Rapid algae removal with minimized cell rupture coupled with phosphorus mitigation via electrocoagulation-flotation

Area of Science:

• Environmental Science
• Water Treatment Engineering
• Analytical Chemistry

Background:

• Harmful algal blooms (HABs) pose significant environmental and health risks.
• Conventional methods struggle with simultaneous algal biomass separation and nutrient removal, often causing secondary pollution.

Purpose of the Study:

• To develop an efficient dual-aluminum electrocoagulation-flotation (ECF) process for HABs.
• To achieve simultaneous cyanobacteria separation and dissolved total phosphorus (DTP) immobilization.
• To minimize algal cell rupture during removal.

Main Methods:

• Utilized a dual-aluminum ECF system with in situ coagulant generation and microbubble flotation.
• Optimized parameters including current density, electrode spacing, and pH.
• Evaluated algal removal, DTP elimination, and cell integrity using various analytical techniques.

Main Results:

• Achieved near-complete algal removal (>99%) and DTP elimination within 20 minutes under optimal conditions.
• Demonstrated minimal algal cell rupture, confirmed by low extracellular potassium ion release and MC-LR measurements.
• Identified Al (hydr)oxide flocs (boehmite-like phases) and microbubbles as key to efficient charge neutralization and phosphorus immobilization.

Conclusions:

• The dual-Al ECF process offers an effective strategy for rapid HABs removal and phosphorus mitigation.
• The method significantly reduces the risk of secondary pollution by minimizing cell lysis.
• The process is cost-effective with an estimated direct operating cost of $0.118/m³.