Biogas

1. Biogas SompornJenkunawat

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 CH4 + CO2 Methanogenesis Undigested Solids & Water Organic Waste Acetogenesis Hydrolysis Organic Matter

5. Laboratory results on high solids digestion before after

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 -164.4 oC

8. Why Methane is suitable for renewable energy source?

9. 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. Organicloads of anaerobicdigesters • Anaerobiclagoon 0.1 to 2 kilo COD/m3/d • Anaerobic contact 1 to 5.5 kilo COD/m3/d • Anaerobicfilter 10 to 15 kilo COD/m3/d • Fluidizedbed 30 to 40 kilo COD/m3/d • UASB 15 to 25 kilo COD/m3/d • Multiplatedigester 9 to 15 kilo COD/m3/d • IC reactor 30 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. Microorganismfor 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 CO2 + CH4 Microorganism : Methanogenic bacteria

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

26. Methanogenic Reactions

27. COMPLEX WASTE ACID FORMATION 65% 15% 20% OTHERINTERTMEDIATES PROPINIC ACID 35% 17% ACETICACID METHANEFERMENTATION 15% 13% 72% CH4 Changing of organicmatterby anaerobic reaction

28. Composition volume (%) Methane 45-60 Carbon dioxide 40-60 Nitrogen 2-5 Oxygen 2-5 Sulfide, disulfide, mercaptane 0-1.0 Ammonia 0.1-1.0 Hydrogen 0-0.2 Carbon monoxide 0-0.2 Other gases 0.01-0.6 Temperature,◦F 100-120 Specific gravity 1.02-1.06 Moisture Saturated High heating value,BTU/M3 400-555

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

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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 1.2 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 2.1 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 biogas effluent weir 3 phase separator settler gas cap baffles gas bubble sludge granule sludge bed influent

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

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.