Effect of pH on biological phosphorus uptake

Area of Science:

• Environmental Engineering
• Water Treatment Technologies

Background:

• Enhanced biological phosphorus removal (EBPR) is crucial for wastewater treatment.
• Sequencing batch reactors (SBRs) are widely used for EBPR.
• Understanding pH effects on EBPR is vital for optimizing treatment processes.

Purpose of the Study:

• To investigate the impact of pH on enhanced biological phosphorus removal in an anaerobic-aerobic SBR.
• To evaluate the simulation capabilities of ASM2d and BNRM1 for EBPR under varying pH conditions.

Main Methods:

• Operation of a laboratory-scale anaerobic-aerobic SBR under seven steady states.
• Monitoring of pH, phosphorus concentrations, and uptake rates.
• Simulation of experimental data using Activated Sludge Model No. 2d (ASM2d) and Biological Nutrient Removal Model No. 1 (BNRM1).

Main Results:

• A significant pH increase was observed during the aerobic phase due to phosphorus uptake and CO2 stripping.
• Phosphorus uptake rate decreased notably when pH exceeded 8.2-8.25.
• Both ASM2d and BNRM1 successfully characterized EBPR performance.
• BNRM1 accurately reproduced pH variations and the observed decrease in phosphorus uptake rate.

Conclusions:

• pH plays a critical role in the efficiency of enhanced biological phosphorus removal in SBRs.
• BNRM1 effectively models pH inhibition of polyphosphate storage, providing insights into EBPR limitations.
• ASM2d requires the inclusion of pH inhibition parameters to accurately simulate phosphorus evolution in A/O SBRs.