A novel method to harvest Chlorella sp. by co-flocculation/air flotation

Area of Science:

• Biotechnology
• Environmental Engineering
• Aquaculture

Background:

• Microalgae biomass harvesting is crucial for biofuel and bioproduct applications.
• Dissolved air flotation (DAF) is a common method, but its efficiency can be improved.

Purpose of the Study:

• To develop and evaluate a more effective co-flocculation/air flotation (CAF) system for harvesting microalgae.
• To optimize micro-bubble generation and flocculation for enhanced Chlorella sp. biomass recovery.

Main Methods:

• A CAF system integrating an ejector for micro-bubble generation and a helix tube flocculation reactor (HTFR) was designed.
• Optimized operating conditions for the ejector (flow ratio 0.14) and HTFR (reaction time 24 s) were determined.

Main Results:

• The optimized system achieved 96% air release efficiency and produced micro-bubbles with optimal size distribution.
• The CAF process resulted in a high harvesting efficiency of 94% for Chlorella sp. biomass.
• Aerated flocs exhibited a fast rising velocity of 96 m/h.

Conclusions:

• Micro-bubbles can be effectively encapsulated within microalgae flocs, enhancing floc stability in the CAF process.
• The developed CAF system is a highly effective approach for microalgae biomass harvesting.