[Optimization of Denitrifying Phosphorus Removal Performance Based on ABR-MBR Combined Process]

Area of Science:

• Environmental Engineering
• Wastewater Treatment Technologies
• Bioreactor Systems

Background:

• Domestic sewage often presents challenges with low C/N ratios, hindering effective nutrient removal.
• Conventional treatment methods struggle with simultaneous nitrogen and phosphorus removal, especially under low carbon conditions.
• Integrated bioreactor systems offer potential for enhanced pollutant removal efficiency.

Purpose of the Study:

• To optimize an integrated anaerobic baffled reactor (ABR) and membrane bioreactor (MBR) system for efficient denitrifying phosphorus removal from domestic sewage with a low C/N ratio.
• To determine optimal operating parameters, including nitrate and sludge recycling ratios, for enhanced nutrient removal.
• To evaluate the performance of the ABR-MBR system in terms of total nitrogen (TN) and soluble phosphate (PO43-) removal.

Main Methods:

• An integrated anaerobic baffled reactor (ABR) and membrane bioreactor (MBR) system was employed for domestic sewage treatment.
• Key operational parameters were optimized, including organic loading rate, hydraulic retention time (HRT), sludge retention time (SRT), sludge reflux ratio, and nitrate recycling ratio.
• System performance was monitored by measuring removal rates of TN and soluble PO43-P, and effluent concentrations.

Main Results:

• Optimized denitrifying phosphorus removal was achieved at an ABR organic loading rate of 2.0 kg·(m3·d)−1, total HRT of 9 h, SRT of 15 d, 100% sludge reflux ratio, and 300% nitrate recycling ratio.
• Average removal rates for TN and soluble PO43-P reached 84% and 94%, respectively.
• Denitrifying phosphorus removal accounted for 87% of total phosphorus removal, with average effluent concentrations of 12.98 mg·L−1 for TN and 0.43 mg·L−1 for soluble phosphorus.

Conclusions:

• The integrated ABR-MBR system, with optimized operating conditions, is highly effective for simultaneous denitrifying phosphorus removal from low C/N ratio domestic sewage.
• Optimized nitrate and sludge recycling ratios are critical for maximizing the efficiency of this integrated wastewater treatment process.
• The system demonstrates significant potential for achieving stringent effluent standards for nitrogen and phosphorus.