Exploring the potential of anaerobic sulfate reduction process in treating sulfonated diazo dye: Microbial community...

Area of Science:

• Environmental microbiology
• Biotechnology
• Wastewater treatment

Background:

• Azo dyes are widely used in textile industries, posing environmental pollution challenges.
• Anaerobic biodegradation offers a promising approach for azo dye removal.

Purpose of the Study:

• To investigate the anaerobic decolorization and biotransformation of azo dye using sulfate-reducing bacteria (SRBs).
• To understand the role of oxidoreductive enzymes in dye metabolism under anoxic conditions.
• To analyze bacterial diversity and identify key SRBs involved in dye degradation.

Main Methods:

• Batch reactor studies with mixed anaerobic SRB cultures.
• Analysis of enzyme activities (phenol oxidase, veratryl alcohol oxidase, lignin peroxidase, azo reductase).
• High-performance liquid chromatography (HPLC) and gas chromatography-mass spectrometry (GC-MS) for dye degradation confirmation.
• Barcoded 16S rRNA gene pyrosequencing for bacterial diversity assessment.

Main Results:

• Complete removal of sulfate and color was achieved at various initial dye concentrations (50-2500 mg/L) with 1000 mg/L sulfate.
• Enzyme activities were induced, indicating their involvement in dye metabolism.
• Cotton Red B degradation was confirmed, yielding aniline and 1,4-diamino benzene as metabolites.
• Bacterial diversity analysis revealed specific SRBs responsible for dye degradation.

Conclusions:

• Sulfidogenic sludge exhibits significant potential for azo dye degradation and mineralization.
• SRBs play a crucial role in the anaerobic biotransformation of azo dyes.
• This study provides insights into microbial mechanisms for azo dye removal in sulfate-reducing environments.