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Published on: September 26, 2016
Anaerobic/oxic/anoxic granular sludge process as an effective nutrient removal process utilizing denitrifying
Naohiro Kishida1, Juhyun Kim, Satoshi Tsuneda
1Department of Chemical Engineering, Waseda University, 3-4-1 Ohkubo, Tokyo 169-8555, Japan.
Water Research
|June 13, 2006
Summary
The anaerobic/oxic/anoxic granular sludge (AOAGS) process effectively removes nitrogen and phosphorus using denitrifying polyphosphate-accumulating organisms (DNPAOs). This biological nutrient removal process cultivates DNPAOs within granular sludge, achieving near-complete nutrient removal.
Area of Science:
- Environmental Science
- Environmental Engineering
- Microbiology
Background:
- Biological nutrient removal (BNR) processes benefit from denitrifying polyphosphate-accumulating organisms (DNPAOs) due to efficient organic carbon substrate use and low sludge production.
- Cultivating DNPAOs alongside nitrifying bacteria in a single reactor presents a challenge in conventional BNR systems.
Purpose of the Study:
- To propose and evaluate the anaerobic/oxic/anoxic granular sludge (AOAGS) process for effective biological nutrient removal.
- To investigate the feasibility of co-cultivating DNPAOs and nitrifying bacteria within granular sludge.
- To assess the nutrient removal efficiency and microbial community structure in the AOAGS process.
Main Methods:
- A laboratory-scale sequencing batch reactor was operated under anaerobic/oxic/anoxic cycles using acetate-based synthetic wastewater.
- Granular sludge formation and characteristics were monitored.
- Microsensor measurements determined oxygen penetration depth, and fluorescence in situ hybridization analyzed microbial community structure.
Main Results:
- Successfully formed granular sludge (500 µm diameter) within 1 month.
- Achieved near-complete removal of nitrogen (NH4-N, NOx-N) and phosphorus (PO4-P) (<1 mg/L effluent concentrations).
- DNPAOs were found to exist deeper within the granular sludge than the oxygen penetration depth, suggesting their role in denitrification within the oxic phase.
Conclusions:
- The AOAGS process is a viable method for cultivating DNPAOs and nitrifying bacteria simultaneously.
- The internal anoxic zones within granular sludge and the post-oxic anoxic phase facilitate effective nutrient removal.
- DNPAOs contribute to denitrification in the oxic phase, enhancing overall nutrient removal efficiency in the AOAGS process.
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