1. Biogas
Somporn Jenkunawat

2. Biogas is gas produced from the fermentation of manure or organic matter by microorganisms in the anaerobic. Biogas is a mixture of gases such as methane (CH4), carbon dioxide (CO2) nitrogen gas (N2) and hydrogen sulfide (H2S), mainly composed of methane and combustible.

3. Biogas is produced from the wastewater treatment of Agricultural products and livestock plants by anaerobic digestion such as cassava, crude palm oil mill , fruit production factory swine farm, alcohol factory and so on.

4. Anaerobic Biological Digestion Process
Bio-gas
Undigested
Solids & Water
Acetogenesis
Methanogenesis
Hydrolysis
Organic
Waste
Organic Matter
CH4 + CO2

5. Laboratory results on high solids digestion
before
after
Laboratory results on high solids digestion

6. Properties of biogas as the fuel gas, depending on the amount of methane (CH4), which is igniting the gas in the atmosphere. The heating value of about 600 BTU / cubic foot (for methane gas to heat 1,000 BTU / cubic foot).

7. Pure methane gas is colorless, odorless when burned will give CO2, water and energy 5,000-6,000 Kcal/M3 at 15 oC. 735 cm of Hg pressure. While the H2S is mixed in will give smelly odor and corrosion. But when it is burned it smells less. The condensation point is oC

8. Why Methane is suitable for renewable energy source?

9. The use of methane as an energy source. 1. No blast occur. 2
The use of methane as an energy source. 1. No blast occur. 2. Have a slight odor so if leak will get the smell. 3. No toxic to human. 4. Heat get could boil 18 liters of water in 9-10 minutes..

10. Factors influence on producing biogas

11. 1. Temperature
2. pH
3. Alkalinity
4. Nutrients
5. Inhibiting and Toxic Materials
6. Organic matter
7. Types of Biogas Plant

12. Effect of temperature
Anaerobic digestion is strongly influenced by temperature and can be grouped as:
Psychrophilic (0–20°C)
Mesophilic (20–42°C)
Thermophilic (42–75°C)
Changes in temperature are well resisted by anaerobic bacteria, as long as they do not exceed the upper limit as defined by the temperature at which the decay rate begins to exceed the growth rate.
However, an important characteristic of anaerobic bacteria is that their decay rate is very low at temperatures below 15°C.

13. Effect of pH and Alkalinity
The optimal pH range for methane producing bacteria is 6.8–7.2 while for acid-forming bacteria, a more acid pH is desirable .
In general, sodium bicarbonate is used for supplementing the alkalinity since it is the only chemical, which gently shifts the equilibrium to the desired value without disturbing the physical and chemical balance of the fragile microbial population .

14. Effect of nutrients
The bacteria in the anaerobic digestion process requires micronutrients and trace elements such as nitrogen, phosphorous, sulphur, potassium, calcium, magnesium, iron, nickel, cobalt, zinc, manganese and copper for optimum growth. .
The required optimum C:N:P ratio for enhanced yield of methane has been reported to be 100:2.5:0.5.

15. Effect of organic loading rate
In anaerobic wastewater treatment, loading rate plays an important role. In the case of nonattached biomass reactors, where the hydraulic retention time is long, overloading results in biomass washout. This, in turn, leads to process failure. Fixed film, expanded and fluidized bed reactors can withstand higher organic loading rate.

16. Organic loads of anaerobic digesters
Anaerobic lagoon to 2 kilo COD/m3/d
Anaerobic contact 1 to 5.5 kilo COD/m3/d
Anaerobic filter 10 to 15 kilo COD/m3/d
Fluidized bed to 40 kilo COD/m3/d
UASB to 25 kilo COD/m3/d
Multiplate digester 9 to 15 kilo COD/m3/d
IC reactor to 40 kilo COD/m3/d

17. Inhibitor
The inhibitors commonly present in anaerobic digesters include:
Ammonia
Sulfide
Light Metal ions
Aluminium
Magnesium
Calcium
Potassium
Sodium
Heavy metal

18. Advantages
Get biogas
Cost of construction is lower
Daily expense is lower
Eliminate chemical odor at least 90 percent
Using of biogas is apart of reducing emission of greenhouse

19. Disadvantages
Need more area not suitable for factory that have limited area.

20. Microorganism for producing biogas
The production of biogas large molecular organic materials is decomposed into smaller molecule and turn to be inorganic matter and gases by bacteria in the anaerobic digester.

21. Anaerobic Digestion Process

22. 1. Liquefaction stage 1.1 Hydrolysis
Carbohydradtes Simple sugar + Alcohol
Proteins Peptide Amino acid
Fats Glycerol Fatty acid
Microorganisms : Fat-decomposing microorganism, Cellulose-decomposing microorganism and Protein-decomposing organism

23. 1.2 Acid formation stage
Complex organics Organic acid CO2
Microorganism :Acid formers

24. 2. Gasification stage
Methane formers
Organic acid CO CH4
Microorganism : Methanogenic bacteria

25. Acetica acid+inert organic residue (digested sludge)
Reactions
Raw materials
Carbohydrate
Protein
Fat
Propionic acid
Acetic acid
Acetica acid+inert organic residue (digested sludge)
Butyric acid
CH4 + CO2

26. Methanogenic Reactions

27. Changing of organic matter by anaerobic reaction
PROPINIC ACID
COMPLEX WASTE
OTHER INTERTMEDIATES
ACETIC ACID
CH4
15%
20%
65%
17%
13%
35%
72%
METHANE FERMENTATION
ACID FORMATION
Changing of organic matter by anaerobic reaction

28. Composition volume (%)
Methane
Carbon dioxide
Nitrogen
Oxygen
Sulfide, disulfide, mercaptane
Ammonia
Hydrogen
Carbon monoxide
Other gases
Temperature,◦F
Specific gravity
Moisture Saturated
High heating value,BTU/M

30. More Details on the Digestion Process
Odor
Acid forming
bacteria
Volatile
Solids (VS)
Volatile
organic acids
Methane forming
bacteria
Methane, carbon dioxide,
water, trace gases

31.                                         <>

33. Bacterial Shapes Rod shape of methanogen bacteria
1.1 non sporulating rod-shaped cells
Methanobacterium solmgenii
Methanobacterium formicicum
Methanobacterium propionicum
1.2 sporulating rod-shaped cells
Methanobacterium omelianskii

34. 2. Round shape of Methanogen bacteria
2.1 Cell not sarcina arrangement
Methanococcus vaniellii Methanococcus mazei
2.2 Cell in sarcina arrangement Methanosarcina methanica Methabosarcina barkerii

36. Anaerobic Sludge Granules (SEM)
Acetate as Substrate (Methanosaeta)
Sucrose as Substrate (mixed culture)

37. Biogas Plants 1. Slow digestion or solid digestion
1.1 fined dome digester floating drum digester or Indian digester

38. 1. Slow digestion or solid digestion
1.3 plastic covered ditch or plug flow digester

39. 2. Fast digestion or wastewater treatment digester. 2
2. Fast digestion or wastewater treatment digester 2.1 Anaerobic Filter: AF

40. 2.2 Upflow Anaerobic Sludge Blanker: UASB
Principles of microbial degradation of organic matter in the absence of oxygen and agglomeration, float up to the top with biogas. When contract with obstacles gas will rise while the microorganisms will fall to the bottom. This is suitable for wastewater with low suspended solids.

41. Upward-flow Anaerobic Sludge Blanket
influent
effluent
biogas
sludge
bed
gas
cap
settler
baffles
sludge granule
gas bubble
weir
3 phase
separator

44. Expanded Granular Sludge Bed
Influent
Effluent
Recycle
Sludge
Bed
settler
gas
cap
biogas
bubble
sludge
granule
Expanded Granular Sludge Bed

45. Cover lagoon
The principle is to cover the pond with blanket to prevent the smell spreading and allows microorganisms to decompose organic substances in wastewater in the anaerobic condition. It takes at least 20 days, the investment is low but the amount of gas produced is less than other systems.

53. UASB - Internal Circulation (IC Reactor)
Brewery (Switzerland), 20 m height

54. UASB - Internal Circulation
Kraft Paper Mill Foul Condensates, Alabama