Towards More Efficient and Economical Phosphorus and Bioenergy Recovery from Source-Diverted Blackwater

  • Author / Creator
    Sun, Huijuan
  • Decentralized source-diverted blackwater resource recovery represents an attractive wastewater management approach. Source-diverted blackwater refers to toilet wastewater, with or without kitchen wastewater, containing over half of the domestic biochemical oxygen demand (BOD) load and over 90% of PO4-P and NH4-N contents. Blackwater has strong buffering capacity as a result of high alkalinity and high pH close to 9. Without the addition of waste streams collected from laundry, washing, showering, and other household wastewaters (i.e., grey water), source-diverted blackwater, especially concentrated blackwater collected from low-flush vacuum toilet systems, is ideal for nutrient and energy recovery. In particular, phosphorus (P) recovery from blackwater helps relieve the dependence on phosphate rock reserves, which is becoming crucial for sustainable waste management in the context of both environment protection and future availability of P. Biogas recovery from blackwater represents a source of renewable energy, which helps increase energy security, reduce the reliance on non-renewable energy, and reduce greenhouse gas emission from non-renewable energy utilization.

    This thesis aims to evaluate, develop, and optimize biological and chemical processes to achieve enhanced P and biomethane recovery from source-diverted blackwater. Specifically, this thesis focuses on three aspects: (i) assessing and developing cost-effective and efficient P recovery from raw blackwater without chemical addition, (ii) evaluating and modelling the role of bioreactor microbiome on biomethane recovery from blackwater; and (iii) developing and optimizing bioreactors for simultaneous P and biomethane recovery from blackwater.

    This thesis successfully demonstrated the feasibility of P recovery through high-quality struvite precipitation from raw concentrated blackwater, which achieved >90% P recovery without any alkali addition. Operational conditions for blackwater biomethane recovery from upflow anaerobic sludge blanket (UASB) reactors were optimized, and the importance of low-abundance microorganisms in UASB reactors was demonstrated. Lastly, simultaneous P and biomethane recovery from source-diverted blackwater was demonstrated, and the mechanisms involved in P precipitation in bioreactors were clarified. Overall, this research developed and optimized blackwater P and biomethane recovery technologies and contributed to the development of more sustainable resource recovery-based wastewater management.

  • Subjects / Keywords
  • Graduation date
    Fall 2023
  • Type of Item
  • Degree
    Doctor of Philosophy
  • DOI
  • 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.