Decolorization of azo dye using PVA-immobilized microorganisms

Area of Science:

• Environmental Microbiology
• Biotechnology
• Wastewater Treatment

Background:

• Azo dyes are widely used in industries but pose environmental challenges due to their persistence.
• Developing efficient and stable methods for azo dye decolorization is crucial for environmental protection.

Purpose of the Study:

• To immobilize a microbial consortium for enhanced azo dye decolorization.
• To evaluate the performance of immobilized cells in continuous operation.
• To investigate the decolorization mechanism and economic feasibility.

Main Methods:

• Immobilization of a microbial consortium using phosphorylated polyvinyl alcohol (PVA) gel.
• Flask culture and continuous operation experiments to assess decolorization efficiency.
• Analysis of decolorization mechanism and microbial composition.
• Evaluation of alternative nitrogen sources for cost-effectiveness.

Main Results:

• Immobilized-cell beads achieved 75% RED RBN decolorization within 12 h at 500 mg l(-1).
• Continuous operation exceeded 90% removal efficiency at hydraulic retention times (HRT) > 10 h.
• The system demonstrated stability over 6 months of operation.
• Decolorization occurred via biological degradation and partial adsorption.

Conclusions:

• Phosphorylated PVA gel immobilization enhances microbial decolorization of azo dyes.
• The immobilized system is effective and stable for continuous wastewater treatment.
• Biological decolorization coupled with adsorption is the primary mechanism.
• Further economic optimization using alternative nitrogen sources is feasible.