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Long-term stability of two-stage aerobic granular sludge system for combined organic matter and nitrogen removal from aerobically digested centrate wastewater
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- Author / Creator
- Kong, Lu
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Nitrogen is an essential element for all living organisms and plays a key role in various biological processes. However, excessive nitrogen levels in the environment can lead to significant ecological issues, including water pollution and eutrophication, resulting in harmful algal blooms, oxygen depletion, and loss of aquatic life. Ammonia is the primary form of nitrogen compound in sewage and requires effective treatment in wastewater treatment plants. High ammonia and high chemical oxygen demand (COD) wastewater pose severe environmental threats, further exacerbating these issues. Effective and energy-efficient nitrogen removal technologies are essential to meet stringent discharge standards.
The overall objective of this thesis is to evaluate a two-stage moving bed biofilm reactor (MBBR) followed by an aerobic granular sludge (AGS) system developed to treat high COD and high ammonia biosolid autothermal thermophilic aerobic digestion (ATAD) centrate. The MBBR efficiently handled high organic loading rates (OLRs) exceeding 20 kg COD/m³/d and reduced the carbon to nitrogen (C/N) ratios from 6 to 3. Treated effluent was then processed in the AGS system, where nitrogen removal was primarily accomplished via the nitritation/denitritation pathway, with removal efficiencies reaching 98.9% for NH₄⁺-N and 91.7% for total inorganic nitrogen (TIN). After 200 days of operation, the AGS system had an optimized hydraulic retention time (HRT) of 10 hours and maintained a sludge volume index (SVI) between 40 to 80 mL/g, achieving a nitrogen treatment capacity of 1.77 kg N/m³/d. Ammonia oxidizing bacteria (AOB) demonstrated substantial nitrogen conversion efficiency, evidenced by nitrogen conversion rates of 0.57 ± 0.02 g N/g VSS/day and denitritation rates of 1.27 ± 0.01 g N/g VSS/day.
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- Subjects / Keywords
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- Graduation date
- Fall 2024
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- Type of Item
- Thesis
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- Degree
- Master of Science
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- License
- This thesis is made available by the University of Alberta Library 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.