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Novel phased isolation ditch system for enhanced nutrient removal and its optimal operating strategy
K i-Ho Hong1, Duk Chang, Joon-Moo Hur
1Department of Environmental Engineering, College of Engineering, Konkuk University, Seoul, Korea.
Summary
A novel phased isolation ditch system simplifies wastewater treatment by removing nitrogen and phosphorus without external clarifiers or sludge recycling. This innovative approach achieves high pollutant removal rates, offering an efficient solution for municipal wastewater management.
Area of Science:
- Environmental Engineering
- Water Treatment Technologies
- Wastewater Management
Background:
- Conventional wastewater treatment often requires complex configurations for simultaneous nitrogen and phosphorus removal.
- Existing methods may involve external clarifiers, pre-anaerobic reactors, and sludge/effluent recycling, increasing operational costs and complexity.
- There is a need for simplified, efficient systems for enhanced biological nutrient removal from municipal wastewater.
Purpose of the Study:
- To evaluate a novel, simplified phased isolation ditch system with an intrachannel clarifier for simultaneous biological nitrogen and phosphorus removal.
- To investigate the impact of operating parameters like hydraulic retention time (HRT), solids retention time (SRT), and cycle time on system performance.
- To determine optimal operating strategies for maximizing nutrient removal efficiency in municipal wastewater treatment.
Main Methods:
- A pilot-scale phased isolation ditch system with an intrachannel clarifier was designed and operated.
- The system eliminated the need for external final clarifiers, pre-anaerobic reactors, and sludge/nitrified effluent recycle.
- Alternating flow and intermittent aeration were employed to achieve anoxic, anaerobic, and aerobic phase separation within the ditches.
Main Results:
- The system achieved high removal efficiencies: 88-97% for BOD, 70-84% for TN, and 65-90% for TP at mixed liquor temperatures above 10°C.
- Longer SRTs significantly decreased effluent TN but increased effluent TP, while shorter cycle times favored nitrogen removal and longer cycle times improved phosphorus removal.
- Optimal performance was achieved with HRTs of 10-14 h, SRTs of 25-30 days, and a cycle time of 4 h.
Conclusions:
- The simplified phased isolation ditch system effectively achieves complete phase separation for enhanced biological nutrient removal without complex configurations.
- Temporal phase separation for phosphorus release was successfully achieved during the anaerobic period without nitrate interference or carbon limitation.
- This novel system offers a promising, simplified, and efficient approach for simultaneous nitrogen and phosphorus removal in municipal wastewater treatment.