Making waves: Riding the densification wave from current understanding to advancement

Area of Science:

• Environmental Engineering
• Wastewater Treatment Technologies
• Biotechnology

Background:

• Continuous-flow (CF) water resource recovery facilities face limitations in treatment capacity.
• Aerobic granular sludge (AGS) systems offer benefits but typically require larger particle sizes.
• There is a need for cost-effective intensification strategies in existing CF facilities.

Purpose of the Study:

• To introduce and evaluate densification as a novel intensification strategy for CF water treatment.
• To explore the coupling of biological and physical selection for granule promotion and retention.
• To investigate the potential for improved sludge settling, nutrient removal, and energy efficiency.

Main Methods:

• Implementation of densification strategy in full-scale CF facilities.
• Integration of biological selection principles (selector design, AGS concepts) with physical selection (hydrocyclones).
• Monitoring of sludge volume index (SVI), particle sizes, and granule fractions.

Main Results:

• Densification promotes the growth and retention of granules at smaller particle sizes compared to typical AGS.
• The strategy leads to a lower sludge volume index (SVI), indicating superior sludge settling.
• Potential for optimized nutrient removal and energy efficiency in low dissolved oxygen conditions.

Conclusions:

• Densification is a promising strategy for enhancing CF water treatment capacity cost-effectively.
• The combination of biological and physical selection is effective in granule formation and retention.
• Further advancements in hydrocyclone design, selector zones, and operational guidelines are key for wider implementation.