the past four years of research and observations between three institutions: the University of Illinois, Iowa State University, and the University of Minnesota. This is an ongoing research effort that will be maintained until the foaming cause has been definitively identified and the problem has been solved with economical and environmentally safe solutions. The information is organized in the following chapters:

1. Swine deep-pit foaming problem statement and background 2. Detailed management survey identifying factors (Spring 2010) 3. Survey on foaming deep-pit swine manure (Fall 2012) 4. Deep-pit manure sampling standardization 5. Causative factors relevant to deep-pit swine manure (University of Minnesota) 6. Solid, liquid, and gas phase system approach to foaming (Iowa State University) 7. Microbial ecology evaluation of foam production (University of Illinois) 8. Field testing pit additives monensin and proloxalene 9. Recommendations to swine producers 10. Future research direction 11. References and bibliography 12. Appendix: Ventilation and energy management for 21st century pig buildings

Funding for this research has been provided by the National Pork Board, Iowa Pork Board, and Minnesota Pork Board. The Agricultural Experiment Stations of Illinois, Iowa, and Minnesota have provided funds to help maintain laboratories and to partially cover salaries of full-time employees.

Swine deep-pit foaming problem statement and background

Chuck Clanton, PE, Larry Jacobson, PE, David Schmidt, PE Bioproducts and Biosystems Engineering

University of Minnesota Deep-pit livestock buildings—facilities that use 6- to 12-ft-deep below-barn pits to provide long-term manure storage—have been used for many years. Foaming on the manure surface in deep-pit barns is not a new phenomenon, but until recently, spontaneous foaming was rare. Reduction in available manure storage volume is the most obvious consequence, so foaming has mainly been viewed as a manure management problem. Foaming incidence has increased significantly over the past three years (Burns, 2010; Jacobson and Schmidt, 2010; Schmidt and Jacobson, 2010; Schmidt, 2011; UM, 2009; UM, 2010a), and concerns over the potential hazards posed by foam have risen accordingly. Typically, several inches of foam are reported to build up and cover the surface in deep-pit swine finishing barns (housing pigs weighing 50 to 280 lb), but foam depths of 5 ft or more have been observed on manure surfaces (Figs. 1-1 and 1-2) and up to 18 inches above slats (Fig. 1-3).

Foam traps and holds biogases generated during typical anaerobic decomposition of stored manure. Disrupting the manure or foam surface releases bursts of biogas with methane concentrations of 50% to 70% by volume. When mixed with ambient air, the resulting concentration can produce interior methane concentrations in the explosive range (5% to 20%). This increases potential for flammable gas levels when a room heater or motor is activated or when a worker begins spark-inducing maintenance tasks (e.g., grinding or welding).

Foaming manure has been implicated as the underlying cause of several barn explosions (referred to as flash fires) in Minnesota, Iowa, and Illinois (Dehdashi, 2009; Jordahl, 2010; RAM, 2009; Vansickle, 2010; Willette, 2010). Hydrogen sulfide also is trapped in this foam, and when it is released, barn concentrations can easily exceed 250 ppm, which is above OSHA Permissible Exposure Limits of 20 ppm (ceiling) and 50 ppm (peak) (DOL, 2010).

Figure 1-1. Foam coming up through slats from below-barn manure pit.

Figure 1-2. Foam visible in a deep-pit pump-out access area.

Figure 1-3. Foam approximately 18 inches deep.

Recent fires associated with foaming manure have caused extensive building damage including melted plastic feed and water lines and ventilation ducts (Fig. 1-4) and bent or warped metal sheeting (Fig. 1-5). Pigs were severely burned and most had to be immediately sent to market or euthanized (Fig. 1-6). No human deaths were associated with the fires, but workers were injured after being propelled by the blast or by exposure to intense heat (two were hospitalized with second- and third-degree burns [Moody et al., 2009; Springer, 2009; Theisen, 2009]). Three reported deaths at swine confinement facilities in 2010 (one in Minnesota and two in Nebraska) have been associated with handling swine manure (Associated Press, 2010; KTTC, 2010; Pieters, 2010a; Pieters, 2010b). It is unknown whether manure foaming was associated with these incidents, but elevated hydrogen sulfide levels were implicated in the deaths.

Current and abrupt increases in manure foaming over the past five years have raised considerable concern among producers and others associated with animal agriculture (Moody et al., 2009; UM, 2009; UM, 2010a). Recent discussions with farm managers during 2009 and 2010 indicate that the number of foaming barns has increased and that foaming problems have spread to new geographic areas. While deep-pit buildings have been used in Midwest swine finishing barns for several decades, management practices continue to evolve. Pork production today is different (genetics, weight gain, efficiency, market weight, manure production, etc.) from that of previous

decades, and manure characteristics change as animals and their diets change. Safe handling of manure in any deep pit requires informed consideration of the prevailing environment and adherence to established protocols. However, foaming introduces new hazards for which there are no established control mechanisms. Given typical building structure, foam in a manure pit is not easily observed by barn managers, and can go unnoticed while hazardous conditions develop.

Figure 1-4. Melted plastics after a flash fire.

Figure 1-5. Warped metal sheeting.

Figure 1-6. Total building loss.

Detailed management survey identifying factors

Larry Jacobson, PE, David Schmidt, PE, Chuck Clanton, PE, Rose Stenglein Bioproducts and Biosystems Engineering

University of Minnesota Researchers at the University of Minnesota received university seed funding for a small pilot project in early 2010 (Rapid Agricultural Response Fund, Minnesota Agricultural Experiment Station) to begin preliminary investigation of foaming causes and the link between foaming and barn explosions. The researchers visited several sites that had experienced flash fires and/or extensive manure foaming and conducted a small-scale qualitative survey of Midwestern swine producers to gain initial insight into the foaming problem. The survey, conducted from January through March 2010, provided a preliminary look into the extent of the foaming problem and possible correlations between foaming incidence and on-site factors such as management practices, diet and building construction (Jacobson et al., 2010). The best data from the survey came from two swine integrator groups. In the first group, 28 of 80 producers responded (35%); in the second group, 66 of 73 responded (90%). In both groups, approximately 25% of the respondents reported some barn foaming, with about half of those barns having foam levels greater than 6 inches (Fig. 2-1). The survey revealed little correlation between production practices and foaming incidence. Based on these preliminary survey results and subsequent conversations and field visits with selected producers, the research team speculated increased foaming over the past two years may have been due to complex and poorly understood interactions. It is clear that foam formation and, more important, foam disruption during pit agitation and pumping, can release significant quantities of explosive methane. Foaming incidence seems to be lower in Nebraska than in Minnesota, Illinois, and Iowa (Stowell, 2010). This phenomenon is being investigated through site visits and manure testing as time and funding permit at barns throughout the four-state region.

Figure 2-1. Percentage of pig rooms with foaming.

Survey on foaming deep-pit swine manure

Neslihan Akdeniz, Larry Jacobson, P.E., Chuck Clanton, P.E., Brian Hetchler, P.E. Bioproducts and Biosystems Engineering

University of Minnesota Survey methodology

Based on the earlier 2010 survey results and subsequent conversations and field visits with selected producers, the research team speculates increased foaming over the past two years may be due to complex and poorly understood interactions. It is clear that foam formation and, more important, foam disruption during pit agitation and pumping, can release significant quantities of explosive methane.

Modification of the 2010 survey is being administered to an expanded list of pork producers at contract growers meetings and via the internet throughout an expanded area past the upper Midwest during late summer, fall of 2012 through winter of 2013. Major additions to the survey compared to the 2010 survey included an extensive analysis of the feeds being consumed and mitigation techniques used or established in the past few years.

Survey results were collected from September 2012 to May 2013 through collaboration among the University of Minnesota, Iowa State University, University of Illinois, University of Missouri, Michigan State University, and Purdue University. The online survey was created using the Survey Monkey tool (http://www.surveymonkey.com). Hard copies of the survey and survey invitations were distributed at producer meetings in Minnesota, Iowa, Illinois, and Missouri and e-mailed/mailed to pork production integrators located in Minnesota, Michigan and Indiana.

The survey consisted of 34 questions covering farm location (state and county); manure storage, agitation, and pumping; pit foaming observations; flash fire incidence and explosions; and feed and water systems. Correlations between the presence of foam and other data collected were assessed using Pearson’s Chi-squared test (JMP 10.0.0, SAS Institute Inc., NC).

A total of 225 producers responded to the survey (Fig. 3-1a and b), representing 1388 rooms (65.5% grow–finish, 34.5% wean-to-finish) and 1334 deep pits. Among respondents, 132 producers (58.7%) reporting having had at least one foaming pit. Foam was present in 322 of 1,334 pits (24.1%). Thirteen producers (9.8% of those who had at least one foaming pit) reported having an explosion or flash fire.

In comparing these data to the 2009-2010 survey, the percentage of pits that are foaming remained the same at approximately 25%. But the percentage of producers that have at least one foaming pit more than doubled, increasing from 25% to 58.7%.

Figure 3-1. Geographical location of the counties participated in the survey (a) and response percentages of the states (b)

Comparison of foaming and non-foaming farms Pumping frequency More than half of responding producers (54.2%) reported pumping manure from pits once a year, while 43.6% pumped twice a year. Foaming pit owners (46.2%) pumped manure twice a year more often compared to the non-foaming pit owners (39.8%), which was expected, since foam decreases pit capacity (Fig 3-2a).

Crust depth Forty-nine producers (21.8%) reported no crusting on the manure surface in pits. Of the 132 producers who had at least one foaming pit, 41 producers (31.1%) reported observing 2 to 3 inches of crust, while the crust depth at 28% of the non-foaming farms was 1 to 2 inches (Fig 3-2b).

Pit additives for non-foaming issues The majority of respondents (65.3%) reported that no pit additives had been used in their facilities (Fig. 3-2c). This finding was unexpected, since during field sampling it was observed that most of the producers used different types of pit additives for reasons unrelated to foaming, such as odor or pH control.

Cleaning rooms during pressure wash Cold water (80.0%) and disinfectant (66.2%) were the most commonly used methods of cleaning rooms at both foaming and non-foaming farms (Fig. 3-2d).

Unpleasant smell in drinking water Most producers (87.6%) reported no unpleasant odors (such as sulfur/rotten egg smell) in their animals’ drinking water, while 16.7% of respondents with foaming pits and 6.5% of the non-foaming farm owners reported using drinking water with unpleasant odors (Fig. 3-2e).

Manure pH and solids content Most respondents did not know pH (81.3%) or solids content (67.6%) of the manure in their facilities. Among the rest, 10.8% of the foaming pit owners and 5.3% of the non-foaming pit owners reported pH levels between 7.0 and 7.5 (Fig. 3-2f) and no reported pH was less than 7.0; 15.2% of the foaming pit owners reported solids contents between 5.0% and 5.9%, while 15.0% of the non-foaming pit owners reported solids contents between 4.0% and 4.9% (Fig. 3-2h).

Antibiotic and additional fat use in feed About half (48%) of respondents did not know if subtherapeutic levels of antibiotics were used in swine feed, but 18% of non-foaming pit owners and 22% of foaming pit owners reported that subtherapeutic antibiotics are added to feed (Fig. 3-2g). A majority of producers (68%) did not know if additional fat was added to feed, but 15.1% reported that additional fat was used at ratios at rates ranging from 5 to 150 lb fat per ton of feed (Fig. 3-2i).

Dried distillers grains with solubles (DDGS) use Both average and maximum DDGS use was asked in the survey. While 38.4% and 50.5% of respondents did not know average or maximum DDGS content of feed, respectively, at both foaming and non-foaming farms, 1% to 10% and 11% to 20% DDGS received the highest response rates for average DDGS content, while 11% to 20% and 21% to 30% DDGS were the most common answers for maximum DGGS use (Fig. 3-2j).

Statistical test results Preliminary statistical analysis indicate significant correlations were found in the survey data. Specifically, an unpleasant smell in drinking water (p-value=0.03) and the solids content of manure (p-value=0.09) were found to be significantly correlated with foam presence.

Farms with foaming pits

Most of the producers who responded to the survey said they noticed foam for the first time in 2010 (31.1%) or 2011 (24.2%). Seasonally, foaming was a concern mainly in summer (43.2%) and fall (37.9%). Foam depth varied from farm to farm, with reports of foam depth at 6 to 12 inches reported for 29.5% of the farms and 13 to 24 inches at another 29.5% of farms responding to the survey.

More than one-third (36.4%) of respondents said they had not taken action, while the rest had used some form of pit additive (45.5% of those attempting to reduce foam), agitated manure (20.5%), sprayed water (9.1%), used a feed additive (7.6%) or manure pumping (5.3%). Most commonly used pit additives were Rumensin-90, Coban-90, Pit Charger, Pit Digester, Knock Down, MOC#7, Profit Pro, Digest O Bac, Foam Eliminator, and Defoamer. Too little data were available to assess effectiveness of these additives or other actions taken to reduce foaming, since pits were not checked after treatment. Survey results showed that producers do not check pits frequently, even after experiencing an explosion or a flash fire. Only 37.1% of the foaming pit owners reported they check pits once a week.

Farms with explosions or flash fires

Thirteen farm owners reported having an explosion or a flash fire at their facilities since 2008. During most of those incidents, rooms were empty (76.9%), there was a spark inducing repair work (61.5%) and ventilation exceeded minimal levels (46.2%).

a

b

c

d

e

f

g

h

i

j

Figure 3-2. Comparison of foaming and non-foaming farms. Foaming farms are farms with at least one foaming pit; non-foaming farms are farms without a foaming pit.

Deep-pit manure sampling standardization

Laura M. Pepple, Richard S. Gates, PE, Angela R. Kent Agricultural and Biological Engineering

Natural Resources and Environmental Sciences University of Illinois at Urbana-Champaign.

A standard operating procedure (SOP) for collecting manure samples from deep-pit manure storages was developed by University of Illinois and is available upon request. The SOP outlines sampling equipment and procedures for use by each of the three-collaborating universities and was developed specifically for foaming research. Included are instructions for manure sample collection, labeling, handling, transporting, and storing. Up to four samples are collected per manure storage depending on manure depth and foaming/crust status (at the time of sampling). The four samples are outlined below and account for any vertical stratification of the manure in the storage.

Vertical stratification are diagramed in Figure 4-1and are:

Layer A - foam or crust only. If no foam or crust is present, then no Layer A sample should be collected.

Layer B - transition from foam or crust to slurry. Sample collected from the liquid surface or from the foam/crust transition to liquid to the slurry. This layer is collected during every sampling event.

Layer C - slurry. Sample collected from the middle of the liquid portion of the storage (see further location definition in Fig. 4-1). This sample should be collected during every sampling event when storage depth is greater than 24 inches.

Layer D - sludge layer. Sample collected from the bottom 6 to 12 inches of storage. This sample should only be collected when the storage depth is greater than 48 inches.

Figure 4-1. Identification of the manure collection layers.

Causative factors relevant to deep-pit swine manure

Mi Yan, Jing Gan, Bo Hu Bioproducts and Biosystems Engineering

University of Minnesota Microbial analysis Early investigations of foaming issues occurring in wastewater treatment facilities, hypothesized that filamentous/Actinomycete species could be the cause of manure foaming in deep pits on Midwestern swine farms. Preliminary microbial screening was done on manure samples collected from both non-foaming and foaming deep pits, on the foam surface and from the bottom of the manure pit. Three replicates of each sample were screened with the denaturing

gradient gel electrophoresis (DGGE) method to identify microbial community differences. Microscopic picture of manure is shown in Fig. 5-1. Fig. 5-2 shows results of DGGE analysis of polymerase chain reaction (PCR) products using universal bacteria primers to characterize the bacterial community. The collection of bands is a “DNA fingerprint” of the microbial community. These band patterns or fingerprints showed a similarity in microbial diversities in both the top and bottom foaming manure samples. The relative abundance of certain microbial species may be different, however. In these tests, while most bands were common among all nine tests, a few clear differences were

observed between foaming and non-foaming samples, indicating potential differences in bacterial populations. After initial screening confirmed the differences between samples from foaming and non-foaming barns, four samples were chosen for 454 DNA pyrosequencing, including a non-foaming liquid manure sample, a liquid manure sample under foaming layer taken in Oct 2010, and two samples taken from the same barn in March 2011. [Pyrosequencing is a second generation DNA sequencing method, high-throughput and more accurate than traditional sanger sequencing. It relies on the detection of pyrophosphate release on nucleotide incorporation, rather than chain termination with dideoxynucleotides.]The results showed some significant differences between foaming and non-foaming samples. The bacteria families Actinomycetaceae, Alcaligenaceae, Bacillaceae, Bacillales_incertae_sedis and Enterococcaceae were observed in significantly greater

Figure 5-1. Microscopic picture of manure. Red arrows point to fibers or filamentous bacteria.

Figure 5-2. DDGE analysis of foaming and non-foaming samples.

populations in foaming samples, but when combined represent a small percentage (<0.5%) of all species and cannot be correlated to foaming. Actinomycetaceae strains, which are the filamentous strains widely isolated from industrial wastewater treatment process with foaming issues, only increased from 0.07% in the non-foaming manure samples to 0.20% in the foaming manure. The difference is too small to be statistically significant. Fluorescence in situ hybridization (FISH) is another method used to detect certain bacteria populations, and a special gene probe can be designed to target specific filamentous bacteria species. Samples were tested at a commercial company in Germany for nine filamentous bacteria commonly seen in the foaming wastewater. Among six samples analyzed, two samples were from non-foaming pits, two were from foaming pits, and two were foaming samples created in the lab from non-foaming samples by adding oleic acid. One foaming sample had no filamentous bacteria. One foaming and one non-foaming had 18% and 14% of bacteria identified as Nacardioform actinomycetes. In summary, observed manure foaming was not related to the amount of filamentous bacteria in the sample. It was confirmed with 454-pyrosequence results that a filamentous bacteria community does not contribute significantly to manure foaming. Illumina pyrosequencing analysis showed that no differences were found on the population of Actinobacteria, which contains most of the foaming filamentous bacteria (Figure 5-3) (Lemmer, Lind et al. 2005). Illumina data did show a significant difference between the foaming manure and non-foaming manure samples in populations of Bacteroidetes, Firmicutes and Proteobacteria. The results indicate that there were microbial community differences between non-foaming and foaming samples, although as noted above it has been determined foaming is not caused by filamentous bacteria. Firmicutes populations were significantly larger in non-foaming manure than in foaming manure, while the other two groups have the opposite relationship. Considering that Firmicutes are predominantly Gram-positive, while Bacteroidetes and Proteobacteria are Gram-negative. The reason for the shift of microbial community toward Gram-negative bacteria in foaming samples is unknown and whether it is due to foaming or whether it causes foaming is not clear. Figure. 5-3. Microbial community analysis of 44 samples via Illumina pyrosequencing.

Non-foaming samples

From these preliminary results, it appears there are microbial community differences between non-foaming and foaming samples, but foaming is not caused by filamentous bacteria. In-lab procedural development of foaming Development of foam requires three components: (1) biogas generation, (2) surfactant from long-chain fatty acids, and (3) stabilizer or hydrophobic particles from fiber and/or filamentous bacteria. The foaming index and stability comparisons used in this research have been modified from the wastewater treatment and brewery industries (Ganidi et al, 2011). The influence of solid particles on formation and stability of foam is dependent on surfactant type, particle size and concentration. Hydrophobic particles entering the foam surfaces can cause an increase or decrease in foam stability. Small particles, if not fully wetted, may become attached to the interface and give some mechanical stability. In wastewater treatment plants, foam stability is often associated with hydrophobic particles such as bacteria cells. Fine fibers also have been found to significantly increase foam stability, using the same mechanisms. Foaming index (FI), used to indicate the foaming capability of manure samples, was measured with a graduated cylinder (length: 1 m, ID: 2.8 cm) at room temperature. Manure samples (25 ml) were poured into the cylinder and nitrogen gas was pumped into the manure through plastic tubing (ID: 0.4cm) at a constant flow rate of 30 ml/min to generate bubbles. The maximum foam height bubbles reached was recorded as the FI (Fig. 5-4). Foam stability (measured immediately after FI measurement) is the time required for the bubbles to collapse, exposing the liquid surface. In this research, foams that persisted for longer than 30 minutes were considered to be stable.

Effects of different components on manure foaming Foaming index laboratory measurements for manure samples immediately after adding various supplements to non-foaming manure or foaming manure (B layer). are shown in Figure 5-5. Adding corn oil to foaming manure immediately dropped FI to almost zero, which indicates that corn oil acts as an anti-foaming agent. Other supplements, such as DDGS and yeast extract did not affect FI (Figure 5-5).

Figure 5-4. Foaming index determination.

Figure 5-5. Foaming index of manure immediately after adding a supplement to non-foaming manure or foaming manure. FI values for non-foaming manure to which a supplement had been added, measured after four weeks of storage, are shown in Figure 5-6. A dramatic change in FI was recorded for the manure samples with added corn oil. Adding yeast extract, DDGS, VFA, and trace metals produced almost no effect or change on FI values of non-foaming manure samples. However, all of the tested samples that included corn oil showed stable and consistent foaming capability, with the FI readings all exceeding the measuring limit. In other words, adding corn oil reduced foaming in the short term (Fig. 5-5); but in the long term, made foaming worse.

Figure 5-6. Foaming index of stored manure with supplements after four weeks. Foaming and non-foaming raw manure came from producers’ deep pits and digested manure came from an anaerobic digester at the University of Minnesota.

When oil is digested by pigs, lipase breaks down triglycerides into glycerol and long-chain fatty acids (LCFA) (Dierick and Decuypere 2002). The research group tested addition of LCFA and glycerol to non-foaming manure and it could be converted to foaming manure as long as LCFA was present. The FI reading was proportional to the amount of LCFA added to manure as shown in Figure 5-7.

Figure 5-7a. Foaming index of non-foaming manure with added oil digestants.

Figure 5-7b. Foaming index of non-foaming manure with added oil digestants.

The FI reading of non-foaming manure jumped to more than 80 ml immediately after addition of free LCFA and gradually decreased to 0 (zero) over five weeks of storage. The higher the concentration of oleic acid added to the manure, the slower the FI reading decreased over time in storage (Figure 5-8). The FI reading dropped to almost 0 (zero) when storage continued beyond five weeks. The greater the amount of DDGS added, the higher the FI reading after two weeks of storage and it took longer for the FI reading to drop to 0 (zero) (Figure 5-8). While manure composition analysis found total fat/oil content is significantly higher in foam layers, but similar between the liquid portion of non-foaming and foaming manure, the analysis was misleading because the common fat/oil analysis was measuring the fatty acid methyl ester (FAME), where all the lipids are hydrolyzed to generate fatty acids and then converted. This analysis did not distinguish between triglyceride and free fatty acids (Dierick, Decuypere et al, 2002). Consequently, the 44 samples were reanalyzed for long-chain free fatty acid concentration. In the second analysis, foam samples were shown to contain significantly higher concentration of all common free fatty acids, including palmitic acid, stearic acid, oleic acid, and linoleic acid, than the rest of the samples, including the liquid portion of non-foaming and foaming samples (Table 5-1).

Figure 5-8. Foaming index readings following addition of DDGS and free fatty acids to non-foaming manure.

Table 5-1. Long-chain free fatty acid analysis of manure samples, mg/L.

Palmitic

Acid Stearic Acid

Oleic Acid

Linoleic Acid


Foaming Mean 651 1652 1707 148 4147 manure N 14 14 14 13 14 samples Std.

Deviation 310 1020 979 92 2183

Non-foaming Mean 426 898 671 77 2048 Samples plus N 27 27 27 19 27 liquid portion of foaming manure

Std. Deviation

347 627 663 100 1596

Feeding trials targeting DDGS With strong evidence from the study, it seems possible that incomplete digestion of long-chain fatty acids supplied by DDGS are serving as a surfactant to initiate foaming and hydrophobic particles (fine fibers from undigested DDGS, and possibly filamentous bacteria) may stabilize foam bubbles. Research will be conducted to further investigate these components and their interaction. Based on the above information, the next step is to develop an experimental design where the targeted long-chain fatty acids (oleic and linoleic acids, the major oil components in DDGS at approximately 25% and 50%, respectively) and comparable fiber (total dietary fiber) is added to the surface of manure in a laboratory setting to determine if there are interactions. Microbial analysis and foaming index measurements will be periodically determined as manure with additives is stored for several months.

Gas, liquid, and physical phase system approach to foaming

Dan Andersen, Kurt Rosentrater, Mark Van Weelden Agricultural and Biosystems Engineering

University of Iowa State Work conducted at Iowa State University is focused in two areas: analyzing manure samples for chemical, physical, foaming, and gas production properties, and feeding trials involving protein and carbohydrate level and sources. Samples collected from swine finisher facilities (according to our SOP) were analyzed for a number of baseline parameters to evaluate the gas, liquid, and physical phases. The gas phase was investigated by determining methane production rate (MPR) and biochemical methane potential (BMP). The liquid phase was characterized by pH, viscosity, surface tension, and density, along with an analysis of volatile and long-chain fatty acid concentrations. Finally, total solids and volatile solids contents were determined to better understand to the solid phase. When these baseline parameters were established, samples were aerated with a lab-scale apparatus developed to determine the capacity of a sample to foam, as well as the ability for the foam to stabilize. It was hypothesized that samples collected from barns with existing foam layers would exhibit significantly different values for key parameters, such as rate of biogas production, concentration of volatile fatty acids, and solids content. In addition, we predicted that the lab-scale foaming capacity and stability test would successfully model the foaming activity of the deep-pit manure storages studied and reinforce trends shown by the other parameters measured in this study. Manure analysis On average, foaming manure had significantly lower VFA (volatile fatty acid) concentrations than non-foaming manure (Fig. 6-1). This trend was significant in all four strata or layers (manure sampling regions A, B, C, and D). Concentrations were highest at the manure surface and tended to decrease with depth. The results indicated that on average, manure from foaming barns had significantly lower VFA concentrations (4400 μg/g) than manure from non-foaming barns (9000 μg/g). LCFA (long-chain fatty acid) levels were elevated within the foam in comparison to the manure below it or manure from non-foaming barns, but actual concentrations were only 400 μg/g on average.

Figure 6-1. Average total VFA concentrations of foaming and non-foaming samples by layer. Error bars are standard error of the mean and letter represent significant differences between layers. The biochemical methane production (BMP) assay provides an estimate of the potential methane production a material could generate under ideal digestion conditions. Results indicated that on average there was less potential for additional methane production from manures obtained from foaming barns than from non-foaming manures. The numerical difference (Fig. 6-2) in remaining biochemical methane production potential between foaming and non-foaming barns suggests that foaming barns are operating as more effective anaerobic digesters than non-foaming barns, indicating that some of the potential for methane production has already been consumed. The methane production rate test indicated that methane is being produced more rapidly in foaming pits than non-foaming pits, leading to greater gas fluxes through the manure (Fig. 6-3 and 6-4). Overall, there was not a significant difference between foaming barns and barns with foamy crusts. A foamy crust is where a 2 inch or less solid crust forms on top of the foam. Thus the need to break the crust to reach the foaming bubbles or allow the gases to escape.

Figure 6-2. Average biochemical methane production (BMP) potential from samples from foaming and non-foaming barn. Error bars represent the standard error of the mean.

Figure 6-3. Average methane production rate of foaming and non-foaming samples by month. Error bars represent one standard deviation of sampled barns. Methane production rates were significantly different every month. Error bars show the standard error of the mean.

Figure 6-4. Average methane flux for foaming and non-foaming facilities, as well as the flux from barns with foamy crusts from January through April. Error bars show the standard error of the mean. Foaming capacity The purpose of the lab-scale foaming capacity and stability test was to establish empirical parameters related to inherent foaming characteristics of manure samples. These parameters were compared to field data regarding the foaming status of facilities during collection as well as the other laboratory tests.

The foaming capacity and stability apparatus used in this study, as well as the parameters used to evaluate the foaming characteristics of swine manure, were adapted from a number of other studies, including Ross et al. (1992), Bindal et al. (2002), Bamforth (2004), and Hutzler (2011). Flow-regulated air (200 cm3/min. or 0.0033 L/s) passed directly into a 2-inch-diameter clear PVC column. . A foaming capacity index was calculated as the height of foam produced divided by the initial level and multiplied by 100. The foam stability measurement was determined immediately after foaming capacity was calculated. Once aeration ceased, the final height of foam became the initial level recorded at time zero. Once this level was established, the descending height of the foam was recorded at expanding time intervals. A first-order exponential decay model fit the data well in most cases. The half-life of the foam was determined as a measure of the foam stability. Foaming capacity and foam stability were greater in manures obtained from foaming barns than from non-foaming barns, with the interface layer having the greatest foaming properties. Results of lab-scale foaming capacity testing of field samples are shown in Figure 6-5. Samples collected from foaming barns showed a significantly greater capacity to foam in most sampling months. Interestingly, the capacity for samples to foam in the lab test increased as foam in the field was depressed in winter months. The interface layer (B) showed the greatest capacity to foam (Figure 6-6). The foaming capacity results by month and sample layer may point to the accumulation of some surfactant at the surface of foaming manure storages, and that this surfactant may be suspended in the foam layer during excessive foaming events. With respect to strata, samples collected closer to surface of the slurry layer showed a significantly higher capacity to foam than did samples collected from the bottom of foaming pits. Meanwhile, non-foaming barns showed similar trends in foaming capacity per stratum. This could indicate that the greater flux of gas through foaming pits is helping to lift some surfactant to the manure surface.

Figure 6-5. Average foaming capacity index of foaming and non-foaming samples by month with standard error of the mean shown.

Figure 6-6. Average foaming capacity index of foaming and non-foaming samples by layer from which the sample was collected with standard error of the mean shown. Dietary effects Swine feeding trials were also conducted. The primary focus of these feeding trials was pig performance evaluation. Collection of the manure for foam properties and biogas production testing was a secondary purpose. Two dietary trials are presented here:

1) protein dietary level and source 2) carbohydrate dietary level and source.

The results of the diet studies showed few consistent statistical differences with respect to diet when tests used on the field samples were performed. In general, it was observed that manure tested in this study exhibited lower methane production rates and higher biochemical methane production potential when compared to field study manure. This probably indicates a less well developed microbial population and less biological processing of the manures. At the conclusion of the diet studies the tanks were aerated to see if foam would develop. This was most successful for the carbohydrate study (Fig. 6-7).

Soybean hulls diet before aeration Soybean hulls diet after foaming

DDGS Diet before aeration DDGS after aeration

Figure 6-7. Various diet manure tanks before and after aeration to determine foaming potential. Manure from these dietary studies failed to spontaneously produce foam (foam could be generated upon aeration, but generally showed only limited stability). In an attempt to spontaneously generate foam, various carbohydrate sources and particle sizes were added directly to the manure to provide readily available carbon source and evaluate whether decomposition of these substances caused formation of a surfactant that could lead to foam formation or stabilization (Fig 6-8).

0

50

100

150

200

250

300

350

400

7 14 21

Foam

ing

Capa

city

Inde

x

Fermentation Time (Days)

Control Ground Soybean Hulls

Unground Soybean Hulls Ground DDGS

Unground DDGS

BC

AA

BCDCD DE

AB

DEDE

F F

CDE

EF

DEFEF

Figure 6-8. Foaming capacity of various feeds added directly to manure.

One additive (soybean hulls) showed enhanced foaming characteristics after one week of fermentation with a decreasing trend in following weeks. Possible explanations for these phenomena include inherent surfactants present in these additives or the production and accumulation of a “biosurfactant” due to microbial activity. Summary Manure in foaming pits is producing methane at a faster rate than manure in non-foaming pits. This appears to be due to greater biological processing of organic matter. Foaming pits had lower VFA concentrations than non-foaming pits. LCFA concentrations were higher in foam than in related manure. Samples from foaming barns showed a greater capacity to foam, especially at the interface layer.

Microbial ecology evaluation of foam production Angela D. Kent, Laura M. Pepple, Richard S. Gates, PE, Katherine Janssen

Natural Resources and Environmental Sciences Agricultural and Biological Engineering

University of Illinois at Urbana-Champaign.

Located in southeastern, east central, and northeastern Iowa, 105 deep-pitted barns have been sampled monthly according to our developed sampling Standard Operating Procedure (SOP). From these barns, 1351 samples have been analyzed for bacterial communities. Depending on the manure depth and foaming/crust status at the time of sampling, one, two, three or four samples were collected from each barn during monthly visits. All samples were analyzed using ARISA (automated ribosomal intergenic spacer analysis) DNA fingerprinting. Preliminary analysis of layer B samples data is shown below.

Differences in microbial communities correlated to foam production

Data from manure samples collected from farms that were consistently foaming or consistently non-foaming on all sampling dates are shown in Figure 1. Comparisons among microbial communities were assessed using the Bray-Curtis similarity statistic, which calculates the percent similarity in species composition among samples. Similarity in community composition can be visualized using non-metric multidimensional scaling analysis (NMDS), which displays similarity among samples as distance among points. This ordination (method of plotting) can reveal patterns in microbial community structure.

In Figure 7-1A, the NMDS displays distinct differences in microbial communities among samples from foaming and non-foaming sites. A multivariable analysis using analysis of similarities (ANOSIM) generated an R = 0.565 between foaming and non-foaming sites and a significant difference at a p-value <0.001). [Note: an R = 0 means no difference, whereas R = 1 means completely different communities.]

In Figure 7-1B, ARISA community fingerprints reveal significantly lower microbial species richness (number of populations) in foaming sites (A layer: p-value =0.024, B layer: p-value <<0.001), suggesting a bloom of dominant microbial species in the foaming samples.

Figure 7-1. Manure samples collected from farms that were consistently foaming or consistently non-foaming on all sampling dates. Each point represents the microbial community observed in a sample collected from consistently foaming (orange) or non-foaming (blue) sites.

Identifying specific microbial populations

Figure 7-2 shows results from the SIMPER (similar percentages) analysis, which compared groups of samples to determine specific microbial populations that contributed to the differences in microbial community composition displayed in Figure 7-1. Farms were classified as consistently non-foaming or foaming, and foaming was further classified as moderate or extensive foaming. Microbial populations that were enriched or depleted in each class of samples are indicated as percent of total microbial abundance. Population 388 was greatly enriched in foaming sites (comprising 13-15% of total microbial populations observed by ARISA). Populations 597 and 860 were also enriched in foaming sites.

Figure 7-2. SIMPER analysis compared groups of samples to determine specific microbial populations that contributed to the differences in microbial community composition. [Note: the number associated with microbial populations are assigned only to this specific research project and have no standardized meaning nor reference.]

On-farm factors correlated to onset of foaming

Correspondence analysis was used to relate differences in microbial community composition between foaming (orange squares) and non-foaming (blue open circles) samples with potential explanatory variables displayed as arrows (longer arrows means more impact or stronger correlation). Farm factors included feed composition (% fiber, fat, protein, DDGS, wheat midds), manure chemical and physical parameters (depth, temperature, pH), or methane production rate (MPR). A positive correlation between explanatory variables increases in the direction of the arrow. Samples with high values for each variable plot close to the arrow.

These data, shown in Figure 7-3A, demonstrated that microbial communities in foaming samples were correlated with high values of dietary fiber (reported as NDF—Neutral Detergent Fiber), greater manure depth, greater methane production rate, and somewhat correlated with higher DDGS. Non-foaming samples are correlated with higher measures of manure pH.

Methane production rates (obtained from colleagues at Iowa State University for the same samples) were overlaid on the correspondence analysis plots (Figure 7-3B) to display the relationship between microbial community composition and MPR. Here each circle represents a microbial sample (as in Figure 7-3A), and bubble size represents relative methane production rate. This demonstrates that microbial samples from consistently foaming sites are correlated with higher MPR.

Figure 7-3A. Correspondence analysis was used to relate differences in microbial community composition between foaming (orange squares) and non-foaming (blue open circles) samples with on-farm factors.

Figure 7-3B and 7-3C. Methane production rates (B) and dietary fiber (C) were overlaid on the correspondence analysis plots (Figure 7-3A) to display the relationship with microbial community composition.

Percent dietary fiber was overlaid as a bubble plot onto the correspondence analysis ordination. Similar to B, each circle represents a microbial sample (as in Figure 7-3A), and bubble size represents relative fiber content in the feed. This demonstrates that microbial samples from consistently foaming sites are correlated with higher NDF.

Summary

Microbial analysis of foaming and non-foaming manure samples from deep-pits have determined: • There are microbial community differences. • Within these communities, there are microbial population differences. • On-farm characteristics affect these populations, primarily dietary fiber and manure depth. • Foaming is correlated to the potential of methane production rates.

Field testing of pit additives monensin and proloxalene Chuck Clanton, PE, Larry Jacobson, PE, Bo Hu, Neslihan Akdeniz, David Schmidt, PE


One of the most promising foam control pit additives is Rumensin®, which has been commonly used to improve production efficiency and health of ruminant animals (National Hog Farmer, 2011a). The active ingredient of Rumensin® is sodium monensin. Monensin is a monovalent carboxylic ionophorous polyether antibiotic, naturally produced by Streptomyces cinnamonensis as a defense against competing microorganisms. It is used in the form of the sodium salt (sodium monensin) (Butaye et al., 2003). It is a hydrophobic compound and therefore most effective against Gram-positive bacteria.

It has been shown that ruminal methane production is decreased 30% by monensin treatment. However, ruminal methanogens are not directly inhibited by monensin; rather, the bacteria responsible to produce substrate (H2) for methanogens are inhibited. Monensin’s anti-bloat effect is mediated by direct inhibition of slime-producing bacteria and reduction in overall ruminal gas production (Callaway et al., 2003).

Another possible pit additive could be poloxalene, an anti-foaming agent (chemical) made available to ruminants on lush or legume pastures to reduce the risk of frothy bloat.

Experimental design

Research was conducted in fall 2011 at 11 Minnesota sites within four integrator or grower groups. Facilities used were typical grow-finish buildings with capacity for, 1000-1100 head, single or double wide, and built over 8-ft-deep pits. Groups of four barns were located on the same or nearby sites and were managed by the same producer to ensure as much as possible the same management style, genetics, diets, and building age.

Within each grouping of sites, four barns within a single site were randomly assigned dosing treatments of 0 (control), 2.5, 5.0, or 10.0 lb of Rumensin® 90 per 100,000 gallons of manure and 5.0 lb of Rumensin® 90 (control), 60 or 100 lb of Bloat Guard® per 100,000 gallons of manure. Experimental units were:

Site A Rumensin® 90 Site B Non-foaming control Site C Bloat Guard®

Site D Rumensin® 90 Site E Rumensin® 90

Research findings

Table 8-1 and the following four bar charts show foam depth (inches) at the time Rumensin® 90 was added to the pits along with foam depths and three weeks and six weeks. Each column is a single pit within a site. Sites B and C were testing different additives that were not successful in reducing foam.

Table 8-1. Foam depth in inches within swine manure deep-pits at four monensin application rates and three time intervals. Site A Site D Site E Application Rate, lb / 100,000 gal

0

2.5

5

10

0

2.5

5

10

0

2.5

5

10

Foam depth, inches Pre-application

20 20 20 20 21 18 21 18 11 14 6 20

3 wk post application

10 0 0 0 12 17 13 12 14 10 1 16

6 wk post application

0 0 0 0 6 0 0 0 14 9 0 3

Site A--Rumensin

0

5

10

15

20

25

Preapplication 3-wk post 6-wk post

Sampling period

Fo

am

de

pth

(in

ch

)

0

2.5

5

10

Application rate (lb)

Site C--Boat Guard

0

5

10

15

20

25

30

Preapplication 3-wk post

Sampling period

Fo

am

de

pth

(in

ch

)Rumensin

BG 60

BG 100A

BG 100B

Application

Site D--Rumensin

0

5

10

15

20

25


Sampling period

Fo

am

de

pth

(in

ch

)

0

2.5

5

10


Site E--Rumensin

0

5

10

15

20

25


Sampling period

Fo

am

de

pth

(in

ch

)

0

2.5

5

10


Rumensin® recommendations for actively foaming pits

Based on our findings, we recommend that producers who have pits at risk for foaming add Rumensin® 90 at a rate of 5 lb per 100,000 gallons of stored manure. A lower rate may help reduce foaming, especially if additional Rumensin® can be added at a later date or more time can be allowed before assessing results. Foam reduction may take as long as two weeks following treatment. While this is our current advice, more work is needed to determine the best dosing rate, timing or season of application, and duration of effects (several months are expected). Take care not to overdose the pit, since that can result in a “dead” pit with no biological activity.

The following are preferred methods for using Rumensin® to control manure foaming (most preferred method is listed first):

• In an all-in/all-out system, after pigs are marketed, sprinkle Rumensin® 90 evenly throughout the empty room or building. As the empty building is power-washed, the additive will be worked through the slats, falling onto the manure surface.

• If the room is occupied, carefully drop Rumensin® 90 through slat openings. The more evenly the product can be applied around the room, the faster and better it will work. This can be accomplished by using a small PVC pipe and funnel (or using a small cup or tablespoon). This method works well under watering cups/bowls or nipple waterers, helping the product move into the pit. If Rumensin® 90 is only added through the slat openings in the alley, follow the addition with five gallons of water to help disperse the granules.

• Add Rumensin® 90 through manure pump-out ports. This method requires time for the product to diffuse throughout the manure pit, which may delay or not accomplish the intended

goal. Agitation may help work the product into manure, but be sure to avoid releasing gases (methane and hydrogen sulfide) and know that agitation may make foaming worse in the short term.

Applying Rumensin® as a solutions through a sprayer is not recommended because Rumensin® 90 is not water-soluble, thus is difficult to maintain in solution and may plug sprayer nozzles.

Coban®

Coban® 90 is another branded monensin product that is used in the poultry industry. It contains the same level of monensin as Rumensin® 90. If Coban® 45 is used, double the product dosage to 10 lbs per 100,000 gallons of manure. If Coban® 60 is used, increase dosage by 50% to7.5 lbs per 100,000 gallons of manure.

Safety and environmental consideration

Avoid human or pig exposure to Rumensin® 90 or Coban®. Both cause burning eyes, skin reactions, and lung irritations if inhaled or ingested. Also note that monensin can be lethal to pigs if ingested.

Material safety data sheets for Rumensin® 90 Premix and Coban® Premix indicate that monensin is toxic to fish at a LC50 (lethal concentration for 50% of the population) 9.0 and 16.6 mg/L (milligrams per liter) for rainbow trout and Bluegill sunfish, respectively; but has a half-life of 7.5 days in soil. Using the application rate recommended in this documents and acceptable nutrient applications rates to cropland, any runoff should yield monensin concentrations in receiving waters less than 1% of the level determined to be detrimental to fish. A comprehensive research program has not been conducted on the environmental effects of monensin in manure.

Note that neither Rumensin® 90 nor Coban® is environmentally approved to be added to manure in a pit if the nutrients will be applied to land. The Minnesota Pollution Control Agency has not made an official statement about use of Rumensin® 90 or Coban® for suppression of foam in manure pits.

Rumensin® 90 and Coban® Premix are not registered as pesticides with the U.S. EPA or Minnesota Department of Agriculture (MDA) and the product manufacturer makes no claims that these products control pests, so they do not fall under MDA jurisdiction. Consequently, no pesticide license or certification is required to use Rumensin® 90 or Coban® Premix.

Based on preliminary research regarding addition of monsensin to deep swine pits to reduce foaming, the researchers estimate that as long as manure is handled and applied to land according to current regulations, monensin contained in manure that has been pumped from deep pits should not be an environmental hazard. To further reduce the risk of monsensin running off the land, manure injection or immediate incorporation is recommended. If pits must be pumped in early spring, wait until soil has thawed to ensure manure is not applied to frozen ground. Monensin has been used in dairy and beef diets for more than 40 years.

Recommendations to swine producers Chuck Clanton, PE, Larry Jacobson, PE


The most important recommendation is for producers to observe and determine the depth of foam (if any) in their deep pits on a regular (at least weekly) basis.

If foam is above the 6-inch depth and within 24 inches of the underside of the slatted floor, then action is needed. This could include one or both of the following: • Use a pit additive to reduce foam depth. • Remove some of the manure to allow additional capacity and headspace above the surface. Be sure to use the proper level of barn ventilation based on outside temperatures along with animal age and size to maintain acceptable air quality and keep methane concentrations below the explosive level. The Appendix has detailed information on ventilation management in swine facilities. The barn’s ventilation system should never be turned off, even if there are no pigs in the building. For the unoccupied building, the minimum ventilation rate used for finishing pigs should be used to prevent methane buildup. The constant running or minimum ventilation rate should be 5 to 10 cfm per pig space (varies with age and size of pigs). Table 1 in the Appendix has detailed information on ventilation management based on animal age and size.

Emergency backup electrical generation is needed in case of main power failure.

Any source of sparking or flames should be eliminated, including: • Cigarettes, cigars, pipes, etc. • Sparking switches or motors • Sparking or pilot light on water and/or space heaters • Welding and/or grinding during repair of gates, feeders, waterers, etc. Additional recommendations include: • Maintain a minimum of 12 inches of space between the top of the manure or foam and lowest

concrete beam for adequate ventilation airflow. • When agitating and/or pumping manure, use the maximum ventilation rate (roughly 10 times

greater than the minimum rate) for an all mechanically ventilated system or the curtains fully open and a breeze (minimum of 10 mph) for naturally ventilated buildings. Animals should be removed. Humans should never enter the building during manure pit pumping.

• No liquid should leave the manure pit surface (rooster tailing) during agitation.

Future research direction

Swine producer and management survey

The swine producer and management survey administered in 2012 will be re-administered three years later to assess impact of this and other projects at the producer or barn level.

Manure testing

Monthly manure sampling of the four levels in swine deep pits will continue for the next two years. Analysis of these manure samples will be conducted by the University of Illinois, Iowa State University, and University of Minnesota.

DDGS diets and manure pit foaming

Jerry Shurson and Pedro Urriola, Animal Science Department, University of Minnesota, and Brian Kerr, USDA-ARS, Iowa State University, are partnering to evaluation the potential connection between distillers dried grains with solubles (DDGS) in diets and manure pit foaming in commercial pork production systems. It is hoped that information gained from this research will determine whether or not feeding DDGS is a causative factor in foaming of swine manure and provide useful information on the amount of long-chain fatty acids and fiber in swine manure necessary to cause foaming. By understanding these fundamental mechanisms, effective mitigation strategies can be developed to manage diet composition and nutrient digestibility to minimize the risk of manure foaming.

Specific objectives include: 1. Determine the amount of long-chain fatty acids excreted in feces of pigs fed diets with or

without DDGS. 2. Determine the amount of long-chain fatty acids from DDGS in manure necessary to produce

foam. 3. Determine the amount of fiber from DDGS necessary to produce foam. 4. Determine the effects of increasing dietary fiber from DDGS on biogas production.

References and Bibliography APHA. 1998. Standard Methods for the Examination of Water and Wastewater, 20th ed.

Washington, D.C.: APHA. Associated Press. 2010. Official: Manure gas killed 2 workers at pump house near West Point

[Neb.]. 1011 News. Available at: www.1011now.com/news/headlines/95983429.html. Accessed June 9, 2010.

Burns, R. 2010. Swine Deep-Pit Barn Fires: Understanding the Causes. Presentation at Iowa Pork Congress, January 27, 2010, Des Moines, IA.

CDC. 2011. Centers for Disease Control and Prevention, Prevention Research Centers, Program Evaluation. Available at: www.cdc.gov/prc/program-evaluation/index.htm. Accessed 12 January 2011.

Clarke K. R., and R. H. Green. 1988. Statistical design and analysis for a biological effects study. Marine Ecology Progress Series 46:213-226.

Davenport, R. J. and T. P. Curtis (2002). “Are filamentous mycolata important in foaming?” Water Science and Technology 46(1-2): 529-533.

Davenport, R. J., R. L. Pickering, et al. (2008). “A universal threshold concept for hydrophobic mycolata in activated sludge foaming.” Water Research 42(13): 3446-3454.

Dehdashti, C. 2009. Ventilate and take other safety measures to prevent manure pit explosions. University of Minnesota News and Information. www.extension.umn.edu/news. November 2009.

de los Reyes, F. L. and L. Raskin (2002). “Role of filamentous microorganisms in activated sludge foaming: relationship of mycolata levels to foaming initiation and stability.” Water Research 36(2): 445-459.

de los Reyes, F. L., D. Rothauszky, et al. (2002). “Microbial community structures in foaming and nonfoaming full-scale wastewater treatment plants.” Water Environment Research 74(5): 437-+.

Ganidi, N., S. Tyrrel, et al. (2009). “Anaerobic digestion foaming causes - A review.” Bioresource technology 100(23): 5546-5554.

Ganidi, N., S. Tyrrel, et al. (2011). “The effect of organic loading rate on foam initiation during mesophilic anaerobic digestion of municipal wastewater sludge.” Bioresource technology 102(12): 6637-6643.

Heard, J., E. Harvey, et al. (2008). “The effect of filamentous bacteria on foam production and stability.” Colloids and Surfaces B-Biointerfaces 63(1): 21-26.

Horozov, T. S. (2008). “Foams and foam films stabilised by solid particles.” Current Opinion in Colloid & Interface Science 13(3): 134-140.

Hu, B., X. Zhou, and L. Forney, Shulin Chen. 2009. Community Change During Chloroform Treatment of Methanogenic Granules for Immobilized Hydrogen Fermentation. Environmental Progress and Sustainable Energy 28(1):60-71.

Hwang, Y. W. and T. Tanaka (1998). “Control of Microthrix parvicella foaming in activated sludge.” Water Research 32(5): 1678-1686.

Liu, W. T., T. L. Marsh, H. Cheng, and L. Forney. 1997. Characterization of Microbial Diversity by Determining Terminal Restriction Fragment Length Polymorphisms of Genes Encoding 16S RRNA. Applied and Environmental Microbiology 63(11):4516-4522.

Jacobson, L. D., and D. R. Schmidt. 2010. Current Understanding of Manure Pit Foaming, Barn Explosions, and Safety Precautions. Presentation to the PorkBridge Webcast Series. August 5, 2010.

Jacobson, L. D., C. J. Clanton, D. R. Schmidt, and R. M Stenglein. 2010. Determining Commonality among Swine Barn Pit Explosions. Progress report submitted to Agricultural Experiment Station, Rapid Agriculture Response Fund.

Jordahl, R. 2010. Foam + Methane = Fire. Pork. www.porkmag.com. March 2010. Kent, A. D., A. C. Yannarell, J. A. Rusak, E. W. Triplett, and K. D. McMahon. 2007. Synchrony

in aquatic microbial community dynamics. The ISME Journal 1:38-47. Legendre L, and P. Legendre. 1998. Numerical ecology. Elsevier Press: Amsterdam, The

Netherlands. KTTC-TV. 2010. Eyota hog farm fined. Sept. 10, 2010. Rochester, Minn. Available at:

http://www.kttc.com/Global/story.asp?S=13134748. Accessed Sept. 11, 2010. Moody, L., R. Burns, and R. Muhlbauer. 2009. Deep Pit Swine Facility Flash Fires and

Explosions: Sources, Occurrences, Factors, and Management. Literature Review. National Pork Board, Des Moines, Iowa.

NIOSH. 2011. National Academies NIOSH Program Review: Agriculture, Forestry, and Fishing. Available at: www.cdc.gov/niosh/nas/agforfish/. Accessed 12 January 2011.

NRC. 1998. Nutrient Requirements of Swine. Tenth Revised Ed. National Acadamies Press. Washington, D.C.

Pagilla, K. R., K. C. Craney, et al. (1997). “Causes and effects of foaming in anaerobic sludge digesters.” Water Science and Technology 36(6-7): 463-470.

Petrovski, S., Z. A. Dyson, et al. (2011). “An examination of the mechanisms for stable foam formation in activated sludge systems.” Water Research 45(5): 2146-2154.

Pieters, J. 2010a. OSHA to look into man's death in hog barn. Rochester Post-Bulletin. Rochester, Minn., www.postbulletin.com. February 19, 2010.

Pieters, J. 2010b. Man killed by fumes in Minn. hog barn. Rochester Post-Bulletin. Rochester, Minn., www.firehouse.com. February 20, 2010.

RAM. 2009. Safety alert – Hog barn explosions. RAM Mutual Insurance Company, Esko, Minn. LC 123, November 2009.

Rees, G. N., D. S. Baldwin, G. O. Watson, S. Perryman, and D. L. Nielsen. 2004. Ordination and significance testing of microbial community composition derived from terminal restriction fragment length polymorphisms: application of multivariate statistics. Antonie Van Leeuwenhoek International Journal of General and Molecular Microbiology 86:339-347.

Sambrook J. and D. Russell. 2001. Molecular Cloning: a laboratory manual. Cold Spring Harbor Laboratory Press: Cold Spring Harbor, N.Y.

Schilling, K. and M. Zessner (2011). “Foam in the aquatic environment.” Water Research 45(15): 4355-4366.

Schmidt, D. R., C. J. Clanton, B. C. Martinez, J.R. Cummings. 2007. Development of a laboratory method for comparing emissions from manure. In Proceedings of the International Symposium on Air Quality and Waste Management for Agriculture. Broomfield, Colo. American Society of Agricultural and Biological Engineers. St. Joseph, Mich.

Schmidt, D. R., and L. D. Jacobson. 2010. Manure, Foam, Methane, Fire, Explosions and Safety. Presentation for Iowa Pork Congress. January 27, 2010. Des Moines, IA.

Schmidt, D. R. 2011. Manure Pit Foaming. Presentation to Iowa Certified Manure Applicator Training Webinar. January 6.

Shen, F. T., H. R. Huang, et al. (2007). “Detection of filamentous genus Gordonia in foam samples using genus-specific primers combined with PCR - denaturing gradient gel electrophoresis analysis.” Canadian Journal of Microbiology 53(6): 768-774.

Springer, D. 2009. Explosion sends man sailing. ABC News, KAAL. Available at: kaaltv.com/article/stories/S1192219.shtml?cat=10151 Accessed Dec. 15, 2009.

State of Minnesota. 2010. Minnesota Government Data Practices Act (MGDPA). Department of Administration. www.admin.state.mn.us/. Minnesota Statutes, Chapter 13, Government Data Practices.

Stowell, R. 2010. Personal Communication. Theisen, D. 2009. Farm safety alert. Epworth Fire Department. Available at:

www.epworthiowafire.org/index.cfm?fs=news.newsView&News_ID=73 Accessed Dec. 15, 2009.

UM. 2009. University of Minnesota Air Quality Team plus additional investigators. Personal communications between pork producers and field consultants, multi-state telephone conference calls, Internet surveys.

UM. 2010a. University of Minnesota Air Quality Team plus additional investigators. Personal communications between pork producers and field consultants, multi-state telephone conference calls, Internet surveys.

UM, 2010b. Human Research Protection Program. University of Minnesota, Institutional Review Board (IRB). www.research.umn.edu/subjects/

DOL. 2010. 29 CFR 1910.1000 Table Z-2. Toxic and Hazardous Substances. U.S. Department of Labor Available at: www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=STANDARDS& p_id=9993 Accessed Nov 27, 2010.

Vansickle, J. 2010. Watch out for foaming manure. National Hog Farmer. www.nationalhogfarmer.com. March 15, 2010.

Vardar-Sukan, F. (1998). "Foaming: Consequences, prevention and destruction." Biotechnology Advances 16(5-6): 913-948.

Wang, X., J. Jiang, and R. Kaye. 2001. Improvement of a wind-tunnel sampling system for odor and VOCs. Water Science and Technology 44(9):71-77.

Willette, J. K. 2010. Foam in manure pits is perplexing issue. AgriNews. March 25, 2010. Xie, B., X. C. Dai, et al. (2007). “Cause and pre-alarm control of bulking and foaming by

Microthrix parvicella - A case study in triple oxidation ditch at a wastewater treatment plant.” Journal of Hazardous Materials 143(1-2): 184-191.

Yannarell, A. C. and E. W. Triplett. 2005. Geographic and environmental sources of variation in lake bacterial community composition. Applied and Environmental Microbiology 71:227-239.

Ventilation and energy management for 21st century pig buildings Larry D. Jacobson


Sept 10, 2012

Pig facilities built and operated in the 21st century need to provide optimum environmental conditions to maximize pig production efficiency, and provide a healthy and safe working environment for both pigs and workers while conserving energy. This requires a fully integrated ventilation system that is specifically designed and installed for the individual barn and animal housed. High quality management and operation of the ventilation system is as important as the proper design and selection of ventilation components such as fans, inlets, and heaters. Control of the air exchange or ventilation rates, adjustment of air inlets and operation of heating and cooling systems need to be regulated with an electronic controller but it is very important that the person(s) managing the pig barn understand how the ventilation system works and how it can be adjusted to maximize the system's effectiveness. The main goal of a ventilation system in a swine building is to provide an optimum environment for the pigs housed. The barn's environment includes parameters such as room temperature and humidity, air speed across the animal, the indoor air quality (primarily gas and dust concentrations), plus others features like light and noise levels, and other building conditions conducive to the animal's comfort and well-being. The main parameter for measuring the quality of the environment, and thus the ventilation system, is room air temperature. Thus, the ventilation system is regulated by a temperature sensor(s) connected to an electronic controller, which determines the airflow rate (by turning exhaust fans on and off), adjusts air inlets or curtains, and turns heaters on and off. There are a number of different types of ventilation systems that can be used in pig buildings but by far the most common is a negative pressure (vacuum) mechanical system that is shown schematically in figure 1. For this type, exhaust fans created a slight negative air pressure inside the building and this "static" pressure difference is why air enters the barn through the designed ceiling or wall inlets. The air exchange or ventilation rate for the barn is determined by the number and size of the exhaust fans in this type of ventilation system. Some pig barns have side wall curtains (vs solid walls) that are closed up tightly during cold weather and operate under a negative pressure during that period of time. However, during warm weather, the sidewall curtains are opened and there is no negative pressure so it reverts to a natural ventilation system that is driven by the wind.

Figure 1. Negative pressure or vacuum mechanical ventilation system

The amount of air exchange or the ventilation rates for different size pigs can be found from Midwest Plan Service (MWPS) (see table 1) or similar publications, which have been calculated from heat and moisture balances of pigs in an insulated building. The minimum ventilation rate, such as the 20 cubic feet per minute or cfm/sow & litter rate for a farrowing facility, is designed to control the moisture produced in the barn by the pigs and others sources while that other two rates, mild and hot weather, are based on controlling the heat produced and thus the barn's air temperatures. Supplemental heat may be necessary in farrowing or nursery barns during cool or cold conditions, as well as in finishing barns during extreme cold weather, to maintain an acceptable room temperature to make up for the heat lost from the minimum ventilation rate. These heaters need to be properly sized and controlled so they work properly with the other components (fans and inlets) of the ventilation system otherwise they can cause large temperature fluctuations and high energy use. Table 1. Recommended Ventilation Rates, cubic feet per minute (cfm) / animal from MWPS-32 (Mechanical Ventilation Systems for Livestock Housing, 1997).

Production phase Minimum Mild Weather Hot Weather Sow & Litter 20 80 500

Nursery, 12-30 lbs 2 10 25 Nursery, 30-75 lbs 3 15 45

Finishing, 75-150 lbs 7 24 75 Finishing, 150-280 lbs 10 35 120

Gestating 12 40 250 Breeding 14 50 300

A large majority of the time in a year, up to 95% for finishing barns, the ventilation system is trying to remove the heat produced by the pigs and thus regulating the barn's temperature or limiting the rise in the barn's temperatures during warm or hot summer days. How does the ventilation system accomplish this heat removal? Figure 2 shows the possible ways that heat is transferred from the pig to the building's air. The majority of heat is removed from the pig by forced convection (air flowing over the pig) until air temperatures in the barn get too warm (between 70 and 85 F depending on size of the pig) and then evaporation (periodic wetting and drying of the pig's skin by water sprinkling) must be used to keep the pig comfortable or in a thermoneutral state. Pigs (especially at the finishing stage) produce a tremendous amount of heat, as anyone who has experienced a power outage in a barn knows. Recent measurements made in simulated studies at the University of Illinois, indicate that in a finishing barn with heavy pig (> 200 lbs) that lose electrical power and ventilation, air temperatures will rise about 1 F per minute and thus in less than 30 minutes barn temperatures can exceed 100 F and the loss of pigs due to heat exhaustion.

Figure 2. How heat is transferred from the pig to the barn's air in a ventilated pig barn. To demonstrate the effect of temperatures on swine productivity, figure 3 shows the relative impact (% of maximum) for feed intake, feed efficiency, and growth rate of finishing pigs (using 1990 genetics) > 150 lbs as a function of the environmental (room) temperature. As can be seen, the growth rate for these large pigs peaks around 60 F while the optinum feed efficiency occurs at about 68 F. An estimate of the thermoneutral range is shown by the red bars which should be the target or set point temperature range for the barn’s ventilation system. So in the summer if outside temperatures are above 70 F, the room temperatures will rise above the themoneutral range and pigs will become heat stressed. Evaporative cooling systems, such as sprinklers, can reduce this stress and the obvious production losses up until outside temperatures reach 85 or 90 F and/or humidity levels or dewpoint temperatures also become high. For these high temperatures and humidity conditions, evaporative cooling becomes ineffective and pigs stop eating and growing. Thus, producers need to run barns cooler during normal summer conditions and also possibly explore non-evaporative cooling techniques to avoid slow or no growth periods during very warm and humid weather which seems to be occurring more frequently. This problem is even further complicated by the new swine genetics. With today's faster growing and leaner pigs they will produce 20% more heat than pigs from the 1990's when MWPS and other designers determined the ventilation rate recommendations previously mentioned. So this fact would push the thermoneutral zone of the present day pig response shown in figure 3 further to the left requiring the lowering of barns target or set point temperatures another 2 or 3 F cooler that what is shown and results in more frequent heat stress conditions and thus the greater need for alternative cooling systems.

Figure 3. Effect of environmental temperature on growing-finishing pig performance (Coffey, et al., University of Kentucky Extension publication ASC-147, 1995). Here are four common ventilation systems problems and potential solutions seen in pig buildings today: 1. Inadequately insulation of building shell. A pig buildings needs to be well insulated , typically a minimum R-value of 15 in the walls, 25 in the ceiling, and at least 5 on perimeter concrete foundation or “knee” walls. These levels of insulation will provide a sufficiently warm surface temperature to prevent condensation during cold weather and prevents the radiate heat loss for pigs to cold surfaces (such as an uninsulated knee wall). Also, insulation will prevent the surfaces of walls and ceiling/roof from getting too hot which can transmit heat by radiation to the pigs during hot conditions. 2. Inability to maintain a static pressure in the building which is needed make the ventilation system functional.

Thermoneutral Range

A fundamental criterion of a mechanical ventilation system is a slight negative pressure (from 0.05 to 0.1 inch of water gauge) in the barn so the ventilation system can function properly. The building shell must be reasonability tight so the exhaust fans will be able to create the static pressure. If there are too many leaks in the barn or only variable speed exhaust fans are running too slowly, not enough static pressure is created and inadequate air exchange will result as well as poor air distribution since air will not enter where it was designed. Often insulating the building will also help tighten up the barn and solve both this and the previous problem. 3. Controller setpoint or target temperatures set too low and with too small differentials Modern controllers today regulate the major components of the ventilation systems, the fans, inlets, and heaters. Most of these controller will allow for selection of the target or setpoint temperature as well as the temperature steps or differentials at which additional fans are activated as a function of the room temperature. Often this setpoint or target temperature is set higher than what the pigs are comfortable at based on the earlier discussion of thermoneutral zones for growing pigs. Also, people tend to set the temperature steps when different fans come on in too small of increments (0.5 or 1 F) which can result in fans turning on and off (cycling) in short periods of time resulting in large temperature variations in the barn. It is best to have larger differential settings (1.5 or 2 F) which allows the controller time to respond to changes in the building’s environment, which will result in more uniform room temperatures 4. Oversized heaters Most pig facilities in the U.S. require heaters (generally non-vented gas fired units) to provide supplemental heat either during extreme cold conditions or when young pigs are housed which require a warmer room temperature. Unfortunately most of these heaters are much larger in size than they need to be and this can cause large temperature swings plus large energy bills. When the controller activates these large heaters (up to 250,000 BTU/hr), they generate large amounts of heat and typically, before the response is detect by the controller temperature sensor, causes the barn’s temperature to increase so much that it results in additional exhaust fans to come on to cool the barn. The increase in the ventilation rate by the extra fans running will drop the room temperature and cause the heater to again be activated and the cycle continues. This overshooting of room temperatures by oversized heaters can be easily solved by replacing them with smaller units or by adjusting of a value on many of the heaters that reduces the output of the heater to about 60% of the its maximum output. These so-called "green" value can greater reduce or eliminate this overshooting problem and save a tremendous amount of energy (LP gas) and money. With today's higher production costs, it is essential that producers provide an environment that pigs can maximize their genetic performance potential and minimize energy and feed use.

deep–pit foaming control - namic - home · agricultural engineering and animal science, a...

Documents