[Simultaneous Nitrification and Denitrifying Phosphorus Removal in Continuous Flow Reactor with Intermittent...

Area of Science:

• Environmental Engineering
• Wastewater Treatment Technologies
• Microbial Ecology

Background:

• Domestic sewage treatment faces challenges in efficiently removing nitrogen and phosphorus.
• Optimizing reactor configurations and aeration strategies is crucial for enhancing treatment performance.
• Understanding microbial community dynamics, like denitrifying phosphorus accumulating organisms (DPAOs) and phosphorus accumulating organisms (PAOs), is key to effective biological nutrient removal.

Purpose of the Study:

• To investigate the impact of varying aeration strategies and compartment configurations in a ten-compartment continuous flow reactor (TCFR) for domestic sewage treatment.
• To optimize the TCFR for simultaneous nitrification and denitrifying phosphorus removal.
• To evaluate the efficiency of nitrogen and phosphorus removal and the activity of key microbial groups under different operational conditions.

Main Methods:

• A ten-compartment continuous flow reactor (TCFR) was employed, with adjustments to anaerobic, anoxic, and aerobic compartment numbers.
• Aeration strategies were varied from continual to intermittent aeration with specific aeration/non-aeration ratios (40 min/20 min, 40 min/30 min, 40 min/40 min).
• Nitrification liquid reflux ratios were progressively reduced from 150% to 0% to assess their impact on treatment efficiency.

Main Results:

• The optimized TCFR configuration with intermittent aeration achieved high removal efficiencies: COD (90%), NH4+-N (98.4%), TN (90.7%), and PO43--P (95.1%).
• Nitrogen removal rates increased from 192.30 mg·h−1 (65.40%) to 244.00 mg·h−1 (95.30%) with optimized conditions.
• The activity of denitrifying phosphorus accumulating organisms (DPAOs) and phosphorus accumulating organisms (PAOs) significantly increased from 36.05% and 38.20% to 140.50% and 133.40%, respectively.

Conclusions:

• Intermittent aeration in a modified TCFR effectively facilitates simultaneous nitrification and denitrifying phosphorus removal from domestic sewage.
• The study provides a viable operational strategy for upgrading existing sewage treatment plants for enhanced nutrient removal.
• Optimized reactor operation significantly boosts nitrogen and phosphorus removal efficiency and enhances the activity of key microbial communities.