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[Nitrite Type Denitrifying Phosphorus Removal Capacity of Cycle Activated Sludge Technology Processes Under Different
Juan Ma1, Jin Wang1, Xiao-Jun Yu1
1School of Environmental and Municipal Engineering, Lanzhou Jiaotong University, Lanzhou 730070, China.
Huan Jing Ke Xue= Huanjing Kexue
|July 3, 2018
Summary
Nitrite addition in cyclic activated sludge technology (CAST) reactors can inhibit denitrifying phosphorus removal, especially under anoxic conditions. However, aerobic nitrite addition can enhance phosphorus removal and sludge reduction over time.
Area of Science:
- Environmental Engineering
- Wastewater Treatment
- Microbial Ecology
Background:
- Cyclic activated sludge technology (CAST) reactors are employed for nutrient removal in wastewater treatment.
- Investigating the impact of different nitrite (NO2-) inducing patterns on CAST reactor performance is crucial for optimizing nutrient removal efficiency.
- Understanding the mechanisms of phosphorus and nitrogen removal under varying conditions is essential for effective wastewater management.
Purpose of the Study:
- To evaluate the phosphorus and nitrogen removal performance of a modified CAST reactor under different nitrite addition strategies.
- To determine the optimal conditions for nitrite addition to enhance denitrifying phosphorus removal and sludge reduction.
- To assess the long-term effects of nitrite addition on the microbial community, specifically denitrifying phosphorus accumulating bacteria (DPAB).
Main Methods:
- Utilized a modified cyclic activated sludge technology (CAST) reactor.
- Investigated different nitrite addition patterns (anoxic vs. aerobic) and dosages (5-20 mg·L-1).
- Monitored effluent phosphorus and nitrogen concentrations, phosphorus removal rates, and sludge settling performance.
Main Results:
- Anoxic nitrite addition showed a more inhibitory effect on denitrifying phosphorus removal compared to aerobic addition.
- Aerobic nitrite addition led to stable phosphorus removal rates exceeding 95% after acclimatization, with effluent phosphorus <0.5 mg·L-1.
- High nitrite dosage (20 mg·L-1) drastically deteriorated performance, but long-term aerobic addition enriched DPAB, increasing uptake capacity 10.4-fold and improving sludge settling and reduction.
Conclusions:
- Aerobic nitrite addition in CAST reactors is more stable and effective for phosphorus removal than anoxic addition.
- While high nitrite concentrations can be inhibitory, long-term aerobic addition promotes the enrichment of DPAB, enhancing phosphorus removal and sludge reduction.
- Optimized nitrite addition strategies can improve the efficiency and stability of nutrient removal in wastewater treatment.
Keywords:
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