Cationic polymer-mediated interbacterial aggregation: A novel approach for rapid aerobic granules development

Area of Science:

• Environmental Science
• Biotechnology
• Chemical Engineering

Background:

• Aerobic granular sludge (AGS) technology is crucial for efficient wastewater treatment.
• Traditional AGS startup can be time-consuming and requires inoculated sludge.
• Developing rapid and stable AGS formation methods is essential for practical application.

Purpose of the Study:

• To introduce a novel method for seeding AGS reactors using cationic polymers, bypassing the need for inoculated sludge.
• To evaluate the efficacy of different cationic polymers (Hydrofloc C4400SA, C8896, polyelectrolyte emulsion) for AGS startup.
• To determine the optimal polymer dose for rapid and stable aerobic granule formation.

Main Methods:

• Three cationic polymers were tested as seeding agents in an AGS sequencing batch reactor (SBR).
• The optimal dose of the most effective polymer was identified.
• Granule formation, size, and stability were monitored over 80 days.
• Wastewater treatment performance (TP, TN, NH4-N, COD removal) was assessed during steady-state operation.

Main Results:

• Hydrofloc C4400SA significantly outperformed other tested polymers in promoting aerobic granule formation.
• Optimal granule development was achieved with 15 ppm of Hydrofloc C4400SA, forming dense granules within 10 days.
• Stable granules (0.6-0.9 mm) were observed after 80 days, with high removal efficiencies for pollutants (e.g., 97% NH4-N, 79% COD).

Conclusions:

• Cationic polymers, particularly Hydrofloc C4400SA, offer a viable and efficient method for seeding AGS reactors.
• This approach significantly reduces AGS startup time and ensures stable granule formation.
• The study highlights the potential of Hydrofloc C4400SA to improve the performance and resilience of AGS in wastewater treatment.