1. Gas out
Biomas in
Biomas out (Digestate)
Biogas production

2. Where are we. Why do we want. How do we manage. What do we need
Where are we? Why do we want? How do we manage? What do we need? From where should we start? What do we want to know?

3. Biogas knowledge piramide
Optimizing operational condition& designing biogas system
Methane productivity& potential, reaction, inhibition operational condition, digetibility
Identification of biogas field in general
Obtaining technical ability to obtain data
to support project

4. Biogas plant concept Pig slurry Biomas out (Digestate) Fe
Additional income for the farmers
Clean energy (kitchen)
Digestate is an excellent fertilizer
Less odour
Sanitaion

5. The microbiology process
Biomasse:
Animal manure
Organic waste
Hydrolysis
Dissolved substrate
Acidogenesis
H2+CO2
Acetognesis
VFA>C2
CH4+H2O+ CO2
CH3-COOH
Methanogenesis

6. Methane produktion Hydrolysis is process rate controlling
Biomasse:
Animal manure
Organic waste
Hydrolysis
Dissolved substrate
Acidogenesis
H2+CO2
Acetognesis
VFA>C2
CH4+H2O+ CO2
CH3-COOH
Methanogenesis
Hydrolysis is process rate controlling
VFA transformation reduced due to:
High NH3
Sudden changes in environment
High H2 concentration
Feedback:
High VFA conc. reduces hydrolysis
Cellulose består af glucose (C6 kulstof)
Hemicellulose består af xylose og andre kulhydrater mannose, arabnose etc.
Hydrolyse ved glycosidase, xylanase
Lipaser
Proteaser

7. Physical process Lysis Non enzymatic decay Phase separation
COMPOSITE MATERIAL
MACROMOLECULES
Physical process: Disintegration
Lysis
Non enzymatic decay
Phase separation
Physical breakdown (shearing)

8. Biological and chemical process
MACROMOLECULES
SIMPLE SUBSTRATES
Hydrolysis (chemical)
A→B1+B2 (H2O is used)
Hydrolytic enzymes (biological/chemical)
Made by micro-organisms – same outcome

9. Acidogenesis: (biological)
SIMPLE SUBSTRATES
VOLATILE FATTY ACIDS
ACETATE & HYDROGEN
Acidogenesis: (biological)
Volatile fatty acids are generated from monosaccarides, fat and aminoacids.
(sugar-degraders & aminoacid-degraders)
Acetogenesis: (biological)
Acetate is generated from LCFAs. (lcfa-degraders) and from sugar (sugar-degraders)

10. Methanogenesis (biogas production) Acetoclastic methanogenesis
ACETATE & HYDROGEN
BIOGAS
Methanogenesis (biogas production)
Acetoclastic methanogenesis
CH3COOH → CH4 + CO2
Hydrogenotrophic methanogenesis
CO2 + 4H2 → CH4 + 2H2O

11. Biogas knowledge pyramide Inhibition
Optimizing operational condition& designing biogas system
Methane productivity& potential, reaction, inhibition operational condition, digetibility
Identification of biogas field in general
Obtaining technical ability to obtain data
to support project

12. H2inhibition
Acetic acid
VFA component

13. Ammonia inhibition
Ammonia inhibition: 1,5 – 2,5 g N/L, after adaptation inhibition at 4 g N/L (Angelidaki og Ahring 1998)

14. Ammonia chemistry pH= -log(H+) Thus if the concentration of [H+] is
Neutral: 10-7 mol then pH = –log(10-7)=7
Acid: mol then pH = –log(10-2)=2
Basic: mol then pH = –log(10-10)=10

15. Ammonia-ammonium equilibrium

16. Ammonia inhibition
In literature ammonia inhibition has been assessed relating biogas production to
Reactive ammonium (NH3)
Total Nitrogen
Ammonium
How is NH3 related to NH4+
How would you recommend that the inhibition is expressed (reactive ammonium, total nitrogen or ammonium

17. Inhibition at high and low pH
SH2
NH3

18. VFA inhibition
Inhibition at a ratio of propionic acid to acetic acid at 1.4:1
Inhibition at 2 g VFA Ltr-1

19. Temperature Bacteria adaptation
Batstone et al. 2002

20. Acidogenesis: (biological)
SIMPLE SUBSTRATES
VOLATILE FATTY ACIDS
ACETATE & HYDROGEN
Acidogenesis: (biological)
Volatile fatty acids are generated from monosaccarides and aminoacids.
(sugar-degraders & aminoacid-degraders)
Acetogenesis: (biological)
Acetate is generated from LCFAs. (lcfa-degraders) and from sugar (sugar-degraders)
What happens if the temperature suddenly drops?

21. Metane production as affected by NH4+ koncentration interacting with temperature
Bemærk ammoniak inhibering øges ved stigende temperatur
20 days retention time in CSTR digester

22. Biogas knowledge piramide Digestibilty
Optimizing operational condition& designing biogas system
Methane productivity& potential, reaction, inhibition operational condition, digestibility
Identification of biogas field in general
Obtaining technical ability to obtain data
to support project

23. Definitioner VS (Volatile solids): Methane productivity:
The fraction of dry matter (DM) in slurry that is transformed to gas at high temperature/incineration (550oC) for one hour
How would you measure VS?
Methane productivity:
CH4 production pr. unit VS
CH4 production pr. unit COD
35.9 MJ energy can be produced pr. m3 CH4 or 45 MJ kg CH4.
En kubikmeter gylle fra kvæg og svin er MJ energi (hvilket omtrent svarer til energien i liter benzin)

24. Source of energy in animal slurry
Mentioned to make clear that this presentation is about animal manure management and about the two green house gases methane and nitroux oxide.
The slide is also presenting the content of the presentation.

25. Energy production
Biogas, CH4 +CO2
CH4 - source

26. Characterisation of biogas potential
In the biological process the maximum biogas production BMP
(liter CH4 kg(VS)-1)
Volume of methane produced when residence time is in principle very long
Biomas
Batchudrådning af gylle
Bemærk
hældning af kurven de første 10 dage
den samlede metan produktion (Bo ultimativ biogas produktion)
Inoculum
BMP is estimated in batch fermentation at 35oC
Fermentation time days

27. Anaerobic Digestibility
The theoretical biogas production can be calculated from knowing the chemical composition of the biomass:TBMP
In the biological process the maximum biogas production: BMP
Anaerobic digestibility =BMP/TBMP
Question
- BMP/TBMP ↑ digestibility??
- BMP/TBMP ↓ digestibility ??

28. Biodegradability (BMP/TBMP) examples
Here we presented BMP, TBMP and BMP per TBMP which we call biodegradability. First BMP were around 200 to 400 and TBMP were around 450 to 530 liter per kg vs ). Here you can see the biodegradability as percentage, For som animal manure and crops, the biodegradability were quite high which were around 80 to 90 percentage, but we also can see that some animal manure have quite low digestibility.

29. Lignocellulose Low digestibility
lignin : Non degradable in anaerobic environments
hydrolysis of cellulose blocked by lignin.
Lignin
glue to hold lignocellulosic matrix
protective coat
used to assess digestibility of feed in animal science

30. Lignocellulose in VS (volatile solid)
The figure shows the lignocellulose fractions in VS. For most animal manure samples, the lignocellulose content were around % of VS except piglet which has quite low lignocellulose, that seems because piglet has milk as daily diet. It is interesting to see the lignocelluloses in Calf manure which are quite high because calf manure contains large amount of straw as bedding materials. That’s why the characteristics of calf manure were close to energy crop rather than animal manure. For the energy crop lignocellulose were around 60 to 80 percentage.

31. Fermentation result - animal manure
The figure shows fermentation results to determine BMP. As you can see it, for the first two weeks the great majority of methane gas were produced. And thereafter only small amounts were released. We can also clearly see that there is some relation between lignin concentration and cumulative methane yield which is BMP.
From this figure, we could also realized that BMP test require such a large amount of work in long period.

32. Digestability of the biomass
CH4 L kg(VS)-1

33. Energy potential of biomass
Dry matter
Volatile solids in pct of dry matter (DM)
Total energy content
Energy production in biogas plant %
MJ/ kg DM
MJ/kg DM
Pig slurry 6 80
16,3
9,8
Cattle slurry 10
15,3
7,6
Clover grass 20 90
18,3
14,6
Straw
19,1
9,6
Why is biogas energy production of straw so low

34. Methane produkcion crops and organic waste
Whey = valle
Bleaching clay -

35. Biogas production estimates
With the Hashimoto equation one can assess production of biogas as affected by:
temperature,
hydraulic retention time,
micro-organism activity
biomass composition

36. Hashimoto equation HRT or θ Hydraulic retention time SRT
Solid retention time Γ
Is the specific gas yield B0
The ultimate or specific methane yield, measured with batch fermentation at more than 60 days and at 35oC.
maximal specific growth rate of the micro organisms, µm a function of temperature and residues feed to the reactor K
is a kinetic parameter depending of the rate of feed, feed composition and bacterial consortium, S0
Concentration of organic components in feed to the reactor
Nm3
The volume CH4 produced, calculated at 0oC (273oK)

37. Hashimoto model predictions’

38. Summarising
Biogas is efficient in producing energy from biomasses with a high water content
Biogas transform the biomas reducing VS and thus reduced GHG emission potential of the slurry
Biogas transform biomas organic N into ammonium that is an efficient fertilizer