Harvesting of microalgae cell using oxidized dye wastewater

Area of Science:

• Environmental Science
• Biotechnology
• Chemical Engineering

Background:

• Microalgae harvesting is crucial for biofuel and bioproduct applications.
• Current harvesting methods can be energy-intensive and costly.
• Wastewater utilization presents an opportunity for sustainable resource management.

Purpose of the Study:

• To investigate the potential of oxidized dye wastewater as a low-cost coagulant for microalgae harvesting.
• To determine optimal oxidation conditions for dye wastewater to maximize its coagulant efficacy.
• To explore the mechanism behind the coagulant properties of oxidized dyes.

Main Methods:

• Selected methylene blue (MB) and methyl orange (MO) as model dyes.
• Applied a Fenton-like reaction at 90 °C for 1 minute for dye oxidation.
• Tested oxidized dye wastewater at various dilution ratios with microalgae cultures.
• Optimized coagulant dosage, dye concentration, and oxidant concentrations (FeCl3, H2O2).

Main Results:

• Achieved over 90% microalgae harvesting efficiency using both oxidized MB and MO.
• Optimal harvesting occurred at a 5:1 dilution ratio (dye wastewater: cell culture).
• Optimal oxidation conditions involved 20 mg/L dye, 1 mM FeCl3, and 0.5% H2O2.
• Oxidized dyes demonstrated coagulant properties, potentially due to exposed amine groups.

Conclusions:

• Properly oxidized dye wastewater can serve as an effective and inexpensive coagulant for microalgae harvesting.
• This approach offers a sustainable method for wastewater valorization.
• Significant cost reduction in microalgae harvesting is achievable using this technique.