Granular activated carbon sparking anaerobic digestion: the path to municipal sewage resource recovery

• Author / Creator

  Zhang, Yingdi

• Anaerobic digestion (AD) is an effective and economical technology that can convert organic pollutants to biomethane, playing a pivotal role in resource recovery and greenhouse gas emission control. However, the anaerobic treatment of municipal sewage under psychrophilic conditions faces significant challenges. The overall goal of this research is to investigate, develop, and optimize carbon-based materials (CBMs) amended AD of municipal sewage under psychrophilic conditions for biomethane recovery. This research deepens understanding of fundamental anaerobic processes, improves AD technology effectiveness, and contributes to implementing a circular economy.
  CBMs, such as granular activated carbon (GAC), have been shown to promote direct interspecies electron transfer (DIET) in anaerobic co-culture experiments; however, their roles in continuous feeding AD with mixed cultures remain unknown. This Ph.D. research thoroughly explored the roles of GAC in laboratory-scale up-flow anaerobic sludge blankets (UASBs) treating municipal sewage, focusing on alteration of electron transfer, biosynthesis of growth factors (e.g., amino acids and vitamins), impacts of sulfate concentrations, as well as microbiome developments and physiological changes. Over the past four and a half years, 14 bioreactors were operated. Experiments were performed at both University of Alberta laboratories and in the field of a full-scale municipal wastewater treatment plant. Under all operation conditions, it was observed that GAC addition could significantly enhance AD reactor performance, methanogenic activities and effectiveness in vital syntrophic partnerships.
  This thesis led to several innovations. In particular, this study is the first to operate continuous GAC-amended UASB for municipal sewage treatment under psychrophilic conditions, focusing on the development of an electro-active microbiome. More importantly, this study fully demonstrates (i) the shift of electron transfer pathway with GAC addition in continuous feeding AD by a range of methods, (ii) the roles of GAC in stimulating the biosynthesis of growth factors and their positive impacts on microbiome development and reactor performance, (iii) the impacts of GAC addition on microbiome resistance to H2S toxicity and sulfate reduction activities.
  The results of this thesis provide insights into the changes in microbial communities, physiologies, and metabolites with GAC addition, and demonstrate that GAC addition is a feasible approach to enhance the AD performance of municipal sewage under psychrophilic conditions. This research deepens our understanding of the roles of CBMs in AD and provides significant guidance both in theory and practice.

• Subjects / Keywords

  • Granular activated carbon
  • Anaerobic digestion
  • Municipal sewage
  • DIET

• Graduation date

  Spring 2023

• Type of Item

  Thesis

• Degree

  Doctor of Philosophy

• DOI

  https://doi.org/10.7939/r3-1dz9-f877

• 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.