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Anaerobic Digestion: Biomass to Bioenergy Douglas W. Hamilton, Ph.D., P.E. Associate Professor, Biosystems and Agricultural Engineering Waste Management.

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Presentation on theme: "Anaerobic Digestion: Biomass to Bioenergy Douglas W. Hamilton, Ph.D., P.E. Associate Professor, Biosystems and Agricultural Engineering Waste Management."— Presentation transcript:

1 Anaerobic Digestion: Biomass to Bioenergy Douglas W. Hamilton, Ph.D., P.E. Associate Professor, Biosystems and Agricultural Engineering Waste Management Specialist, Oklahoma Cooperative Extension Service

2 Anaerobic Digestion of Manure  Understanding Basic Processes

3 Digestion Process CH 4 CO 2 H 2 NH 3 H 2 S + Biogas

4 Acid Formers Methane Formers Liquifiers

5 Acid Formers Methanogens Hydrolizers

6 Community Needs 1.Food 2.Proper pH 3.Sufficient Temperature 4.Sufficient Time to Reproduce 5.Absence of Inhibitory Substances

7 Community Needs Proper pH : ~ 6.5 to 7.5

8 Community Needs Sufficient Temperature Psychrophilic (15-25 o C) Mesophilic (30-38 o C) Thermophilic (50-60 o C)

9 Community Needs Sufficient time to reproduce

10

11 HRT = Volume of Reactor/Flow out

12 SRT = Solids in Reactor/Solids Leaving

13 Anaerobic Digestion of Manure  Understanding Basic Processes  Types of Reactors

14 Low Rate Reactor SRT = HRT

15 High Rate Reactor SRT > HRT

16 How much energy?

17 Anaerobic Digestion of Manure  Understanding Basic Processes  Types of Reactors  Organic Matter of Wastewater and Manure  Methane Production Potential  Toxic and Inhibitory Materials

18 Codigestion Mixing a highly digestible material with a source of microorganisms (manure) to produce a large volume of biogas.

19 Methane Potential  Volatile Solids Content

20 Combustion OM + O 2 → CO 2 + H 2 O + Ash + Heat

21 Combustion OM + O 2 → CO 2 + H 2 O + Ash + Heat TS FS

22 Combustion OM + O 2 → CO 2 + H 2 O + Ash + Heat TS FS VS

23 VS db % Beef Manure82 Dairy Manure84 Wood Shavings99 Alfalfa Silage95 Grease99

24 Aerobic Catabolism OM + O 2 → CO 2 + H 2 O + Cells + Heat

25 Aerobic Catabolism OM + O 2 → CO 2 + H 2 O + Cells + Heat Oxygen Demand

26 Aerobic Catabolism OM + O 2 → CO 2 + H 2 O + Cells + Heat Oxygen Demand COD BOD u

27 Methane Potential  Volatile Solids Content  COD

28 Anaerobic Catabolism OM + Heat → CH 4 + CO 2 + H 2 O + Cells

29 Anaerobic Catabolism OM + Heat → CH 4 + CO 2 + H 2 O + Cells Biogas

30 Combustion OM + Heat → CH 4 + CO 2 + H 2 O + Cells CH 4 + 2O 2 → CO 2 + H 2 O + Heat

31 Combustion OM + Heat → CH 4 + CO 2 + H 2 O + Cells CH 4 + 2O 2 → CO 2 + H 2 O + Heat Oxygen Demand

32 Combustion CH 4 +2O 2 → CO 2 + H 2 O + Heat Two moles O 2 per mole CH 4

33 Combustion CH 4 +2O 2 → CO 2 + H 2 O + Heat 2n OD = n CH4

34 Combustion CH 4 +2O 2 → CO 2 + H 2 O + Heat PV = nRT

35 Combustion CH 4 +2O 2 → CO 2 + H 2 O + Heat V CH4 = 2n OD RT/P

36 Ultimate Gas Yield CH 4 +2O 2 → CO 2 + H 2 O + Heat 0.38 L CH 4 produced per kg OD 20 o C and 1 atm

37 VS db % COD:VS Beef Manure821.2 Dairy Manure841.2 Wood Shavings Alfalfa Silage Grease

38 Methane Potential  Volatile Solids Content  COD  BMP

39 BMP Biochemical Methane Potential

40 D.P. Chynoweth

41 VS db % COD:VS COD converted to CH 4 % Beef Manure Dairy Manure Wood Shavings Alfalfa Silage Grease

42 D.P. Chynoweth Specific Methane Yield (L CH 4 g -1 VS)

43 VS db % COD:VS COD converted to CH 4 % Specific Methane Yield L CH 4 g -1 VS Beef Manure Dairy Manure Wood Shavings Alfalfa Silage Grease

44 Community Needs 1.Food 2.Proper pH 3.Sufficient Temperature 4.Sufficient Time to Reproduce 5.Absence of Inhibitory Substances

45 Methane Potential  Volatile Solids Content  COD  BMP  ATA

46 ATA Anaerobic Toxicity Assay

47 Inhibition (%) I = (1 - Pt/Pc) X 100 Where: Pc = gas produced 0% inclusion Pt = gas produced at test inclusion

48 ATA Anaerobic Toxicity Assay

49 Methane Potential  Volatile Solids Content  COD  BMP  ATA  Pilot Testing

50 Pilot Scale Testing

51 B o S o θ v 1 - K µ m θ s – 1 + K VRE = Chen, Y.R. and A.G. Hashimoto Substrate utilization kinetic model for biological treatment processes. Biotech &. Bioeng. 22:

52 Any Questions?


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