1 / 20

Energy from Wastes

Energy from Wastes. Goals. Obtain additional value from wastes – wastewaters, animal wastes, sludges and solid wastes from agricultural, industrial and municipal sources Reduce amount of waste that must be disposed of by other means. Technologies Available. Direct combustion

leland
Télécharger la présentation

Energy from Wastes

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Energy from Wastes

  2. Goals • Obtain additional value from wastes – wastewaters, animal wastes, sludges and solid wastes from agricultural, industrial and municipal sources • Reduce amount of waste that must be disposed of by other means

  3. Technologies Available • Direct combustion • Biological conversion to ethanol • Anaerobic digestion to produce biogas • Digesters • Covered lagoons

  4. Drawbacks of Biomass Energy • Dispersed feedstock if using crop wastes • Distributed small-scale production for on-site conversion • High transportation costs for centralized conversion • Technical expertise required to implement • High capital and operating expenses

  5. Fermentative bacteria Focus: Biogas Production Acetogenic bacteria Methanogenic bacteria

  6. Focus: Biogas Production Hydrolysis Acidogenesis Acetogenesis Methanogenesis

  7. Types of Digesters • Completely mixed (CSTR)

  8. Types of Digesters • Contact digester (CSTR with recycle)

  9. Types of Digesters • Plug flow

  10. Types of Digesters • Packed bed/fixed film

  11. Types of Digesters • Upflow anaerobic sludge blanket

  12. Two-stage

  13. Types of Digesters • Covered lagoon

  14. Covered Lagoon

  15. Types of Digesters • Landfill

  16. Digester Operation • Solids concentration: ≤ 10% to pump as slurry • Solids separation to remove large particles • Temperature: • Mesophilic • Operates at 95 – 100 °F (35 – 38 °C) • Most common for manure treatment • Hydraulic retention time: 10 – 30 d • Thermophilic • Operates at 125 – 140 °F (50 – 60 °C) • Hydraulic retention time: 6 h – 10 d

  17. Digester Operation • Feedstock composition • C:N ratio should be 8 – 25 • Most manure within acceptable range • If bedding or crop residue mixed with manure, C:N may be too high • pH 6.0-8.0, optimum 7.0

  18. Biogas Production • Composition • CH4 50-70 % typically 60 % • CO2 30-50 % typically 40 % • H2 0-2 % • H2S 100-7000 ppm • Energy content: 20 MJ/m3(540 Btu/SCF) • Biogas yield: 0.3-0.5 m3/kg VS (4.8-8.0 SCF/lb VS) • Production rate: 1-5 m3/m3(digester vol)·d

  19. Biogas Utilization • Heating on-site is most economical usage • may be applied to heat buildings for swine operation in colder climate • usually not enough heating demand in dairies • Generate electricity • may supply electrical energy for operation with some to sell back to grid • difficult to get utility company to accept • capital investment costly • Pipeline quality gas • must be scrubbed to remove CO2, H2S, NH3 and other impurities

More Related