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Nitrogen control in AO process with recirculation of solubilized excess sludge
1Department of Environmental Engineering and Biotechnology, Myongji University, San 38-2, Namdong, Yongin, Kyonggido 449-728, South Korea.
Water Research
|February 21, 2004
Summary
Ozonized sludge (OS) can serve as an energy source for denitrification, but it also releases nitrogen, making it insufficient to fully process all nitrogen compounds in wastewater treatment.
Area of Science:
- Environmental Engineering
- Water Treatment
- Wastewater Management
Background:
- Conventional wastewater treatment generates significant sludge.
- Sludge disposal is costly and environmentally challenging.
- Developing sludge-free processes is a key goal in wastewater management.
Purpose of the Study:
- To investigate the potential of using ozonized sludge (OS) as a carbon source for denitrification.
- To evaluate OS as a sustainable energy source in an anoxic-oxic (AO) wastewater treatment process.
- To assess the nitrogen balance and efficiency of OS in a sludgeless process.
Main Methods:
- Laboratory-scale batch and continuous experiments using an anoxic-oxic (AO) process.
- Ozonation of excess activated sludge at a specific ozone dose (1.2g O(3)/g MLVSS).
- Analysis of solubilized organic matter, chemical oxygen demand (COD), total nitrogen (TN), and nitrogen species during incubation.
Main Results:
- Ozonation solubilized 63.2% of MLVSS and reduced COD by 12.7%.
- OS supernatant provided a carbon source for denitrification, consuming 24-41% of its COD.
- Ammonia accumulation occurred during both oxic and anoxic incubation, indicating OS is also a nitrogen source.
Conclusions:
- Ozonized sludge can act as both a reducing power and a nitrogen source in wastewater treatment.
- The carbon content in OS is insufficient to completely remove all nitrogen originating from the sludge itself.
- Further optimization is needed to achieve a truly sludgeless process with complete nitrogen removal.