The Impact of Semi-continuous and Alternating Microbial Feeding Patterns on Methane Yield from UASB Reactors

• Author / Creator

  Yuan, Yiyang

• The anaerobic treatment of wastewater is considered a promising technology for simultaneous organic matter removal and energy recovery. Compared to aerobic digestion, anaerobic digestion conserves energy and is cost-effective in handling high-strength wastewater and wastes. However, the high sensitivity of anaerobic systems to operational conditions such as temperature, pH, mixing conditions and feeding regimes has limited their application. In particular, feeding patterns have been shown to significantly impact the reactor operations, while a flexible feeding regime is commonly needed when treating the unequalized feedstock. To date, our understanding of the impact of bioreactor feeding strategies on anaerobic bioreactor performance is still limited.
  The overall objective of this thesis is to evaluate the impact of various feeding strategies on the development of robust microbial communities in bioreactors and the anaerobic bioreactor treatment performance. Three feeding strategies, including continuous, semi-continuous (with starvation-feast cycle), and alternate feeding (with high loading-low loading cycle), were compared in this study to assess anaerobic digestion of synthetic wastewater and methane yields using three continuously operating laboratory-scale up-flow anaerobic sludge blanket (UASB) reactors. Observation of this study revealed that both long and short starvation-feast cycles provided by semi-continuous feeding did not sustain stable anaerobic digestion, whereas alternate feeding with high and low loading cycles promoted microbial community development. With dominant methanogens shifted from Methanosaeta in the continuous reactor to Methanosarcina in semi-continuous feeding reactors, significantly higher methanogenic activities were observed once reactors were recovered. Interestingly, the reactor undergoing the alternate feeding mode successfully maintained a stable operation and thus the alternate feeding pattern is preferred over semi-continuous feeding when reactor feeding is not continuously and consistently available.

• Subjects / Keywords

  • Anaerobic digestion
  • Feeding patterns
  • Methane yield
  • UASB

• Graduation date

  Spring 2023

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/r3-eq9t-fp65

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.