Comparative Effects of GAC Addition on Methane Productivity and Microbial Community in Mesophilic and Thermophilic Anaerobic Digestion of Food Wastes

• Author / Creator

  Ryue, John

• The abundance and potential of food wastes for high bio-methane potential has generated considerable interest in its application for anaerobic digestion (AD). The mechanism
  of direct interspecies electron transfer (DIET) was recently discovered which provided an
  alternative method of electron transfer and has been shown to greatly enhance methane
  production and improve kinetics. However, DIET-AD studies involving food waste are sorely
  lacking. Furthermore, DIET studies have typically operated in mesophilic conditions due to the
  intensive energy requirements at thermophilic conditions.
  In this study, the relative effects of granular activated carbon (GAC) addition (25 g/L)
  in anaerobic digestion of food waste at mesophilic (37°C) and thermophilic (55°C)
  temperatures were investigated using biochemical methane potential (BMP) test. The addition
  of GAC significantly reduced lag phases for methane production in comparison with the
  unamended control at both temperatures. Microbial community analyses revealed that GAC
  addition increased the diversity and richness of both bacterial and archaeal communities.
  Besides, several known or potential electroactive fermentative bacteria (e.g., Calorameter,
  Sporanaerobacter, Coprothermobacter, etc.) were found in GAC-amended bioreactors at both
  temperatures, suggesting the possibility of DIET-based syntrophy in these reactors. At
  mesophilic temperature, GAC amendment increased methane productivity (L CH4/kg-VS) by
  almost two-fold in comparison with the control; however, methane production at the
  thermophilic temperature was unaffected by GAC addition. These results indicate that
  enhanced process kinetics at thermophilic temperature might diminish the visible impact on
  methane productivity due to the addition of GAC.

• Subjects / Keywords

  • Anaerobic Digestion
  • Thermophilic
  • Bioenergy
  • Mesophilic
  • GAC
  • Direct Interspecies Electron Transfer

• Graduation date

  Fall 2019

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/r3-09se-zk59

• License

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