Biogas potential of spent, coffee husk and pulp

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Presented by B. Assefa, D. Abate and B. Leta at the First Bio-Innovate Regional Scientific Conference, Addis Ababa, Ethiopia, 25-27 February 2013

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Biogas potential of spent, coffee husk and pulp

  1. 1. B. Assefa, D. Abate, B. LetaFirst Bio-Innovate Regional Scientific Conference, Addis Ababa, Ethiopia, 25-27 February 2013 BioInnovate Project 04/2010 1
  2. 2.  Coffee is the worlds second most valuable commodity after petroleum Ethiopia ◦ Contributes about 3 % for global coffee market. ◦ Produces about 380,000 tons ◦ About 16% coffee bean is produced by wet process while 84 % by dry process. 2 BioInnovate Project 04/2010
  3. 3.  The dry processing generates ◦ the solid waste (coffee husk) ◦ piled up in field causing serious environmental problem The wet processing generates ◦ The wastewater released untreated ◦ Solid waste with high moisture content (pulp and mucilage) ◦ Dispose in the water and field 3 BioInnovate Project 04/2010
  4. 4.  Estimated annual generation of solid wastes ◦ Husk 430,920 tons/year; ◦ Pulp 72,960 tons/year It is huge resources; 4 BioInnovate Project 04/2010
  5. 5.  Characteristics of coffee husk No Parameters Mean 1 Moisture content (%) 9.63 3 2 Bulk Density (mg/cm ) 0.74 3 Volatile matter (%) 82.7 4 Fixed matter (%) 7.65 5 Ash (%) 7.65 6 Total Carbon (%) 53.67 5 BioInnovate Project 04/2010
  6. 6.  Characteristics of the Pulp Parameters Mean TS, % 70.13 VS/TS, % 93.0 Moisture Content, % 29.87 Fixed Solid, % 6.99 Total Carbon (%) 50.18 pH 6.8 6 BioInnovate Project 04/2010
  7. 7.  The waste has high organic content It can be a good feed stock for biogas production Concern ◦ The biomass might be cellulosic materials ◦ the rate of biodegradability may be low ◦ Tannin, caffeine and phenols could poison anaerobic bacteria 7 BioInnovate Project 04/2010
  8. 8. ◦ Decomposing the biomass using (oyster) mushroom would improve biodegradility◦ Reduce the poisoning effect of TCP chemicals using the use of biomass for mushroom BioInnovate Project 04/2010 8
  9. 9.  Determination of biogas potential of coffee husk, coffee husk spent after mushroom production and pulp Comparison of the results against the hypothesis 9 BioInnovate Project 04/2010
  10. 10. Materials The inoculums ◦ brought from an active, food leftover based biogas plant found in the same institution; ◦ Amount of inoculums: 800 ml (volume); Substrates: ◦ Coffee pulp, coffee husk, and spent coffee husk. ◦ The pulp are kept in a deep freezer (less than - 120C) ◦ The spent is brought from a mushroom cultivation experiment (after three cycle of harvest) 10 BioInnovate Project 04/2010
  11. 11. 11BioInnovate Project 04/2010
  12. 12.  Composition of substrate added into the flasks Substrates TS (%) VS (%) Husk 87.5 80.8 Spent 27.8 89.8 Pulp 12.1 79.9 Inoculums 2.3 63.3 12 BioInnovate Project 04/2010
  13. 13. Apparatus◦ Erlenmeyer Flask — Gas analyzer◦ Tubes — Syringe◦ Water bath (Thermostat) — Balance◦ Gas bags — pH meter◦ Shredder — Stop cock◦ Muffle furnace◦ Drying oven 13 BioInnovate Project 04/2010
  14. 14. Methods◦ The samples are added in 1:2 ratio VS of substrate to inoculum in order maintain constant food to micro-organism ratio◦ the experiments were run at 37oC◦ The temperature is maintained by thermostat◦ The pH is measured initially and at the end of the experimentation◦ Gas is collected regularly by gas bag 14 BioInnovate Project 04/2010
  15. 15. Measurement Mass of substrate ◦ Precision balance is used Gas volume ◦ the volume of the gas was measured using syringe of known volume, 50ml and100 ml. Temperature ◦ the temperature of the room is measured regularly when the gas volume is measured using (thermometer)thermocouple 15
  16. 16. Experimental Set up BioInnovate Project 04/2010 16
  17. 17. BioInnovate Project 04/2010 17
  18. 18. Biogas yield [l/g Methane gasItems VS] [l/g VS] [%] Pulp 0.863 0.081 0.460 56 Husk 0.486 0.071 0.266 58Spent 0.188 0.068 0.090 49 BioInnovate Project 04/2010 18
  19. 19.  Pulp gave output as of comparable to ◦ Organic wastes from food industry : 0.4- 0.8 m3 biogas/kgVS (Gunaseela, 1997) ◦ Fruit and vegetables solid waste and wastewater 0.2-0.4 m3 CH4/kgVS Husk gave output as of comparable to ◦ Crops (straw, beet collars) 0.35-0.4 m3biogas/kgVS ◦ Rice straw 0.2 m3 CH4/kgVS (Dinuccio et al., 2009) ◦ Barley straw 0.2 m3 CH4/kgVS (Dinuccio et al., 2009) BioInnovate Project 04/2010 19
  20. 20.  Spent substrate gave the lowest output ◦ It is lower estimated potential all biomass ◦ It seems that the mushroom taken up significant easily digestible stuff BioInnovate Project 04/2010 20
  21. 21. ◦ Coffee waste can be as a good feed for biogas production◦ Coffee husk much higher gas potential than spent coffee husk  The use of coffee husk for mushroom production did not improve gas production and its rate◦ The pulp collected from wet processing gives much higher gas production coffee husk◦ Spent coffee husk has still significant gas potential BioInnovate Project 04/2010 21
  22. 22. Thank for yourattention BioInnovate Project 04/2010 22

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