Anaerobic Digestion of Finishing Cattle Manure

A.K. Watson, S.C. Fernando, G.E. Erickson, T.J. Klopfenstein University of Nebraska, Lincoln, NE

Integrated BioRefinery

Feedlot Ethanol Plant

Anaerobic Digester

Distillers Grains

Manure Crop

Production

Grain

FertilizerSo

lubles

and H

eat

Biogas

(met

hane

)

Integrated BioRefinery

Feedlot Ethanol Plant

Anaerobic Digester

Distillers Grains

Manure Crop

Production

Grain

FertilizerSo

lubles

and H

eat

Biogas

(met

hane

)

Integrated BioRefinery

Feedlot Ethanol Plant

Anaerobic Digester

Distillers Grains

Manure Crop

Production

Grain

FertilizerSo

lubles

and H

eat

Biogas

(met

hane

)

ObjectivesTrial 1

• Impact of cattle diet on manure quality

Trial 2• Impact of cattle housing and ash contamination

Materials and Methods

• Seven, 1 L digesters– Turnover every 20 days (sample

and feed 1/20th every day)– 9% DM– 37° C– pH 7.00 (sodium hydroxide)– Anaerobic conditions, constant

flow of N2 gas

30 35 40 45 50 55 60 650.00

0.05

0.10

0.15

0.20

0.25

0.30

3 d 9 d18 d

°C

Met

hane

pro

ducti

on, L

/g O

M fe

d

37°C20 d RT

Mesophilic Thermophilic

Varel et al. 1980. Effect of temperature and retention time on methane production from beef cattle waste. Applied and Environmental Microbiology 40:217-222.

Materials and Methods

• Methane Production– Methane Detector

• RKI instruments

– Concentration & flow rate = methane production

• DM and OM degradation– Feed 9.0% DM– Measure DM and OM of

effluent

Impact of Diet

• Control Cattle– 82.5% DRC– 5% Molasses– 7.5% Alfalfa– 5% Supplement

• 0.986% urea

• WDGS Cattle– 47.5% DRC– 40% WDGS– 7.5% Alfalfa– 5% Supplement

Impact of Diet

• Complete collection in cement gutter– 4 steers on each diet– 3 d– Manure slurry analyzed and weighed into individual

feeding allotments• Switchback design– 7 digesters– Digesters on trt for 42 d (2 complete turnovers)– Measurements made last 5 d

Cattle Performance

0 5 10 15 20 25 30 35 40 450.145

0.150

0.155

0.160

0.165

0.170

0.175

Corn DGS Inclusion, % of diet DM

G:F

Bremer et al. 2011. Effect of distillers grains moisture and inclusion level in livestock diets on greenhouse gas emissions in the corn-ethanol-livestock life cycle. Prof. Anim. Sci. 27:449-455.

Linear Quad

WDGS < 0.01 < 0.01

MDGS < 0.01 0.05

DDGS < 0.01 0.45

Digestibility

0 400

20

40

60

80

100

Corn WDGS Inclusion, % of diet DM

Tota

l Tra

ct D

iges

tibili

ty, %

Corrigan et al. 2009. Effect of corn processing method and corn wet distillers grains plus solubles inclusion level in finishing steers. J. Anim. Sci. 87:3351-3362.

P-value

Starch 0.92

OM 0.05

DM 0.08

NDF 0.72

Digestibility

0 15 30 45 600

20

40

60

80

100

0.0

0.5

1.0

1.5

2.0

2.5

Corn/Sorghum WDGS Inclusion, % of diet DM

Tota

l Tra

ct D

iges

tibili

ty, %

Feca

l OM

, kg/

d

Luebbe et al. 2012. Wet distillers grains plus solubles concentration in steam-flaked-corn-based diets: Effects on feedlot cattle performance, carcass characteristics, nutrient digestibility, and ruminal fermentation characteristics. J. Anim. Sci. 90:1589-1602.

Linear Quad

Starch < 0.01 < 0.01

OM < 0.01 0.99

NDF < 0.01 0.89

Fecal OM 0.04 0.32

Impact of Diet% of DM CONT

ManureCONT Effluent

WDGS Manure

WDGS Effluent

Total N 3.95a 6.93d 3.79a 6.02c

P 1.88a 4.40c 2.64b 4.82d

S 0.45a 0.83c 0.51b 0.75c

Mg 0.48a 1.08c 0.65b 1.19c

a,b,c,d Means within a row without a common superscript differ (P<0.05).

Impact of Diet

• Two 6-week periods (switchback design)

CONT WDGS SEM P-value

DMD 42.7 44.9 1.1 0.05

OMD 51.0 52.9 1.1 0.10

Impact of Diet

• Two 6-week periods (switchback design)

CONT WDGS SEM P-value

Methane, L/d

0.551 0.634 0.05 0.10

Methane, L/g OM fed

0.116 0.137 0.01 0.05

Impact of DietCONT WDGS SEM P-value

OMD 51.0 52.9 1.1 0.10

Methane, L/g OM fed

0.116 0.137 0.01 0.05

Methane, L/g OM degraded

0.237 0.261 0.03 0.44

• Samples taken from digesters on each treatment at 4 time points

• Started with 100,000 sequences and 10,000 OTUs– Data analyzed represents 3,500 OTUs– Ribosomal Database Project (Michigan State

University)

Microbial Community Analysis

Effluent Sample DNA PCR 454

SequencingDiversity

Identity

Effluent Samples-Eubacteria at Phylum Level

Fibrobacteres

Firmicutes

Tenericutes

Actinobacteria

Synergistetes

Chloroflexi

Bacteriodetes

Proteobacteria

Verrucomicrobia

Unclassified

WDGS

CONT

Thermoprotei

Thermoplasmata

Methanomicrobia

Methanobacteria

WDGS

CONT

Effluent Samples-Archaea at Class Level

Microbial Community Analysis

-0.5 -0.4 -0.3 -0.2 -0.1 0 0.1 0.2 0.3 0.4 0.5

-0.5

-0.4

-0.3

-0.2

-0.1

0

0.1

0.2

0.3

0.4

0.5

Bacteria-WDGS Bacteria-CONT Archaea-WDGS

Archaea-CONT

PC1 (23.6% - Bacteria, 53.9% - Archaea)

PC2

(15.

5% -

Bact

eria

, 14.

0% -

Arc

haea

)

Species Diversity• Eubacteria populations– WDGS 177 OTUs common to all 4 samples– CONT 47 OTUs common to all 4 samples

• Homova P < 0.001• Amova P < 0.001

• Archaea populations– WDGS 137 OTUs common to all 4

samples– CONT 87 OTUs common to all 4 samples

• Homova P = 0.019• Amova P < 0.001

Impact of Housing

• Open lot manure quality affected by– Cattle ration– Environmental conditions• season

– Animal stocking density– Pen cleaning frequency– Distance from the feed bunk

Feedlot Pen Surface0 5 10 15 20 25 30

0

5

10

15

20

25

Organic Matter, %

Dep

th, c

m

Organic Layer

Interface Layer

Soil Layer

Mielke et al. 1974. Soil profile conditions of cattle feedlots. J. Environ. Quality 3:14-17.

Feedlot Pen Surface0 5 10 15 20 25 30

0

5

10

15

20

25

Organic Matter, %

Dep

th, c

m

Organic Layer

Interface Layer

Soil Layer

Mielke et al. 1974. Soil profile conditions of cattle feedlots. J. Environ. Quality 3:14-17.

Impact of Housing

• Complete confinement manure, 88% OM (CONF)

• Open feedlot manure, 26% OM (FDLT)

• One 6-week period– 3 digesters on CONF– 4 digesters on FDLT (3 failed due to

ash buildup)

Impact of Housing

CONF FDLT SEM P-value

OMD, % 46.7 24.8 3.11 < 0.01

Methane, L/d

0.478 0.229 0.07 < 0.01

Methane, L/g OM fed

0.103 0.189 0.03 0.01

• 4 remaining digesters

Next Steps

• New design– 45 L, ash removal

• Varying levels of ash contamination– “Pure” manure 80% OM

– Soil surface of pen 10% OM– Stockpiled 20% OM– Fresh 25% OM– Cement pad 50% OM

Frequency and area of pen cleaning

Summary

• Feeding WDGS to cattle– Improves cattle performance– Decreases digestibility in cattle– Enhances digestibility and methane production

• Changes in OM composition of manure• Changes in microbial community

• Open lot manure can be used as anaerobic digester feedstock if ash buildup is avoided– 95% of feedlot cattle in open lot soil based pens

Questions??

Himark BioGasVegreville, AB, Canada