Co-digestion of Hog Manure with Glycerol to Boost Biogas Production Oswald Wohlgemut (MSc) July 14,...
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Transcript of Co-digestion of Hog Manure with Glycerol to Boost Biogas Production Oswald Wohlgemut (MSc) July 14,...
Co-digestion of Hog Manure with Glycerol to Boost Biogas Production
Oswald Wohlgemut (MSc)July 14, 2008
Farm-scale Anaerobic Digestion
Background
Anaerobic digestion
Lab Research
• Co-digesting hog manure with Glycerol
• Goals– To find optimal glycerol
dosage– To boost biogas and methane
production– To determine nutrient (N,P)
fate through digestion– To gather information to be
used for operating a pilot-scale model
Biodiesel
Glycerol
Why co-digest with glycerol? To find a valuable use for biodiesel waste
To help boost biogas and methane production
Make the process more economical
To reduce GHG emissions
To increase “green energy” in Manitoba
Experimental Setup
4 bench-scale anaerobic digesters (4L) Complete-mix, mesophilic (35ºC), semi-
continuous fed, with gas collection
Experimental Setup
1. Shock Loading Effect – addition of 1%, 2%, 4% pure glycerol (by weight)
2. Comparison Study – comparing 1% pure glycerol to 1% crude glycerol (by weight)
3. Digester Recovery – testing microbial resistance to high COD glycerol loading over time
Feed Characteristics
Hog manure screened and diluted (~1% TS)
pH 7.6Digester Feed COD (g/l) Additional COD
load
Manure (Control) 16.7
Manure + 1% Pure Glycerol 29.7 1.7x
Manure + 2% Pure Glycerol 42.3 2.5x
Manure + 4% Pure Glycerol 72.3 4.3x
Manure + 1% Crude Glycerol 30.1 1.8x
Results
Shock Loading Experiment Control (Manure) ~ 72% CH4
Manure + 1% pure glycerol ~ 64% CH4
Results
Shock Loading Experiment Reactors with 2% and 4% pure glycerol addition
were overloaded with SCOD and did not stabilize
Results
Comparison Experiment Control (Manure) ~ 70% CH4
Manure +1% pure glycerol ~ 63% CH4
Manure + 1% crude glycerol ~ 67% CH4
1.8 X
Results
Digester Recovery Can bacteria recover from overloading? Comparing 2% glycerol loading in
experiment 1 & 3
Experiment 1
Glycerol startGlycerol stop
2.8 X
Experiment 3
Results
Methane Yield and Composition
Substrate m³CH4/kg COD added
% CH4 composition
Control (Manure) 0.239 71
1% pure glycerol + manure
0.257 63
1% crude glycerol + manure
0.245 67
2% pure glycerol + manure
0.244 59
Conclusion
• Biogas and methane production increased with glycerol addition
• A high glycerol shock loading can cause digester failure with a buildup of VFAs
• Bacteria were able to recover and utilize high glycerol COD loading over time
• Methane composition decreases with increasing glycerol addition
• Crude glycerol did not have inhibitory effects
Future Research
Batch experiments with raw manure to determine BMP (Biochemical Methane Potential) of manure with different concentrations of glycerol
Analysis to determine nutrient (P, N) fate through digestion with glycerol
Future Research
Pilot-scale digester in a solar greenhouse
Acknowledgements
Manitoba Agriculture, Food and Rural Initiatives
Dr. Nazim Cicek Dr. Jan Oleszkiewicz My colleagues in the lab
Questions?