Covered Anaerobic Digester
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Transcript of Covered Anaerobic Digester
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
?