Combining continuous flow aerobic granulation using an external selector and carbon-efficient nutrient removal with...

Area of Science:

• Environmental Engineering
• Microbiology
• Wastewater Treatment

Background:

• The James R. Dolorio Water Reclamation Facility sought to optimize energy efficiency and nutrient removal.
• Traditional methods faced challenges in sludge settling and process intensification.

Purpose of the Study:

• To evaluate the effectiveness of AvN aeration controls and hydrocyclone-based wasting for improved wastewater treatment.
• To assess the impact on aeration energy, nutrient removal, and sludge settling characteristics (SVI).

Main Methods:

• Implementation of AvN aeration controls for low dissolved oxygen (DO) conditions.
• Utilized hydrocyclone-based wasting to selectively remove lighter microbial fractions.
• Conducted molecular analysis to identify microbial communities, including comammox.
• Performed ex-situ batch tests to identify denitrifying phosphorus-accumulating organisms (DPAO).

Main Results:

• Sludge Volume Index (SVI) improved from 200 ± 52 mL/g to 83 ± 22 mL/g.
• Aeration energy demand was reduced by 50% under low DO conditions (< 0.3 mgO2/L).
• Achieved excellent effluent nitrogen (TIN < 11 mgN/L) and phosphorus (TP < 1 mgP/L) removal.
• Demonstrated preferential retention of PAO and nitrifiers in dense aggregates.

Conclusions:

• AvN aeration controls and hydrocyclone-based wasting offer a carbon-efficient solution for nutrient removal and process intensification.
• Selective wasting uncoupled the sludge retention time (SRT) of different microbial populations, enhancing settling.
• The presence of comammox and DPAO likely contributed to the observed efficient biological nutrient removal.