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Covered Anaerobic Digester Developing an Environmental Management System (EMS) Approach for Agriculture and Agribusiness Dec. 18, 2000 Julian Barham Barham Farms Zebulon, NC
Covered Anaerobic Digester
Developing an Environmental Management System (EMS) Approach for Agriculture and
Agribusiness Dec. 18, 2000
Julian Barham
Barham Farms
Zebulon, NC
Case Study - Barham Farm
• Located - Johnston County, NC
• modern swine farm• populated in 1994• owned and managed
by Julian and Elaine Barham
Background Information
• 4000 sow - farrow to wean• 4 gestation barns• 2 farrowing barns• slatted floors (grates)• shallow pit/recharge• flush pit 4/8 day cycle• waste gravity flow
Process Diagram
1994 - 1996 Effluent from barns to anaerobic lagoon
40,000 gallons/day (total solids < 1.0%)• lagoon surface = 6 + acres
Traditional Anaerobic Lagoon Design
Freeboard
Rainfall/Storms
Storage
Treatment
Sludge
FieldApplication
Evaporation Emissions
Covered Anaerobic Digester ?
1 Odor Control 2 Energy Resource3 Ammonia Emissions4 Rainfall Exclusion (*)
Anaerobic Digester and Storage pond
Treatment
Sludge
Biogas
Anaerobic Digester Storage Pond
Rainfall
Digester effluent
Lagoon Cover Design
• partial cover ?
• bank to bank ?
lower cost (?)
rainwater into lagoon
odor reduction
high maintenance
rain exclusion
no emissions (sealed)
biogas storage
low maintenance
Partial Cover - Practical Application !
Bank to Bank Cover - Practical Application
Things Involved
Biogas• Methane + CO2 + H2S• Greenhouse gasOptions• Flare• IC Engine• Micro Turbine• Burner/Boiler
Equipment NeededBoiler for hot water
- 10,000 gallon hot water storage
- hot water for space heating and mats
Engine for co-generation
- 120 KW for peak shaving
- engine heat recovery - hot water
Lagoon PerformanceBarham Lagoon Performance
0
200
400
600
800
1000
1200
1400
1600
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec1997 & 99
Bio
gas
Yiel
d (c
u.ft.
/hr.)
30
40
50
60
70
80
90
100
110
Predicted BiogasMeas.Biogas 97Meas.Biogas 99Predicted Temp. Meas. Temp. 97Meas. Temp 99
Lago
on T
empe
ratu
re (F
)
** readings middle of month
estimated data pt.
Covered Anaerobic Digester Effluent
Organic Carbon - reduced 85%
TKN - reduced 30%
Total P - reduced 75%
K - reduced 20%
Ref: ASAE Proceedings
8th InterNatl Symp.
Oct 2000
Eval. of Alternat. Waste Sys.
Digester Effluent Use:
Apply at agronomic rate to low value hayland!
Digester Effluent Use:
Nutrient rich for high value produce in green house environment!
Benefits Seen
Biofilter - low energy input process
Reduce Ammonia Emissions (NH4 to NO3)
Lower pH
Greenhouse
Other Results and ConclusionIt’s not
“A Sows Ear to a Silk Purse”
but
Demonstrated
Energy Resource
Reduced Emissions
Marketable Produce
Manageable System
?
