Rainwater system

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Effect of operating conditions and reactor
configuration on efficiency of full-scale biogas
plants
Irini Angelidaki, Kanokwan Boe and Lars Ellegaard
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Presentation content

• Biogas in Denmark A typical Centralized Biogas
  Plant
• Main Results of the investigation
• Conclusions

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Location of Centralized biogas plants in Denmark
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Typical centralized biogas plant
Ribe biogas plant
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Full-scale investigation

• Process stability
• Process efficiency
• Microbiology

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Potential methods to improve recovery efficiency
from manure

• Increase stabilily of the digestion process
• Pre-treatment of incoming substrate (to increase
  degradability)
• Increase retention time of the manure reactor(s)
• Arrange post-digestion systems (to increase
  degradation efficiency)

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Stability in Danish Biogas Plants
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Correlation between ammonia and VFA.
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Residual methane production
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Residual methane production
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Residual methane production
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Restgastab i forhold til total produktion
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Temperature and residual methane
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Distribution of the total methane potential
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Main reactor residual methane loss versus
retention time
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Temperature effect on residual biogas potential
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INCREASING TEMPERATURE
Samples previously incubated at 10? -15?C for a
long period have been moved to process
temperature (37?-54?C)
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INNOVATIVE SOLUTIONS

• SITUATION
• The majority of the biogas plants have Reactors
  with good efficiency
• Many plants are loosing a lot and the gap between
  the theoretical and the practical potential is
  still wide

MAIN OBSTACLE hydrolysis is the real rate
limiting step for the further methanogenesis ?
increase HRT to provide a better substrate
hydrolysis
SOLUTIONS
TRADITIONAL SOLUTIONS
Increase the HRT in main reactor
INNOVATIVE SOLUTIONS
New process configurataion Utilization of the
After-Storage.
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Conclusions

• Significant amounts of CH4 are lost (5-30)
• Plants with HRTlt 15 days are lossing more CH4
  from the main reactor
• Post-digestion is highly influenced by the
  temperature
• Post-digestion at low temperature are increasing
  the total methane potential of the material
• Manure-plants are dominated by Methanosarcina,
  while sludge plants by Methanosaeta.

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Acknowledgements

• The study was funded by the Danish Energy
  Agency,Development of Renewable Energy
• The operational staff of the Biogas Plants
  participating in the investigation is greatly
  acknowledged
• Researchers
• Kanokwan Boe
• Lars Ellegaard
• Dimitar Karakshlev
• Damien Batstone
• Irini Angelidaki
• Students
• Simone Labo
• Lucía Fernández García
• Eva Arler
• He Zhen
• Chao Pan
• Troels Hilstrøm
• Søren H. Laursen